Patent Publication Number: US-7722678-B2

Title: Intramedullary compliant fixation

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Ser. No. 11/326,561, filed Jan. 5, 2006, now U.S. Pat. No. 7,476,254, which is a continuation-in-part of U.S. Ser. No. 10/797,692, filed Mar. 9, 2004, now U.S. Pat. No. 7,141,073, which is a continuation-in-part of U.S. Ser. No. 10/305,620, filed Nov. 17, 2002, now U.S. Pat. No. 6,712,855, which is a continuation of U.S. Ser. No. 09/776,584, filed Feb. 2, 2001, now U.S. Pat. No. 6,508,841, which is a continuation of U.S. Ser. No. 09/003,061, filed Jan. 5, 1998, now U.S. Pat. No. 6,197,065, which is a continuation-in-part of U.S. Ser. No. 08/535,532, filed Sep. 28, 1995, now abandoned, which is a continuation-in-part of U.S. Ser. No. 08/146,510, filed Nov. 1, 1993, now abandoned. The disclosures of the above applications are incorporated herein by reference. 
    
    
     INTRODUCTION 
     Various known external fixation devices for amputation or trauma include compliant mechanisms for holding a prosthesis against a planar surface of the bone. In devices of this type, the compliant fixation mechanism provides a compressive stress at the bone interface for preventing bone resorption over time. Typically, a metal portion of the fixation device may extend beyond the cut surface of the bone, such that soft tissue is attached to the metal, rather than the bone. 
     Although the known compliant fixation devices can be satisfactory for their intended purposes, intramedullary compliant fixation devices and associated methods that allow soft tissue attachment to bone, rather than metal, are desirable. 
     SUMMARY OF THE INVENTION 
     The present teachings provide an intramedullary fixation device. The intramedullary fixation device includes a first intramedullary component having a first bone-attachment end and a first elongated member, a second intramedullary component having a second bone-attachment end and a second elongated member, and a compliant member coupling the first and second intramedullary components for applying bone-compressing stress. The second intramedullary component defines a sleeve such that the first elongated member can pass therethrough. 
     The present teachings provide a method for intramedullary bone fixation. The method includes inserting first and second intramedullary components into a medullary canal defined by a bone, coupling the first and second intramedullary components with a compliant member, attaching the first and second intramedullary components to spaced apart first and second attachment sites of the bone, and enabling the compliant member to transmit compressive stress on the bone. 
     The present teachings also provide an intramedullary fixation device that includes a first intramedullary component at least partially configured telescopically relative to a second intramedullary component, and a compliant member coupling the first and second intramedullary components for applying bone-compressing stress. 
     Additional objects, advantages, and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various advantages of the present invention will become apparent from the following specification and appended claims by reference to the following drawings in which: 
         FIG. 1  is a partial cut-away view illustrating the environment of the device of the present invention in connection with a remaining bone portion following resection; 
         FIG. 2  is an enlarged cross-sectional view illustrating a bone attachment device as it is secured within a remaining bone portion following resection; 
         FIG. 3  is a cross-sectional view illustrating one embodiment of an anchor body secured within a cavity of remaining bone portion; 
         FIG. 4  is a cross-sectional view illustrating the upper compliant portion of the bone attachment device of the present invention; 
         FIG. 5  is a top view illustrating a portion of the device shown in  FIG. 4 , taken from the perspective  5 - 5  in  FIG. 4 ; 
         FIG. 6  is a bottom view illustrating the compliant section of the bone attachment device of the present invention, taken from a perspective  6 - 6  in  FIG. 4 ; 
         FIG. 7  is a cross-sectional view illustrating a bone attachment assembly of the present invention which includes fluid sealing means for reducing access of wear particles; 
         FIG. 8  is a perspective view illustrating a guide device for creating one or more apertures within a remaining bone portion for accepting one or more engagement means; 
         FIG. 9  is a side view illustrating a self-centering drill bit of the present invention; 
         FIG. 10  is a partial cut-away view illustrating a milling device used for milling the osteotomy surface in a preselected geometry; 
         FIG. 11  is a partial cut-away view illustrating a milling device used for milling the osteotomy surface in a preselected geometry; 
         FIG. 12  is a cross-sectional view illustrating a bone attachment device in conjunction with an orthopedic appliance; 
         FIG. 13  is a cross-sectional view illustrating a percutaneous bar connected to a device of the present invention; 
         FIG. 14  is a perspective view illustrating a reaming device of the present invention; 
         FIG. 15  is an elevational view with partial breakaway illustrating the environment of a second embodiment of the bone attachment assembly of the present invention in an implanted condition in connection with a remaining bone portion following resection; 
         FIG. 16  is an elevational view with partial breakaway illustrating a second embodiment of bone attachment assembly of the present invention, prior to preloading the assembly; 
         FIG. 17  is an elevational view with partial breakaway illustrating the bone attachment assembly shown in  FIG. 16 , during preloading of the assembly; 
         FIG. 18  is an elevational view with partial breakaway illustrating the environment of a second embodiment of the bone attachment assembly of the present invention from a perspective 90□ removed from that shown in  FIGS. 15 through 17 , in a preloaded implanted condition in connection with a proximal femur prosthesis; 
         FIG. 19  is an elevational view with partial breakaway illustrating another version of a second embodiment of the bone attachment assembly of the present invention, prior to preloading; 
         FIG. 20  is an end view illustrating the bone attachment assembly shown in  FIG. 19 ; 
         FIG. 21  is an elevational view with partial breakaway illustrating the bone attachment assembly shown in  FIGS. 19 and 20  in a preloaded condition; 
         FIG. 22  is a side cross-sectional view illustrating the version of the second embodiment of the bone attachment assembly of the present invention shown in  FIGS. 19 through 21  in an implanted condition in connection with a primary hip prosthesis; 
         FIG. 23  is a side elevational view illustrating the bone attachment assembly of the present invention shown in  FIG. 22  from a perspective 90□ removed from that shown in  FIG. 22 ; 
         FIG. 24  is an elevational view illustrating another version of the second embodiment of the present invention; 
         FIG. 25  is a top view of the version of apparatus shown in  FIG. 24 ; 
         FIG. 26  is an elevational view in partial breakaway illustrating another version of the second embodiment of bone attachment assembly of the present invention, in modular form; 
         FIG. 27  is an elevational view illustrating a first version of a third embodiment of bone attachment assembly of the present invention, including a main body and an anchor body with integral compliant section, in exploded form; 
         FIG. 28  is a top view illustrating the main body component of the bone attachment assembly shown in  FIG. 27 ; 
         FIG. 29  is a side view of an anchor body with integral compliant section, from an angle 90 degrees removed from the angle shown in  FIG. 27 ; 
         FIG. 30  is a partial cross-sectional view illustrating insertion of a compliant section of the bone attachment assembly within a sleeve formed as part of the main body shown in  FIG. 27 ; 
         FIG. 31  is a partial cross-sectional view illustrating a main body with integral sleeve and anchor body with integral compliant section, disposed upon and within a remaining bone portion, with the anchor body secured to the surrounding bone cortex prior to the application of traction to the compliant section; 
         FIG. 32  is an elevational view in exploded form illustrating a second version of the third embodiment of the present invention, including a main body and anchor body with integral compliant section, in modular form; 
         FIG. 33  is a partial cross-sectional view illustrating the components shown in  FIG. 32 , in assembled form and disposed within a remaining bone portion, with secured anchor, with traction applied to the compliant section, and with an intercalary segment attached thereto; 
         FIGS. 34 ,  35  and  36  are perspective views illustrating three different sizes of an alternative configuration of anchor body and integral compliant section, each having a tapered, self-tapping threaded section; 
         FIG. 37  is a bottom perspective view illustrating the cutting thread configuration for any of the anchor bodies shown in  FIG. 34 ,  35  or  36 ; 
         FIG. 38  is a perspective view illustrating a configuration of screw used for securing a main body to a compliant section integrally formed with an anchor body; 
         FIG. 39  is a partial cross-sectional view illustrating a main body attached through the use of the screw shown in  FIG. 38  to a tapered threaded anchor body and integral compliant section disposed within a remaining bone portion; 
         FIG. 40  is a partial cross-sectional view illustrating the attachment of a tibial tray to an compliant section and integral threaded anchor body; 
         FIGS. 41 ,  42  and  43  are perspective views illustrating three different sizes of specially-shaped tapered reamers for use in enlarging the intramedullary canal of a remaining bone portion for the insertion of any of the tapered threaded anchors shown in  FIG. 34 ,  35  or  36 ; 
         FIG. 44  is a partial cross-sectional view illustrating the use of a tapered reamer for enlarging the intramedullary canal of a remaining bone portion; 
         FIG. 45  is a partial cross-sectional view illustrating use of an anchor inserter and threaded rod assembly for accomplishing the insertion of a threaded anchor within a prepared intramedullary cavity of a remaining bone portion; 
         FIG. 46  is a partial cross-sectional view illustrating the use of a guide device for drilling apertures through the cortex of a remaining bone portion within which an anchor body of the cross-secured type is being installed; 
         FIG. 47  is a partial cross-sectional view illustrating the use of a face reamer for milling an interface surface of a remaining bone portion to a predetermined angle; 
         FIG. 48  is a cross-sectional view illustrating another version of bone attachment assembly of the present invention, having a convexly exteriorly shaped main body shoulder portion; 
         FIG. 49  is an alternative version of the bone attachment assembly shown in  FIG. 48 ; 
         FIG. 50  is an alternative version of the bone attachment assembly shown in  FIGS. 48 and 49 , with a sleeve disposed for inhibiting non-axial relative displacement of the compliant section and main body; 
         FIG. 51  shows the version of bone attachment assembly shown in  FIG. 48 , installed within a proximal femur; 
         FIG. 52  is a partial cross-sectional view of a non-coaxial version of bone attachment assembly; 
         FIG. 53  is a sectional view of a compliant fixation device for an external prosthesis according to the present teachings; 
         FIG. 54  is an environmental sectional view of a compliant fixation device for an external prosthesis according to the present teachings; 
         FIG. 55  is an environmental sectional view of an intramedullary fixation device according to the present teachings; 
         FIG. 56  is an environmental sectional view of an intramedullary fixation device according to the present teachings; 
         FIG. 57  is a side view of a component of an intramedullary fixation device according to the present teachings; 
         FIG. 58  is a side view of a component of an intramedullary fixation device according to the present teachings; and 
         FIG. 59  is an environmental sectional view of an intramedullary fixation device according to the present teachings. 
     
    
    
     DESCRIPTION OF VARIOUS EMBODIMENTS 
     It should be understood that while this invention is described in connection with particular examples, the scope of the invention need not be so limited. Rather, those skilled in the art will appreciate that the following teachings can be used in a much wider variety of applications than the examples specifically mentioned herein. 
     Referring now to  FIG. 1 , there is shown a bone assembly  10 , which includes a first remaining bone portion  12  and a second portion  14 , as is the case involving a mid-diaphyseal segment replacement. The second portion  14  may be an orthopedic appliance, an orthopedic appliance connected to a second remaining bone portion, or may be replaced by a percutaneous bar suitable for the attachment of an external appliance, as will be discussed below. The second remaining bone portion may be a portion of the same bone as the first remaining bone portion, or may be a portion of another bone. 
     The first remaining bone portion  12  is shown to include a first intramedullary cavity  16 , which can be an enlarged longitudinal cylindrically-shaped bore created to a preselected depth from the osteotomy surface. The first intramedullary cavity  16  may substantially coincide in its longitudinal axis with the natural intramedullary canal of the bone. In those situations where the second portion  14  is in the form of an orthopedic appliance connected to a second remaining bone portion, the second remaining bone portion may similarly include a second intramedullary cavity (not shown), which may preferably be substantially similar in size and shape to the first intramedullary cavity  16 . Also, the means of connecting the second remaining bone portion may be entirely different from this arrangement, including the use of bone cement or other suitable materials. 
     Disposed as a part of the bone assembly  10  is a biocompatible bone attachment assembly, shown generally at  18 . In one aspect, the bone attachment assembly  18  can include a first bone attachment device  20 , which is located about the first remaining bone portion  12 . The first bone attachment device  20  may be secured to the second portion  14  through the use of a clamp  76 , which can be of a type discussed below in connection with  FIGS. 5 and 6 . The bone attachment assembly  18  may also further include a second bone attachment device (not shown) located about the second portion  14 , in the situation where the second portion  14  is a second remaining bone portion. 
     Referring now to  FIG. 2 , the first bone attachment device  20  is described in greater detail.  FIG. 2  is an enlarged cross-sectional view illustrating a bone attachment device  20  as it is secured within the first remaining bone portion  12 . The first bone attachment device  20  is shown to include a main body  22  which is constructed of a suitable biocompatible material. Examples of suitable materials are titanium alloys such as Ti-6Al-4V, CoCr (cobalt chromium) alloys and commercially pure titanium. Other suitable materials may be used. In one aspect, the components of the bone attachment assembly  18  can be constructed of the same material. The main body  22  can be substantially cylindrically-shaped, and may include a shoulder portion  24 , at least one pin channel  26  and a longitudinal bore  28 . In one aspect, the main body  22  is operable to be positioned upon a milled end portion  30  of the first remaining bone portion  12 . It will be appreciated that the main body  22  will replace a portion of the length of bone being removed during the surgical procedure, by virtue of its position upon the milled end portion  30 . 
     The milled end portion  30  is created in a preselected geometry relative to the cylindrically-shaped first intramedullary cavity  16 . Preferably, as shown in  FIG. 2 , the milled end portion  30  is formed to an axisymmetric geometry, and most preferably to a convex conical geometry, whose cross-section has a preselected included angle of inclination relative to the longitudinal axis in the direction of the first remaining bone portion  12 . Other preselected geometries and angles may also be used. The main body  22  includes an interface surface  32  which is most preferably constructed to substantially match the geometry of the milled end portion  30 , thereby providing a substantially flush interface between the milled end portion  30  and the interface surface  32 . As such, the interface surface  32  may also be created in an axisymmetric or concave conical geometry, or in another suitable geometry. The interface surface  32  can be operable for accepting biological bone attachment by bone ingrowth and/or ongrowth. 
     The main body  22  is shown to preferably include a cannulated stem portion  34 , which can be in the form of a single unitary structure. The cannulated stem portion  34  may be of a substantially cylindrical shape, as shown in  FIG. 1 , or may be tapered along its length at one of several selected major and minor diameter configurations, depending upon the diameter of the original natural intramedullary canal of the bone and also upon the extent of reaming required in forming the first intramedullary cavity  16 . Preferably, the major diameter of the cannulated stem portion  34  is represented by a cylindrical portion of the stem, which may fit with reduced lateral movement against the walls defining the first intramedullary cavity  16 . As shown in  FIG. 2 , the cannulated stem portion  34  may occupy a substantial length of the first intramedullary cavity  16 . The cannulated stem  34  may be made from the same selection of materials as the main body  22 . The cannulated stem portion  34  also includes a longitudinal bore  36  that is coaxial with the longitudinal bore  28  disposed through the main body  22 . Preferably, the longitudinal bore  28  and the longitudinal bore  36  are substantially identical in diameter and are relatively positioned so as to form a single continuous bore. 
     The first bone attachment device  20  further includes means for anchoring the device in an enhanced stationary position within the first intramedullary cavity  16 . The means for anchoring the first bone attachment device is shown to be in the form of an anchor body  38  which is located within the first intramedullary cavity  16  at its distal end. The anchor body  38  may be made from the same material as the main body  22 . The anchor body  38  includes one or more apertures  40  that are operable for accepting the insertion of one or more fixation devices. The apertures  40  may preferably be a plurality of staggered apertures of substantially the same preselected diameter. One possible staggered arrangement for the apertures  40  is the arrangement shown in  FIG. 1 . It will be appreciated, however, that any suitable arrangement for the apertures  40  may be used, including those wherein the apertures  40  are in perpendicular or other non-parallel arrangements. 
     To provide a passageway for the insertion of suitable fixation devices to engage the anchor body  38 , one or more fixation bores  42  are provided through the first remaining bone portion  12 . The fixation bores  42  are preferably sized and located to substantially match the size and location of the apertures  40  upon the anchor body  38 . As such, the fixation bores  42  may also preferably be disposed as a plurality of staggered bores created through the first remaining bone portion  12 . 
     The first bone attachment device  20  also includes one or more engagement devices that are operable to provide an engagement between the anchor body  38  and the first remaining bone portion  12 , so as to enhance a substantially secured relation of the anchor body  38  within the first intramedullary cavity  16 . In one embodiment, the selection of engagement device is one or more transverse pins  44  which traverse one or more fixation bores  42  on at least one side of the anchor body  38 , and also traverse one or more apertures  40  disposed across the anchor body  38 . Most preferably, a plurality of transverse pins are used in the same preselected staggered arrangement as the apertures  40  and the fixation bores  42 . The transverse pins  44  may be disposed in a substantially parallel relation, as shown. It will be appreciated, however, that the transverse pins  44  may be disposed perpendicularly, or at other preselected relative angles. 
     The selection of engagement device may also be one or more of interlocking screws  46 , as is shown in  FIG. 3 .  FIG. 3  is a cross-sectional view illustrating one embodiment of an anchor body  38  secured within the intramedullary cavity of a remaining bone portion. The interlocking screws  46 , like the transverse pins  44 , preferably traverse one or more apertures  40  and one or more fixation bores  42 . The interlocking screws  46  may be threaded from one side of the first remaining bone portion  12 , or may alternatively be threaded from opposite sides. The interlocking screws  46  may also be disposed perpendicularly, or at other preselected relative angles. As before, the interlocking screws  46  may be disposed in a staggered arrangement so as to enhance the stability of the anchor body  38  within the first intramedullary cavity  16 . The transverse pins  44  and interlocking screws  46  may both be made from the same materials as the main body  22 . 
