Patent Publication Number: US-10327817-B2

Title: Internal joint stabilizer device, system and method of use

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation-in-part of co-pending U.S. patent application Ser. No. 13/943,078, which is a divisional of U.S. patent application Ser. No. 12/534,595, filed on Aug. 3, 2009 and entitled Internal Joint Stabilizer Device, System and Method of Use, now U.S. Pat. No. 8,506,606, which claimed priority to: Provisional Patent Application No. 61/085,651, filed on Aug. 1, 2008 and entitled “Internal Joint Stabilizer And Method Of Use”; Provisional Patent Application No. 61/094,228, filed on Sep. 4, 2008 and entitled “Internal Joint Stabilizer And Method Of Use”; Provisional Patent Application No. 61/100,138, filed on Sep. 25, 2008 and entitled “Internal Joint Stabilizer And Method Of Use”; Provisional Patent Application No. 61/139,274, filed on Dec. 19, 2008 and entitled “Internal Joint Stabilizer And Method Of Use”; and Provisional Patent Application No. 61/163,693, filed on Mar. 26, 2009 and entitled “Axis Locator Jig And Method”; those applications being incorporated herein, by reference, in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to the stabilization of joints for the purpose of facilitating healing and the early re-establishment of adequate range of motion at the joints. 
     DESCRIPTION OF THE RELATED ART 
     Dislocation and subluxation of joints are serious clinical problems that if persistent, recurrent or chronic can result in irreversible damage. These chronic instabilities are usually the result of damage to the supporting joint ligaments and/or the result of loss of bony integrity. Treatment of these conditions includes restoration of the proper relationships or “reduction” of the bones involved. Reduction must be maintained for a period of time sufficient to allow for healing of the damaged tissues. Also, it is desirable to maintain joint motion during this period in order to prevent ankylosis and to maintain a healthy articular cartilage. Thus, the ideal immobilization for a dislocated or subluxed joint would prevent abnormal translational movements but allow motion similar to its normal kinematics. 
     Hinged external fixators have been devised for the purpose of allowing the desired motion in the joint after reduction of the dislocation. These external fixators have been used primarily on the elbow but can also be used on the knee or the ankle. Hinged external fixators have provided satisfactory end results, allowing patients to regain adequate range of motion as well as stability of the joint. However, despite being considered “external” devices the installation of hinged external fixators require open surgery in order to properly identify the axis of rotation of the joint, a critical aspect of their functionality, because it has proven difficult or impossible to determine such axis from outside the body. Surgery, open or percutaneous, is also required to affix the position of the installed hinged external fixator by inserting multiple pins into the adjacent bones. 
     The intrinsic bulkiness of external fixators, combined with pain and frequent complications at the pin tracts have limited the quality of the clinical results of these devices. Patients have difficulty in actively moving these joints primarily due to pain in the pin tract sites. Patients are also limited in carrying out everyday functions due to the cumbersome nature of the device which must remain installed for a relatively long time, normally five or six weeks on average. 
     The need remains for a device that will maintain reduction while allowing early post-operative normal motion of the joint but that will eliminate the problems of device bulkiness and pin tract pain and complications associated with existing hinged external fixators. 
     There additionally exists a need for a guide, system and method for locating the axis of rotation of a joint, prior to stabilization and for, subsequently, affixing a joint stabilizer. 
     BRIEF SUMMARY OF THE INVENTION 
     It is accordingly an object of this invention to provide an internal joint stabilizer device, system and method which overcomes the above-mentioned disadvantages of the heretofore-known devices. A joint stabilizer device is provided including an axle and a portion that can be affixed to a bone. The device is placed internally in order to prevent pin tract problems and to stabilize the joint while allowing motion of the joint along its natural trajectory. 
     Additionally, a method for using the device is provided that includes inserting the axle into a first bone forming a joint, and attaching the fixable portion to a second bone of the joint. A trajectory guide that can optionally be used to locate the axis of rotation of the joint, prior to stabilization, is additionally provided. 
     Although the invention is illustrated and described herein as embodied in an Internal Joint Stabilizer Device, System and Method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of the specific embodiment when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are perspective views of two different particular embodiments of an internal joint stabilizer of the instant invention. 
         FIG. 2  is a perspective view of the internal joint stabilizer of  FIG. 1A  with bone screws attached. 
         FIG. 3  is a perspective view of the internal joint stabilizer of  FIG. 2  after it has been installed in the humero-ulnar joint.  FIG. 3A  is an enlarged detail view of the humero-ulnar joint of  FIG. 3 . 
         FIG. 4  is a plan view of the internal joint stabilizer after it has been installed in an interphalangeal joint. 
         FIG. 5  is a side elevational view of the internal joint stabilizer of  FIG. 4  after it has been installed in an interphalangeal joint. 
         FIG. 6  is an exploded perspective view of an exemplary joint including an internal joint stabilizer of the instant invention used in conjuction with a prosthetic implant, in accordance with a further embodiment. 
         FIG. 7  is a side elevational view of an exemplary joint including the internal joint stabilizer of  FIG. 6  after installation. 
         FIG. 8  is a perspective view of a further particular embodiment of the internal joint stabilizer of the instant invention. 
         FIG. 9  is an exploded perspective view of the internal joint stabilizer of  FIG. 8 . 
         FIGS. 10A and 10B  are enlarged side elevation views of the plate portion of the internal joint stabilizer of  FIG. 8 . 
         FIGS. 11A and 11B  are enlarged perspective views of the plate portion of the internal joint stabilizer of  FIG. 8 . 
         FIGS. 12A, 12B, 12C, 13A and 13B  are enlarged perspective views of the turret portions of the internal joint stabilizer of  FIG. 8 . 
