Abstract:
A method for removing a bearing that is coupled to a prosthetic implant by a ring includes advancing a distal end of a removal tool in a first direction and into a slit formed in the ring. The ring can be caused to expand radially from engagement with the bearing. The distal end of the removal tool can be advanced in a second direction such that the removal tool engages the bearing. The distal end of the removal tool can be further advanced in the second direction such that the removal tool urges the bearing away from the prosthetic implant.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/553,624, filed Sep. 3, 2009, which is a continuation-in-part of PCT/US2008/003045, filed Mar. 6, 2008, which claims priority to U.S. patent application Ser. No. 11/714,991, filed Mar. 7, 2007 now U.S. Pat. No. 7,572,294 issued Aug. 11, 2009. The entire disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to implants and more particularly to a method and apparatus for removing an acetabular bearing. 
       INTRODUCTION 
       [0003]    Traditional shoulder joint replacement provides a ball and socket implant with a metal ball replacing the humeral head and a glenoid socket attached to the scapula. The traditional ball and socket implant can work properly when the rotator cuff muscles are substantially intact and function to provide stability against displacement of the ball relative to the socket by the strong deltoid muscle during movement of the shoulder. Patients with rotator cuff impairment can be provided with a reverse ball and socket prosthesis in which the socket is attached to the humeral implant and the ball (“glenosphere”) is attached to the scapula. The reverse ball and socket prosthesis cooperates with the deltoid muscle to provide shoulder mobility, is sufficiently stable and does not rely on a functioning rotator cuff for stability. In some examples, the reverse ball and socket prosthesis can include a humeral tray and modular bearing. Modular bearings are often readily removable and, in such cases, they have the further advantage of facilitating revision surgery, which may become necessary in cases of traumatic injury or bearing surface wear, by enabling replacement of the bearing without removing the humeral tray. A need exists for a system to facilitate efficient removal of the bearing from the humeral tray. 
       SUMMARY 
       [0004]    A method for removing a bearing that is coupled to a prosthetic implant by a ring includes advancing a distal end of a removal tool in a first direction and into a slit formed in the ring. The ring can be caused to expand radially from engagement with the bearing. The distal end of the removal tool can be advanced in a second direction such that the removal tool engages the bearing. The distal end of the removal tool can be further advanced in the second direction such that the removal tool urges the bearing away from the prosthetic implant. 
         [0005]    Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a perspective view of a system according to the present teachings including an acetabular cup assembly and a removal tool, the acetabular cup assembly including a cup, a bearing and a ring; 
           [0008]      FIG. 2  is a top perspective view of a distal end of the removal tool of  FIG. 1 ; 
           [0009]      FIG. 3  is a bottom perspective view of the distal end of the removal tool of  FIG. 1 ; 
           [0010]      FIG. 4  is a perspective view of the acetabular cup assembly shown with the bearing in a locked position within the acetabular cup and the distal end of the removal tool initially engaged with a slit defined in the ring; 
           [0011]      FIG. 5  is a perspective view of the acetabular cup assembly and removal tool subsequent to removal of the ring and bearing; 
           [0012]      FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 3  shown with the distal end of the tool initially engaging the ring; 
           [0013]      FIG. 7  is the sectional view of  FIG. 6  shown with the distal end of the tool engaging the bearing; 
           [0014]      FIG. 8  is the sectional view of  FIG. 7  shown with the distal end of the tool tilted and urging the bearing away from the cup; 
           [0015]      FIG. 9  is an exploded side perspective view of the system of  FIG. 1 ; 
           [0016]      FIG. 10  is a perspective view of a system according to additional features of the present teachings including an acetabular cup assembly and a removal tool, the acetabular cup including a cup, a bearing and a ring; 
           [0017]      FIG. 11  is a perspective view of a notch formed in the acetabular cup of  FIG. 10 ; 
           [0018]      FIG. 12  is a partial perspective view of the acetabular cup of  FIG. 11  shown with the ring in an installed position; 
           [0019]      FIG. 13  is a perspective view of the removal tool; 
           [0020]      FIG. 14  is a side view of the distal end of the removal tool of  FIG. 13 ; 