     Referring again to  FIG. 2 , the first bone attachment device  20  is further shown to include means for attaching the main body  22  to the means for anchoring the bone attachment device  20 . The means for attaching the main body  22  is provided in the form of a cylindrically-shaped connecting rod  48  that is sized to traverse the longitudinal bore  36  of the cannulated stem  34  and the longitudinal bore  28  of the main body  22 , while moving freely longitudinally without substantial restriction from engagement with the cannulated stem portion  34  and the main body  22 . The connecting rod  48  may be made from the same material as the main body  22 . The connecting rod  48  is operable to be inserted through the main body  22  and the cannulated stem portion  34  to an engagement with the anchor body  38 , such that the connecting rod  48  extends from the anchor body  38  through the milled end portion  30 . The connecting rod  48  also includes a lower threaded portion  50  that is operable to engage a correspondingly threaded bore  52  located in the upper portion of the anchor body  38 . The connecting rod  48  may also be conveniently threaded over its entire length. The connecting rod  48  has a degree of compliancy relative to bone in its construction, such that its disposition alone between the main body  22  and the anchor body  38  provides a compliant fixation between the main body  22  and the anchor body  38 . 
     As shown in  FIG. 3 , the means for attaching the main body  22  to the means for anchoring the biocompatible bone attachment device  22  may be provided as a connecting rod  48  that is an integral extension of the anchor body  38 . As such, the connecting rod  48  also extends from the anchor body  38  through the milled end portion  30 . 
     Referring now to  FIG. 4 , the means for attaching the main body  22  to the means for anchoring the first bone attachment device  20  may also further include a supplemental interposed compliant device for enhancing the compliance of the bone attachment assembly  18 . The supplemental interposed compliant device operates by biasing the connecting rod  48  against the main body  22 .  FIG. 4  is an enlarged cross-sectional view illustrating a portion of the first bone attachment device  20  of the present invention. The supplemental interposed compliant device may be contained within a cylindrically-shaped recess  54  located atop the main body  22 , or may also be operable to abut against another suitable surface of the main body  22 . In some arrangements, the supplemental interposed compliant device may project partially from within the recess  54 . The supplemental interposed compliant device preferably includes one or more washer springs  56  positioned about the upper portion of the connecting rod  48 . As shown in  FIG. 4 , a plurality of washer springs  56  may be oriented in adjacently opposite directions upon the connecting rod  48 . It will be appreciated that other suitable biasing arrangements may be used. 
     The washer springs  56  may be made from the same materials as the main body  22  set forth above, or may also be made from a nickel-titanium alloy, such as nitinol. The use of nitinol as a material selection for the washer springs  56  tends to reduce the number of individual spring members required. The washer springs  56  may be replaced, however, by at least one compressible elastic cylinder made from a material selected from the group consisting of plastics and polymers. A suitable selection for an elastic cylinder material is polyurethane. 
     In order to secure the washer springs  56  in a biasing relationship between the main body  22  and the connecting rod  48 , a spring biasing means is provided. The spring biasing means may serve the double function of locking means, which may be a lock nut  58  which may be advanced upon an upper threaded portion  60  of the connecting rod  48  at least until it contacts the supplemental interposed compliant device. The lock nut  58  may be made from the same material as the main body  22 . The lock nut  58  may be further advanced upon the connecting rod  48  to compress the spring means to a desired degree. The lock nut  58  can be advanced upon the connecting rod  48  so as to compress the washer springs  56  until increased resistance is noted. This may occur at above about 75% compression, and may preferably occur at about 90% compression. A gap  62  located across the lock nut  58  may be suitably closed to enhance a substantially secured position of the lock nut  58  upon the upper threaded portion  60  of the connecting rod  48 , thereby securing the washer springs  56  within the recess  54 , and thereby providing a supplemental biasing arrangement between the connecting rod  48  and the main body  22 . As such, the first bone attachment device  20  is in an enhanced compliantly attached arrangement. 
     The lock nut  58  can be optionally provided with retention means for enhancing the substantially secured relation of the lock nut  58 . The retention means is shown in the form of a retention screw  64  which is operable to traverse a correspondingly threaded receiving hole disposed across the lock nut  58  on either side of the gap  62 . The retention screw  64  is operable to be threadably tightened to close the gap  62  to the point where the lock nut  58  is enhanced in a substantially secured relation against the upper threaded portion  60  of the connecting rod  48 . The relative positions of the lock nut  58 , the washer springs  56  and the recess  54  are illustrated in  FIG. 5 , which is a top view illustrating a portion of the bone attachment device shown in  FIG. 4 , taken from the perspective  5 - 5  in  FIG. 4 . It will be appreciated that other suitable spring biasing means and retention means may be used. For example, a nut without a gap followed by a lock nut may be used. A lock wire disposed through a hole in a nut is also suitable as a locking means for the spring biasing means. 
     The spring biasing means may also be provided as a combination of a nut without a gap, followed by means for enhancing a secured relation of the nut upon the connecting rod. This may be provided as a lock nut, as previously described, or may be provided in another suitable form, such as a lock wire disposed through an aperture of the nut. 
     Referring again to  FIG. 4 , the first bone attachment device  20  may also be provided with a porous interface coating  66  located upon the interface surface  32 . The porous interface coating  66  may be applied by any suitable technique and is for enhancing bone ingrowth into the first bone attachment device  20  from an adjacently positioned milled end portion of a bone, such as that shown at  30  in  FIG. 2 . The porous interface coating  66  may be made from varieties of the same material as the main body  22 , or may also be CoCr (cobalt chromium) beads of diameter approximately 20/1000ths of an inch, sintered together, or a pressed and sintered multiple layer wire grid of titanium alloy wires, or a pressed and sintered coarse wire of one of the above materials, or a plasma sprayed titanium. The porous interface coating  66  may also include a hydroxyapatite layer in conjunction with any of the above material layers. 
     With reference again to  FIG. 4 , the first bone attachment device  20  may be provided with one or more antirotation pins  68  which are disposed within the pin channel  26  and protrude from the interface surface  32  in the region where the main body  22  contacts an adjacently positioned milled end portion of a bone, such as that shown at  30  in  FIG. 2 . Referring now to  FIG. 6 , which is a bottom view illustrating the compliant section of the bone fixation device, taken from a perspective  6 - 6  in  FIG. 4 , it can be seen that a plurality of antirotation pins  68  are disposed in a substantially equally spaced circular arrangement about the central axis of the longitudinal bore  28 . It will be appreciated that any suitable number of antirotation pins  68  may be employed. Usually, at least one, up to about twelve antirotation pins  68  will be most practical. In one aspect, the length of projection, above the interface surface  32 , of each antirotation pin  68  is less than four times the diameter of each pin. The antirotation pins  68  may be made from the same material as the main body  22 . 
     In the situation where only a mid-diaphyseal segment replacement is performed, the second portion  14  discussed in connection with  FIG. 1  may in part take on a substantially similar construction as the first remaining bone portion  12 . Thus, a bone attachment assembly  18  may be formed from two substantially identically constructed bone attachment devices. Alternatively, the second portion  14  may be provided entirely as an orthopedic appliance. Alternatively, the resection could include adjacent portions of two end-on-end disposed long bones, such that the two attachment assemblies and an interposed orthopedic appliance would serve to restore physiologic linkage between the two long bones. In this way, the two long bones could also be functionally fused, according to the selected interposed orthopedic appliance. 
     In this situation, a second bone attachment device (not shown) may be provided to be substantially similar to the first bone attachment device  20 . It may also be substantially different, for example, attached to its receiving surface with bone cement. With reference now to  FIG. 7 ,  FIG. 7  illustrates a bone attachment assembly, indicated generally at  18 . The bone attachment assembly  18  is shown to include a first bone attachment device  20  which is fixedly secured to a first remaining bone portion  12 , in the manner previously described. The first bone attachment device  20  may then be connected through the use of a clamp  76  to a second portion  14  which is in the form of an orthopedic appliance. The orthopedic appliance may then be similarly connected to a second bone attachment device in a similar manner. In this arrangement, the first bone attachment device  20  acts as a connector, in addition to the orthopedic appliance, which may replace a portion of the length of bone removed during the surgical procedure. In this arrangement, the first bone attachment device  20  and the second bone attachment device are each provided with a compliant capability. 
     The biocompatible bone attachment assembly  18  is also shown to include means for enhancing a fluid seal between the intramedullary cavity  16  and the external environment. Optionally, this is provided as one or more sealing devices, such as o-rings  70  and  72 , which are disposed in a contacting relation with the main body  22  or the connecting rod  48 . As such, the o-rings  70  and  72  may be disposed about the edge of the main body  22 , within a recess  74  created at the lower surface of the main body  22  adjacent to the connecting rod  48 , as shown in  FIG. 7 , or may be disposed upon other suitable regions of the main body  22 . The o-rings  70  and  72  may thus also be disposed about the lock nut  58  or the washer springs  56 . 
     When one or more o-rings  70  and  72  are used, they may enhance a sealed condition of the first bone attachment device  20  as connected to an orthopedic appliance, such as that shown at  14  in  FIG. 1 . Multiple sealing devices may sequentially reinforce a seal of the first bone attachment device  20  at the entrance to the recess  54  and the entrance to the longitudinal bore  28 . 
     The bone attachment assembly  18  further includes means for securing the first bone attachment device  20  in an enhanced secured relation to the second portion  14  which may be an orthopedic appliance, as shown in  FIGS. 1 ,  4  and  7 . This can be provided as a clamp which is operable to substantially surround a portion of the main body  22  of the first bone attachment device  20  and a portion of the opposing orthopedic appliance, or second portion  14 . One type of clamp is a cylindrically-shaped sleeve clamp  76  which is operable for being enhanced in a secured relation. As shown in  FIGS. 5 and 6 , the sleeve clamp  76  includes an aperture  78  that is operable to be closed through the threaded rotation of one or more retention screws  80 . The sleeve clamp  76  may be made from the same material as the main body  22 . It will be appreciated that other suitable means for coupling the first bone attachment device  20  and the second portion  14  may also be used. 
     The first bone attachment device  20  may also include means for preventing rotation of the sleeve clamp  76  with respect to the main body  22  and the orthopedic appliance  14 . This can be provided as a key  82  disposed in an engaging relation between the sleeve clamp  76  and the main body  22 , as shown in  FIG. 5 . It will be appreciated that this may be provided by any suitable device disposed between the sleeve clamp  76 , the main body  22  and the orthopedic appliance  14 . 
     Referring now to  FIG. 8 ,  FIG. 8  is a perspective view illustrating a guide device which can be temporarily applied for creating one or more apertures in the first remaining bone portion for accepting one or more engagement means, such as the transverse pins  44  or interlocking screws  46  shown in  FIGS. 2 and 3 . The guide device, shown generally at  84 , is operable to be attached to a means for anchoring a bone attachment assembly, such as the anchor body  38 . The guide device  84  is made from aluminum, a titanium alloy, or stainless steel. It will be appreciated that other suitable materials may be used. The guide device  84  includes a guide body  86  that can be of length at least equal to the total, combined length of the connecting rod  48  and the anchor body  38 . 
     The guide device  84  is shown to include a guide body  86  operable for being disposed adjacent to the first remaining bone portion  12 . The guide body  86  includes an upper connecting aperture  88  and a locking screw  90  that is operable for closing the connecting aperture  88 . The guide body  86  also includes one or more guide holes  92  for guiding an aperture-forming procedure by accepting the insertion of both alignment devices and drilling implements, as will be discussed below. 
     The guide device  84  also includes a cannulated holder bar  94  that is operable for being positioned upon the anchor body  38  and connecting rod  48  within the first intramedullary cavity  16  in a coaxial relationship. The holder bar  94  can be positioned so as to abut against the top of the anchor body  38 . The holder bar  94  is of preselected length and configuration to match the dimensions of the reamed first intramedullary cavity  16 . As such, the length of the holder bar  94  can be sufficient to protrude from the osteotomy surface, yet is short enough to allow the holder bar  94  to be substantially secured to the connecting rod  48  by a nut  96  threaded onto the connecting rod  48  substantially against the upper surface of the holder bar  94 . The holder bar  94  may be of cylindrical shape, and may include a tapered section  98  disposed between a large section  100  having a major diameter and a small section  102  having a minor diameter. The large section  100  can be operable to fit with reduced lateral movement against the walls defining the first intramedullary cavity  16 , so as to serve as a means for establishing a precise coaxial position of the anchoring means within the first intramedullary cavity  16 . One or more other suitable surface irregularities on the holder bar  94  may serve as a means for establishing a precise depth of insertion. 
     The guide device  84  is also shown to include a positioning bar  104  operable for being mounted between the holder bar  94  and the guide body  86 . The positioning bar  104  includes a connecting aperture  106  that is operable for engaging a portion of the holder bar  94 . The positioning bar  104  also includes a locking screw  108  for closing the connecting aperture  106  so as to enhance a secured relation between the holder bar  94  and the positioning bar  104 . The positioning bar  104  can be sized so as to engage the upper connecting aperture  88  of the guide body  86 , such that the tightening of the locking screw  90  enhances a secured relation between the positioning bar  104  and the guide body  86 . It will be appreciated that the various components of the guide device  84  described above are relatively manipulable and may thus be independently adjusted and set for each particular aperture-forming procedure upon each particular first remaining bone portion  12 . The guide device  84  can be set to provide one or more guide holes  92  in substantial alignment with one or more apertures  40  disposed within the anchor body  38 , so that a drilling procedure directed through one or more guide holes  92  may result in the proper formation of the fixation bores  42  shown in  FIGS. 2 and 3 . 
     As shown in  FIGS. 8 and 9 , the present invention also contemplates the use of one or more self-centering drill bits  112  as especially suitable for creating at least one fixation bore  42  by being inserted through each of the guide holes  92  and directed toward the outer surface of the first remaining bone portion  12 . The self-centering drill bit  112  is known in the machine tool industry, and is shown to include a main bit portion  114  and a centering bit portion  116  protruding beyond the main bit portion  114  for drilling a centering hole which guides the drilling operation of the main bit portion  114 . The drill bit  112  also includes a drill attachment portion  118  operable for attaching directly to a drilling device (not shown), such as a conventional hand drill. This procedure may also be performed with a standard drill bit (not shown). 
     Referring now to  FIG. 10 ,  FIG. 10  is a partial cut away view illustrating a milling device, shown generally at  120 , for milling the osteotomy surface of a first remaining bone portion  12  in a preselected geometry to be coaxial with a first bone attachment device  20 . The milling device  120  is shown to include a milling body  122  having a cutting edge  124  of preselected geometry. The preselected geometry of the cutting edge  124  may preferably be such that it creates a conical shape, and more preferably creates a convex conical shape. The milling device  120  further includes means for positioning the milling body  120  upon an osteotomy surface of a first remaining bone portion  12  in a coaxial relationship with the first intramedullary cavity  16 . This may be provided as a cannulated pilot member  126  that is operable for being inserted into the first intramedullary cavity  16  up to an abutting relationship with the anchor body  38 . Preferably, the cannulated pilot member  126  is of a generally tapered configuration, and includes a cylindrical portion  128  having a major diameter substantially equal to the diameter of the first intramedullary cavity  16 . As such, this major diameter defines the nominal size of the cannulated stem portion  34  which is subsequently inserted into the first intramedullary cavity  16 . The cannulated pilot member  126  further includes a tip portion  130  which is operable to abut against the anchor body  38 . The cannulated pilot member  126  includes a longitudinal aperture  132  that is sized to accept the traverse of the connecting rod  48 . 
     The milling device  120  further includes means for positioning the milling body  122  in a coaxial relationship with the first intramedullary cavity  16 . This is provided by the cylindrical portion  128  as previously described and the connecting rod  48  in the longitudinal aperture  132 . The milling device  120  also includes means for establishing a preselected depth for a milling procedure upon the osteotomy surface. This is provided in the form of a preselected length of the cannulated pilot member  126  from the cutting edge  124  to the tip portion  130 . This distance is preselected to be substantially equal to a desired distance from the anchor body  38  to the subsequently milled osteotomy surface. The cannulated pilot member  126  further includes a shaft portion  134  of preselected length to engage a recess  136  of preselected length within the milling body  122 . The milling body  122  may further include a means for enhancing a substantially secured relation between the milling body  122  and the cannulated pilot member  126 , such as a set screw  138 . The milling body  122  also includes a drill attachment portion  140  for attaching the milling body  122  to a drilling device, such as a conventional hand drill. 
     As shown in  FIG. 11 , the means for positioning the milling body  122  in a coaxial relationship with the first intramedullary cavity  16 , as well as the means for establishing a preselected depth for a milling procedure can both be provided with a different cannulated pilot member  126 , and through a special configuration of the milling body  122  with respect to the connecting rod  48 .  FIG. 11  is a cross-sectional view illustrating a milling device used for milling an osteotomy surface in a preselected geometry. The milling body  122  may be disposed upon the connecting rod  48  such that the connecting rod  48  extends into the recess  136 , and wherein the recess  136  is disposed in a coaxial relation to the first intramedullary cavity  16 , by way of the longitudinal aperture  132  in a truncated cannulated pilot member  127 . In this arrangement, the means for establishing a preselected depth for a milling procedure is provided by the cylindrical walls defining the recess  136  being of a preselected length substantially equal to the length of the portion of the connecting rod  48  which is greater than the desired distance from the anchor body  38  to the subsequently milled osteotomy surface. 