         FIG. 14  is a partially exploded perspective view of selected portions of the internal joint stabilizer of  FIG. 8 . 
         FIGS. 15A-15B  are side elevational views, and  FIGS. 15C-15D  are exploded perspective views, of selected portions of the internal joint stabilizer of  FIG. 14 . 
         FIG. 16  is a perspective view of the internal joint stabilizer of  FIG. 8  indicating the different types of adjustment capabilities. 
         FIGS. 17A and 17B  are perspective and exploded perspective views of a further embodiment of the plate portion and turret assembly of the internal joint stabilizer of  FIG. 8 . 
         FIGS. 18A-18B  are a perspective view and an exploded perspective view, respectively, of selected portions of an internal joint stabilizer in accordance with a further embodiment of the instant invention. 
         FIG. 18C  is a perspective view an internal joint stabilizer using the selected portions shown in  FIGS. 18A-18B . 
         FIGS. 18D and 18E  are perspective views of a plate useful with an internal joint stabilizer in accordance with another embodiment of the invention. 
         FIG. 18F and 18G  are perspective views of a double-sided internal joint stabilizer in accordance with another embodiment of the invention. 
         FIG. 18H  is a plan view from the posterior side of the elbow joint showing the internal joint stabilizer of  FIG. 18F  being attached to the ulna and with axle portions mated in the humerus (shown as transparent, for clarity) in accordance with one particular embodiment of the invention. 
         FIG. 19  is a side elevational view of an axis trajectory guide and its component parts, in accordance with one particular embodiment of the present invention and  FIG. 20  is an exploded view of the axis trajectory guide of  FIG. 19 . 
         FIGS. 21-27  illustrate one particular method of using the axis trajectory guide of  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures of the drawings in detail and, more particularly, to  FIGS. 1A and 2 , there is shown one particular embodiment of an internal joint stabilizer  1  in accordance with the present invention. The internal joint stabilizer  1  is designed to be placed internally, so as to prevent pin tract problems and to stabilize the joint, while allowing motion at the joint along its natural trajectory. 
     The internal joint stabilizer  1  of  FIG. 1A , is particularly adapted for use in connection with hinged joints, such as an elbow, and is preferably made of metal (such as titanium, cobalt chrome or stainless steel or a combination of titanium portions and cobalt chrome portions); bioabsorbable material (such as PLA or PGA) or a combination of metal and bioabsorbable material. The internal joint stabilizer  1  includes a plate portion  2 , which is, preferably, formable (i.e., bendable). Extending through the plate portion  2  are holes  3  and  4 , which are adapted to receive bone screws  7  and  8 . Note that the holes  3  and/or  4  can be embodied by a slot and that none, more or fewer holes  3  and/or  4  to receive bone screws  7 ,  8  can be included in the plate portion  2 , as desired. The bone screw  7  is preferably a compression screw to be attached to a bone through hole or slot  3 . If provided, holes  4  are preferably adapted to receive, indiscriminately, compression screws and/or angle-stable screws  8  to be attached to the same bone as screw  7 , at an angle selected by the surgeon. If selected, angle-stable screws  8  become engaged with holes  4  upon fully setting, providing further stability at the selected angle. Note that, as shown more particularly in  FIG. 1B , an internal joint stabilizer in accordance with the instant invention can have a very simple form. For example, the entire internal joint stabilizer  1 ′ of  FIG. 1B , including the fixable portion  2 ′, holes  3 ′, neck portion  5 ′ and axle portion  6 ′ can be made from a section of K-wire or a Steinmann pin, for example, partially pre-bent to form, at least, holes  3 ′ configured to receive compression and/or angle stable screws and still be within the scope of the instant invention. 
     Referring now to  FIGS. 4 and 5 , there is shown another particular embodiment of an internal joint stabilizer  11  in accordance with the present invention. The internal joint stabilizer  11  is designed to be placed internally, so as to prevent pin tract problems and to stabilize the joint, while allowing motion at the joint along its natural trajectory. 
     The internal joint stabilizer  11  of  FIGS. 4, 5  is particularly adapted for use in connection with other hinged joints, such as the interphalangeal joints of the hand known as PIP (proximal interphalangeal joint), DIP (distal interphalangeal joint) and IP (interphalangeal joint of the thumb), and is preferably made of metal (such as titanium, cobalt chrome or stainless steel), bioabsorbable material or a combination of both. The internal joint stabilizer  11  includes a plate portion  12  which is preferably formable. Extending through the plate portion  12  are hole or slot  13  and holes  14 , which are adapted to receive bone screws  17  and  18 . Note that none, fewer or more holes  14  to receive bone screws  18  can be included in the plate portion  12 , as desired. The bone screw  17  is preferably a compression screw to be attached to a bone through hole or slot  13 . If provided, holes  14  are preferably adapted to receive, indiscriminately, compression and/or angle-stable screws  18  to be attached to the same bone as screw  17 , at an angle selected by the surgeon. If selected, angle-stable screws  18  become engaged with holes  14 , upon fully setting, providing further stability at the selected angle. 