           [0021]      FIG. 15  is a partial perspective view of the acetabular cup assembly shown with the bearing in a locked position within the acetabular cup and the distal end of the removal tool initially engaged with a slit defined in the ring; 
           [0022]      FIG. 16  is a perspective view of the acetabular cup assembly and removal tool subsequent to removal of the ring and the bearing; 
           [0023]      FIG. 17  is a plan view of the acetabular cup assembly; 
           [0024]      FIG. 18  is a sectional view of the acetabular cup assembly taken along line  18 - 18  of  FIG. 17  shown with the removal tool inserted into the notch; 
           [0025]      FIG. 19  is an exploded perspective view of a shoulder prosthesis assembly and removal tool according to additional features of the present teachings; 
           [0026]      FIG. 20  is a cross-sectional view of the shoulder prosthesis assembly and shown with the distal end of the tool initially engaging the ring; 
           [0027]      FIG. 21  is the sectional view of  FIG. 20  shown with the distal end of the tool engaging the bearing; 
           [0028]      FIG. 22  is the sectional view of  FIG. 21  shown with the distal end of the tool tilted and urging the bearing away from the humeral tray; 
           [0029]      FIG. 23  is an exploded side perspective view illustrating additional components of the shoulder prosthesis assembly; 
           [0030]      FIG. 24  is a perspective view of a system according to additional features of the present teachings including the shoulder prosthesis assembly of  FIG. 19  and a removal tool according to additional features of the present teachings; 
           [0031]      FIG. 25  is a perspective view of a notch formed in the humeral tray of  FIG. 24 ; 
           [0032]      FIG. 26  is a partial perspective view of the humeral tray of  FIG. 25  shown with the ring in an installed position; 
           [0033]      FIG. 27  is a partial perspective view of the shoulder prosthesis assembly shown with the bearing in a locked position within the humeral tray and the distal end of the removal tool initially engaged with a slit defined in the ring; 
           [0034]      FIG. 28  is a perspective view of the shoulder prosthesis assembly and removal tool subsequent to removal of the ring and the bearing; 
           [0035]      FIG. 29  is a top view of the shoulder prosthesis assembly of  FIG. 19 ; and 
           [0036]      FIG. 30  is a sectional view of the shoulder prosthesis assembly of  FIG. 24  shown with the removal tool inserted into the notch and the tool engaging the bearing subsequent to spreading of the ring. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    The following description of the embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0038]    With initial reference to  FIG. 1 , a system for replacing a portion of a hip joint is shown and generally identified at reference  10 . The system  10  can generally include an acetabular cup assembly  12  and a removal tool  14 . The acetabular cup assembly  12  can include an acetabular cup  20 , a liner or bearing  22  and a ring  24 . As will become appreciated, the ring  24  can be adapted to retain the bearing  22  relative to the acetabular cup  20  in a locked position. The removal tool  14  can be adapted to engage the ring  24  and operatively spread the ring  24  to an unlocked position, and subsequently lever the bearing  22  away from the acetabular cup  20 . 
         [0039]    With particular reference now to  FIGS. 1 ,  4  and  5 , the acetabular cup assembly  12  will be further described. In general, the acetabular cup  20  may include a porous metal portion  26  and a solid metal portion  28 . The porous metal portion  26  generally may be formed on an outer bone engaging surface  30  of the acetabular cup  20 , while the solid metal portion  28  may be formed on an inner surface  32  ( FIG. 5 ). The porous metal and solid metal portions  26  and  28 , respectively, may comprise biocompatible metal, such as stainless steel, titanium, titanium alloys, and cobalt-chromium alloys. In one example, the porous metal portion  26  may be formed of porous metal defining about 60-70% porosity. In one example, the porous metal portion  26  can be sintered onto the solid metal portion  28 . The solid metal portion  28  may define a solid rim  36  and a bearing engaging surface  38 . In one example, the solid rim  36  may be defined entirely through a thickness of the acetabular cup  20  at the solid rim  36 . While not specifically shown, an interface between the porous metal portion  26  and the solid metal portion  28  may comprise interlocking annular rings and pockets. A discussion of a similar acetabular cup may be found in co-pending U.S. patent application Ser. No. ______ [Atty. Doc. No. 5490-000410/CPD], which is hereby incorporated by reference. 