     Referring now to  FIG. 12 ,  FIG. 12  is a cross-sectional view illustrating a first bone attachment device  20  secured in conjunction with an interposed orthopedic appliance  142 . The orthopedic appliance  142  is shown to include a plurality of recesses  144 ,  146  and  148  for accommodating the insertion of one or more of the washer springs  56 , the lock nut  58  and the connecting rod  48 . In this example, it should be noted that the main body  22  is shaped somewhat differently than previously described in that the recess  54  may be substantially smaller, thereby allowing the protrusion of one or more of the above components. 
     Referring now to  FIG. 13 ,  FIG. 13  is a cross-sectional view illustrating a percutaneous bar  150  connected to a device of the present invention. The percutaneous bar  150  is secured substantially as before by a cylindrically-shaped sleeve clamp  76 . The percutaneous bar  150  is used in the case of amputees, wherein the skin  152  may be repaired around the percutaneous bar  150  during the surgical procedure. The percutaneous bar  150  is shown to include as an example a threaded portion  154  which is operable to be threadably engaged with one of several types of external appliances (not shown). The length of the percutaneous bar  150  preferably allows sufficient length of the threaded portion  154  for a satisfactory threaded engagement with the external appliance used. The percutaneous bar may be constructed from a material selected from the group consisting of metals and carbon fiber-reinforced resins, although it will be appreciated that other suitable materials may be used. The percutaneous bar  150  may further be coated with a material that allows the biological attachment of soft tissue, such as skin, and inhibits bacterial access from the external environment. This can be provided as a coating  156  disposed upon at least a portion of the external surface of the percutaneous bar  150 . Preferably, the coating material is hydroxyapatite, although it will be appreciated that other suitable coating materials may be used. 
     Referring now to  FIG. 14 ,  FIG. 14  is a perspective view illustrating a reaming device  158  of the present invention. The reaming device  158  is operable for creating an enlarged cylindrical intramedullary cavity, such as the first intramedullary cavity  16 , within a first remaining bone portion  12 . The reaming device  158  is shown to include a cylindrical portion  160  preferably having a plurality of cutting surfaces, and a tapered tip portion  162  disposed in communication with the cylindrical portion  160 . The tapered tip portion  162  also preferably has a plurality of cutting surfaces. The reaming device  158  also includes a drill attachment portion, which is provided as a drill attachment post  164 . The reaming device  158  can be a left spiral, right cutting device, made for use with standard clockwise hand drills. As such, the reaming device  158  is operable for establishing a first intramedullary cavity  16  within the first remaining bone portion  12 , is self-centering, creates a cylindrical cavity, and will not seize in the bone. 
     In the method of the present invention, a bone segment is replaced with a biocompatible bone attachment assembly, such as that shown at  20 . The surgical procedure, as applied to a mid-shaft osteotomy of a femur, generally involves preparing the lateral aspect of the femur for surgery with povidone iodine, and draping the limb for aseptic surgery. The lateral aspect of the femur is then approached between the muscle bellies of the biceps femoris and the vastus lateralis. Wound closure is of a routine nature to those skilled in the art. 
     The method includes the step of resecting the femur at a preselected location by suitable means of sawing, thereby performing a transverse osteotomy of the femur. This procedure yields a first remaining bone portion  12 . The preparation of the first remaining bone portion  12  may then be accomplished as follows. An enlarged cylindrically-shaped first intramedullary cavity  16  is formed within the first remaining bone portion  12  up to a diameter dictated by intramedullary cavity dimensions and to a preselected depth. The preselected depth can be sufficient to allow for the insertion of a means for anchoring the first bone attachment device  20  within the first intramedullary cavity  16  to such a depth that subsequent connection of a means for compliantly attaching the main body  22  to the first remaining bone portion  12  may protrude from the osteotomy surface. 
     The enlarged first intramedullary cavity is formed by attaching the reaming device  158  to a drilling device, such as a conventional hand-held power drill, henceforth denoted as a hand drill, at the drill attachment post  164 . The reaming device  158  is then inserted into the intramedullary canal. The hand drill is then activated, and the reaming device  158  is advanced in a longitudinal direction into the first remaining bone portion  12 , while the reaming device  158  is being rotated by the drilling device. This is repeated with progressively larger reamers until the reaming device  158  has clearly engaged the inner walls. A larger reamer may be used at the outlet than at the depth of the intramedullary cavity. A cylindrically-shaped enlarged first intramedullary cavity  16  as an enlargement of the natural intramedullary canal of the first remaining bone portion  12  is thus created. 
     The holder bar  94  of appropriate nominal diameter is first positioned upon the connecting rod  48  in an abutting relation with the anchor body  38 . A nut  96  is then advanced onto the upper threaded portion  60  of the connecting rod  48  until substantially tightened against the top surface of the holder bar  94 . The positioning bar  104  is then engaged with the holder bar  94  in a substantially perpendicular relation such that the holder bar  94  passes through the connecting aperture  106 . The guide body  86  is engaged with the positioning bar  104  in a substantially perpendicular relation by sliding the upper connecting aperture  88  over the positioning bar  104 . The apertures  40  in the anchor body  38  are then aligned with the guide body holes  92  in the guide body  86 , by way of temporary rods (not shown) traversing both the guide body holes and the anchor body holes. The locking screws  90  and  108  may then be substantially tightened, thereby enhancing a secured relation between the guide body  86  and the anchor body  38 . 
     Once the above components of the guide device  84  are positioned and secured, the holder bar  94  is inserted into the intramedullary cavity  16  to the depth indicated by a gauge on the side of the holder bar (not shown). 
     The self-centering drill bit  112  is connected to a drilling device, such as a hand drill at the drill attachment portion  118 . The self-centering drill bit  112  is then inserted through a guide hole  92  in a substantially perpendicular direction to the guide body  86  to meet the outer surface of the first remaining bone portion  12 . The centering bit portion  116  is first advanced into the first remaining bone portion  12  as the self-centering drill bit  112  is rotated by the drilling device. The fixation bores  42  are thus created by advancing the centering bit portion  116 , followed by the main bit portion  112 , through the first remaining bone portion  12  and into the anchor body  38 . The self-centering drill bit  112  may be further advanced through the entire width of the first remaining bone portion  12 . 
     Once the first fixation bore  42  is created, the self-centering drill bit  112  is left in the fixation bore  42  while additional fixation bores  42  are created using additional self-centering drill bits  112 , to additionally stabilize the guide device  84  for the remaining drilling procedures. The above steps may be repeated as many times as desired to create several fixation bores  42 . 
     The fixation bores  42  may be created to form contiguous straight channels through the entire width of the first remaining bone portion  12  from one external surface to the other. It will be appreciated that the fixation bores  42  may be created to a limited depth within the first remaining bone portion  12  as well. A similar procedure may be employed to create one or more fixation bores  42  through the first remaining bone portion  12  from opposite sides of the first intramedullary cavity  16  or from preselected relative angles. The fixation bores  42  may thus be created all parallel in the same direction, or may be a series of oppositely or angularly disposed fixation bores  42  created from opposite or adjacent external surfaces of the first remaining bone portion  12  on opposite or adjacent sides of the first intramedullary cavity  16 . 
     Once the desired fixation bores  42  have been created, one or more fixation elements, such as transverse pins  44  or interlocking screws  46  are then forcibly inserted or threadably inserted into each fixation bore  42  and into each aperture  40 , so as to engage the anchor body  38  and the first remaining bone portion  12 . The first self-centering drill bit  112  is removed only after the first fixation element has been inserted. The guide device  84  is then disengaged and removed. 
     The milling device  120  is then used to create a milled end portion  30  upon the first remaining bone portion  12 . Where the milling device  120  includes a cannulated pilot member  126 , as set forth in  FIG. 10 , the cannulated pilot member  126  is inserted into the recess  136  of the milling body  122 , until the upper edge of the cylindrical portion  128  contacts the cutting edge  124 . A set screw  138  is suitably tightened to enhance a secured relation between the milling body  122  and the cannulated pilot member  126 . The milling body  122  is then attached at the drill attachment portion  140  to a drilling device, such as a hand drill. The cannulated pilot member  126  is then inserted into the first intramedullary cavity  16  such that the milling device  122  is positioned atop the first remaining bone portion  12  with its longitudinal axis in a substantially collinear relation with that of the first remaining bone portion  12 . Pressure is then exerted in a downward axial direction as the milling device  120  is rotated by the drilling device, thereby rotating the cutting edge  124  upon the osteotomy surface, and thereby removing portions of the bone from this surface. The rotation is continued until the tip portion  130  of the cannulated pilot member  126  abuts against the anchor body  38 . At this point, the preselected dimensions of the above components will have caused the rotation of the cutting edge  124  to form a milled end section  30  of a preselected geometry corresponding to that of the cutting edge  124 , which is located at a preselected distance from the anchor body  38 . 
     In the situation where a truncated cannulated pilot member  127  is employed, as shown in  FIG. 11 , the milling body  122  may be connected to a drilling device, such as a hand drill, at the drill attachment portion  140 , as before. The milling body  122  and truncated cannulated pilot member  127  may then be disposed upon the connecting rod  48 , such that the connecting rod  48  extends into the recess  136  of the milling body  122 . Then, the milling body  122  may be rotated by the hand drill as before, with the milling body forced in a downward axial direction until the upper surface of the connecting rod  48  contacts the upper surface of the recess  136 . At this point, the preselected dimensions of the connecting rod  48  and the recess  136  will result in the formation of a milled end portion  30  of preselected geometry and location, as before. 
     In accordance with the method of the present invention, the main body  22  is then positioned in an abutting relation between the interface surface  32  and the milled end portion  30 , such that the connecting rod  48  traverses the longitudinal bore  28  of the main body  22  and protrudes into the recess  54  of the main body  22 . It will be appreciated that the connecting rod  48  may protrude above any suitable contact surface upon the main body  22 . As shown in  FIG. 2 , where the main body  22  includes a cannulated stem portion  34 , the cannulated stem portion  34  is inserted into the first intramedullary cavity  16  as the main body  22  is positioned upon the milled end portion  30 . The connecting rod  48  then traverses both the longitudinal bore  28  of the main body  22  as well as the longitudinal bore  36  of the cannulated stem portion  34 . Once the main body  22  is positioned upon the milled end portion  30 , the pin channels  26  may be used to guide a suitable drilling device for the creation of one or more recesses in the milled end portion  30  for accepting the antirotation pins  68 . Once this drilling operation is completed, one or more antirotation pins  68  are disposed within one or more pin channels  26  into the milled end portion  30 , thereby preventing rotation of the main body  22  with respect to the milled end portion  30 . 
     One or more fluid seal devices, such as o-rings  70  and  72 , may then be positioned at such locations as the recess  74  shown in  FIG. 7 , and also along the top rim of the main body  22 . 
     In the next step of the method of the present invention, one or more supplemental interposed compliant devices, which are preferably one or more washer springs  56 , or one or more compressible elastic cylinders, may optionally be positioned upon the connecting rod  48  such that they are retained within the recess  54  of the main body  22 . When a plurality of washer springs  56  are used, in one aspect, they can be used in an adjacent oppositely disposed relation. A retaining means, such as a lock nut  58 , is advanced upon the upper threaded portion  60  of the connecting rod  48  until the lock nut  58  compresses the washer springs  56  or elastic cylinders until increased resistance is noted. This may occur at above about 75% compression, and may preferably occur at about 90% compression. The lock nut  58  is then enhanced in a secured relation against the connecting rod  48  by tightening the retention screw  64 , which closes the gap  62 . Where the supplemental interposed compliant devices are not employed, the lock nut  58  is advanced directly to the bottom of the recess  54 . 
     In the situation where the second portion  14  is an orthopedic appliance, as shown in  FIGS. 1 and 7 , the sleeve clamp  76  shown in  FIGS. 5 and 6  is first positioned upon a portion of either of the main body  22  of the first bone attachment device  20  or the orthopedic appliance. Thereafter, the main body  22  of the first bone attachment device  20  is brought in an end to end abutting relation with a suitable portion of the orthopedic appliance, and the sleeve clamp  76  is positioned so as to substantially surround the main body  22  and a section of the artificial bone portion, and the key  82  is engaged, if it is to be used. The sleeve clamp  76  is then enhanced in a substantially secured relation by tightening the retention screws  80 . 
     In the situation where two compliant bone fixation devices are used in connection with a first remaining bone portion  12  and a second portion  14 , which is in the form of a second remaining bone portion of the same or a different bone, the above steps for creating and positioning the first bone attachment device  20  upon the first remaining bone portion  12  are repeated in substantially identical form for creating and positioning a second bone attachment device (not shown) upon the second portion  14 . Alternatively, the second bone portion may be attached by a means not in accordance with this invention. In this arrangement, the second bone attachment device may be attached to an interposed orthopedic appliance, which is shown at  142  in  FIG. 12 . A sleeve clamp  76  as shown in  FIGS. 5 and 6  or other connecting means is positioned upon either of the main body  22  of the first bone attachment device  20  or the interposed orthopedic appliance  142 . The main body  22  of the first bone attachment device  20  is then brought in an end to end abutting relation with the interposed orthopedic appliance  142 . The sleeve clamp  76  is then positioned so as to substantially surround a portion of both the main body  22  and the interposed orthopedic appliance  142 , and is tightened as before. 
     In the situation where it is necessary to provide for the attachment of external appliances following amputation, the steps of this method are provided with reference to  FIG. 13 . The components of the first bone attachment device  20  are substantially assembled, as before. A percutaneous bar  150  is positioned in an abutting relation to the main body  22  and the sleeve clamp  76  is secured as before. In this procedure, the skin  152  is repaired to substantially surround the percutaneous bar  150  at the end of the surgery, so that the percutaneous bar  150  is operable to extend through the repaired skin section for subsequent connection to an external appliance. 
     A second embodiment of the present invention will now be described with reference to  FIGS. 15-25 . Referring now to  FIG. 15 , there is shown an elevational view with partial breakaway illustrating the environment of a second embodiment of the apparatus of the present invention.  FIG. 15  shows a bone attachment assembly  200  in an implanted condition within a remaining bone portion  202  following resection. The first remaining bone portion  202  is shown to be in the form of a resected femur, although it will be appreciated that the present invention may be used with other bones as well. The bone attachment assembly  200  is suitable for being connected to a second remaining bone portion, an orthopedic appliance connected to a second remaining bone portion, an orthopedic appliance serving as a complete bone replacement, a percutaneous bar suitable for the attachment of an external appliance or any other suitable device. Therefore, it will be appreciated that the apparatus of the present invention may be used as part of a replacement for a long bone diaphysis or may be used in another portion of any suitable bone. As before, any second remaining bone portion to which the bone attachment assembly  200  may be connected may be a portion of the same bone as the first remaining bone portion  202 , or may be a portion of another bone. 
     The first remaining bone portion  202  is shown to include a first intramedullary cavity  204 . The first intramedullary cavity  204  may preferably be a longitudinal bore that includes of at least a portion of the natural intramedullary cavity of the bone. Alternatively, the first intramedullary cavity  204  may be a bore created in any suitable section of bone, such as within or across a proximal section of a femur. In any arrangement, the first intramedullary cavity  204  is created within the bone to a preselected depth from a cut bone surface or the natural external bone surface. This preselected depth preferably corresponds to the expected depth of insertion of a portion of the bone attachment assembly  200  within the bone. 
     In the version of the second embodiment of the present invention shown in  FIG. 15 , the first intramedullary cavity  204  is an enlarged natural intramedullary cavity of the bone. The first intramedullary cavity  204  thus substantially coincides in its longitudinal axis with that of the natural intramedullary cavity of the bone. The bone attachment assembly  200  may also be inserted within the natural intramedullary cavity of the bone, without further enlargement, where suitable. 
     The bone attachment assembly  200  is constructed of a suitable biocompatible material, such as those previously described. It will be appreciated that all of the materials set forth in the second embodiment herein may be made from the same materials as previously described or any other suitable materials. The bone attachment assembly  200  includes a main body  206  that is substantially cylindrically-shaped, and can be operable to be positioned upon a surface of the first remaining bone portion  202 . To provide means for contacting a bone surface in a special relation, the main body  206  may include a special configuration or extension, such as a shoulder portion  208 . The surface of the first remaining bone portion  202  which contacts the bone attachment assembly  200  may be a cut bone surface, a natural external bone surface, or a specially configured bone surface, such as milled end portion  210 . Although the milled end portion  210  is shown in a convex conical geometry, it will be appreciated that any suitable geometry may be used. The main body  206  preferably includes an interface surface  212  for abutting against a surface of the first remaining bone portion  202 . The interface surface  212  may be formed in any desired configuration upon the main body  206 , the shoulder portion  208  where present, or both. Suitable configurations for the interface surface  212  include geometries corresponding to geometries naturally occurring or formed upon the bone surface, including planar, concave, convex, concave conical and convex conical. In one aspect, geometries for the interface surface  212  are selected from those that can maximize the advantages of maintaining desired contact, pressure and centering with relation to the bone surface. The concave conical arrangement shown in  FIG. 15  is an exemplary geometry. It will be appreciated, however, that other suitable geometries may be used, which may include grooves, pins or any other features as may be desirable. 
     As shown in  FIG. 15 , the bone attachment assembly  200  further includes an extension  214  connected to the main body  206 . The extension  214  is configured in a male tapered arrangement for connection with any of the devices or remaining bone portions mentioned above. The extension  214  may be connected to or may be integrally formed with the main body  206 . It will be appreciated that the extension  214  may also include any suitable configuration for facilitating attachment to any device or bone portion mentioned above. It will further be appreciated that the main body  206  and the extension  214  may replace a portion of the length of bone being removed during the surgical procedure, by virtue of their position upon the milled end portion  210  of the first remaining bone portion  202 . The extension  214  may include one or more configured surfaces for engagement of one or more devices or appliances. As shown in  FIGS. 15-17 , this may include one or more engagement recesses  215 . 
