Abstract:
A joint prosthesis for mounting in a first bone and presenting a prosthetic joint surface for engaging an opposing joint surface of a second bone, the joint prosthesis comprising:
       a sleeve which is adapted for partial disposition in an opening formed in the first bone;   a center adapter which is adapted for disposition within the sleeve; and   a prosthetic joint surface mounted to the center adapter;   wherein the disposition of the center adapter is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the prosthetic joint surface is adjustable, both longitudinally and rotationally, relative to the opposing joint surface of the second bone.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
       [0001]    This patent application claims benefit of: 
         [0002]    (i) pending prior U.S. Provisional Patent Application Ser. No. 61/278,782, filed Oct. 10, 2009 by Barry T. Bickley et al. for METHOD AND APPARATUS FOR RESTORING A JOINT, COMPRISING THE PROVISION AND USE OF A LONGITUDINALLY-ADJUSTABLE AND ROTATIONALY-ADJUSTABLE JOINT PROSTHESIS (Attorney&#39;s Docket No. SIM-6 PROV); and 
         [0003]    (ii) pending prior U.S. Provisional Patent Application Ser. No. 61/368,424, filed Jul. 28, 2010 by Barry T. Bickley et al. for METHOD AND APPARATUS FOR RESTORING A JOINT, COMPRISING THE PROVISION AND USE OF A LONGITUDINALLY-ADJUSTABLE AND ROTATIONALY-ADJUSTABLE JOINT PROSTHESIS (Attorney&#39;s Docket No. SIM-8 PROV). 
         [0004]    The two (2) above-identified patent applications are hereby incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0005]    This invention relates to medical procedures and apparatus in general, and more particularly to medical procedures and apparatus for restoring a joint. 
       BACKGROUND OF THE INVENTION 
       [0006]    Joint replacement surgery seeks to replace portions of a joint with prosthetic components so as to provide long-lasting function and pain-free mobility. 
         [0007]    During joint replacement surgery, one or more of the operative elements of the joint are replaced by prosthetic components. More particularly, many joints (e.g., the hip, the shoulder, etc.) comprise a ball-and-socket construction. During total joint replacement surgery, the head of the bone which provides the ball is replaced by a prosthetic ball-and-stem, and the portion of the bone which provides the socket is replaced by a prosthetic cup, whereby to provide the prosthetic total joint. In a partial joint replacement surgery, only one of the operative elements of the joint may be replaced, e.g., the head of the bone which provides the ball. 
         [0008]    The present invention is directed to situations where the head of the bone which provides the ball is replaced by a prosthetic ball-and-stem, or where the head of the bone which provides the socket is replaced by a prosthetic socket-and-stem, as will hereinafter be discussed in further detail. For convenience, the present invention will generally be discussed in the context of replacing the head of a bone with a prosthetic ball-and-stem, although it should be appreciated that the present invention is equally applicable to situations where the head of a bone is replaced by a prosthetic socket-and-stem. 
         [0009]    In order to replace the head of a bone with a prosthetic ball-and-stem, the head of the bone is first distracted from its socket so as to expose the head of the bone. Then an osteotomy is performed so as to remove the neck and head of the bone from the remainder of the bone. This action also exposes the intramedullary canal (sometimes hereinafter referred to as “the bone canal”) of the bone. Next, the proximal end of the bone canal is prepared to receive the stem of the prosthesis. More particularly, a rasp, reamer, broach, etc. is used to hollow out, clean and enlarge the proximal end of the bone canal so as to create an elongated cavity which will receive the stem of the prosthesis. Finally, the stem of the prosthesis is inserted into the bone canal so that the ball of the prosthesis is appropriately presented to the socket. 
         [0010]    Typically, the ball of the prosthesis is manufactured separately from the stem of the prosthesis, with the ball component and the stem component being united at the time of use, although it is also possible to form the ball integral with the stem at the time of manufacture. 
         [0011]    Furthermore, it should also be appreciated that, during the surgery itself, it is common to temporarily position a selected trial stem in the bone, attach a selected trial ball to the positioned trial stem, and then temporarily reduce the joint so as to confirm the joint reconstruction before the actual prosthetic stem is secured in position within the bone. 
         [0012]    It will be appreciated that, when replacing the head of a bone with a prosthetic ball-and-stem, the surgeon must consider the position of the prosthetic ball relative to the socket, and that this must be done in both longitudinal and rotational terms. Specifically, the surgeon must consider (i) the longitudinal position of the prosthetic ball relative to the socket, and (ii) the rotational position of the prosthetic ball relative to the socket. This is necessary because, if either the longitudinal position or the rotational position of the prosthetic ball is “off” (i.e., mispositioned) vis-à-vis the socket, the ball will not seat properly in the socket and the prosthesis will not function as intended. As a practical matter, these positioning considerations require that a large inventory of prosthetic devices, of differing lengths and with differing angular orientations, must be maintained so that the prosthetic ball can be properly positioned in the patient. However, this is a costly requirement, and failures in inventory re-stocking can result in cancelled surgeries. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention addresses the aforementioned problems associated with the prior art through the provision and use of a novel longitudinally-adjustable and rotationally-adjustable joint prosthesis. 