         [0040]    The solid rim  36  can define a first interlocking portion  40 . In the example shown, the first interlocking portion  40  is in the form of lobbed fingers  42  defined around an upper perimeter of the solid rim  36 . The lobbed fingers  42  can be generally raised relative to an annular shoulder  44  ( FIG. 5 ) defined around the solid rim  36 . The solid metal portion  28  can further define an inboard annular groove  46  formed around the bearing engaging surface  38 . The solid rim  36  can further include a first and second slot  50  and  52 , respectively. In one example, the first and second slots  50  and  52  may be formed at diametrically opposing locations on the solid rim  36 . The first slot  50  can include a sloped or ramped surface  54  (as best shown in  FIG. 6 ). The ramped surface  54  can slope downward generally from an outboard portion to an inboard portion of the acetabular cup  20 . The second slot  52  can define a surface generally parallel to the annular shoulder  44 . 
         [0041]    The bearing  22  will now be described in greater detail. The bearing  22  may be formed of polyethylene or other suitable bearing material. The bearing  22  can generally include an outer cup engaging surface  58  and an inner femoral component engaging surface  60 . An outboard annular groove  62  can be formed around the outer cup engaging surface  58 . The outer cup engaging surface  58  can be generally convex, while the inner femoral component engaging surface  60  can be generally concave. The bearing  22  can define a uniform thickness, below the outboard annular groove  62  (as viewed in  FIG. 6 ) and can act as a bearing surface for a head  64  of a femoral component  66  ( FIG. 9 ) so as to dissipate stresses over the entire bearing  22 . A second interlocking portion  70  can be formed around a rim portion  72  of the bearing  22 . In the example shown, the second interlocking portion  70  is in the form of complementary lobbed notches  74  defined around the rim portion  72 . The first and second interlocking portions  40  and  70  can cooperatively mate in an assembled position ( FIG. 4 ) such that the lobbed fingers  42  nest with the lobbed notches  74  and, therefore, inhibit rotational motion of the bearing  22  within the acetabular cup  20 . In the particular example shown, the lobbed notches  74  outnumber the lobbed fingers  42  by a factor of two. It is appreciated that other configurations may be used. 
         [0042]    The ring  24  will now be described in greater detail. The ring  24  may be formed of any suitable biocompatible material. In one example, the ring  24  may be formed of similar material found in the locking ring offered in the RingLoc® system offered by Biomet, Inc., of Warsaw, Ind. The ring  24  can generally define a radial body  78  defining a discontinuation or slit  80 . As will become appreciated, the material properties of the ring  24  should be selected such that the ring  24  is permitted to flex in a radial direction toward its outer perimeter upon an applied force and return to a static position upon removal of the force. 
         [0043]    A pair of fingers  82  can be formed at opposing portions of the slit  80 . The fingers  82  can extend outboard relative to a circumferential outer surface of the radial body  78 . An annular protrusion  84  can be integrally formed on the ring  24 . In one example, the annular protrusion  84  can be diametrically opposed to the fingers  82 . As explained, the ring  24  can be adapted to locate within the inboard annular groove  46  of the acetabular cup  20 . In the locked position, the inboard annular groove  46  of the acetabular cup  20  is operable to snapingly receive the ring  24  to secure the bearing  22  within the concave surface of the acetabular cup  20 . Explained further, the ring  24  can be adapted to partially nest within the inboard annular groove  46  of the acetabular cup  20  and, concurrently, partially nest within the outboard annular groove  62  of the bearing  22  in the locked position. The annular protrusion  84  of the ring  24  can nest within the second slot  52 . In this way, the ring  24  may be discouraged from rotating around a longitudinal axis of the acetabular cup  20 . 