     When the bone surface contacting the bone attachment assembly  200  is a cut surface of a long bone diaphysis, a milled end portion  210  can be created in a preselected geometry relative to the first intramedullary cavity  204 , as described previously. A specially configured bone contact surface, of any type, which may be similar to the milled end portion  210  shown in  FIG. 15 , may also be prepared upon any suitable section of bone. In one arrangement, shown in  FIG. 15 , the milled end portion  210  is formed to an axisymmetric geometry, and most preferably to a convex conical geometry, whose cross-section has a preselected included angle of inclination relative to the longitudinal axis in the direction of the first remaining bone portion  202 . This same principle can be translated to the formation of any bone contact surface on any section of bone, especially where it is desirable to obtain certain advantages of contact described above. It will therefore be appreciated that other preselected geometries and angles may also be used. The geometry of the interface surface  212  is most preferably constructed to substantially match the geometry of the milled end portion  210 , thereby providing a substantially flush interface between the milled end portion  210  and the interface surface  212 . The interface surface  212  can be operable for accepting biological bone attachment by bone ingrowth and/or ongrowth. The interface surface  212  may also enhance stability of the main body  206  with respect to the bone. Thus, the interface surface  212  may include a suitable coating or other surface treatment, as well as ridges or undulations for this purpose. 
     To provide means for anchoring the bone attachment assembly  200  in a substantially stationary position within a cavity of the first remaining bone portion  202 , an anchor body  216  is provided. The anchor body  216  is disposed at the distal end of the bone attachment assembly  200  relative to the main body  206 . The anchor body  216  can be sized and located relative to the main body  206  to be disposed within the first intramedullary cavity  204  at its distal end when the bone attachment assembly  200  is placed within and upon a bone. The anchor body  216  includes one or more apertures  218  that are operable for accepting the insertion of one or more fixation devices. The apertures  218  may preferably be a plurality of staggered apertures of substantially the same preselected diameter. One possible staggered arrangement for the apertures  218  is the arrangement shown in  FIG. 15 . It will be appreciated, however, that any suitable arrangement for the apertures  218  may be used, including those wherein the apertures  218  are in perpendicular or other non-parallel arrangement. The apertures  218  may also be of any suitable number and size. 
     To provide a passageway for the insertion of suitable engagement devices to engage the anchor body  216 , one or more fixation bores  220  are created through the first remaining bone portion  202 . The fixation bores  220  are preferably sized and located to substantially correspond to the size and location of the apertures  218  located within the anchor body  216 . As such, the fixation bores  220  may also preferably be a plurality of staggered bores created through the first remaining bone portion  202 . 
     The bone attachment assembly  200  also includes one or more engagement devices that are operable to provide an engagement between the anchor body  216  and the first remaining bone portion  202 . The engagement devices enhance a substantially secured relation of the anchor body  216  within the first intramedullary cavity  204 . In the embodiment shown in  FIG. 15 , the selection of engagement device is one or more transverse pins  222  operable for being inserted through one or more fixation bores  220  on at least one side of the anchor body  216 , and also through one or more apertures  218  disposed across the anchor body  216 . Most preferably, a plurality of transverse pins  222  are inserted through the apertures  218  and the fixation bores  220  on both sides of the anchor body  216 . Although the transverse pins  222  may be disposed in a substantially parallel relation as shown, it will be appreciated that the transverse pins  222  may be disposed in other preselected directions and at other angles as the apertures  218  and the fixation bores  220  may be disposed. As before, it will be appreciated that the selection of engagement device may also be one or more interlocking screws or other suitable devices. In addition, the engagement devices may be inserted from opposite sides of the anchor body  216 , as before. 
     The bone attachment assembly  200  of the present invention exhibits a preselected state of compliance that is retained in the implanted condition of the assembly. Furthermore, the bone attachment assembly  200  in an implanted condition applies a force across the milled end portion  210  which maintains interface stability. The force applied by the compliant section  224  in an expanded condition is generally in the range of from about 100 lbs. to about 1000 lbs. A typical amount of force applied is 400 lbs. Upon implantation, this force is distributed across the area of the bone surface, represented by the milled end portion  210 . It will be appreciated the desired amount of force exerted will vary from application to application, and will depend upon the size of bone involved and the cortical wall thickness and may depend upon other features of the bone or the patient. Preferably, this involves loading the bone attachment assembly  200  to a condition of expansion prior to implantation. To provide means for allowing the bone attachment assembly  200  to exhibit a condition of compliance, the bone attachment assembly  200  includes a compliant section  224 . The compliant section  224  is disposed between the main body  206  and the means for anchoring the bone attachment assembly  200 . The compliant section  224  can be an elongated bar or rod that is an integrally formed extension between the main body  206  and the anchor body  216 . Alternatively, the compliant section  224  may take on any suitable construction where the compliant section  224  is manufactured separately from the main body  206  and the anchor body  216 , and assembled or attached after the individual components are manufactured, or during the surgical procedure. This may include a modular system of like or differing materials, and can include a traction rod attached to the compliant section  224 , where the traction rod itself is compliant relative to the bone, such that it contributes to the compliance of the system. The compliant section  224  may preferably be of a cylindrical shape having a diameter equal to or greater than the anchor body  216 . In this arrangement, the compliant section  224  and the anchor body  216  fit snugly within the first intramedullary cavity  204 . The bone attachment assembly  200  can be preloaded prior to implantation by expanding the compliant section  224  alone to a preselected condition of expansion, according to the forces desired as allowed by the elastic properties of the compliant section  224 . It will be appreciated, however, that the means for allowing the bone attachment assembly  200  to exhibit to a condition of compliance may take on any other suitable form. For example, the bone attachment assembly  200  may include more than one compliant section or may include a compliant section disposed in a different configuration or at a different location upon the bone attachment assembly  200  as may be desirable for accomplishing particulars of compliance or attachment. Also, it will be appreciated that the loading of the bone attachment assembly  200  can be accomplished in any suitable manner prior to, during or after implantation. The compliant section  224  is maintained in a condition of expansion following implantation by securing the anchor body  216  at a preselected location within the first intramedullary cavity  204  during a maintained expansion of the compliant section  224  while the milled end portion  210  abuts the interface surface  212 . 
     In a state of expansion during an inserted condition within a bone, the compliant section  224  is operable for experiencing expansion and contraction in response to physiological expansion and contraction in the adjacent bone. Thus, one function of the bone attachment assembly  200  involves the expansion and contraction of the compliant section  224  as necessary to allow the substantial transfer of physiologic loads through the surrounding bone, rather than through the implanted device. The compliant section  224  can be formed as an elongated extension that is made compliant to the desired degree and with the desired characteristics. Various configurations for accomplishing the compliance of any compliant section  224  discussed herein include perforation into the shape of a single or double helical spring, or springs in the shape of an accordion, although it will be appreciated that any suitable perforated configuration for any compliant section discussed herein may be used. The configuration shown in  FIGS. 15-17  is a single helical spring configuration. Such configurations allow the compliant section  224  to expand and contract as a coil spring. The number of turns, the inner diameter of the spring, the outer diameter of the spring, the size of each turn and the angle of each turn of the spring configuration in the compliant section  224  can be manipulated as desired to achieve a specific load, a specific spring rate and a specific deflection capacity. It will be realized that in other arrangements, other suitable non-helical configurations or perforations or other features may be used for the compliant section  224 . The present and other embodiments of the present invention are advantageous because they provide compliant fixation through an integrally formed apparatus. 
     An advantage of the bone attachment assembly  200  of the present invention involves the method by which the compliant section  224  is made. The stock from which the bone attachment assembly  200  is made is first machined to a desirable shape by methods well known to those skilled in the art. The portion of the assembly that is in the form of an elongated bar or rod is then perforated or cut into a configuration that will result in a compliance in this section of the assembly. The perforation or cutting may be accomplished by electrical discharge machining (EDM), which involves the use of a material that conducts electricity to remove material to form desired shapes in another material by using electric spark to remove pieces of the material. This process is applied to the elongated bar or rod portion of the bone attachment assembly  200  to form perforations of a desired shape, such as a helical spring arrangement, directly therein. Typically, a brass wire of a thickness ranging from about three thousandths of an inch to about sixteen thousandths of an inch is used to form the desired perforations. A brass wire of about twelve thousandths of an inch is one common wire used. It will be appreciated that this process may be accomplished using other material selections, configurations and sizes for the material used to create the perforations. 
     In the method of the present invention, the perforations in the elongated bar or rod are made by contacting a cutting wire with a surface of the elongated bar or rod, or by drilling an aperture into the bar or rod into which the cutting wire may be inserted. Where the cutting wire contacts the external surface of the elongated bar or rod, a single helix is formed. Where the cutting wire is inserted into an aperture formed within the elongated bar or rod, a double helix is formed. An aperture may also be created longitudinally through the elongated bar or rod as well. Where the cutting wire contacts the external surface of the elongated bar or rod, the cutting is accomplished by turning the bar or rod and feeding the wire at an angle suitable for the desired shape of cut. Where the cutting wire is inserted into an aperture formed within the elongated bar or rod, the cutting is accomplished by turning the bar or rod and feeding the wire into the material. The speed at which the wire is fed along the bar or rod relative to its speed of rotation determines the configuration of the resulting perforation, such as the pitch of a helical spring being created. It will be appreciated that the selection of base material and cutting material, the angle of cutting, the inside and/or outside diameter of the bar or rod, the length of cutting and other particulars of the cutting process may be varied to adjust the characteristics of the spring being created. Alternatively, other methods may be utilized to form a spring within the elongated bar or rod portion of the bore attachment assembly  200 . These include water jet cutting, blade cutting and laser cutting, as well as other methods that those skilled in the art will appreciate. 
     As mentioned previously, the bone attachment assembly  200  can be loaded to a condition of expansion prior to completion of the surgical procedure. The condition of expansion is an amount of expansion sufficient to assure adequate interface compression force between the milled end portion  210  and the interface surface  212  upon completion of the surgical procedure. This is accomplished by converting the compliant section  224  to a preselected condition of expansion, before, during or after the anchor body  216  is inserted into the first intramedullary cavity  204 . To provide means for converting the compliant section  224  to a condition of expansion, the present invention provides multiple methods. In one method, a preloading rod  250  is operable to expand the compliant section  224  by engaging the bone attachment assembly  200  on both sides of the compliant section  224 , and forcing the two sides of the assembly in opposite directions. As shown in  FIGS. 16 and 17 , the preloading rod  250  is sized for insertion within an elongated bore  252  disposed through the extension  214 , the main body  206 , the compliant section  224  and into the anchor body  216  to a depth proximal of the apertures  218 . To provide means for engaging the preloading rod  250  with the bone attachment assembly  200 , the preloading rod  250  includes a threaded portion  254  that may be threaded into a threaded bore  256  located at the proximal end of the bore  252 . The preloading rod  250  is of a greater length than that of the bore  252  so that the portion of the preloading rod  250  distal to the threaded portion  254  may be inserted to or almost to the complete length of the bore  252 . Once this distal portion of the preloading rod  250  is inserted into the bore  252 , the distal end of the preloading rod  250  engages the distal end of the bore  252 . Once the preloading rod  250  contacts the distal end of the bore  252 , any further advancement of the preloading rod  250  will cause an expansion of the compliant section  224 . Thus, subsequent threading of the threaded portion  254  into the threaded bore  256  causes the distal end of the preloading rod  250  to push against the distal end of the bore  252 , progressively forcing the distal end of the bore  252  in a distal direction, and causing the compliant section  224  to expand progressively as the threaded portion  254  is advanced into the threaded bore  256 . The preloading rod  250  further includes means for engaging a tool, such as a knob  258  at its proximal end for facilitating advancement of the preloading rod  250 . 
     An additional method is where the anchor body  216  and the main body  206  are in place, and a traction member extends from the compliant section  224  through the main body  206  and the extension  214 . A removable traction device applies a traction force to this traction member, thereby elongating the compliant section  224  and simultaneously applying an equal interface force across the interface surface  212 . When the desired force is achieved, a position-holding device is attached to the traction bar, preventing it from reassuming the non-expanded condition as traction is removed. A third method is to have an extension of a compliant section extending to or through an aperture of the main body  206 , the extension including a threaded portion at its proximal end. A threaded member can be advanced upon the threaded portion of the extension against the main body  206 , thereby causing the expansion of the compliant section  224  in a proximal direction. 
       FIG. 16  shows the bone attachment assembly  200  in a condition prior to insertion of the preloading rod  250 , with the compliant section  224  in a non-expanded condition.  FIG. 17  shows the bone attachment assembly  200  with the preloading rod  250  threaded fully into the bone attachment assembly  200 , with the compliant section  224  at an intermediate state of expansion. It will be appreciated that the preloading rod  250  may be threaded into the bone attachment assembly  200  to any desired degree. Preferably, the preloading rod  250  is used in the above manner to preload the bone attachment assembly  200  by expanding the compliant section  224  prior to implantation. The compliant section  224  will typically be expanded prior to implantation by an amount sufficient to assure adequate interface compression force upon removal of the preloading rod  250 . Once the bone attachment assembly  200  is inserted within the first intramedullary cavity  204  and the anchor body  216  is secured as described above, the subsequent dethreading of the preloading rod  250  and its withdrawal from the assembly will leave the compliant section  224  in a substantially maintained state of expansion. The expanded condition of the compliant section  224  is maintained in the implanted state by the abutment of the interface surface  212  against the milled end portion  210  in combination with the maintained stationary condition of the anchor body  216  by the fixation devices such as the transverse pins  222 . 
     Referring now to  FIG. 18 , there is shown a bone attachment assembly  200  according to the present invention in conjunction with a femoral prosthesis  270 . The femoral prosthesis  270  is shown to include an aperture  272  having a female taper substantially corresponding to the male taper of the extension  214 . Thus, the femoral prosthesis  270  can be press fitted upon the bone attachment assembly  200 . The femoral prosthesis  270  is typically used in reconstructive and limb salvage surgeries. It will be appreciated that the femoral prosthesis  270  is one of several types of devices which can be attached to the bone attachment assembly  200 . The femoral prosthesis  270  is shown to include an intercalary extension segment  274  and a femoral component  276 . It will be appreciated that any of the devices used for connecting the bone attachment assembly  200  can be made of one or more pieces or segments. The femoral prosthesis  270  is constructed of titanium alloy, although it will be appreciated that other suitable materials may be used. In addition, one or more surfaces of the femoral prosthesis  270  or any other attached device may include a coating or other surface treatment such as ridges or undulations, for promoting bone ingrowth and/or ongrowth, for enhancing stability, or for enhancing any other characteristic of the device. 
     Referring now to  FIGS. 19 and 20 , there is shown another version of the second embodiment of the present invention. In this version, a bone attachment assembly is shown generally at  280 . The bone attachment assembly  280  includes a main body  282  which includes a shoulder portion  284 . The main body  282  is further shown to include an interface surface  286 , which is of a concave conical geometry in similar fashion as before. In this version of the bone attachment assembly  280 , the main body  282  is shaped in a tapered configuration. 
     The bone attachment assembly  280  is further shown to include an anchor body  288  located at its distal end. The anchor body  288  is shown in this arrangement to include four apertures  290  for containing suitable fixation devices for fixation of the anchor body  288  to a surrounding remaining bone portion. As can be seen in  FIG. 19 , the apertures  290  are located in a square arrangement which is different from the staggered arrangement of five apertures discussed previously. It will therefore be appreciated that in any version of assembly discussed herein, any suitable aperture configuration may be used. 
     The bone attachment assembly  280  further includes a compliant section  292  which is an elongated section disposed integrally between the main body  282  and the anchor body  288 , in similar fashion as before. The bone attachment assembly  280  further includes an extension  294  which is generally of a male tapered configuration, and is suitable for direct attachment of a suitable orthopedic device, as before. The bone attachment assembly  280  also includes an elongated bore  296  that traverses the extension  294 , the main body  282  and the compliant section  292 . As before, the bore  296  is suitable for accepting the insertion of a rod (not shown) for expanding the compliant section  292  to a condition of expansion. The bone attachment assembly  280  also includes a threaded bore  298  disposed at the proximal end of the bore  296 . The bore  296  and the threaded bore  298  function in substantially the same way as the bore  252  and threaded bore  256  previously described. In the arrangement shown in  FIG. 19 , the compliant section  292  is in a non-expanded condition. 
     Referring now to  FIG. 21 , the bone attachment assembly  280  shown in  FIGS. 19 and 20  is shown in a preloaded condition. To provide means for loading the compliant section  292  to a condition of expansion, the present invention provides a preloading rod  302 , having a threaded portion  304  and a knob  306  in similar fashion as before. In this arrangement shown in  FIG. 21 , the compliant section  292  is shown to be in an expanded double helical configuration. This expanded configuration is the result of inserting the preloading rod  302  within the bore  296  and threading the threaded portion  304  within the threaded bore  298 , in similar fashion as before. 
     Referring now to  FIGS. 22 and 23 , there is shown the bone attachment assembly  280  described in connection with  FIGS. 19-21 , in an implanted condition within a proximal femur  308 . In this arrangement, a femoral head prosthesis  310  is shown to be press fitted upon the extension  294 . Referring now to  FIG. 23 , it can be seen that a plurality of transverse pins  312  are used to maintain the anchor body  288  in a substantially stationary position within a cavity  314  disposed within the proximal femur  308 . It will be therefore appreciated that the bone attachment assembly of the present invention can be used within other portions of bone besides an intramedullary cavity. 