     Referring now to  FIGS. 1A, 2, 4 and 5  the internal joint stabilizer  1 ,  11  additionally includes a neck portion  5 ,  15  extending from the edge  2   a ,  12   a  of the plate portion  2 ,  12 . An axle portion  6 ,  16  extends from the end of the neck portion  5 ,  15  distal from the plate  2 ,  12 . The neck portion  5 ,  15  is preferably formable (i.e., bendable) such that it can be formed by the surgeon intraoperatively in any of three axes X, Y, Z to conform to the anatomy of the patient after the axle portion  6 ,  16  has been placed in alignment with the natural axis of rotation of the hinged joint where it is being used. As an example, in the case where the hinged joint is the elbow, the plate portion  2  would be rigidly affixed to the ulna on its lateral, posterior or its medial aspect, while the axle portion or projection  6  would project through a hole in the humerus, aligned to the natural axis of joint rotation. In another example, in the case where the hinged joint is an interphalangeal joint, the plate portion  12  would be rigidly affixed to the more distal phalanx on its ulnar or radial aspect, while the axle portion or projection  16  would project through a hole in the more proximal phalanx, aligned to the natural axis of joint rotation. It should be noted that the relationship between the plate portions  2 ,  12  and neck portions  5 ,  15  of internal joint stabilizers  1 ,  11  have been adapted to the anatomy to which the internal joint stabilizer is being applied. In the case of internal joint stabilizer  1  the axis of the neck portion tends to be substantially perpendicular to the axis of the plate portion (i.e. forming an inverted T) while in the case of internal joint stabilizer  11  the axis of the neck portion tends to be substantially in line with the axis of the plate portion. The relationship between the plate portion and the neck portion can be further adapted for other parts of the anatomy where the internal joint stabilizer will be applied while staying within the scope of the present invention. 
     The plate portion  2 ,  12  and neck portion  5 ,  15 , respectively, of the internal joint stabilizer  1 ,  11  could be constructed in accordance with that described in U. S. patent application Ser. No. 12/463,037, which application is being incorporated herein, by reference, in its entirety. 
     One particular method of utilizing the internal joint stabilizer  1  will now be described in connection with  FIGS. 1A-3A . More particularly,  FIGS. 3-3A  illustrate the internal joint stabilizer  1  attached to the humero-ulnar joint. It can be seen that the axle portion  6  (shown in dotted line) has been inserted into the humerus  20 , in alignment with the natural axis of rotation of the humero-ulnar joint. The plate portion  2  is attached to the ulna  21  (in this example, on the lateral side) using the bone screw  7 , in compression mode, while the screws  8  further attach the plate portion  2  to the ulna  21  in compression or in angle-stable mode. Additionally, the radius bone  22  is shown for reference only, since it is not affected by the procedure. 
     Furthermore,  FIGS. 4 and 5  illustrates the internal joint stabilizer  11  attached to an interphalangeal joint (a PIP joint, in particular). It can be seen that the axle portion  16  (shown in dotted line) has been inserted into the more proximal phalanx  30 , in alignment with the natural axis of rotation of the interphalangeal joint. The plate portion  12  is attached to the ulnar (shown) or the radial aspect of the more distal phalanx  31  using the bone screw  17 , in compression mode, while the screws  18  further attach the plate portion  12  to the more distal phalanx  31  in compression or in angle-stable mode. 
     To install the internal joint stabilizer the surgeon approaches the affected joint through lateral and/or medial incisions (in the case of the elbow) or radial and/or ulnar incisions (in the case of the interphalangeal joint). The dislocated joint is reduced and a first point on the axis of rotation of the joint determined. This can be accomplished by visual inspection of the anatomy. Alternatively, the joint can be moved through its range of motion allowing the surgeon to identify and mark the isometric point on the proximal bone of the joint (the humerus in the case of the elbow or the more proximal phalanx of the affected joint in the case of an interphalangeal joint) which locates a first point on the axis of rotation. In the case of the elbow this point is located in the center of the capitellum next to the base of the lateral epicondyle. Similarly, a second point on the axis of rotation on the opposite side of the proximal bone  20 ,  30  of the joint can be identified by fluoroscopy, direct inspection or with the aid of a specialized axis trajectory guide (for example, the axis trajectory guide  400  of  FIG. 19 ) and marked. A hole is then drilled through the axis of rotation in preparation for installation of the internal joint stabilizer. 
     The axle portion  6 ,  16  is then inserted in the hole drilled in the proximal bone of the joint. If and as required, the neck portion of the internal joint stabilizer is then formed by the surgeon in such a way that hole or slot  3 ,  13  of the plate portion  2 ,  12  will lie in its proper position, flat against the relatively flat portion of the lateral (shown), posterior or medial aspect of the ulna  21  in the case of the elbow or the radial or ulnar (shown) aspect of the more distal bone of the affected joint  31  in the case of an interphalangeal joint. A bone screw  7 ,  17  is inserted into hole or slot  3 ,  13  and screwed into the bone. If holes or slots  4 ,  14  are provided, the plate portion  2 ,  12  is further formed by the surgeon, as required, so that holes or slots  4 ,  14  lie approximately flat against the lateral (shown), posterior or medial aspect of the ulna  21  in the case of the elbow or the radial or ulnar (shown) aspect of the more distal bone of the affected interphalangeal joint. Compression or angle-stable screws  8 ,  18  are then inserted into holes  4 ,  14  at an angle selected by the surgeon and screwed into the ulna  21  or phalanx  31  as the case may be. If desired, after screws  8 ,  18  have been attached, the bone screws  7 ,  17  that were originally affixed through holes or slots  3 ,  13  may be removed and substituted by angle-stable screws  8 ,  18 . 
     Range of motion and stability of the joint is again tested. Incisions are closed by the surgeon in standard fashion. 
     If required, internal joint stabilizers made of metal may be removed surgically after a period of time sufficient to allow healing of the damaged tissues. In an alternate embodiment all or some portions of the stabilizer or, at least, its axle portion would be made of bioabsorbable material, i.e.: polylactic acid, thus reducing the need for surgical removal of some or all portions of the internal joint stabilizer. 