         [0014]    More particularly, the present invention comprises a new joint prosthesis for replacing the ball of a ball-and-socket joint. This new joint prosthesis comprises (i) a sleeve which is adapted for disposition in the intramedullary canal of a bone, (ii) a center adapter which is adapted for disposition within the sleeve, and (iii) a ball mounted to the center adapter, wherein the disposition of the center adapter is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the ball is adjustable, both longitudinally and rotationally, relative to the socket. 
         [0015]    Alternatively, the ball of the new prosthesis may be replaced by a socket, in order that the new prosthesis may replace the socket of a ball-and-socket joint. In this case, the disposition of the socket is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the socket is adjustable, both longitudinally and rotationally, relative to the ball. 
         [0016]    In one preferred form of the present invention, there is provided a joint prosthesis for mounting in a first bone and presenting a prosthetic joint surface for engaging an opposing joint surface of a second bone, the joint prosthesis comprising: 
         [0017]    a sleeve which is adapted for partial disposition in an opening formed in the first bone; 
         [0018]    a center adapter which is adapted for disposition within the sleeve; and 
         [0019]    a prosthetic joint surface mounted to the center adapter; 
         [0020]    wherein the disposition of the center adapter is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the prosthetic joint surface is adjustable, both longitudinally and rotationally, relative to the opposing joint surface of the second bone. 
         [0021]    In another preferred form of the present invention, there is provided a method for restoring a joint, the method comprising: 
         [0022]    providing a joint prosthesis for mounting in a first bone and presenting a prosthetic joint surface for engaging an opposing joint surface of a second bone, the joint prosthesis comprising: 
         [0023]    a sleeve which is adapted for disposition in an opening formed in the first bone; 
         [0024]    a center adapter which is adapted for partial disposition within the sleeve; and 
         [0025]    a prosthetic joint surface mounted to the center adapter; 
         [0026]    wherein the disposition of the center adapter is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the prosthetic joint surface is adjustable, both longitudinally and rotationally, relative to the opposing joint surface of the second bone; 
         [0027]    forming an opening in the first bone; 
         [0028]    deploying a sleeve in the opening formed in the) first bone; 
         [0029]    positioning a center adapter partially within the sleeve; 
         [0030]    adjusting the longitudinal and rotational position of the center adapter with respect to the sleeve; and 
         [0031]    securing the center adapter to the sleeve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
           [0033]      FIGS. 1-9  are schematic views showing various aspects of a first embodiment of the present invention; 
           [0034]      FIGS. 10-13  are schematic views showing various aspects of a second embodiment of the present invention; 
           [0035]      FIGS. 14-20  are schematic views showing various aspects of a third embodiment of the present invention; 
           [0036]      FIGS. 21-25  are schematic views showing various aspects of a fourth embodiment of the present invention; 
           [0037]      FIG. 26  is a schematic views showing various aspects of a fifth embodiment of the present invention; 
           [0038]      FIGS. 27-29  are schematic views showing various aspects of a sixth embodiment of the present invention; and 
           [0039]      FIGS. 30-36  are schematic views showing additional aspects of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    The present invention is directed at a new joint prosthesis for replacing the ball of a ball-and-socket joint. This new joint prosthesis comprises (i) a sleeve which is adapted for disposition in the intramedullary canal of a bone, (ii) a center adapter which is adapted for disposition within the sleeve, and (iii) a ball mounted to the center adapter, wherein the disposition of the center adapter is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the ball is adjustable, both longitudinally and rotationally, relative to the socket. 
         [0041]    Alternatively, the ball of the new prosthesis may be replaced by a socket, in order that the new prosthesis might replace the socket of a ball-and-socket joint. In this case, the disposition of the socket is adjustable, both longitudinally and rotationally, relative to the sleeve, so that the disposition of the socket is adjustable, both longitudinally and rotationally, relative to the ball. 