     Referring now to  FIGS. 24 and 25  there is shown another version of bone assembly according to the present invention at  380 . The bone assembly  380  includes a main body  382 , a compliant section  384  and an anchor body  386 , formed in a cylindrical arrangement. The anchor body  386  includes threads  388  for engaging the walls of a cavity within a bone, such as the first intramedullary cavity  204  or a cavity created within a bone. In the version shown in  FIGS. 24 and 25 , the bone assembly  380  is fitted with a tibial tray  390  that is attached to the main body  382  via a post  392  threaded into the threaded bore  394  located within the main body  382 . The tibial tray  390  is operable to engage a prepared tibial surface, another tibial surface or a device attached to a tibia. The bone assembly  380  is thus operable to be engaged within a bone cavity via threads  388  so that any attachment, such as the tibial tray  390  may engage the bone at another surface. It will be appreciated that a tibial tray attachment is only one of several arrangements for this version of the present invention. 
     The compliant extension  384  can be expanded to a desired condition of expansion after the bone assembly  380  is threaded into a bone cavity by any suitable device. One possible device utilizes the threaded bore  394  to pull the main body  382  in a proximal direction using a tibial surface, another bone surface or a device mounted upon a tibial surface or other bone surface as a reference. In another arrangement, shown in  FIG. 25 , a hexagonal headed screw  396  is recessed within the tibial tray  390  and can be dethreaded with a suitable tool within a stem of the tibial tray  390 . Alternatively, the compliant section  384  can be expanded to a desired condition of expansion prior to implantation, using a preloading rod or other preloading device, as previously described. Alternatively, a traction rod can extend from the compliant section  384  and the traction applied to the traction rod with counterforce applied against the tibial tray  390  expands the compliant section  384  to the desired amount. A locking member is then advanced on the traction rod down against the tibial tray  390 , preventing re-contraction of the compliant section  384 . The traction is then removed from the traction rod, leaving residual expansion of the compliant section  384  and a state of compression at the interface between the tibial tray  390  and the bone. 
     Referring now to  FIG. 26 , there is shown another version of the second embodiment of the present invention. In this version, the bone attachment assembly, designated as  400 , is in a modular form. The bone attachment assembly  400  includes a main body  402  having a shoulder portion  404  and an interface surface  406 . A porous coating  407  is disposed upon the interface surface  406  in this version of the invention. The porous coating  407  can be a titanium particle plasma spray. Alternatively, other suitable porous coating materials may be used, including sintered cobalt beads and titanium fibermesh pads. The porous coating  407  is operable to promote bone ingrowth and/or ongrowth and is operable to enhance the engagement of the main body  402  with the bone interface. The porous coating  407  is shown to be formed with a plurality of ridges  408 . These ridges  408  further enhance the engagement of the main body  402  with the bone interface, and increase the surface area for bone ingrowth and/or ongrowth. It will be appreciated that any of the versions of the device discussed herein may include a porous coating of this type. An extension  409  is attached to the main body  402 , which is generally of the same configuration as previously described. In this version, the main body  402  includes a plurality of recesses  410  in similar fashion to the recesses  215  described in connection with  FIGS. 15-17 . Here, however, there are eight recesses  410  disposed about the main body  402  approximately 45° apart. 
     The bone attachment assembly  400  includes an anchor body  412  having a plurality of apertures  414  for securing the anchor body  412  within a bone cavity. The anchor body  412  is shown here to be a separate component that includes a threaded recess  416  for connection to the remainder of the assembly. The bone attachment assembly  400  includes a compliant section  418  in the form of a helical spring, in similar fashion as before. The compliant section  418  includes a threaded post  420  that is operable for connection to the anchor body  412  by being threaded into the threaded recess  416 . 
     In this version, the bone attachment assembly is implanted by first inserting the anchor body  412  into the bone cavity, such as the first intramedullary bone cavity  204  described in connection with  FIG. 15 . The anchor body  412  is substantially secured in place by any of the methods described herein. The milling of the end of the bone is then performed, using the anchor body  412  to help establish an axis. The compliant section  418  is expanded with an expansion bolt. The assembly is then inserted into the bone cavity. The main body  402  is then rotated so as to thread the threaded post  420  into the threaded recess  416 . As this is done, the engagement of the interface surface  406  with the bone interface surface eventually occurs, and further advancement of the threaded post  420  into the threaded recess  416  is not possible. This occurs before the shoulder of the threaded post abuts against the anchor body  412 . The expansion bolt is then removed. 
     As shown in  FIG. 26 , a sizing ring  422  is operable to be disposed upon the bone attachment assembly  400 . The sizing ring  422  is operable to effectively enlarge the diameter of at least a portion of the bone attachment assembly  400  that is inserted within a bone cavity. The sizing ring  422  also assists in centering the bone attachment assembly  400  with respect to the bone. The sizing ring  422  is therefore disposed upon the bone attachment assembly  400  in situations where at least a portion of the bone assembly  400  is smaller than at least a portion of the bone cavity in which it is to be disposed. The sizing ring  422  can be a cylindrical tube of internal diameter that is approximately equal to the external diameter of the anchor body  412  and the compliant section  418 . The sizing ring  422  is operable to be slid upon the anchor body  412  and the compliant section  418  up to the point where it contacts the interface surface  406 . Alternatively, the sizing ring  422  may be disposed upon any suitable section of the bone attachment assembly  400 . 
     The sizing ring  422  includes an inner surface  424  that preferably engages snugly against the external surface of the elongated bar making up the anchor body  412  and the compliant section  418 . The sizing ring  422  may preferably include a split  426  at which the sizing ring  422  may be slightly enlarged to facilitate its positioning upon the bone attachment assembly  400 . The sizing ring  422  can be made of a titanium alloy, such as Ti-6Al-4V, although it will be appreciated that any suitable material may be used. It will also be appreciated that the sizing ring  422  may take on other suitable shapes and sizes as may be desirable for assisting in centering the bone attachment assembly  400  with respect to the bone, and in enlarging the effective size of the bone attachment assembly  400 . 
     It will be appreciated that in this procedure, the order of steps may be altered without departing from the invention. For example, in the procedure described above in connection with  FIG. 26 , the proximal bone surface may not be milled until after the insertion of the anchor body  412  within the bone cavity. In addition, the anchor body  412  may be secured within the cavity by threading it directly into the cavity, in similar manner as that described in connection with  FIG. 24 . 
     In the method of this embodiment of the present invention, a bone is prepared by cutting or other removal or shaping of bone surfaces through methods well known to those skilled in the art. A suitable bone cavity is prepared along the natural intramedullary canal of the bone or through any other region of bone through methods well known to those skilled in the art. One or more suitable engagement surfaces are prepared for the engagement of the components of the device discussed herein, including any special geometries, by methods well known to those skilled in the art. Where desired, suitable fixation bores are created through the bone, also by methods well known to those skilled in the art. 
     The compliant section of any version of the bone attachment assembly described above is converted to a preselected condition of expansion. Where it is desirable that this be done prior to implantation, means for loading the compliant section to a condition of expansion, such as the preloading rods and other devices discussed herein, are used to expand the compliant section. This may include expanding the compliant section to the degree where the apertures through an anchor body will be aligned with fixation bores disposed within the bone or with another suitable reference. This can include inserting the rod described above into the bore of the bone attachment assembly and engaging the rod with a portion of the bone attachment assembly, such as threading a threaded portion of the rod into a threaded portion of the bore, thereby expanding the compliant section to a preloaded condition. The bone attachment assembly is then implanted within a cavity within the bone. Once the preloaded bone attachment assembly has been inserted within the bone, the means for anchoring the bone attachment assembly is secured in a substantially secured relation and the rod is disengaged from the bone attachment assembly and removed. Where expansion of the compliant section is performed following insertion within a bone cavity, the insertion process is performed by threading or otherwise, and the expansion of the compliant section is then performed by utilizing a suitable expansion device. The bone attachment assembly is then secured in place, with the compliant section in expansion. 
     It will be appreciated that several of the components described herein can be made in an integral fashion, or may be formed as separate components that can be threaded or otherwise attached. Additionally, the compliant section in each version can be formed in different configurations and having different perforations of predefined configurations to achieve certain desired results in terms of load, spring rate and deflection. It will be appreciated that the principle of compliant fixation set forth herein can be used in conjunction with any type of bone by varying the sizes and configurations of the components without deviating from the invention. Thus, it will be appreciated that the present invention may be used with any large bone of the body, including a femur, tibia, bones about the elbow and ankle, a finger, a toe or at other suitable anatomical locations where an anchoring device with compliant fixation is desired. In addition, it should be recognized that this principle of compliant fixation may also be useful in other applications, such as in a cabling technique. 
     Referring now to  FIGS. 27-31 , there is shown a first version of a third embodiment of the present invention. In this embodiment, the bone attachment assembly is provided with a sleeve for inhibiting tilting of the compliant section of the assembly in a non-axial direction. This sleeve can be an integral extension connected to the main body of the assembly. The bone attachment assembly also includes several additional variations of anchor bodies, which may be secured within a remaining bone portion in different ways. In addition, in this embodiment, the compliant section is provided as an integral extension upon the anchor body. 
       FIG. 27  is an exploded elevational view of a bone attachment assembly, generally at  500 , in a modular form. The bone attachment assembly  500  includes a main body  502  having a shoulder portion  504  and an interface surface  506 , in similar manner as before. The interface surface  506  is shown to be disposed at an angle relative to the longitudinal axis of the main body  502 . When the interface surface  506  is so angled relative to the longitudinal axis of the assembly, the main body has the ability to become radially constrained against a remaining bone portion upon installation. It will be appreciated, however, that the interface surface  506  may be disposed at any other suitable angle, including a right angle, relative to the longitudinal axis of the main body  502 . 
     The main body  502  includes a cylindrically shaped sleeve  508  disposed as an integral extension upon the lower surface of the main body  502 . The sleeve  508  includes a recess  510  of a generally cylindrical shape that can be operable for containing a substantial portion, or the entire portion, of the compliant section discussed below. The inside diameter of the recess  510  can be slightly greater than the outer diameter of the compliant section and anchor which it is designed to contain, so that the main body  502  and compliant section are free to move in an axial direction relative to one another, but are substantially constrained in their abilities to move or angulate in non-axial directions relative to one another. The recess  510  can be only slightly greater in inside diameter than the outer diameter of the compliant section. It is believed that reducing non-axial deformation of the compliant section of the assembly enhances performance by reducing movements and tilting of the main body relative to the remaining bone portion after implantation. 
     The main body  502  and the sleeve  508  are shown in  FIG. 27  to be coaxial, although this need not be the case. It will therefore be appreciated that any bone attachment assembly set forth herein may utilize a non-coaxial configuration between the main body and sleeve. In such arrangements, it will be appreciated that the interface surface, such as  506 , may be disposed at any suitable angle relative to the sleeve, such as  508 . 
     The main body  502  also includes an extension  512  for attachment to any suitable device, including an artificial limb, an intercalary segment or an opposing main body of an opposing bone attachment assembly or an articular component. The extension  512  is shown to be of a truncated conical configuration, although it will be appreciated that any suitable connection shape may also be used. An aperture  514  is disposed through the main body  502  and extension  512 , opening into the recess  510  at its far end. A recess  516  is also provided at the near end of the extension  512 , opening into the aperture  514 . Together, the recess  510 , the aperture  514  and the recess  516  provide a specially-configured continuously hollow interior designed to accept the insertion of, and interact with, those additional portions of the assembly that allow the assembly to apply interface pre-stress and exhibit compliance in the implanted condition. It will be appreciated that the various configurations and versions of this embodiment of the present invention will allow this general principle to be adjusted to any configuration necessary to accomplish this desired result. Accordingly, it will also be appreciated that various combinations of assembly components may be used to accomplish the compliant result in this embodiment, and that different components may be substituted throughout to achieve this end. For example, in one version discussed below, the recess  510 , aperture  514  and recess  516  cooperate to allow the insertion of a traction rod integrally formed with a compliant section of the assembly. A nut or other engagement device inserted within the recess  516  operates to secure the traction rod relative to the main body of the assembly. It will be appreciated that the axis of the sleeve  508  may be the same as or may differ from the axis of the extension  512 . 
     The bone attachment assembly  500  also includes an anchor body  520 . The anchor body  520  is shown to be formed at its far end in the shape of a hemisphere for ease of insertion. It will be appreciated that other suitable shapes which forward any advantage, including ease of insertion and other advantages, may also be used. It is believed that hemispherical and tapered configurations generally tend to be more easily inserted into an enlarged intramedullary cavity of a remaining bone portion. The version of anchor body shown at  520  in  FIG. 27  is the type secured within an enlarged intramedullary cavity of a remaining bone portion by cross-pinning the anchor body  520  through the cortex of the remaining bone portion. Apertures  522  are provided for the passage of appropriate pins or other fixation devices through the anchor body  520 . Although four such apertures  522  are shown in  FIG. 27 , disposed about the perimeter of the hemisphere, it will be appreciated that any suitable number and configuration of apertures  522  may also be used. In addition, the apertures  522  may be angled, tapered, threaded or otherwise configured as appropriate to utilize any advantage of any chosen method of fixation through the bone cortex, including screws and expanding mechanisms. 
     The bone attachment assembly  500  also includes a compliant section  524 . In this embodiment, the compliant section  524  is provided as an integral extension connected to the anchor body  520 . This arrangement is believed to have advantages both in facilitating installation and in performance. In keeping with the modular nature of this assembly, however, it will be appreciated that the anchor body  520  may be releasably attachable to and from the compliant section  524 , such as through the use of a cooperating threaded portion and recess. The compliant section  524  can be of a cylindrical shape and sized for insertion within the recess  510 . The compliant section  524  may preferably be formed as a double helical structure, although it will be appreciated that other configurations, including a single helical structure and other spring-type structures, perforations, indentations and other configurations may also be acceptable. Also, the compliant section  524  may consist of a solid bar, if the material and dimensions of that bar render it sufficiently elastic such that it is more compliant than the section of bone between the interface and the anchor. Determination of a desired configuration for the compliant section  524  may depend on such factors as spring constant, degree of unwinding upon application of force (during installation loading or during subsequent operation), deflection of helices away from the axis with axial loading, and the relative radial positions of start and finish of the helices, or left-hand versus right-hand direction of helices, and choice of material. The compliant section  524  may preferably be formed by electron discharge machining or water jet cutting a cylindrical piece of material integrally formed with the anchor body  520 . Other suitable means may also be used. An aperture  526  is shown to run through the compliant section  524  and the anchor body  520 , which is believed to facilitate manufacture and function of the compliant section  524 , as well as reduce the overall weight of the assembly. 
     The bone attachment assembly  500  also includes means for applying traction to the compliant section  524 , which may also be described as means for converting the compliant section  524  to a condition of expansion. A traction rod  528  is disposed integrally as an extension from the near portion of the compliant section  524 . Engagement of the traction rod  528  in a suitable manner relative to the main body  502  converts the compliant section  524  to a desired condition of expansion during installation. In this version of this embodiment, the traction rod  528  is of a generally cylindrical configuration, and of a size suitable for insertion within the aperture  514 , and extending into the recess  516 . The traction rod  528  includes a threaded portion  530  at its near end for engagement with a suitable engagement device, such as a nut, described below. Since the traction rod communicates force to and from the compliant section  524 , engagement of the traction rod  528  relative to the main body (which engages the remaining bone portion) acts to apply traction to the compliant section  524 , and converts the compliant section  524  to a preselected condition of expansion. The amount of traction or expansion which may be applied to the compliant section  524  is intended to be limited to a preselected range or guided to a specific amount by certain configurations of the assembly and instrumentation design. As such, the compliant section  524  may be expanded to and beyond the elastic limit but not exceeding static ultimate stress. In a condition of expansion, the compliant section  524  has the ability to react elasticly to deflections in opposing axial directions, which is believed to be the desired reaction for a compliant implant device. It will be appreciated that the compliant section  524  may be adjusted in its degree of expansion as may be desirable to achieve the desired applied interface pre-stress forces in the implanted condition. This may be accomplished through several portions of the assembly, including the sizing of certain components and the selected degree of engagement between such components such as the traction rod  528  and the nut described below, and through the planned milling of bone which defines the distance between the step (described below) located upon the anchor body  520  and the interface surface of the remaining bone portion. 
     The anchor body  520  and compliant section  524  include several design features intended to facilitate working with the bone attachment assembly  500  in installation, adjustment and alignment. A step  532  is provided along the near surface of the compliant section  524 . This step  532  acts as a limit for expansion of the compliant section  524  against the interior end of the recess  510 . A step  534  is also provided about the near perimeter of the anchor body  520 . The step  534  provides an engagement surface for insertion tools and the like during installation of the anchor body  520 . The anchor body  520  also includes a notch  536  or other geometric irregularity that is specifically designed for engagement by an insertion and alignment tool to assure proper rotational alignment of the anchor body  520  during the creation of bony apertures used in the cross-pinning of the anchor body  520  within a remaining bone portion into which the anchor body  520  is inserted. It will be appreciated that other appropriate design features may be incorporated for facilitating installation, adjustment and alignment. 
       FIG. 28  is a top view illustrating the main body  502 , including the shoulder portion  504 , extension  512 , aperture  514  and recess  516 . In this figure, the shoulder portion  504  is shown to be of a generally elliptical configuration. It will be appreciated that any other suitable configuration for the shoulder portion  504  may also be used, including a circular configuration. It will also be appreciated that any of the components shown herein may suitably be manufactured in a non-coaxial configuration between the main body  502  and the sleeve  508 . The sleeve  508  may also be off-center relative to the shoulder portion  504 , regardless of the circular, elliptical or other configuration of the shoulder portion  504 .  FIG. 29  is an elevational side view of the anchor body  520 , compliant section  524 , and traction rod  528 , shown in  FIG. 27 . In this side view, 90□ removed from the side view shown in  FIG. 27 , the configuration of the apertures  522  through the anchor body  520  can be seen. 