     Referring now to  FIGS. 6 and 7 , there is shown a further embodiment of an internal joint stabilizer  40  in accordance with the instant invention. In certain cases, the surface or end of the proximal bone  50  of the joint may be damaged, and may need to be replaced. As such, in accordance with the principles of the present invention, an axle portion  42  of the internal joint stabilizer  40  of the present invention can be inserted into a prosthetic implant  60  inserted into the damaged proximal bone  50 . For example, as shown in  FIGS. 6 and 7 , the internal joint stabilizer  40  is particularly adapted for use in the cases where the articular surface of the proximal bone  50  (in this case, the humerus of the humero-ulnar joint) is damaged and needs to be replaced by a prosthetic implant  45 . Note that the exemplary use of the humero-ulnar joint is not meant to be limiting, as the use of the internal joint stabilizer  40  can be adapted for use in other joints (for example, in the PIP joint) when the use of a prosthetic implant is indicated. 
     As shown more particularly in  FIG. 6 , in the present example, a prosthetic implant  45  is provided that includes a surface  45   a  to replace the damaged articular surface of the humerus  50  and a shaft  45   b  to be inserted into, and affixed to, the medullary cavity  50   a  of the humerus  50 . The prosthetic implant also includes a pre-drilled hole  46  sized to receive the axle portion  42  of the internal joint stabilizer  40 . Alternatively, the surgeon may drill the hole  46  for the axle  42  intra-operatively. Optionally, a bearing sleeve  48  preferably made of plastic material can be provided to be inserted into the hole  46  of the prosthetic implant prior to inserting the axle  42  of the internal joint stabilizer  40 . When using the optional bearing sleeve, the hole  46  in the prosthetic implant  45  will be sized and otherwise configured to receive the bearing sleeve  48 . 
     To install the internal joint stabilizer shown in  FIGS. 6 and 7 , the surgeon approaches the affected joint (i.e., the elbow in the illustrated example) through an incision and proceeds to remove the damaged articular surfaces of the proximal bone  50  (for example, the humerus) as shown in  FIG. 6 , to prepare the medullary cavity  50   a  of the proximal bone  50  to receive the shaft  45   b  of the prosthetic implant  45 . The prosthetic implant  45  is then inserted and affixed with screws and/or cement and/or other means to the proximal bone  50 , such that the axis of the hole  46  is aligned with the natural axis of rotation of the proximal bone  50 . 
     The axle portion  42  is then inserted into the hole  46  in the prosthetic implant  45 . Alternately, if provided, the optional bearing sleeve  48  may be inserted into an appropriately sized hole  46  in the prosthetic implant  45  prior to inserting the axle portion  42  through a hole  48   a  into the bearing sleeve  48 . 
     Once the axle portion  42  and/or bearing sleeve  48  and axle portion  42  has been inserted into the hole  46  in the prosthetic implant  45 , the surgeon proceeds with the operation by following the steps previously described above in connection with the internal joint stabilizers of  FIGS. 1-5 . 
     Referring now to  FIGS. 8-11B , there is shown another embodiment of an internal joint stabilizer  110  in accordance with the instant invention. The internal joint stabilizer  110  includes additional components directed towards providing additional degrees of adjustability. The present particular embodiment of the internal joint stabilizer  110  includes a plate portion  120 , a turret assembly  130 , a neck portion  150 , a swivel joint  170 , an eyelet  171  and an axle portion  160 . All component portions of the internal joint stabilizer  110  but, at least, neck portion  150  and axle portion  160  can be provided in different sizes to accommodate the particular anatomy of the patient. 
     In particular, the internal joint stabilizer  110  includes a plate portion  120  which, in the preferred embodiment, is bendable (i.e., formable) intraoperatively. The plate portion defines an interior surface  121 , configured to engage a bone, and an exterior surface  122 , opposite the interior surface  121 . As shown more particularly in  FIG. 10B , the plane of the exterior surface  122  is preferably chosen to be oblique to the plane of the interior surface  121 , diverging from parallel by an angle A 1  in the range of 0&gt;A 1 &gt;=45 degrees. However, if desired, another angle can be chosen or the surface  122  may be selected to be parallel to the surface  121 . 
     As can be seen more particularly from  FIGS. 11A and 11B , at least two holes  123  extend through the plate  120 , between the interior surface  121  and the exterior surface  122 . Holes  123  are adapted to receive a fixation device therethrough, for example, compression bone screws ( 124  of  FIG. 10A ) or angle-stable bone screws (not shown). In one particular embodiment, the perimeter surrounding the screw holes  123  on the interior surface  121  of the plate can be provided with protrusions  125  that enhance frictional engagement with the bone. Additionally, a turret hole  126  extends through the plate  120 , between the interior surface  121  and exterior surface  122 . Turret hole  126  includes a circumferential lip  127  and is adapted to receive a turret assembly ( 130  of  FIG. 9 ). As shown in  FIGS. 11A and 11B  the turret hole  126  defines an axis Y-Y′, perpendicular to exterior surface  122 , around which the turret assembly ( 130 ) can rotate. 
     Referring now to  FIGS. 11A to 14B , there will be described a turret assembly  130  for use with one particular embodiment of the present invention. Turret assembly  130  includes a turret portion  131 , a turret nut portion  132  and a turret set screw  133 . The turret portion  131  is dimensioned to be inserted into the turret hole  126  of the plate  120 , from the side of the exterior surface  122 , until it is engaged with (i.e., seated against the exterior wall of) the circumferential lip  127 . The turret nut portion  132  is dimensioned to be inserted into the turret hole  126  from the side of the interior surface  121  of the plate  120  until it is seated against the interior surface of the circumferential lip  127 . The turret portion  131  and the turret nut portion  132  are precisely dimensioned to fit inside their respective sides of the turret hole  126  while allowing sufficient clearance to permit their rotation inside the turret hole  126  around the axis Y-Y′ (RT′ of  FIG. 14 ). The turret portion  131  and turret nut portion  132  are fixed loosely together, each on its respective side of the circumferential lip  127 , by the turret set screw  133 , with the lip portion  134  of the turret portion  131  disposed therebetween. The lip portion  134  of the turret assembly  130  is designed to loosely engage the circumferential lip  127  and permit rotation of the turret assembly  130 . Further tightening of the turret set screw  133  draws the turret nut portion  132  into frictional engagement with the circumferential lip  127 , thereby impeding further rotation of the turret assembly  130 . 