         [0044]    With reference now to  FIGS. 1-3 , the removal tool  14  will be described in greater detail. In general, the removal tool  14  can include a longitudinal body  90  having a proximal end  92  and a distal end  94 . The proximal end  92  can include a handle  96  disposed thereon. The distal end  94  can include an engaging portion  98 . In one example, the engaging portion  98  can be defined at an angle relative to a longitudinal axis of the longitudinal body  90 . The longitudinal body  90  can define a shaft  100  extending between the handle  96  and the distal end  94 . 
         [0045]    The distal end  94  can further define an upper portion  104  ( FIG. 2 ) and a lower portion  106  ( FIG. 3 ). The lower portion  106  can define a ring engaging portion  110  having a ring engaging surface  112 . A terminal end  114  of the removal tool  14  can define a bearing engaging portion  118  having a bearing engaging surface  120 . The distal end  94  can include an intermediate section  122  defined between the longitudinal body  90  and a sloped section  124 . 
         [0046]    The ring engaging surface  112  can be further defined by a pair of outwardly ramped surfaces  128 . The outwardly ramped surfaces  128  can slope generally outward from the lower portion  106  toward the upper portion  104 . 
         [0047]    An exemplary method of removing the ring  24  and bearing  22  with the removal tool  14  will now be described. With initial reference to  FIG. 4 , the acetabular cup assembly  12  is shown with the ring  24  nested within the inboard annular groove  46  of the acetabular cup  20  and the bearing  22  secured within the bearing engaging surface  38  of the acetabular cup  20  (locked position). As shown, one of the lobbed notches  74  of the bearing  22  can provide access to an upper surface of the ring  24  at the pair of fingers  82 . Also, notably, the first slot  50  can be substantially aligned with and provides additional access to the fingers  82 . Once the ring engaging portion  110  of the removal tool  14  has been located atop the ring  24  at the fingers  82 , downward force (as viewed in  FIG. 4 ) may be applied by the removal tool  14  at the slit  80  of the ring  24 . The downward force of the removal tool  14  encourages the outwardly ramped surfaces  128  of the removal tool  14  to ride along the opposing surfaces of the slit  80  and, therefore, incrementally urge the ring  24  to spread radially outward toward an unlocked position. It is appreciated that sufficient outward clearance exists in the inboard annular groove  46  of the acetabular cup  20  to accommodate initial outward radial movement of the ring  24 . Once the ring  24  has flexed radially outward a predetermined amount, the ring  24  can be substantially displaced from the outboard annular groove  62  of the bearing  22 . 
         [0048]    With the ring  24  still in an outwardly flexed position, the removal tool  14  can then be tilted in a direction counter-clockwise, as viewed in  FIGS. 7 and 8 . As a result, the bearing engaging surface  120  of the distal end  94  of the removal tool  14  can engage the bearing  22  and exert a prying action (i.e., in a direction toward the rim portion  72 ) to further encourage the bearing  22  to remove from the acetabular cup  20  (i.e., as illustrated in the sequence from  FIG. 7  and  FIG. 8 ). It is important to note that the interaction of the removal tool  14  with the bearing  22  (i.e., at the bearing engaging surface  120 ) does not substantially deface the bearing  22 . 
         [0049]    Turning now to  FIGS. 10-18 , a system  200  for replacing a portion of a hip joint according to additional features is shown. The system  200  can generally include an acetabular cup assembly  202  and a removal tool  204 . The acetabular cup assembly  202  can include an acetabular cup  220  a bearing  22 , and a ring  24 . The acetabular cup  220  can be substantially similar to the acetabular cup  20  described above. The acetabular cup  220  can include a first slot  230  and a cavity  232 . The slot  230  and the cavity  232  can be positioned inboard of a continuous rim portion. The cavity  232  can define a terminal surface  234  substantially perpendicular to an upper surface  236  of the slot ( FIG. 18 ). As will be described, the removal tool  204  can be adapted to engage the ring  24  and operatively spread the ring  24  to an unlocked position, and subsequently lift the bearing away from the acetabular cup  220 . 