       FIG. 30  is a partial cross-sectional view of the bone attachment assembly  500  in partially assembled form. In this illustration, the traction rod  528  is shown to be inserted within the aperture  514 . The compliant section  524  is also shown to be inserted within the recess  510 . Once the anchor body  520  is secured within a remaining bone portion such as by cross-pinning, and the end of the remaining bone portion is optionally milled as desired, the bone attachment assembly  500  is assembled to the form shown in  FIG. 30 . In this form, traction can be applied to the traction rod  528  at the threaded portion  530  in order to apply traction to the compliant section  524  and convert the compliant section  524  to a desired condition of expansion. 
       FIG. 31  illustrates this version of bone attachment assembly  500  in assembled form and installed within a proximal femur, prior to converting the compliant section  524  to a degree of expansion. Specifically, the bone attachment assembly  500  is shown to be inserted within a prepared cavity  538  of a remaining bone portion  540 . The prepared cavity  538  can be formed by reaming with a standard cylindrical reamer or any of the reamers set forth herein, although it will be realized that any suitable method may be used. The remaining bone portion  540  may be any human or animal bone, such as a human femur. Pins  542  are inserted through the cortex of the remaining bone portion  540  and through the apertures  522  in the anchor body  520 . It will be appreciated, however, that screws or any other suitable engagement devices may also be used. A nut or other engagement device (not shown) may be subsequently threaded upon or may otherwise engage the threaded portion  530  of the traction rod  528  within the recess  516 , against the interior end surface of the recess  516 , as means for engaging the traction rod  528 . In this arrangement, it can be seen that the forces applied to the compliant section  524  in opposing directions by virtue of the pins  542  securing the anchor body  520  to the cortex of the remaining bone portion  540 , combined with the subsequent engagement of a nut upon the threaded portion  530  and against the interior end surface of the recess  516 , will cause the compliant section  524  to be expanded and maintained in this condition. Thus, it can be seen that the design of the overall recess structure of the assembly allows for this communication of force to take place. The degree to which the compliant section  524  is expanded is based on how far the nut is threaded upon the threaded portion  530 , limited by the engagement of the step  532  with the interior end surface of the recess  510 . 
     The bone attachment assembly  500  may preferably be made of Ti-6Al-4V alloy, 17-4 PH stainless steel, Co—Cr—Mo alloy, 316 LVM stainless steel or any other suitable material. Certain components described herein may purposefully be made of a different material from other components where advantageous. Further, it will be appreciated that in any version of this embodiment, one or more of the various components may be altered in its size, shape and/or connectivity. Certain components of the bone attachment assembly of the present invention may be formed in a separate connecting fashion, rather than in an integrally formed fashion. For example, the threaded rod  528  may be a separately-formed component, attachable by threading or otherwise to the compliant section  524 . Also, the nut and threaded portion  530  may be replaced by any suitable engagement features that maintain the principle of maintaining the compliant section  524  in a desired degree of expansion through the application of opposing forces from opposing ends of the assembly (such as by securing the anchor body  522  with respect to the bone cortex and by securing the threaded rod  528  with respect to the main body  502 ). Additional examples of the variations possible for the bone attachment assembly of the present invention are discussed below. It will be appreciated that as a general matter, many characteristics of the components described with respect to any of the embodiments herein may be combined, adjusted, substituted and modified to create many different combinations of assemblies suitable for achieving the desired compliant fixation. 
       FIGS. 32 and 33  disclose a second version of the third embodiment of the present invention. Specifically,  FIG. 32  shows a bone attachment assembly generally at  600 , which includes a main body  602 , as before. In this version, however, the main body  602  is of a somewhat different configuration than the main body  502  described in  FIGS. 27 ,  28 ,  30  and  31 . The main body  602  includes a shoulder portion  604  with an inclined interface surface  602  that is angled relative to the longitudinal axis of the assembly. The shoulder portion  604  is configured in this version to have a near surface at approximately a right angle to the longitudinal axis of the assembly. As before, the shoulder portion  604  may take on any suitable shape, such as a circular shape or an elliptical shape, when viewed from above. The main body  602  also includes a cylindrically shaped sleeve  608  for reducing non-axial deformation of the compliant section discussed below when the bone attachment assembly  600  is in an assembled condition. A cylindrically shaped recess  610  extends through the sleeve  608  as before. In this version, however, the recess  610  also extends through the main body  602  and through a portion of the conically shaped extension  612  connected to the upper portion of the main body  602 . Thus, in this configuration, the recess  610  is able to accommodate insertion of a much longer portion of compliant section, if desired. As before, the extension  612  is operable for connection to any suitable appliance. 
     The bone attachment assembly  600  also includes an aperture  614  that is operable for allowing the passage of a traction rod in similar manner as before. A recess  616  is located within the near portion of the extension  612 , which opens into the aperture  614  in similar manner as before. The recess  616  again allows the insertion of means for engaging the traction rod in similar manner as before. In this arrangement, the recess  616  also includes a threaded portion  618  for facilitating a connection to any suitable external appliance. 
       FIG. 32  also shows an anchor body  620  that is formed in an elongated cylindrical configuration. The anchor body  620  includes apertures  622  in a staggered configuration for cross-pinning of the anchor body  620  within a remaining bone portion. A compliant section  624  is integrally formed with the anchor body  620  and may be formed in a single helix, double helix, or any other suitable compliant configuration, as discussed previously. In this arrangement, the anchor body  620  and the compliant section  624  can be configured to have substantially similar outer diameters. Alternatively, the outer diameter of the anchor body  620  may also be greater than the outer diameter of the compliant section  624 . A traction rod  628  is integrally formed upon the near end of the compliant section  624 , and contains a threaded portion  630  in a similar manner as before. 
     This configuration of bone attachment assembly also includes certain configurations intended to enhance the insertion and operability of the device. A step  632  is provided at the near end of the compliant section  624  as a stop against the near surface of the recess  610  when the bone attachment assembly  600  is in an assembled condition. Thus, the step  632  acts as a means for limiting the expansion of the compliant section  624 . A recess  634  is also provided to allow for the insertion of a sleeve, discussed below, surrounding the upper portion of the anchor body  620 , as a buffer between the anchor body  620  and the sleeve wall defined by the recess  610 . 
       FIG. 33  shows the bone attachment assembly  600  in an assembled condition and disposed within an enlarged intramedullary cavity  638  of a remaining bone portion  640 . In the installed configuration shown in  FIG. 33 , the anchor body  620  is substantially secured within the intramedullary cavity  638  through the use of pins  642  extending through the cortices of the remaining bone portion  640  and through the apertures  622  in the anchor body  620 . The compliant section  624  is in an expanded condition through the engagement of a nut  644  upon the threaded portion  630  of the traction rod  628  and engagement of the nut  644  against the interior base surface of the recess  616 . A sleeve  646  is disposed within the recess  634  for reducing contact between the compliant section  624  and the cylindrically shaped wall defining the recess  610 . The sleeve  646  may be made of any suitable material, such as a polymer material or bioresorbable material. It may also extend over the length of the compliant section  624 . An intercalary segment  648  is also shown to be disposed upon the extension  612 . It will be appreciated that the intercalary segment may be any suitable appliance. 
       FIGS. 34-36  are three elevational views illustrating three sizes of a threaded anchor body which is an alternate to the cross-pinned versions of anchor body shown at  520  and  620 . The threaded anchor bodies  700 ,  720  and  740  are each shown to be of a generally tapered configuration and include tapered helical cutting threads  702 ,  722  and  742 . The threaded anchor bodies  700 ,  720  and  740  may also be of a generally cylindrical configuration. The tapered helical cutting threads  702 ,  722  and  742  each include a plurality of notches  704 ,  724  and  744  which are disposed longitudinally across the helical threads, thereby giving them a cutting character. Accordingly, the threaded anchor bodies  700 ,  720  and  740  are self-tapping anchor bodies that can be directly threaded into an enlarged intramedullary cavity or otherwise prepared cavity of a remaining bone portion and secured in place without the cross-pinning used in previous versions of this embodiment. Each threaded anchor body is shown to be integrally formed with a compliant section  706 ,  726  and  746 . In similar manner as before, however, in keeping with the modular nature of the assembly, it will be appreciated that any of the threaded anchor bodies may be releasably attached to a compliant section, such as through the use of a cooperating threaded insertion portion and recess. Any of the compliant sections may be formed as a single helix, a double helix, or other suitable configuration. Also as before, the compliant sections  706 ,  726  and  746  are preferably formed by electron discharge machining or water jet cutting. 
     In this arrangement of threaded anchor bodies, the compliant sections  706 ,  726  and  746  each include a threaded recess  708 ,  728  and  748  for accepting a threaded screw of the type described in connection with  FIG. 38 . Apertures  710 ,  730  and  750  extend through the threaded anchor bodies  700 ,  720  and  740  as well as through the compliant sections  706 ,  726  and  746 , in similar manner as before. 
     This configuration of anchor body also includes certain configured surfaces to facilitate insertion, adjustment and securing of the threaded anchor bodies  700 ,  720  and  740 . A hexagonal engagement surface is provided on each threaded anchor body at  712 ,  732  and  752  to provide transmission of insertion torque. Alternatively, slots or tabs of any suitable configuration or other means may also be used as engagement surfaces. This surface is suitable for engagement by a correspondingly shaped hexagonal insertion tool that can be used to rotatably thread any of the anchor bodies into a secure position within an enlarged intramedullary cavity. Each threaded anchor body may also be provided with a step, at  714 ,  734  and  754  to provide an abutment surface for engagement of a suitable insertion tool. 
       FIG. 37  is a bottom perspective view illustrating the geometry of the tapered helical cutting threads  702  disposed upon the threaded anchor body  700 . It will be appreciated that this configuration is applicable to any sized threaded anchor body  700 ,  720  or  740 , and that the tapered helical cutting threads  702  are representative of any of the tapered helical cutting threads  702 ,  722  or  742 . The tapered helical cutting threads  702  are shown to be separated by specifically shaped notches or cutting flutes  704  that are designed to provide a cutting action for the arrangement. Between any two cutting flutes, the major radius R of the thread preferably remains constant. This is shown by the radii indicia at R 1 , R 2 , R 3  and R 4 . A jump in radius  ˜ R occurs for the cutting threads  702  at each cutting flute  704 . As such, as one follows a thread from the trailing margin of a cutting flute to the leading margin of the next cutting flute, the major radius of the thread does not change. As one crosses the cutting flute, there is a discrete increase in the thread radius. This change in thread radius need not be constant, however, among the various levels of the cutting threads  702 . For a conical shaped anchor body, however, the change in thread radius  ˜ R among cutting flutes  704  would generally be constant. It will be appreciated that this principle applies to a single, double or other multiple cutting flute arrangement and that any suitable shape for the notches or flutes  704  may be used. 
       FIG. 38  is an elevational view illustrating a threaded screw  760  that is suitable for being threadably inserted into the threaded recess  708 ,  728  or  748  in any of the threaded anchor bodies  700 ,  720  or  740 . The threaded screw  760  includes a head  762  having a recess  764  that is shown in a configuration suitable for engagement of a flat-bladed screw driver. It will be appreciated, however, that any suitable engagement means may also be used, including a hexagonal internal recess (such as for engagement of a hex key wrench) or a hexagonal external surface for engagement of a conventional-type socket wrench or similar tool. The threaded screw  760  also includes a threaded portion  766  at its opposing end. The threaded portion  766  is suitable for direct engagement within the threaded recesses  708 ,  728  or  748  of any of the threaded anchor bodies shown in  FIGS. 34-36 . An optional, preferably hemispherical, washer  768  is also provided below the head  762  for engagement within a suitable recess that is formed as part of a main body, extension portion or other suitable attachment forming part of the bone attachment assembly of the present invention. The washer  768  may be threaded upon the threaded screw  760 . 
       FIG. 39  is a partial cross-sectional view illustrating a third version of the third embodiment of the present invention. In this version, a threaded anchor body of the type shown in  FIG. 35  is used in combination with a main body of the type shown in  FIG. 27 , with a threaded screw of the type shown in  FIG. 38  included as a means for applying traction to the compliant section or means for expanding the compliant section to a preselected degree of expansion. 
     A bone attachment assembly is provided generally at  800  and includes a main body  802 . The main body  802  includes a shoulder portion  804  having an interface surface  806 , in similar manner as before. A sleeve  808  is disposed upon the main body  802 , and includes a recess  810 . An extension  812 , of a generally conical configuration, is disposed upon the near end of the main body  802 . An aperture  814  is disposed within the main body  802 , which opens into the recess  810 . A recess  816  is provided at the near end of the extension  812 , which opens into the aperture  814 , such that the recess  816 , the aperture  814 , and the recess  810  provide a passageway for insertion of a threaded screw  860 . 
     A threaded anchor body  820  is shown to be inserted within an enlarged intramedullary cavity  838  of a remaining bone portion  840 . The threaded anchor body includes tapered helical cutting threads  822  having notches  824 , in similar manner as before. The bone attachment assembly  800  also includes a compliant section  826 , integrally formed with the near end of the threaded anchor body  820 . A threaded recess  828  is provided at the near end of the compliant section  826  so that means for engaging the compliant section with respect to the main body, in the form of a threaded screw  860 , may be threadably inserted. An aperture  830  is disposed through the compliant section  826  and the threaded anchor body  820 , also as before. Engagement surfaces  832 , of different geometry than the hexagonal engagement surface previously described, and step  834  are also provided for engagement of this section of the bone attachment assembly  800  by a suitable tool. 
     Means for engaging the compliant section  826  with the main body  802  is provided in the form of a threaded screw  860  that is inserted through the aperture  814  and is threaded by its threaded portion  866  into the threaded recess  828 . The threaded screw  860  may preferably be of the type shown at  760  in connection with  FIG. 39 . As the threaded screw  860  is advanced into the threaded recess  828 , engagement of the head  862  against the interior end surface of the recess  816  causes expansion of the compliant section  826 , since the threaded anchor body  820  is retained in place within the remaining bone portion by the tapered helical cutting threads  822 . A recess  864  is provided upon the head  862  to facilitate tightening of the threaded screw  860 , as previously described. It will be appreciated that the threaded screw  760  shown in  FIG. 39  may also be used in conjunction with a recess, such as that shown at  828  in  FIG. 40 , as a means for expansion of the compliant section in any other embodiment described herein, such as in FIGS.  27  and  29 - 31 . 
       FIG. 40  illustrates a fourth version of the third embodiment of the present invention, wherein a standard tibial tray is used as an alternative attachment for any of the main bodies previously described. The tibial tray  870  includes a recess  872  that is operable for accepting the insertion of a threaded screw  874 , which may be a modified version of the screw  760  shown in  FIG. 38 . Of course, it will be appreciated that the length of the screw  862  may be adjusted to suit the particular need. The screw  862  may even be of excessive length so as to project into the compliant section and even into the anchor body  820 . The tibial tray  870  is shown to be attached to an integral anchor body  820  and compliant section  826  from the discussion accompanying  FIG. 39 , although it will be appreciated that any form of anchor body and compliant section, integrally formed or not, may also be used. In addition, the compliant section  826  may also be attached directly to the tibial tray  870 . 
     The method of using this embodiment of the present invention is discussed with reference to  FIGS. 41-47 . It will be appreciated, however, that in similar manner as before, different combinations of method steps are intended to be capable of substitution for use with any of the assembly embodiments described herein. In this embodiment of the method of the present invention, an intramedullary cavity or other cavity of a remaining bone portion is suitably prepared for containing any of the anchor bodies described herein. In the case of the cross-secured version of anchor body  520  or  620  described in connection with  FIGS. 27-33 , a standard cylindrical reamer (not shown) well known to those skilled in the art may be used. In those arrangements, however, where one of the threaded anchor bodies  700 ,  720  or  740  illustrated in  FIGS. 34-36  are used, specially-shaped reamers shown in  FIGS. 41-43  are preferably used. These reamers may also be used as an alternative with the cross-secured version of anchor body  520  or  620 . Three reamers of different sizes are shown in  FIGS. 41-43  at  900 ,  910  and  920 . Each reamer includes a shaft  902 ,  912  and  922  having graduated scale markings  904 ,  914  and  924  for identifying depth of insertion of the reamer. The shaft  902 ,  912  or  922  may be attached to any power drill or other suitable powered instrument, or may alternatively be powered by hand. A cutting end  906 ,  916  and  926  located at the far end of each reamer includes specially-shaped cutting surfaces  908 ,  918  and  928  that are designed to form a portion of an intramedullary cavity of a remaining bone portion to compliment the shapes of the threaded anchor bodies shown in  FIGS. 34-36 . The cutting surface  928  is shown to have a maximum diameter d representing the maximum diameter to which a cavity will be reamed using the instrument. Preferably, the diameter d is greater than or equal to the maximum thread diameter of the anchor body to be inserted within the aperture being reamed. This principle applies for all reamer sizes. 
       FIG. 44  shows a suitable method for preparing an intramedullary cavity  938  of a remaining bone portion  940 , for insertion of a threaded anchor body of the type shown in  FIGS. 34-36 . In the steps of this method of the present invention, the bone within which the bone attachment assembly of the present invention is to be inserted is first cut as desired. Cutting of the bone may involve the removal of diseased or defective bone portions, as appropriate. The bone is cut through methods well known to those skilled in the art, preferably at a 90□ angle relative to the longitudinal axis of the bone. It will be appreciated, however, that this angle of cutting may also be adjusted for several factors, including but not limited to the configuration of the natural intramedullary cavity of the bone, certain adjustments in the configuration of the main body, anchor body or compliant section of the bone attachment assembly (including non-coaxial configurations), or for other considerations. The remaining bone portion  940  may be a tibia or any other suitable bone portion. The resulting bone abutment surface  950  may optionally be subsequently milled through any suitable method discussed herein or other methods known to those skilled in the art. 