     Referring now to  FIGS. 12A-14 , it can be seen that the turret portion  131  is provided with a hole  135 , dimensioned to receive and frictionally engage with a neck portion  150 . Hole  135  is preferably cylindrical with its centerline defining an axis Z-Z′. As additionally shown, in the present embodiment, the turret portion  131  also includes a slot  136  tofacilitate clamping of neck portion  150  to turret portion  131  upon tightening of turret set screw  133 . The slot  136  is parallel to the axis Z-Z′ and extends through a portion of the turret portion  131 , from one end of the hole  135  to the other end of the hole  135 . Correspondingly, the neck portion  150  has a cylindrical cross-section and is dimensioned to be inserted, at least partially, into the cylindrical hole  135 . Once inserted, neck portion  150  can rotate about the axis Z-Z′ (RT of  FIG. 14 ) within the cylindrical hole  135 . Neck portion  150  can also slideably translate longitudinally along axis Z-Z′ of hole  135  (TR of  FIG. 14 ). However, once turret screw  133  is fully tightened into the turret nut portion  132 , friction between hole  135  and neck portion  150  clamps neck portion  150  and impedes any further rotational or translational movement of the neck portion  150  within the hole  135 . The mechanism for clamping the neck portion  150  described above is not intended to be limited to the details shown since other methods of clamping can be used without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     As shown more particularly in  FIGS. 14-15B , a swivel joint  170  can also be provided, permitting rotation of the neck portion  150  around the axis X-X′ (RT″ of  FIG. 14 ), while swivel joint screw  151  is loosely attached. More particularly, rotation of the swivel joint  170  allows the angular displacement of neck portion  150  relative to axis W-W′ of axle portion  160  after such axle has been threadably attached to eyelet  171  of swivel joint  170 . Rotation of swivel joint  170  can be impeded by fully tightening swivel joint screw  151 . 
     Referring now to  FIGS. 15A-15D ,  FIGS. 15A and 15B  show exemplary translational displacements of neck portion  150  in the turret assembly  130 . For example,  FIG. 15A  shows the neck portion  150  as fully inserted into the turret assembly  130  while  FIG. 15B  shows neck portion  150  fully extended above the turret assembly  130 .  FIGS. 15C-15D  illustrate a further embodiment of swivel joint  170  where it can be observed that the corresponding surfaces of swivel joint  170  can be matchingly splined (i.e., “grooved”) on the surfaces  173 ,  174  (as seen in  FIG. 15C ) or splined on one surface  173  and ridged circumferentially with a deformable (softer) metal on the other surface  175  (as seen in  FIG. 15D ) to advantageously allow the swivel joint to be fixed at any desired angle. In a still further embodiment it can be seen in  FIG. 15D  that neck portion  150 ′ is totally straight, that is, totally aligned with axis Z-Z′ as opposed to neck portion  150  ( FIG. 15A-15B ) that is partially straight and partially curved and where only the straight portion aligns with axis Z-Z′. Additionally, the lower end of neck portion  150 ,  150 ′ can be grooved longitudinally with grooves  152  which provide increased friction with hole  135  and allow for burr-free cutting if, after installation, neck portion  150 ,  150 ′ protrudes more than desired below turret portion  131 . 
     Referring now to  FIG. 16 , the internal joint stabilizer  110  described in connection with  FIGS. 8-15C , provides  4  degrees of freedom for adjustment: a.) rotation of neck portion  150 ,  150 ′ around axis Z-Z′ (RT); b.) longitudinal translation of neck portion  150 ,  150 ′ along axis Z-Z′ (TR); c.) rotation of turret assembly  130  around axis Y-Y′ (RT′) with resulting angular displacement of neck portion  150 ,  150 ′; and d.) angular displacement of neck portion  150 ,  150 ′ relative to axle portion axis W-W′ resulting from rotation of swivel joint  170  around axis X-X′ (RT″). 
     Referring now to  FIGS. 17A and 17B , there is shown a further embodiment of a plate portion and turret assembly for use with an internal joint stabilizer of the instant invention. For example, if desired, the plate  201  and turret assembly  200  of  FIGS. 17A-17B  can be substituted for the plate  120  and turret assembly  130  in the internal joint stabilizer  110  of  FIGS. 8-16 . More particularly, the plate  201  and turret assembly  200  are configured to provide the internal joint stabilizer of the instant invention with an additional degree of freedom for adjustment. As shown, turret assembly  200  includes a cylindrical hole  290 , therethrough, which defines an axis V-V′. The cylindrical hole  290  receives a correspondingly sized cylindrical shaft portion  280 , extending between the two plate sockets  295 . Each plate socket  295  includes a screw hole  123  and can include protrusions  125 , similar to those previously described in connection with the plate  120  of  FIGS. 8-16 . As also shown in  FIG. 17B , the turret assembly  200  can be used with turret portion  131 , turret nut portion  132  and turret set screw  133 , of the previously described turret assembly  130 . The turret assembly  200  can additionally mate with a neck portion  150 ,  150 ′ in the manner described in connection with  FIG. 14  above. 
     When plate portion  201  and turret assembly  200  are used as part of an internal joint stabilizer, such as the internal joint stabilizer  110  of  FIG. 8 , an additional (fifth) degree of freedom is advantageously obtained. More particularly, this further degree of freedom permits rotation of the turret assembly  200  around axis V-V′ (RT″ of  FIG. 17B ), resulting in a further corresponding rotation of a connected neck portion  150 ,  150 ′. 