         [0042]    Looking first at  FIGS. 1-9 , there is shown a new joint prosthesis  5  for replacing the ball of a ball-and-socket joint. Joint prosthesis  5  generally comprises a sleeve  10  ( FIGS. 1-3 ) which is adapted for disposition in the intramedullary canal of a bone. Sleeve  10  generally comprises an elongated body  15  having a central lumen  20  ( FIG. 2 ) formed therein, and terminating at its proximal end in a crown  25  having a plurality of peripheral detents  30  formed therein. A center adapter  35  ( FIGS. 1 ,  4  and  5 ) is adapted for variable disposition within, and extension out of, central lumen  20  of sleeve  10 . The disposition of center adapter  35  relative to sleeve  10  is adjustable, both longitudinally and rotationally. More particularly, center adapter  35  comprises an elongated shaft  40  terminating in a head  45 . Elongated shaft  40  of center adapter  35  comprises a mount section  50  which comprises a plurality of horizontally-extending slots  55  and a plurality of longitudinally-extending slots  60 . A two-piece collar  65  ( FIGS. 6 and 7 ), having at least one longitudinally-extending internal rib  70  formed on at least one of the halves of the collar, and having at least one horizontally-extending internal rib  75  formed on at least one of the halves of the collar, and having at least one radially-projecting nib  78 , is selectively fitted about crown  25  of sleeve  10  and mount section  50  of center adapter  35 , as will hereinafter be discussed. Screws  80  ( FIG. 1 ) are used to selectively hold the two halves of collar  65  together about crown  25  of sleeve  10  and mount section  50  of center adapter  35 . 
         [0043]    On account of the foregoing construction, when the two halves of collar  65  are loose, center adapter  35  is able to move both longitudinally and rotationally relative to collar  65 , and collar  65  is able to move both longitudinally and rotationally relative to sleeve  10 , since longitudinally-extending internal rib  70  of collar  65  will not project into a longitudinally-extending slot  60  of center adapter  35 , and horizontally-extending internal rib  75  of collar  65  will not project into a horizontally-extending slot  55  of center adapter  35 , and radially-projecting nib  78  of collar  65  will not project into a peripheral detent  30  of crown  25  of sleeve  10 . However, when the two halves of collar  65  are tightened about crown  25  of sleeve  10  and mount section  50  of center adapter  35 , the collar makes a binding fit with (i) center adapter  35 , by virtue of the engagement of the collar&#39;s horizontally-extending internal rib  75  with one of the horizontally-extending slots  55  of the center adapter, and by virtue of the engagement of the collar&#39;s longitudinally-extending internal rib  70  with one of the longitudinally-extending slots  60  of the center adapter, and (ii) sleeve  10 , by virtue of the engagement of the collar&#39;s radially-projecting nib  78  with one of the peripheral detents  30  on crown  25  of sleeve  10 . In this way, by appropriately loosening collar  65  about crown  25  of sleeve  10  and mount section  50  of center adapter  35 , the disposition of head  45  of center adapter  35  may be adjusted, both longitudinally and rotationally, relative to sleeve  10 ; and by appropriately tightening collar  65  about crown  25  of sleeve  10  and mount section  50  of center adapter  35 , the disposition of head  45  of center adapter  35  may be fixed relative to sleeve  10 . 
         [0044]    Ball  85  ( FIG. 8 ) is adapted to be secured to head  45  of center adapter  35 . By way of example but not limitation, ball  85  may include a stem  86  for positioning in a recess  87  formed in head  45 . 
         [0045]    Accordingly, it will be appreciated that, in view of the foregoing construction, the disposition of ball  85  can be adjusted, both longitudinally and rotationally, relative to sleeve  10 , and hence the disposition of ball  85  may be adjusted, both longitudinally and rotationally, relative to a bone in which sleeve  10  is disposed. In this way, the present invention provides a new joint prosthesis which permits the disposition of the ball to be adjusted, both longitudinally and rotationaly, relative to a socket. 
         [0046]    If desired, a cage  90  ( FIG. 9 ) may be mounted to the opposing side of head  45  ( FIG. 1 ). By way of example but not limitation, a screw  91  ( FIG. 1 ) received in a hole  92  ( FIG. 9 ) in cage  95  and a hole  93  ( FIG. 5 ) in head  45  may be used to secure cage  90  to head  45 . The provision of a cage on the prosthesis, preferably diametrically opposed to the ball, permits soft tissue or bone to be secured to the prosthesis, e.g., with sutures. 
         [0047]    Also, if desired, openings  95  ( FIG. 5 ) may be formed in center adapter  35  (e.g., in head  45 ), in collar  65  and/or in cage  90 , so as to receive a suture or a suture anchor, or like fastening element, whereby to permit soft tissue and/or bone to be secured to the joint prosthesis. 
         [0048]    In use, sleeve  10  (preferably having collar  65  loosely secured thereto) is disposed in the intramedullary canal of a bone, center adapter  35  (preferably having ball  85  secured thereto) is inserted into central lumen  20  of the sleeve and is moved longitudinally and rotationally as needed so as to present the ball for proper seating in the socket, and then collar  65  is tightened (e.g., with screws  80 ) so as to secure center adapter  35 , and hence ball  85 , in the desired longitudinal and rotational position relative to sleeve  10 , and hence in the desired longitudinal and rotational position relative to the socket. 