     The surgeon determines the desired width and depth for enlargement of the natural intramedullary cavity of the remaining bone portion  940  by first determining the size and configuration of the components of the bone attachment assembly to be used. This is accomplished through selecting, from those different trial sizes available, the appropriately sized and configured main body, tibial tray or other assembly component. Once the surgeon determines the amount of space to be taken by the chosen assembly component, a trial base plate  952  is selected for performing a reaming operation upon the natural intramedullary cavity of the remaining bone portion  940 . The trial base plate  952  is chosen to be of a size and configuration that will correspond to the selected attachment to be placed upon the bone abutment surface  950  when the bone attachment assembly as a whole is installed. The trial base plate  952  is temporarily pinned into a substantially stationary position for the reaming and plug insertion process, preferably with several ⅛″ pins that pass through the trial base plate  952  and into the bone, through methods well known to those skilled in the art. The trial base plate  952  includes a notched aperture  954 . A centering disc  956 , of a substantially circular configuration, includes a notched perimeter surface  958  that is intended to substantially correspond to the notched aperture  954  of the trial base plate  952 . In this arrangement, insertion of the centering disc  956  within the notched aperture  954  of the trial base plate  952  provides a removable and replaceable means for guiding a reaming operation. The centering disc  956  includes an angled aperture  960  that is of a generally conical configuration and is offset from a vertical configuration by an angle □ relative to the longitudinal axis of the natural intramedullary cavity of the remaining bone portion  940 . A possible selection for the value of the angle □ is 5□, although it will be appreciated that other suitable angle values may be used. The minimum internal diameter for the centering disc  956  is located at its far end, as the angled aperture  960  is angled away from the longitudinal axis in the near direction. The angled aperture  960  is configured in this way to allow for some freedom of angular movement during a reaming operation, while keeping the location of intersection between the reamer longitudinal axis and the trial base plate substantially unchanged. As such, the minimum internal diameter for the angled aperture  960  is located upon the far surface of the centering disc  956 , or at the desired level of said intersection. It will be appreciated that different diameters for the angled aperture  960  may be substituted by merely substituting differently sized centering discs  956 . Thus, in this arrangement, a variety of freedom of movement ranges may be achieved through the use of differently sized centering discs  956 . 
     In the reaming operation shown in  FIG. 44 , multiple graduated sized reamers, such as the ones shown in  FIGS. 41-43 , are used in a progressive manner to enlarge the natural intramedullary cavity of the remaining bone portion  940 , until the cortical bone is reached that is suitable for securing an anchor body of the types used in the present invention. The reamers are used, preferably from smallest to largest desired size, by placing the desired centering disc  956  upon the shaft of the particular reamer selected, and then reaming either using a powered device or by hand. In the illustration shown in  FIG. 44 , an intermediate-sized reamer  911  is used as a variation of the configuration shown for the intermediate reamer  910 . This reamer  911  has a cylindrical portion  917  corresponding to the design of the anchor body being used. The reamer  911  is shown to have a centering disc  956  placed upon its shaft  912  and positioned upon the notched aperture  954  of the trial base plate  952 . Powering of the reamer  911  either by hand or with power assisted equipment results in the formation of an enlarged intramedullary cavity, designated by the numeral  938  in  FIG. 44 . This operation is repeated through a progressively larger series of reamers until the desired size for the enlarged intramedullary cavity  938  is achieved. The graduated scale markings  915  are used to identify the desired insertion depth I for the reamer  911 . 
       FIG. 45  illustrates the installation of a threaded anchor body of the type shown in connection with  FIGS. 34-36 . For purposes of illustration, the anchor body  720  from  FIG. 35  is shown in the  FIG. 45  illustration. In this step of the method of the present invention, once the natural intramedullary cavity of the remaining bone portion  940  has been sufficiently enlarged, a threaded anchor body, such as that shown at  720 , is inserted into the enlarged intramedullary cavity  938 . With a trial base plate  952  in place upon the bone abutment surface  950 , a suitably sized centering disc  956  is placed upon the cannulated shaft  972  of an anchor inserter  970 . 
     The anchor inserter  970  is a device used for securing the threaded anchor body  720  in place within the enlarged intramedullary cavity  938  by rotatably threading it into place so that the tapered helical cutting threads  722  become secured within the cortex of the bone at the desired distance from the bone abutment surface  950 . The cannulated shaft  972  of the anchor inserter  970  includes an aperture  974  that is specially sized to a small diameter over the near portion of the cannulated shaft  972 , while being sized to a larger diameter over the far portion of the cannulated shaft  972 . The purpose for this configuration of the aperture  974  is to allow the cannulated shaft  972  to be inserted over the compliant section  726  of the threaded anchor body  720 . A hexagonal recess  976  located at the far end of the aperture  974  is sized and configured to engage the hexagonal engagement surface  732  of the threaded anchor body  720 . Rotation of the cannulated shaft  972  then accomplishes a rotating insertion of the threaded anchor body  720  within the enlarged intramedullary cavity  938 . Graduated scale markings  978  may preferably be disposed upon the cannulated shaft  972  for determining the desired insertion depth I of the threaded anchor body  720  by this device. A handle  980  is provided as part of the anchor inserter  970  to assist in rotation of the cannulated shaft  972  by hand. Alternatively, it will be appreciated that other configurations may also be used to assist in this insertion. 
     A positioning rod  982  is also provided for helping to maintain the desired positioning and attitude of the threaded anchor body  720  during the insertion procedure. The positioning rod  982  can also be used for extraction. The positioning rod  982  includes a shaft  984  having a threaded portion  986  at its far end. In the operation of this device, the positioning rod  982  is engaged with the threaded recess  728  of the threaded anchor body  720  through the threaded portion  986 . A knob  990  or other torque applying means is provided at the near end of the shaft  984  to facilitate gripping by hand. Preferably, the positioning rod  982  is threadably engaged to the threaded recess  728  so that the threaded anchor body  720  may be held in place during the rotation of the anchor inserter  970  that causes fixation of the threaded anchor body  720 . 
     In the use of the centering disc  956  in this step of the method of the present invention, the centering disc  956  may or may not be the same size of centering disc  956  used in connection with  FIG. 44 . As can be seen in  FIG. 45 , the centering disc  956  has an angled aperture  960  displaced in similar manner as before at an angle φ relative to the longitudinal axis of the remaining bone portion. The angle of offset represented by φ may or may not be the same as the angle □ described in connection with  FIG. 44  in the use of the reamer  911 . 
     The depth of insertion I for the threaded anchor body  720  is determined from a reading of the graduated scale markings  915  along the shaft  913  of the reamer  911  during the reaming operation. The threaded anchor body  720  is then advanced in an amount corresponding to the depth I read originally from the reamer  911  during the reaming exercise and matching the depth markings  978  along the shaft  972  of the anchor inserter  970 . Alternatively, it may be advanced a preselected number of turns after cortical engagement is noted. The threads  722  cut into the bone surface adjacent the enlarged intramedullary cavity  938  to a certain distance beyond the reamed distance, typically about 1 or 2 mm. The surgeon also notes the depth of the threaded anchor body  720  to determine the length of screw to apply to the compliant section  726  for expanding the compliant section  726  to the desired degree. The trial base plate  952  and centering disc  956  are then removed. 
     Referring again to  FIG. 39 , in the next step of the method of the present invention, the desired assembly component, such as the main body  802 , a tibial tray such as that shown at  870  in  FIG. 40 , or other suitable assembly component is then placed upon the remaining bone portion  840 . In the case where a tibial tray such as that shown at  870  in  FIG. 40  is used, the tibial tray  870  is merely placed onto the end of the remaining bone portion above the compliant section  826 . In the situation where a main body is used such as in  FIG. 39 , the main body  802  is positioned upon the remaining bone portion  840  such that the sleeve  808  is inserted within the enlarged intramedullary cavity  838  over the compliant section  826 . A screw, such as that shown at  864  in  FIG. 39 , is then inserted through the aperture  814  so that the threaded portion  866  may be threadably inserted into the threaded recess  828 . The threaded screw  860  is then advanced by a sufficient number of turns to expand the compliant section  826  to the desired amount. 
       FIG. 46  demonstrates the method of the present invention used for cross-securing, such as by cross-pinning, an anchor body of the types shown in connection with  FIGS. 27-33 , within an intramedullary cavity or other prepared cavity. In  FIG. 46 , however, this is illustrated as one possible variation in the configuration of the anchor body  520 . Specifically, the anchor body  520  is provided with a chamfered flange  550  that both facilitates component assembly and provides limited contact area between the anchor body  520  and the anchor holder  1002 , and allows small variations in the angle between the anchor body  520  and sleeve. Accordingly, the chamfered flange  550  will also provide limited contact area between the anchor body  520  and any sleeve disposed as an extension of any main body. It is believed that such freedom of angle is advantageous toward function of the assembly as a whole. 
     Discussion of the present method of the invention describes the steps used for creating apertures within the surrounding bone cortex, in an aligned relationship with the apertures  522  of the anchor body  520 . It will be appreciated that similar steps may be undertaken to install the anchor body  620 . The apertures created through the bone cortex are used to secure the anchor body  520  in a substantially secured relation by cross-securing, such as through cross-pinning, cross-screwing or the like.  FIG. 46  shows an anchor body  520  with integral compliant section and integral traction rod  528  in relation to an enlarged intramedullary cavity  1038  of a remaining bone portion  1040 . Once the components of the assembly have been inserted within the enlarged intramedullary cavity  1038 , a preferably adjustable drill guide, designated generally at  1000 , is used to prepare apertures within the bone cortex as described above. The drill guide  1000  includes an anchor holder  1002 , a cross-bar  1004  and an adjustable drill jig  1006 . The anchor holder  1002  includes a recess  1008  that is of a generally similar configuration to the sleeve  508  of the main body  502  previously described. As such, the anchor holder  1002  does serve the function of setting the depth and establishing the axis of the anchor holder  1002  for accomplishing the cross-drilling function. A tab  1010  is provided at the far end of the anchor holder  1002 , for engaging the notch  536  in the anchor body  520 . The cross-bar  1004  and the drill jig  1006  can be aligned by the surgeon such that the apertures  1014  in the drill jig  1006  are in the proper location for guiding a drilling procedure within the bone cortex. A nut  1051  or other suitable engagement device is tightened upon the traction rod  528  to secure the anchor holder  1002  relative to the anchor body  520 . A knob  1053  is used to tighten the drill jig  1006  in an aligned position relative to the anchor body  520 . Rods (not shown) may be inserted through the apertures  1014  to facilitate and test the alignment of the jig  1006  both prior to drilling and following the drilling of any aperture in the bone cortex. Once the drill guide  1000  is aligned and tightened by the surgeon and inserted into the bone, a power drilling device of the type well-known to those skilled in the art is then inserted through the apertures  1014  and drilling is undertaken through the bone cortex of the remaining bone portion  1040 , through the apertures  522  of the anchor body  520  and through the opposing side of the bone cortex. This operation is performed for all apertures  522  of the anchor body  520 . When drilling is complete, pins are inserted through the apertures  1014  of the drill jig  1006 . The pin length is selected by a measurement process. After the pins are placed, the nut  1051  or other engagement device is removed and the drill guide  1000 , including the anchor holder  1002 , is removed. 
     Once the anchor body  520  has been secured within the remaining bone portion  1040 , a main body, tibial tray or other suitable attachment is placed upon the anchor body  520  and the compliant section  524 , in similar manner as before. Once the above components are in place, a suitable engagement device such as a nut similar to that at  1051  used for securing the anchor holder  1002  during the drilling procedure is applied to the threaded portion  530  of the traction rod  528 . The nut is tightened a sufficient number of turns as determined by the surgeon for expanding the compliant section  524  to the desired degree. 
       FIG. 47  shows a tool for use in the optional milling of a bone abutment surface. More specifically,  FIG. 47  shows a pilot member  1060  that fits over the compliant section  524  of the bone attachment assembly, in similar manner as before. The pilot member includes a recess  1062  so that the pilot member  1060  can be inserted over the compliant section  524  until it meets the step  534  forming a portion of the near surface of the anchor body  520 . The anchor body  520  is also shown to include a different configuration, in the form of a spherically-shaped contact region  552  of radius r that facilitates component assembly and provides a small angular freedom between it and any sleeve attached to any main body, in a different way than the chamfered flange  550  shown in  FIG. 46 . The pilot member  1060  includes a shaft  1064  designed to be fitted over the traction rod  528  integrally formed with the compliant section  524 . 
     A milling device  1070  is shown to include a cutting end  1072  at a predetermined angle relative to the longitudinal axis of the remaining bone portion  1040  to be milled. This angle can be perpendicular to the longitudinal axis or at any suitable angle. The milling device  1070  also includes a recess  1074  shaped to fit over the shaft  1064  of the pilot member  1060 . A shaft  1076  is also provided for attachment to a power drill or any other powered attachment suitable for rotating the milling device  1070  at a high speed. A set screw  1078  is also provided for tightening the milling device  1070  against the shaft  1064 . 
     In operation, rotation of the milling device  1070  against an abutment surface  1050  of a remaining bone portion  1040  causes the cutting end  1072  to mill the abutment surface  1050  into a shape represented by the cutting end  1072 . As shown in  FIG. 47 , operation of the milling device  1070  shapes the abutment surface  1050  to an angle in a direction corresponding to the angle represented by the cutting end  1072 . Following this procedure, the milling device  1070  and pilot member  1060  are removed, and the remaining steps of the procedure for securing the bone attachment assembly components and for expanding the compliant section are followed in similar manner as previously described. 
     Yet another embodiment of the bone attachment assembly of the present invention is described in connection with  FIGS. 48-51 . Specifically,  FIG. 48  shows one version of this embodiment of bone attachment assembly generally at  1100 . The bone attachment assembly  1100  includes a main body  1102  having an articular portion  1104 . In this configuration, the articular portion  1104  is of a generally convex cross-section so as to have a complimentary shaped interface surface  1106 . As such, the interface surface  1106  is suitable for being applied directly upon a surface of a remaining bone portion, such as a proximal femur, that has been shaped through milling or other available methods to a generally convex configuration. 
     The bone attachment assembly  1100  also includes an anchor body  1120  having apertures  1122  for securing the anchor body  1120  by cross-pinning or cross-screwing in a similar manner as before. The anchor body  1120  also includes a compliant section  1124 . An aperture  1126  is also shown to pass through the anchor body  1120  and compliant section  1124 , in a similar manner as before. In this arrangement, the anchor body  1120 , the compliant section  1124  and the main body  1102  are shown to be integrally formed. A threaded recess  1128  is provided at the far end of the aperture  1126  for threaded engagement of an expansion rod  1130 , which is inserted from the far end into the aperture  1126 , threaded with its threaded portion  1132  into an engagement with the threaded recess  1128 , and removed from the far end of the assembly once the anchor body  1120  is secured in place. A knob  1134  may preferably be provided for facilitating insertion of the expansion rod  1130  and engagement with the threaded recess  1128 . It will be appreciated that the knob  1134  may take on any suitable shape, such as a hexagonal shape, and may include a suitable means, such as a slot or recess, for engagement by a suitable tool, such as a screwdriver or a hex key wrench.  FIG. 48  shows the knob  1134  to be provided with a hexagonal recess  1136  that is engaged by a torsion applying instrument such as hexagonal shaft  1138 . 
     Alternatively, it will be appreciated that the expansion rod  1130  may also take the form of a long shaft having a threaded portion at mid-section, effectively combining the knob  1134  and hexagonal shaft  1138 . In a similar manner as before, insertion of the expansion rod  1130  within the aperture  1126  and subsequent threading of the threaded portion  1132  with the threaded recess  1128  operates to expand the compliant section  1124  to a preselected condition of expansion. Since the expansion rod  1130 , as well as the expansion rods shown in connection with  FIGS. 49-51 , expand each of the respective compliant sections from beneath, they must each be removed from beneath following the cross-pinning or other securing of the respective anchor bodies. This can be accomplished by a removal of the expansion rod through a continuation of the aperture into which the assembly is inserted, through a smaller diameter extension of this aperture or through a complimentary aperture formed from the end of the remaining bone portion opposite the main body. 
       FIG. 51  illustrates the installation of the version of bone attachment assembly shown in  FIG. 48  within a human femur. The femoral head is first prepared to a spherical, cylindrical or conical configuration through methods well known to those skilled in the art. The configured femoral head may also include chamfered ends adjacent the spherical, cylindrical or conical configuration. A cavity  1150  is then reamed along the axis of the femoral neck by any of the methods described herein. An aperture  1151  is prepared through reaming, drilling or otherwise as an extension of the cavity  1150  passing through the cortex opposing the main body  1102 . The aperture  1151  may be created from either cortex along the longitudinal axis of the cavity  1150 . The aperture may preferably be of smaller diameter than the cavity  1150 , and can be created after the cavity  1150  is created. Alternatively, the cavity  1150  may be prepared to extend entirely through the femur  1152 . 
     An expansion rod is provided in  FIG. 51  in an extended length form at  1160 , with a centrally-located threaded portion  1162  for engaging the threaded recess  1128 . The expansion rod  1160  may also preferably include an engagement configuration such as a hexagonally-shaped end  1164  for engagement by a wrench or other tool. The expansion rod  1160  is inserted into the aperture  1126  and threaded into the threaded recess  1128  to expand the compliant section  1124  to its intended force. The components of the bone attachment assembly  1100 , including the anchor body  1120 , the compliant section  1124  and main body  1102 , including the articular portion  1104 , are then inserted within the cavity  1150  and applied upon the prepared exterior surface of the femur. The expansion rod  1160  extends through the aperture  1151  and through the cortex proximate the anchor  1120 . The aperture  1151  allows for any adjustment of expansion of the compliant section  1124  to be made. In the case where an extension rod of the type shown at  1130  in  FIG. 48  is used, it can also be manipulated through the aperture  1151 . 