     Referring now to  FIGS. 18A and 18B , there is shown a further embodiment of a plate portion and turret assembly for use with an internal joint stabilizer of the instant invention. For example, if desired, the plate  301  and turret assembly  300  of  FIGS. 18A-18B  can be substituted for the plate  120  and turret assembly  130  in the internal joint stabilizer  110  of  FIGS. 8-16 . More particularly, the plate  301  and turret assembly  300  are configured to provide the internal joint stabilizer of the instant invention with one more additional degree of freedom for adjustment as that provided by the plate  201  and turret assembly  200 . As shown, turret assembly  300  includes a cylindrical hole  390 , therethrough, which defines an axis V-V′. The cylindrical hole  390  receives a cylindrical shaft portion  380  of corresponding diameter but of greater length than cylindrical hole  390 , extending between the two plate extensions  395 . Plate  301  includes a screw holes  123  similar to those previously described in connection with the plate  120  of  FIGS. 8-16  and a slot  323  configured to receive a compression screw. As also shown in  FIG. 18B , the turret assembly  300  includes turret portion  331 , turret nut portion  332  and turret set screw  333 , similar to previously described turret assembly  130 . The turret assembly  300  can additionally mate with a neck portion  150 ,  150 ′ along axis Z-Z′ in the manner described in connection with  FIGS. 14  above. 
     When plate portion  301  and turret assembly  300  are used as part of an internal joint stabilizer, such as the internal joint stabilizer  110  of  FIG. 8 , an additional (sixth) degree of freedom is advantageously obtained. More particularly, this further degree of freedom permits longitudinal translation of the turret assembly  300  along axis V-V′ (TR′ of  FIG. 18A ), resulting in a further possible adjustment of a connected neck portion  150 ,  150 ′. 
       FIG. 18C  shows internal joint stabilizer  310 , which includes plate portion  301 , turret assembly  300 , neck portion  150 ′, swivel joint  170  and axle portion  160  described above after installation on the posterior part of the ulna  21  in the humero-ulnar joint. It should be noted that the humerus  20  is shown semi-transparent to permit visualization of the axle portion  160  through the axis of rotation of the joint, while the ulna  21  and the radius  22  are shown solid. 
     A further embodiment of the present invention is illustrated in  FIGS. 18D-18H . Note that, throughout the embodiments, like reference numbers are used in the drawings to represent like parts. More particularly, referring now to  FIG. 18F , a double-sided internal joint stabilizer  310 A is provided that includes a plate portion  301 A that differs from the plate portion  301  of  FIGS. 18A-18C  in that it includes attachment points for two turret assemblies  300 , instead of merely one turret assembly  300 , as described in connection with  FIGS. 18A-18C . The double-sided internal joint stabilizer  310 A is particularly advantageous in that, when installed, provides a closed construct more stable than a single-sided internal joint stabilizer. The plate  301 A includes two pairs of plate extensions  395 , with each pair including a cylindrical shaft portion  380  extending therebetween. A turret  300 , (each of which comprises a turret portion  331 , a turret nut portion  332  and a turret set screw  333 ), are attached to the shaft portions  380  in a mirrored configuration, and can rotate about their respective cylindrical shaft potion  380 . Additionally, in a preferred embodiment, each turret  300  can be translated longitudinally up and/or down the shaft portion  380 . In short, each turret assembly  300  and its attachment portion, can be exactly as described above in connection with the turret assembly  300  and attachment portion of  FIGS. 18A-18C , but, in the present embodiment, in mirrored orientation to one another (i.e., with each turret nut portion  320  on the outside, away from the bone). 
     Similarly, each turret assembly  300  mates with a neck portion  150 ′, along an axis (e.g., axis Z-Z′ of  FIG. 18B ) in the manner described in connection with  FIGS. 14 and 18A-18C . A swivel joint  170 , as described above in connection with  FIGS. 14-15B , is additionally provided on each side of the plate  301 A (i.e., in association with each turret assembly  300 ). 
     However, in the present particular embodiment, the axle portion is made up of two mating parts  160 A and  160 B. More particularly, the axle portions  160 A and  160 B are inserted from two sides of the humerus  20  when the plate  301 A is attached to the ulna  21 , and are mated together inside the bone  20 . Axle portion  160 A resembles the axle portion  160  described in connection with the previous embodiment, however, axle portion  160 B is cannulated to receive internal thereto, a portion of the shaft of axle portion  160 A. The axle portion  160 A can include markings that provide a visual indication to the physician regarding whether or not the axle portions  160 A,  160 B are mated and, if so, how far the axle portion  160 A has been inserted into the cannulation  161 B of axle portion  160 B. With the exception of the mating of the axle portions  160 A and  160 B, and the mirrored approach of those axle portions  160 A,  160 B to the humerus  20 , each of the two turret assemblies  300 , axles  150 ′ and swivel assemblies  170  of the embodiment of  FIGS. 18D-18H  are otherwise adjusted as described in connection with the individual parts of  FIGS. 18A-18C , or otherwise herein. 
     To install an internal joint stabilizer of the instant invention, such as the internal joint stabilizer  110  of  FIG. 8, 310  of  FIG. 18C or 310A  of  FIG. 18F , the surgeon approaches the elbow through a lateral or a medial incision. A first point on the axis of rotation is determined and marked. This can be accomplished by visual inspection of the anatomy. Alternatively, the joint can be moved through its range of motion allowing the surgeon to identify and mark the isometric point on the humerus which locates a first point on the axis of rotation. This point is located at the center of the capitellum, next to the base of the lateral epicondyle. Similarly, another end point of the axis of rotation on the opposite side of the humerus can be identified by fluoroscopy, direct inspection or with the aid of a guide (for example, the axis trajectory guide  400  of  FIG. 19 ). A hole is then drilled connecting both end points of the axis of rotation in preparation for installation of the internal joint stabilizer. 