         [0049]    Looking next at  FIGS. 10-13 , there is shown an alternative form of the new joint prosthesis for replacing the ball of a ball-and-socket joint. The new joint prosthesis  105  of  FIGS. 10-13  is generally similar to the joint prosthesis  5  shown in  FIGS. 1-9 , except that (i) center adapter  35  of  FIGS. 1-9  is replaced by the center adapter  135  shown in  FIGS. 10-13 , and (ii) collar  65  of  FIGS. 1-9  is replaced by the hinged collar  165  shown in  FIGS. 10-13 . 
         [0050]    More particularly, the center adapter  135  of  FIGS. 10-13  is substantially the same as the center adapter  35  of  FIGS. 1-9 , except that the mount section  50  of center adapter  35  is replaced by the mount section  150  of center adapter  135 . In mount section  150 , the horizontally-extending slots  155  ( FIG. 12 ) and the longitudinally-extending slots  160  are effectively superimposed on one another, in the manner shown in  FIG. 12 . 
         [0051]    In addition, the hinged collar  165  of  FIGS. 10-13  comprises two halves  166  which are hinged together by a pivot pin  167  rising out of sleeve  10 . A locking pin  168  ( FIG. 10 ) is used to selectively lock the two halves  166  together. At least one, and preferably both, of the two halves  166  includes longitudinally-extending internal ribs  170  which are formed on a horizontally-extending internal rib  175 . Thus, with the construction shown in  FIGS. 10-13 , the longitudinally-extending internal ribs  170  are effectively superimposed on the horizontally-extending internal ribs  175 . 
         [0052]    It will be appreciated that, in this form of the invention, when the two halves  166  of collar  165  are separated from one another, the horizontally-extending internal ribs  175  and the longitudinally-extending internal ribs  170  of collar  165  will be separated from the horizontally-extending slots  155  and the longitudinally-extending slots  160  of center adapter  135 , and the center adapter will be free to move longitudinally and rotationally relative to the collar, and hence longitudinally and rotationally relative to the sleeve  10  to which the collar is mounted. 
         [0053]    It will also be appreciated that, in this form of the invention, when the two halves  166  of collar  165  are locked together with locking pin  168 , horizontally-extending internal ribs  175  of collar  165  will seat in horizontally-extending slots  155  in center adapter  135 , and longitudinally-extending internal ribs  170  of collar  165  will seat in longitudinally-extending slots  160  of center adapter  135 , whereby to lock center adapter  135  longitudinally and rotationally relative to the collar, and hence to the sleeve  10  to which the collar is mounted. 
         [0054]    Accordingly, in view of the foregoing construction, the disposition of ball  85  can be adjusted, both longitudinally and rotationally, relative to sleeve  10 , and hence may be adjusted, both longitudinally and rotationally, relative to a bone in which sleeve  10  is disposed. In this way, the present invention provides a new joint prosthesis which permits the disposition of the ball to be adjusted, both longitudinally and rotationaly, relative to a socket. 
         [0055]    Looking next at  FIGS. 14-20 , there is shown another alternative form of the new joint prosthesis for replacing the ball of a ball-and-socket joint. The new joint prosthesis  205  of  FIGS. 14-20  is generally similar to the joint prosthesis  105  shown in  FIGS. 10-13 , except that the collar  165  used in the construction of  FIGS. 10-13  is replaced by a latched collar  265  as shown in  FIGS. 14-20 . 
         [0056]    More particularly, latched collar  265  comprises two halves  266  pivotally mounted to the pivot pin  167  of sleeve  10 . The two halves  266  of latched collar  265  are substantially the same as the two halves  166  of hinged collar  165 , except that the two halves  266  of latched collar  265  also each comprise a latch mechanism  269  at its free end. Thus, at least one, and preferably both, of the two halves  266  includes a horizontally-extending internal rib  275  carrying a plurality of longitudinally-extending internal ribs  270  thereon. Accordingly, it will be appreciated that with the construction shown in  FIGS. 14-20 , the longitudinally-extending internal ribs  270  are again effectively superimposed on the horizontally-extending internal ribs  275 . Latch mechanisms  269  engage one another when the two halves  266  are brought together so that the two halves can catch to one another. A locking pin  268  ( FIG. 14 ) may be used to secure the two halves in their closed condition. 