     While the main body  1102 , including the shoulder portion  1104 , is held against the prepared femur surface, the anchor body  1120  is secured in place within the femur  1152  such as through the use of pins  1158 , using similar method steps involving cross-drilling of apertures through the bone cortices and anchor body apertures  1122  and subsequent insertion of pins as previously described. Screws or other suitable fixation devices may also be used. Once the anchor body  1120  has been secured within the femur  1152 , the expansion rod  1160  is removed from within the aperture  1126 , through the aperture  1151  so as to allow the compliant section  1124  to exert force directly on the bony surfaces contacting the cross-pins and the main body  1102 . Alternatively, it will be appreciated that a threaded traction rod may be integrally formed with the compliant section  1124  and expanded using a nut arrangement, in similar manner as before. 
     Another version of this embodiment of the present invention is shown in  FIG. 49 . Specifically,  FIG. 49  illustrates a two-piece bone attachment assembly generally at  1200 . The bone attachment assembly  1200  includes a main body  1202  having an articular portion  1204  which includes an interface surface  1206  in substantially the same shape as that described in connection with  FIG. 48 . In this arrangement, however, the main body  1202  contains a threaded recess  1208  for allowing assembly of the components of the bone attachment assembly  1200  during the surgical procedure. 
     The bone attachment assembly  1200  includes an anchor body  1220  having apertures  1222  suitable for cross-pinning, cross-screwing or the like. An integrally formed compliant section  1224  is also provided in a similar manner as before, and an aperture  1226  extends through the anchor body  1220  and the compliant section  1224 , also in a similar manner as before. A connecting rod  1228  is provided at the near end of the compliant section  1224 , and includes a threaded portion  1230  for engaging the threaded recess  1208  of the main body  1202 . In a similar manner as before, the compliant section  1224  is expanded through the insertion of an expansion rod  1234  within the aperture  1226  and engaging the threaded portion  1236  of the expansion rod  1234  with a threaded recess  1232  located at the far end of the aperture  1226 . 
     In the method involving this two-piece embodiment of the bone attachment assembly  1200 , the femoral head is prepared substantially as before. A cavity and aperture are also prepared within the femur as before along the axis of the femoral neck. The expansion rod  1234  is inserted within the aperture  1226  and is threaded into the threaded recess  1232 , thereby pre-expanding the compliant section  1224 . The components are then inserted and placed upon to the remaining bone portion in similar manner as before. After the anchor body  1220  is affixed to the surrounding bone cortices with cross-pins or the like using the drill guide as before, the main body  1202  is then threaded onto the connecting rod  1228  snugly against the bone interface, and then the expansion rod  1234  is removed through the end of the bone aperture proximate the anchor  1220  so as to allow the compliant section  1224  to exert force directly on the bony surfaces contacting the cross-pins and the main body  1202 . Alternatively, in this two-piece arrangement, the main body  1202  can be threadably attached to the compliant section  1224  before the cross-pinning has occurred and before the expansion rod is removed. 
       FIG. 50  illustrates yet another version of this embodiment of the present invention, wherein a bone attachment assembly is provided generally at  1300 . The bone attachment assembly  1300  includes a main body  1302  having an articular portion  1304  with an interface surface  1306  in similar configuration as before. In this arrangement, however, a cylindrically shaped sleeve  1308  is provided as an extension upon the main body  1302  in a similar manner as in previous embodiments. The sleeve  1308  is shown to include a recess  1310  with a threaded aperture  1312  at its near end. This arrangement also allows for separate assembly of these components during the surgical procedure. 
     The bone attachment assembly  1300  also includes an anchor body  1320 , which is of a similar shape as the anchor body  520  shown in  FIG. 31 . The anchor body  1320  includes apertures  1322  and includes a step  1332  for engaging a suitable installation tool, and for acting as a stop against the far surface of the sleeve  1308  that regulates the amount of expansion for the compliant section  1324 . The compliant section  1324  is integrally formed with the anchor body  1320  and an aperture  1326  extends through the anchor body  1320  and the compliant section  1324  in a similar manner as before. A connection rod  1328  is provided as an integral extension from the near end of the compliant section  1324 . The connection rod  1328  includes a threaded portion  1330  suitable for engaging the threaded aperture  1312 . The installation of this version of bone attachment assembly  1300  involves insertion of the compliant section  1324  into the recess  1310  and threading the threaded portion  1330  into the threaded aperture  1312 . An expansion rod (not shown) having a threaded portion is used in similar manner as before for engaging a threaded recess  1338  located at the far end of the aperture  1326 . Threading such an expansion rod into the aperture  1326  causes expansion of the compliant section  1324  in similar manner as before. In similar manner as before, the expansion rod is removed from within the aperture  1326  following installation and cross-pinning and application of the main body  1302 , to activate the compliant force directly onto the bony surfaces adjacent the main body  1302  and the cross-pins. 
     Yet another version of this embodiment of the present invention is shown in connection with  FIG. 52 . In this version, a bone attachment assembly is provided at  1400  in a non-coaxial configuration. The bone attachment assembly  1400  includes a main body  1402  having a shoulder portion  1404  and an interface surface  1406  with a bone ingrowth enhancing texture. A sleeve  1408  extends from the main body  1402  in similar manner as before. An anchor body  1410  and compliant section  1412  are integrally formed, with a threaded recess  1414  disposed at the near end of the compliant section  1412 . A traction rod  1416  is also provided for expanding the compliant section  1412  relative to the main body  1402 . In this arrangement, however, an extension  1418  is provided upon the main body  1402  in a non-coaxial relationship relative to the sleeve  1408 . The traction rod  1416  is suitable for being inserted through the main body  1402  to the side of the extension  1418 . This version is intended to demonstrate the ability of any component of the invention to be altered in its axial configuration relative to other components to achieve any advantage. In this arrangement, the non-coaxial configuration of the extension  1418  allows increased freedom of sleeve placement within the bone, thereby allowing positioning of a femoral head, for example, independent of the sleeve position. Furthermore, the orientation of the ingrowth interface may be independent from the axis of the extension  1418  and the sleeve  1408 . It will be appreciated that the method steps applicable to this arrangement are substantially as previously described in connection with other similar configurations, and will not be repeated here. 
     Referring to  FIGS. 53 and 54 , a compliant fixation device  1500  for attaching an external prosthetic device  1590 , such as an external prosthesis or external prosthesis adapter, to a bone  1592  is illustrated. The fixation device  1500  includes a main body  1502  with a compliant portion  1512  that can be expanded and contracted as described hereinabove in various embodiments. The compliant portion  1512  can include washer springs, accordion-like springs, helical springs, etc., or other compliant structures as already disclosed. The main body  1502  includes a bone tray  1504  at a first end  1503 , and is coupled to an extension  1506  at a second end  1505 . The main body  1502  and the extension  1506  can be modular components coupled to each other by known means, including, for example, a Morse taper connection. In the exemplary embodiment of  FIG. 53 , the extension  1506  defines a male taper  1507  received in a female taper  1509  of the main body  1502 . The main body  1502  and the extension  1506  can also be integrally formed. The bone tray  1504  provides an abutment surface  1513  for engagement with the bone  1592 . The abutment surface  1513  can be flat or concave toward the bone  1592  or have any other shape suitable for engagement with the bone  1592 . The main body  1502  can include a plurality of apertures  1531  through the abutment surface  1513  for receiving fasteners  1533  to prevent rotation relative to the bone  1592 . 
     The fixation device can also include an anchor  1510  which can be modularly or integrally connected to the compliant portion  1512 . The anchor  1510  can be attached to a cavity  1593  in the bone  1592  with cross pins or helical threads  1522  as described hereinabove in various embodiments. The anchor  1510  can also be directly attached to the main body  1502 . The main body  1502  can include a post  1550  threadably coupled with the compliant portion  1512  through the bone tray  1513 . As described above, an expansion rod can be provided for expanding the compliant portion  1512  relative to the main body  1502 . The expansion rod can be threadably coupled to the compliant portion  1502  to cause the compliant portion  1502  to expand while connected to the anchor  1510 . Other expansion methods can also be used as described above. 
     The main body  1502  defines a first engagement surface  1530 , which can be, for example, in the form of a shoulder, and the extension  1506  defines a second engagement surface  1532 , which can be, for example, in the form of a ring or cap, as illustrated in  FIG. 53 . The first and second engagement surfaces  1530 ,  1532  can be configured to constraint a bone graft or other vascularized graft  1540  that is attached to the bone  1592 . In the exemplary application of  FIG. 54 , the fixation device  1500  is attached to a distal femoral bone  1592 , and the bone graft  1540  is a knee patella. It will be appreciated, that the graft  1540  can be a different vascularized graft depending on the particular application. The main body  1502  or at least a portion thereof can have a porous or other growth promoting coating. 
     The extension  1506  may include a second ring  1534  that includes suture apertures  1535  for capturing the skin  1594  which is also sutured to the bone graft  1540 . The first and second rings  1532 ,  1534  may be integrally formed as a single cap, for example. In one aspect, the extension  1506  can include a blind bore  1511  with internal threads  1537  for threadably connecting to the external prosthesis device  1590  by, for example, a universal prosthesis adapter. In the event that the external prosthesis device  1590  needs to be replaced because or failure or changing needs, the external prosthesis device  1590  can be easily removed without disturbing the skin or the bone fixation. Additionally, the blind bore  1511  prevents contamination and an infection from reaching the skin interiorly. 
     Referring to  FIGS. 55-59 , various aspects of a compliant intramedullary fixation device  1600  are illustrated. The intramedullary fixation device  1600  can be received within axially aligned medullary canals  1680  of opposing bone portions  1602 ,  1604  across a fracture or osteotomy surface  1601  for fusion therebetween, as illustrated in  FIG. 59 . The intramedullary fixation device  1600  can also be received within the medullary canal  1680  of a single bone  1602  for applying compressive stress away from a resected bone end, and, in the case of amputation of trauma, for allowing attachment of soft tissue to bone rather than metal of a prosthetic component, as illustrated in  FIGS. 55 and 56 . 
     The intramedullary fixation device  1600  can include first and second intramedullary components  1606 ,  1608 . The first intramedullary component  1606  can include a first bone-attachment end  1610  and a first elongated member  1612  coupled thereto. The first bone-attachment end  1610  can include holes or other openings  1614  for receiving transverse pins, nails or other bone fasteners, including, for example, expanding, threaded or toothed anchor plugs. The first bone-attachment end  1610  can be configured for coupling to a modular adapter  1616  with conforming taper portions, such as male/female Morse tapers, or other integral or modular connectors  1618 ,  1620 . The modular adapter  1616  can be used for attaching various prosthetic devices, such as, for example, total joint components, percutaneous attachments for prosthetic limbs, or other prosthetic components. The geometry of the first bone-attachment end  1610  and/or the modular adapter  1616  can substantially or at least significantly seal the medullary canal  1680  from any infectious agents that could enter the body percutaneously. 
     The second intramedullary component  1608  can include a second bone attachment end  1622  having bone attachment openings  1615  and a second elongated member  1624 . The second intramedullary component  1608  is cannulated defining an axial bore  1626  therethrough. The first elongated member  1612  of the first intramedullary component  1606  can be received within and at least partially through the axial bore  1626  extending partially beyond the second bone-attachment end  1622 , such that the second intramedullary component  1608  defines a sleeve  1628  for at least a portion of the first elongated member  1612 , as illustrated in  FIGS. 55 ,  56 , and  59 . The sleeve  1628  can function as a protective device and/or as a spacer during assembly and implantation of the intramedullary fixation device  1600 , as discussed below. Accordingly, the first and second intramedullary components  1606 ,  1608  are, at least partially, configured in a telescopic arrangement. 
     A compliant member  1630  can be used to couple the first and second intramedullary components  1606 ,  1608  and provide compressive stress for bone fusion across the osteotomy/fracture surface  1601 , as illustrated in  FIG. 59 , or against a portion of a bone  1602  for reducing bone resorption, as illustrated in  FIGS. 55 and 56 . In one aspect, the compliant member  1630  can be in the form of Belleville washers or other washer springs  1630   a , as illustrated in  FIGS. 55 and 59 . The washer springs  1630   a  can be attached to a portion of the first elongated member  1612  that extends through the bore  1626  and outside the second bone-attachment end  1622 . The washer springs  1630   a  can be confined between an abutment spacer  1632  and a locking device  1640  for actuating/biasing the washer springs  1630   a . The locking device  1640  can include, for example, a lock ring or nut  1634  that is coupled to a groove or threaded portion  1636  of the first elongated member  1612 . Tightening the lock ring/nut  1634  compresses the washer springs  1630   a  and provides compressive stress across the fracture/osteotomy surface  1601 , as illustrated in  FIG. 59 , or between the first and second bone attachments sites  1603 ,  1605 , as illustrated in  FIG. 55 . 
     A Referring to  FIG. 56 , in another aspect the compliant member  1630  can be in the form of a helical spring  1630   b  that comprises a portion of the first elongated member  1612  that is received and protected from bending within the sleeve  1628 . Tightening the lock ring/nut  1634  of the locking device  1640  actuates the helical spring  1630   b  to stretch in tension and causes compressive stress to be transmitted to a portion of the bone  1602  by the first bone-attachment end  1610 , as discussed below. 
     Referring to  FIGS. 57 and 58 , the first and second intramedullary components  1606 ,  1608  can be provided with corresponding male/female alignment tabs or other alignment devices  1642 ,  1644  to facilitate alignment of the first and second intramedullary components  1606 ,  1608 . 
     It will be appreciated that the compliant member  1630  can be any device capable of storing energy that can be released as a compressive stress at a particular bone site, and is not limited to helical springs or washer springs. The intramedullary fixation device  1600  can also include a release mechanism  1650  for releasing the stored energy of the compliant member  1630  and causing the application of compressive stress after the intramedullary fixation device  1600  is fully implanted, and, in the case of bone fusion, after the bone ends are abutted across the osteotomy/fracture surface  1601 , as illustrated in  FIG. 59 . The release mechanism  1650  can be, for example, a pin or other spacer device  1651  that prevents the washer springs  1630   a  from compressing until the spacer device  1651  is removed. The release mechanism  1650  can also be a biodegradable spacer device  1651  or portion thereof made of natural or synthetic materials of desired degradation rates after implantation. The spacer device  1651  can be for, for example, a polymeric spacer having biological or accelerated (faster than biological) degradation rate. In such case, the release mechanism  1650  transmits compressive stress gradually, as the spacer degrades. 
     Referring to  FIGS. 55 ,  56  and  59 , the first and second bone attachment ends  1610 ,  1622  are positioned in a spaced-apart relationship and are attached to spaced-apart first and second bone attachment sites  1603 ,  1605 . In the exemplary intramedullary fixation device illustrated in  FIG. 55  or  59 , the compliant member  1630  extends along the medullary canal  1680  outside the region defined by the first and second bone attachment sites  1603 ,  1605 . In this arrangement, the compliant member  1630  can be biased in compression by various procedures. In one aspect, for example, the second intramedullary component  1608  can be fixed at the second bone attachment site  1605 , and compression applied by tightening the lock ring/nut  1634  or by pulling the first intramedullary component  1606  away from the second intramedullary component  1608 , prior to attaching the first intramedullary component  1606  to the bone  1602 . In either procedure, the compliant member  1630  can be compressed between the abutment spacer  1632  and the locking ring/nut  1634 . 
     In the exemplary arrangement illustrated in  FIG. 56 , the compliant member  1630  extends along the medullary canal  1680  along at least a portion of the region defined by the first and second bone attachment sites  1603 ,  1605 . In this arrangement compressive stress is transmitted to the bone  1602  by stretching/tensioning the compliant member  1630 . The compliant member  1630  can be stretched, for example, by tightening the lock ring/nut  1634 , or by attaching the second intramedullary component  1608  to the bone  1602  and pulling the first intramedullary component  1606  away therefrom, prior to attaching the first intramedullary component  1606  to the bone  1602 . 
     It will be appreciated that any features of any of the examples and embodiments and/or method steps set forth herein are intended to be substituted, shared and/or moved among the various versions and methods involving the assembly. As an example, it will be appreciated that any of the threaded anchor bodies described herein may be substituted for cross-pinned versions. Another contemplated arrangement involves the switching of positions of the compliant section and anchor, so that the anchor is threaded or cross-secured to the near side of the compliant section relative to the main body. 
     Yet another contemplated arrangement involves the ability of the compliant section to be switchable between extension and compression conditions, referring to the at-rest condition of the compliant section prior to engagement by an extension or compression rod, respectively. In the case of an extension compliant section, an extension rod expands or pulls the compliant section, such as by abutting a closed-ended aperture within the compliant section. In the case of a compression compliant section, a compression rod having a head or knob passes from the end opposite the main body through an aperture through the anchor body and compliant section to compress or push the already-expanded compliant section to a lesser degree of expansion. Force is applied to the compression version of compliant section by the knob or head against the end of the compliant section when the compression rod is threaded into a threaded recess in the main body. The present invention also contemplates the use of Belleville washers within a recess of a sleeve disposed integrally with or otherwise attached to the anchor body, as a substitute for the compliant section. The Belleville washers are compressed by applying force to a plate or other device to the end washer such as by threading a compression rod with such a plate or other device through the washer section from a side opposite the main body. Thus, it will be appreciated that several methods are contemplated for the application of force in a compression or extension environment, using various compression and expansion implements, from either direction relative to the main body of the assembly. 
     The foregoing discussion discloses and describes merely exemplary arrangements of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.