     All portions of the internal joint stabilizer  110 ,  310  with the exception of axle portion  160  ( 160 B, in the embodiment of  FIG. 18F ) are loosely assembled. While keeping the turret set screw ( 133 ,  333  of  FIGS. 14, 18B, 18F ) and the swivel joint screw ( 151  of  FIG. 14 ) loosely attached in order to allow relative movement between its different portions, the surgeon introduces the internal joint stabilizer into the incision, while identifying an optimal location (lateral, medial or posterior) for installing the plate portion  120 ,  201 ,  301  to the ulna  21 . The plate portion  120 ,  201 ,  301  is then attached to the ulna  21  with compression screws or with angle-stable screws, as desired. The eyelet of the swivel joint ( 171  of  FIG. 14 ) is moved into contact with the humerus  20  just opposite the entry point of the hole previously drilled in the humerus  20 . An appropriately sized axle portion  160 ,  160 B is inserted through the eyelet  171  and into the previously drilled hole. Axle portion  160 ,  160 B is tightly screwed into the eyelet  171 . The surgeon adjusts the longitudinal and angular position of the neck portion  150 ,  150 ′ by rotating and sliding along axis Z-Z′ and by rotating the turret portion ( 131  of  FIG. 14  and  FIG. 17B or 331  of  FIG. 18A-18B, 18F ) and by adjusting the rotation of the swivel joint ( 170  of  FIG. 14 ). The swivel joint screw ( 151  of  FIG. 14 ) and the turret set screw ( 133  of  FIG. 14  and  FIG. 17B or 333  of  FIGS. 18B, 18F ) are tightened and range of motion is tested. If necessary finer adjustments are performed by sequentially loosening and tightening the turret set screw  133 ,  333  and/or the swivel joint screw  151  until optimal range of motion is achieved. Incisions are then closed by the surgeon in standard fashion. In the embodiment of  FIGS. 18D-18H , wherein a double-sided plate portion  301 A is used, the above-described steps can be repeated for the axle and turret assembly on the opposite side of the humerus  20 , with the addition being that the axle portion  160 A inserted in this side of the humerus  20  is then mated with the cavity of the cannulated axle portion  160 B previously inserted. 
     Referring now to  FIGS. 19-27 , therein will be described an axis trajectory guide and method that can, optionally, be used to locate the axis of rotation of a joint, prior to stabilization using one of the devices described in connection with  FIGS. 1-18H . It is important to note that the axis trajectory guide can be used as part of a system, in combination with the internal joint stabilizer devices described herein, but is not limited thereto. Rather, the axis trajectory guide of  FIGS. 19-27  can also be used to locate the axis of rotation of a joint for the insertion of a known and/or different type of fixator or joint stabilizer or in any other situation when it is desired to locate the axis of rotation of a joint. 
     In order to locate the axis of rotation of a joint, it is sufficient to identify two points pertinent to the joint&#39;s rotation. Once identified, the axis of rotation for the joint can be represented by a straight line containing the two identified points. 
     For example, referring to the case of an elbow joint for illustrative purposes only, the location of two pertinent points of rotation of this joint will permit the axis of rotation to be visualized. Approaching the humero-ulnar joint through a lateral incision a surgeon can visually identify one such point. This first point is located in the center of the capitulum next to the base of the lateral epicondyle. A second point can be assumed to be a point in the center line of the “spool” shaped trochlea (the humeral portion of the ulnar-humeral joint). In order to locate this point, a guide is provided herein, such as the axis trajectory guide  400  of  FIG. 19 , having an arcuate (i.e. in the shape of an arc of a circle) portion that can be fitted over the trochlea to particularly identify a second point on the axis. 
     The axis trajectory guide  400  of  FIG. 19  will now be described, more particularly, in connection with  FIGS. 19-20 . Referring now to  FIG. 19 , there is shown an elevational view of an axis trajectory guide and its principal component parts, in accordance with one particular embodiment of the present invention.  FIG. 20  is a perspective exploded view of the axis trajectory guide  400  of  FIG. 19 . 
     In particular, the axis trajectory guide  400  of  FIGS. 19-20  includes a handle portion  410 , a center locator  420 , and a removable alignment sleeve  430  which is configured to receive a K-wire  440  of known length L. The handle portion  410  can be made from any desired material, but is preferably made of metal, such as stainless steel, or plastic. 
     As shown more particularly in  FIG. 20 , the center locator  420  of the axis trajectory guide  400  includes an arcuate distal portion  422  defining a periphery. Please note that the arcuate distal portion of the center locator need not be limited to proscribing a particular arc of a circle. Rather, if desired, the partially open arcuate area defined can be equal to a semi-circle, larger than a semi-circle as shown in  FIG. 20 , or even smaller, as desired. Center locators  420  with different diameters of distal portion  422  can be provided to accommodate different anatomies. The proximal end of the center locator  420  can be either fixed to (as shown), integrally formed with or, preferably, removably attached to, a distal end  411  of the handle portion  410 , thus, together, forming the body of the axis trajectory guide  400 . Additionally, handle portion  410  is configured to receive the cannulated extension pin portion  434  of removable alignment sleeve  430  through opening  412  located on the side of handle portion  410  which is opposite to the location of center locator  420 . Note that, when adapted for use in joints other than the elbow, the distal portion of the center locator  420  of the axis trajectory guide  400  would be, correspondingly, geometrically adapted to engage a portion of a bone in the joint and locate the desired axis trajectory thereof. 