         [0057]    It will be appreciated that, in this form of the invention, when the two halves  266  of collar  265  are separated from one another, the horizontally-extending internal ribs  275  and the longitudinally-extending internal ribs  270  of collar  265  will be separated from the horizontally-extending slots  155  and the longitudinally-extending slots  160  of center adapter  135 , and the center adapter will be free to move longitudinally and rotationally relative to the collar, and hence longitudinally and rotationally relative to the sleeve  10  to which the collar is mounted. 
         [0058]    It will also be appreciated that, in this form of the invention, when the two halves  266  of collar  265  are locked together with locking pin  268 , horizontally-extending internal ribs  275  of collar  265  will seat in horizontally-extending slots  155  in center adapter  135 , and longitudinally-extending internal ribs  270  of collar  265  will seat in longitudinally-extending slots  160  of center adapter  135 , whereby to lock center adapter  135  longitudinally and rotationally relative to the collar, and hence to the sleeve  10  to which the collar is mounted. 
         [0059]    Accordingly, in view of the foregoing construction, the disposition of ball  85  can be adjusted, both longitudinally and rotationally, relative to sleeve  10 , and hence may be adjusted, both longitudinally and rotationally, relative to a bone in which sleeve  10  is disposed. In this way, the present invention provides a new joint prosthesis which permits the disposition of the ball to be adjusted, both longitudinally and rotationaly, relative to a socket. 
         [0060]    Looking next at  FIGS. 21-25 , there is shown another alternative form of the new joint prosthesis for replacing the ball of a ball-and-socket joint. The new joint prosthesis  305  of  FIGS. 21-25  is generally similar to the joint prosthesis  205  shown in  FIGS. 14-20 , except as will hereinafter be discussed. 
         [0061]    More particularly, with the joint prosthesis  305  of  FIGS. 21-25 , collar  265  is omitted and the sleeve  10  of  FIGS. 14-20  is replaced by a new sleeve  310 . Sleeve  310  comprises a plurality of horizontally-extending internal ribs  375  ( FIGS. 23 and 25 ) which are separated from one another by bands of recessed wall  376 . Each of the horizontally-extending external ribs  375  carries a plurality of longitudinally-extending internal ribs  370  ( FIG. 23 ) thereon. A threaded keyway  377  ( FIG. 23 ) is formed in the side wall of sleeve  310 . Threaded keyway  377  communicates with central lumen  320  of sleeve  310 . 
         [0062]    In this form of the invention, the center adapter  135  of  FIGS. 14-20  is replaced by a new center adapter  335  ( FIG. 22 ). Center adapter  335  is substantially the same as the center adapter  135  of  FIGS. 14-20 , except that center adapter  335  comprises a plurality of horizontally-extending ribs  378  which are separated from one another by bands of recessed wall  379 . Thus, the bands of recessed wall  379  essentially comprise horizontally-extending slots in center adapter  335 . Each of the horizontally-extending ribs  378  carries a plurality of longitudinally-extending slots  381  ( FIG. 23 ) thereon. 
         [0063]    And in this form of the invention, there is also provided a key lock  382  which is radially movable along threaded keyway  377  via a screw  383 . 
         [0064]    As a result of, this construction, and looking now at  FIG. 25 , when it is desirable to adjust the position (either longitudinally or rotationally) of center adapter  335  relative to sleeve  310 , key lock  382  is backed out along threaded keyway  377 , center adapter  335  is moved longitudinally relative to sleeve  310  as desired and then, in order to accommodate rotational adjustment, center adapter  335  is moved slightly longitudinally if and as needed so as to align the horizontally-extending ribs  378  of center adapter  335  with the bands of recessed wall  376  of sleeve  310  and so as to align the bands of recessed wall  379  of center adapter  335  with the horizontally-extending ribs of  375  of sleeve  310 , whereupon the rotational position of the center adapter may be adjusted vis-à-vis the sleeve. Then center adapter  335  is moved longitudinally slightly, so that the horizontally-extending ribs  378  of the center adapter are aligned with the horizontally-extending ribs  375  of sleeve  310 , with the longitudinally-extending internal ribs  370  of sleeve  310  being received within the longitudinally-extending slots  381  of center adapter  335 . This action locks center adapter  335  against rotational movement relative to sleeve  310 . Then key lock  382  is advanced along threaded keyway  377  via screw  383  until the inner end of the key lock engages one of the bands of recessed wall  379  in center adapter  335 . In other words, the distal end of key lock  382  projects into the horizontally-extending slot formed in the center adapter by the band of recessed wall  379  disposed between two adjacent horizontally-extending ribs  378 . This action locks center adapter  335  against longitudinal movement relative to sleeve  310 , since the inner end of key lock  382  engages the two horizontally-extending ribs  378  of center adapter  335  which are disposed on either side of key lock. 