     The removable alignment sleeve  430  further includes a knob  431  having an opening  432  therethrough that further continues through cannulated extension pin  434 . The opening  432  is sized to receive a K-wire  440  of known length L or other type of longitudinally extending device, as shown more particularly in  FIG. 20 . As seen more clearly in  FIGS. 26-27  the cross-section of cannulated extension pin  434  is cylindrical throughout approximately three quarters (¾) of its perimeter, the last quarter protruding slightly to form a cam. When the cam is in neutral position as shown on  FIGS. 26-27  the cannulated extension pin  434  can slide longitudinally along the axis of opening  412 . By rotating knob  431  clockwise the cam shaped cannulated extension pin  434  engages the correspondingly configured opening  412 , locking it in place and thereby impeding further longitudinal sliding of cannulated extension pin  434  along the axis of opening  412 . 
     The center locator  420 , alignment sleeve  430  and K-wire  440  can be made of any desired material, but, preferably, are made of metal, such as stainless steel. 
     A method for using the axis trajectory guide  400  of  FIG. 19  will now be described in connection with  FIGS. 21-27  using an elbow joint, for illustrative purposes. The surgeon proceeds, as previously described, by approaching the humero-ulnar joint through a lateral incision and marking a first point  460  (as seen in  FIG. 21 ) on the axis of rotation of the joint. 
     Referring now to  FIG. 21 , the surgeon distracts the humerus from the ulna and inserts the center locator  420  into the distracted joint until it “sits” on the humeral trochlea  455 . The handle  410  is used to manipulate the center locator  420  into the joint. 
     As shown in  FIGS. 22-23 , once the center locator  420  has been correctly seated on the trochlea  455 , the cannulated extension pin  434  of the alignment sleeve  430  is inserted into the opening  412  in the handle portion  410  of the axis trajectory guide  400  so that the distal end of cannulated extension pin  434  is almost touching the first point  460  previously marked by the surgeon on the humerus  450  but sufficiently distant to allow visual observation of point  460 . The surgeon then locks the cannulated extension pin  434  in that position by turning knob  431  clockwise. 
     As further shown in  FIG. 24 , once the alignment sleeve  430  has been locked within opening  412  of handle portion  410 , the surgeon inserts a K-wire  440  of known length L until it engages the humerus  450  at first marked point  460 . 
     Under fluoroscopy, the K-wire  440  is carefully drilled into the humerus  450 , while the surgeon visually ascertains that the K-wire  440  is centered within the arcuate portion  422  of the center locator  420  and while taking care to drill to just beyond the distal edge of the arcuate portion  422  of the center locator  420  but short of the distal cortex of the humerus. 
     Referring now to  FIGS. 24-25 , subsequent to the placement of the K-wire  440 , the knob  431  on alignment sleeve  430  is turned counterclockwise to release the cannulated alignment pin  434 . The alignment sleeve  430  is first removed from opening  412  and then the remainder of axis trajectory guide  400  is removed from the joint, while the K-wire  440  is left in place. The K-wire  440  now defines the axis of rotation of the joint. Using a depth gauge (not shown) the surgeon measures the protruding length L 2  of K-wire  440 . Since the total length L of K-wire  440  is known, the length L 1  of K-wire  440  embedded in humerus  450  is calculated and noted. 
     Thus defined, the axis of rotation of the subject joint, as located using the axis trajectory guide  400  of  FIGS. 18-26 , can be used to further act on the subject joint. For example, the surgeon can use a cannulated drill to insert over the K-wire  440  and create a cylindrical cavity of now known length L 1  aligned to the natural axis of rotation of the joint and capable of accepting an axle portion  160  of, at most, length L 1  of a joint stabilizing device. 
     The axis trajectory guide and method described herein can be used to locate the axis of rotation of a joint in order to facilitate the stabilization of that joint utilizing an internal and/or external joint stabilizer. However, as noted above, this is not meant to be limiting, as the presently described guide and method can be used in any situation wherein it is desired to locate the axis of a joint, whether or not the joint is subsequently stabilized. 
     It is advantageous to provide the axis trajectory guide described herein as part of a kit including the internal joint stabilizer device, wherein the kit can also include a plurality of axles and necks of different lengths, to permit the surgeon to adapt an internal joint stabilizer to the anatomy of the particular patient, intraoperatively. For example, after determining the length L 1 , the surgeon can select an axle having a body length shorter than, but closely approximating, the length L 1  from a plurality of axles provided in the kit. Similarly, the surgeon can select a neck portion, intraoperatively, from a plurality of necks of different lengths and shapes provided in the kit, order to accommodate the particular anatomy of the patient. In such an embodiment, the selected neck can be further attached to one of a plurality of adjustment portions, such as the different turret assemblies described herein. 
     Although described above in connection with the elbow and the interphalangeal joints, this is not meant to be limiting, as other internal joint stabilizers and axis trajectory guides can be made in accordance with the description herein, but of different size or scale, so as to treat instability, subluxation or dislocation of other joints, such as the ankle, or chronic instability such as occurs on the first metatarso-phalangeal joint or bunion. Additionally, it can be seen from the description herein that the internal joint stabilizer of the present invention can be adapted for use with joints having more complex translational geometries, or more than one axis of rotation, such as the carpometacarpal (CMC) joint of the thumb or the knee, wherein the device would be adapted to allow for the unique motions of these joints. For example, in one particular embodiment, the internal joint stabilizer of the present invention can be modified to further include more than one axle or linkage arms placed at the appropriate isometric points. As such, although the invention is illustrated and described herein in various embodiments including an axle portion that is rotatable relative to a fixable portion using various particularly described mechanisms, such as a bendable neck portion, a turret assembly and/or a swivel portion, etc., it is nevertheless not intended to be limited to only these details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.