         [0065]    Accordingly, it will be appreciated that, in view of the foregoing construction, the disposition of ball  85  can be adjusted, both longitudinally and rotationally, relative to sleeve  10 , and hence the disposition of ball  85  may be adjusted, both longitudinally and rotationally, relative to a bone in which sleeve  10  is disposed. In this way, the present invention provides a new joint prosthesis which permits the disposition of the ball to be adjusted, both longitudinally and rotationaly, relative to a socket. 
         [0066]    It is also possible for the prosthesis to provide a socket, rather than a ball, at the free end of the center adapter. 
         [0067]    Thus, for example,  FIG. 26  shows a novel joint prosthesis  405  which provides a socket  485 , rather than the head  45  and ball  85 , at the proximal end of center adapter  135 . In this respect it should also be appreciated that the joint prosthesis  405  shown in  FIG. 26  comprises the aforementioned center adapter  135  (except modified to include socket  485 ) in combination with the aforementioned sleeve  310 , with key lock  382  being used to selectively lock center adapter  135  to sleeve  310 . Thus, in this form of the invention, rotational locking is provided by virtue of the disposition of the longitudinally-extending internal ribs  370  in the longitudinally-extending slots  160  of center adapter  135 , and longitudinal locking is provided by virtue of the disposition of the toe of key lock  382  in the horizontally-extending slots  155  in center adapter  135 . 
         [0068]    By way of further example,  FIGS. 27-29  show another novel joint prosthesis  405  which provides an alternative form of socket  486  at the distal end of center adapter  135 . If desired, a support collar  487  may be provided between the top of sleeve  310  and the bottom of socket  486  so as to provide increased support for the socket element. Furthermore, if desired, this support collar may be formed in two separate halves, united at the time of use, so as to facilitate deployment at the surgical site. 
       Example 
     Intended Use 
       [0069]    The device and its associated method of use provide, in one exemplary use, a proximal humerus replacement prosthesis. The purpose of this exemplary device is to replace the humeral head articular surface when the bone is damaged. These situations would include fractures and/or dislocation, aseptic necrosis or various forms of arthritis such as osteoarthritis, rheumatoid arthritis or post traumatic arthritis, failed joint replacement or any other situation where arthrodesis or other reconstructive procedures would not be expected to give a satisfactory outcome. 
       Design 
       [0070]    The exemplary shoulder prosthesis system includes prosthetic components and instrumentation for the implantation of a modular proximal humerus replacement. Some unique aspects of this system, among others, are that it allows adjustment of the final prosthesis in height and rotation (version), i.e., longitudinally and rotationally, as well as having special features to facilitate re-attachment of bone and soft tissue if that is desired. The height and version (i.e., the longitudinal disposition and the rotational disposition) of the humeral prosthesis are critical factors in performing a shoulder replacement procedure. These variables are particularly difficult to measure in cases of fracture or other situations of distorted anatomy such as aseptic necrosis or fracture malunion. These variables are normally measured through a trialing process. However, in the setting of a fracture, it is very difficult to secure the trial to the shaft of the humerus. Therefore the trial moves and shifts easily, making measurements very inaccurate and hard to reproduce. Some alterations to the trial as well as holding jigs have been tried with varying degrees of success. Patient size and position also contribute to inaccuracy. Finally there is the difficulty of making measurements based on landmarks that are fairly distant such as the transcondylar axis at the distal humerus and forearm external rotation as references for prosthetic rotation. Adding to the difficulty is the fact that once the final components are placed, either by cementing or in a press-fit fashion, there is no allowance for adjustment. The prosthesis position cannot be changed without significant structural risk to the shoulder bone stock. This causes significant delays in the procedure as the surgeon checks and re-checks the position of the trial, knowing that no changes can be made once the final prosthesis is secured in place. 
         [0071]    The shoulder prosthesis system of the present invention, however, has a distinctive mechanism that simplifies the procedure and allows for adjustment of these critical factors with the final prosthesis. The procedure and method for placement of the shoulder prosthesis follows. The process of describing the procedure will also outline the key design features of the system. 
       Procedure 
       [0072]    The first step in the procedure is to prepare the humeral shaft. This is done by reaming the intramedullary canal to create space for and determine the size of the initial component. This initial component is a tubular sleeve with a flange-like collar at its top end, e.g., the aforementioned sleeve  310 . See  FIG. 30 . Note that, the tubular sleeve  310  shown in  FIG. 30  is substantially the same as the sleeve  310  disclosed above, except that the flange-like collar F shown in  FIG. 30  is not circular. More particularly, the flange-like collar F is preferably extended radially outwardly in the portion containing threaded keyway  377 , whereby to make the key lock  382  disposed in threaded keyway  377  more easily accessible to the surgeon. 
         [0073]    The sleeve will be cemented into place in the same fashion as for all prosthesis of the shoulder. The sleeve is cemented fully seated down to its collar and need only be cemented in a position that allows access to the key lock portion of the collar (described below). The sleeve&#39;s collar is preferably protected by a separate cover (not shown) during the cementing procedure in order to prevent cement from getting into the mechanisms on the collar which are used to secure the center adapter to the collar. Once the cement is hardened and all extraneous cement is removed, the protective cover is removed. It is into this sleeve that the prosthesis stem (e.g., the aforementioned center adapter  335 ) is placed. See  FIG. 31 . 
         [0074]    The sleeve diameter selected determines the corresponding prosthesis stem (e.g., center adapter) that will fit into the sleeve. Therefore, once the reaming is completed and determines the sleeve diameter, that in turn determines the prosthesis stem (e.g., center adapter) that fits the sleeve. No further trialing is necessary inasmuch as the sleeve and stem (e.g., center adapter) are provided as a matched set. 
         [0075]    The upper portion of the sleeve and the shaft of the prosthesis stem (e.g., center adapter) have a mechanism that allows the coupling of the two components but also allows adjustment for both height and rotation. See, for example,  FIG. 32 , which shows the aforementioned sleeve  310  and the aforementioned center adapter  335 . As discussed above, sleeve  310  comprises a plurality of horizontally-extending internal ribs  375  which are separated from one another by bands of recessed wall  376 . Each of the horizontally-extending external ribs  375  carries a plurality of longitudinally-extending internal ribs  370  thereon. A threaded keyway  377  is formed in the side wall of sleeve  310 . Threaded keyway  377  communicates with central lumen  320  of sleeve  310 . As also discussed above, center adapter  335  comprises a plurality of horizontally-extending ribs  378  which are separated from one another by bands of recessed wall  379 . Thus, the bands of recessed wall  379  essentially comprise horizontally-extending slots in center adapter  335 . Each of the horizontally-extending ribs  378  carries a plurality of longitudinally-extending slots  381  thereon. And as also discussed above, the key lock  382  is radially movable along threaded keyway  377  via a screw  383  so as to secure center adapter  335  in a desired position relative to sleeve  310 . 
         [0076]    All known current prostheses do not allow any significant adjustment of the prosthesis after the cement has hardened. However, since with the present invention a cylindrical sleeve is installed first, it provides a foundation from which the stem (e.g., center adapter) can be adjusted. It is the aforementioned coupling mechanism between the sleeve and the stem (e.g., center adapter) that allows this adjustment option. This is a tremendous advantage to the surgeon and patient as the position of the articular surface can be optimized rather than having only one chance to estimate the proper position while cementing-in a final prosthesis that is firmly fixed after the cement hardens. 
         [0000]    From the foregoing disclosure, it will be appreciated that, in one form of the invention, the coupling mechanism entails a series of splines on the shaft of the stem that match into corresponding splines on the upper portion of the sleeve. In one preferred form of the invention, there are three levels of splines within the sleeve to engage three levels of splines on the stem (e.g., center adapter). Engaging three levels of splines creates strength in resisting rotational force and also the top-to-bottom length of this engagement prevents toggle of the stem (e.g., center adapter) within the sleeve as well. These splines on each component are separated by a smooth recessed area. This smooth band is preferably laser-marked black to assist in demonstrating proper positioning of the stem (e.g., center adapter) for adjustment and locking options as described below. It will be appreciated that the distance between the spline bands sets the increment of height change, and the number of splines determines the increment of rotational adjustment. The coupling mechanism is preferably constructed so that it allows rotational adjustment in 10 degree increments and height adjustment in 4 mm increments. The sleeve has a locking key that is driven by a screw mechanism. As the screw is turned in a clockwise direction, it drives the locking key toward the center of the sleeve. When the stem (e.g., center adapter) is aligned with a dark laser-marked smooth area exposed immediately above the flange-like collar F, this is the locking position. In this position, the splines on the stem (e.g., center adapter) are engaged with the splines on the sleeve and a smooth area is aligned with the entry window of the locking key. As the locking key advances forward, it fits into the smooth area on the shaft of the stem (e.g., center adapter) below the first engaged spline at the top of the sleeve. With the locking key tightened into place, this holds the prosthesis stem (e.g., center adapter) within the sleeve, preventing any superior or inferior movement of the stem (e.g., center adapter). At the same time, in this position, the splines are engaged as well, locking the prosthesis in rotation. 
         [0077]    If adjustment is desired, then the key lock is backed up to disengage the prosthesis stem (e.g., center adapter). The stem can then glide superiorly or inferiorly to adjust the height of the prosthesis. If rotational adjustment is desired, then the stem (e.g., center adapter) is held so one of the splines aligns with the superior rim of the sleeve. This puts the splines in alignment with the smooth bands and thus they do not engage. In this way rotation can be adjusted. When the desired rotation is obtained, then the stem (e.g., center adapter) is moved either superiorly or inferiorly so the splines engage at the desired height. The key lock is advanced, with the stem (e.g., center adapter) held in the locking position, and a laser-marked black smooth band aligned at the top edge of the sleeve. 
         [0078]    When the final desired height and rotation are obtained, and the key lock is tightened into place, a locking cover  500  ( FIG. 33 ) is preferably applied to the sleeve so as to close off keyway  377 . This locking cover fits into grooves which are formed within the window for the key lock on the sleeve. See  FIG. 33 . The locking cover covers the key lock, abutting against it and preventing back-out of the key lock. If the key lock cannot move backward, then the coupling mechanism remains secure. However, even at this stage, the locking cover  500  can be easily removed from the sleeve and allow access to the key lock if needed. The locking cover  500  preferably has scallops at its superior and inferior margins in order to accommodate a flat removal tool. This removal tool can easily lever out the locking cover if further adjustment of the prosthesis is deemed necessary. Therefore the surgeon can make adjustments to the prosthesis position at any time in the procedure and is never at a point where this option is eliminated. 
         [0079]    Re-attachment of soft tissue and bone are frequently needed in a joint restoration procedure, particularly in the instance of a fracture. The greater and lesser tuberosity fragments have the tendons of the rotator cuff muscles attached to them. They are usually re-attached by suturing them to the prosthesis and the shaft of the bone. However, there is a high failure rate of the tuberosities uniting. Because a prosthesis is made of metal, and while it is often coated with a substance to enhance healing, it is difficult for fractured bone to heal to such a surface. This is made worse by the fact that there is frequently diminished surface area contact between the bone and such a surface. Some prostheses allow for some bone graft to be placed through a window in the prosthesis to facilitate bone-to-bone healing. This has improved tuberosity union rates, confirming that the concept is sound. However, the shape of such a bone plug in a small window on the prosthesis also does not allow enough surface area to allow good opportunity for healing. 
         [0080]    To address this issue, the shoulder prosthesis of the present invention preferably has an optional bone cage that can be applied to the back of the prosthesis, e.g., the cage  90  previously discussed. See  FIG. 34 . This cage can be packed with bone graft or similar bone substitute and/or osteoconductive material. The windows of the bone cage are shaped and sized to maximize contact of the graft and the native bone being applied. The bone graft could be packed separately in a holding bowl that could stabilize the cage. Once the bone graft is sufficiently packed, it can be compressed with a tamp that is shaped like the back side of the prosthesis in order to ensure proper fit once the cage was applied to the prosthesis. With the graft packing completed, the cage can then be applied to the prosthesis and secured with a screw, e.g., screw  91 . Significantly, because the bone cage is preferably shaped so as to follow the contours of the back of the prosthesis stem, the forces on the screw are dispersed. In addition, there is preferably a slight offset between the threaded hole in the prosthesis (e.g., the aforementioned hole  93 ) and the hole in the back of the bone cage (e.g., the aforementioned hole  92 ). As the screw fully seats, it places some tension on the bone cage. This tension, which places a lateral force on the shaft of the screw, will prevent the screw from backing out. The bone cage preferably also has multiple attachment points for suturing of the tuberosities to the prosthesis in order to ensure secure hold and apposition to the graft. 
         [0081]    An additional feature that is present to enhance attachment of bone and soft tissue to the prosthesis are optional suture anchors ( FIG. 35 ) that can be placed in threaded holes on the prosthesis stem&#39;s head portion, e.g., the threaded holes  395  shown in  FIG. 34 . See, for example, FIG.  36 ., which shows bone anchors (with attached suture) disposed in head  45 . These suture anchors can be placed anteriorly as well as posteriorly. Because the stem (e.g., center adapter) of the prosthesis can be rotated and adjusted at any time, this allows access to the posterior aspect of the prosthesis for anchoring of the tuberosities in a fracture setting. 
         [0082]    Normally, with the prosthesis fixed in place, it is very difficult to access the posterior aspect and all of the anchoring is applied to the anterior accessible aspect. These additional features increase the choices available to the surgeon to achieve bony and soft tissue union in this very difficult reconstructive environment. Because these features are optional, the surgeon can use them at his/her discretion to address the situation at hand. 
       Applicable Joints 
       [0083]    It will be appreciated that the prosthesis of the present invention may be used in a variety of joints within the body, e.g., the elbow, the wrist, the distal radius, proximal radius, hip, etc. 
       Modifications of the Preferred Embodiments 
       [0084]    It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.