         [0050]    With reference now to  FIGS. 13 and 14 , the removal tool  204  will be described in greater detail. In general, the removal tool  204  can include a longitudinal body  240  having a proximal end  242  and a distal end  244 . The proximal end  242  can include a handle  248  disposed thereon. The distal end  244  can include an engaging portion  250 . The longitudinal body  240  can define a shaft  252  extending between the handle  248  and the distal end  244 . 
         [0051]    The distal end  244  can further define an upper portion  254  and a lower portion  256 . The lower portion  256  can define a ring engaging portion  260  having a ring engaging surface  262 . The ring engaging surface  262  can be further defined by a pair of outwardly ramped surfaces  264  ( FIG. 15 ). The outwardly ramped surfaces  264  can slope generally outward from the lower portion  256  toward the upper portion  254 . The upper portion  254  can include a bearing engaging portion  268  having an engagement lip  270  adapted to engage an underside surface  272  ( FIG. 18 ) of the bearing  24 . 
         [0052]    An exemplary method of removing the ring  24  and the bearing  22  with the removal tool  204  will now be described. With reference to  FIG. 12 , the acetabular cup assembly  202  is shown with the ring  24  nested within the inboard annular groove  46  of the acetabular cup. The bearing  22  is not shown in  FIG. 12  for illustrative purposes but is shown installed in the locked position in  FIGS. 17 and 18 . As shown, the first slot  230  can be substantially aligned with and provides additional access to the fingers  82 . 
         [0053]    Once the ring engaging portion  260  of the removal tool  204  has been located atop the ring  24  at the fingers  82 , downward force (as viewed in  FIG. 10 ) may be applied by the removal tool  204  at the slit  80  of the ring  24 . It is important to note that at this time, the bearing  22  is still in a nested position with the cup  220  (as shown in  FIG. 18 ). The bearing  22  is shown slightly elevated in  FIG. 10  simply to shown the interaction between the tool  204  and the ring  24 . The downward force of the removal tool  204  encourages the outwardly ramped surfaces  264  of the removal tool  204  to ride along the opposing surfaces of the slit  80  and, therefore, incrementally urge the ring  24  to spread radially outward toward an unlocked position. It is appreciated that sufficient outward clearance exists in the inboard annular groove  46  of the acetabular cup  220  to accommodate initial outward radial movement of the ring  24 . Once the ring  24  has flexed radially outward a predetermined amount, the ring  24  can be substantially displaced from the outboard annular groove  62  of the bearing  22 . 
         [0054]    With the ring  24  still in an outwardly flexed position, the removal tool  204  can then be translated upwardly (as viewed in  FIG. 18 ) along a longitudinal axis of the tool  204 . During the upward translation, the engagement lip  270  engages the underside surface  272  of the bearing  22  to lift the bearing  22  away from the cup  220  ( FIG. 16 ). It is appreciated that translation about the longitudinal axis of the tool  204  may be advantageous in such minimally invasive surroundings. In another example, the tool  204  may additionally or alternatively rotate about its longitudinal axis to provide a prying action to the bearing  22 . 
         [0055]    Turning now to  FIG. 19 , a system for replacing a portion of a shoulder joint is shown and generally identified at reference numeral  310 . The system  310  can generally include a shoulder prosthesis assembly  312  and the removal tool  14 . The shoulder prosthesis assembly  312  can include a humeral tray  320 , a liner or bearing  322  and a ring  24 . While the shoulder prosthesis assembly  312  is illustrated in the drawings as a reverse shoulder prosthesis, other shoulder prostheses are contemplated. As will become appreciated, the ring  24  can be adapted to retain the bearing  322  relative to the humeral tray  320  in a locked position. The removal tool  14  can be adapted to engage the ring  24  and operatively spread the ring  24  to an unlocked position, and subsequently lever the bearing  322  away from the humeral tray  320 . 
         [0056]    The humeral tray  320  can generally include a platform portion  326  and a stem portion  328 . The platform portion  326  can have an upper rim  329 . The humeral tray  320  can have a bearing engaging surface  338 . The humeral tray  320  may comprise biocompatible metal, such as stainless steel, titanium, titanium alloys, and cobalt chromium alloys. The rim  329  can have a first inner locking portion  340 . In the example shown, the first interlocking portion  340  is in the form of tabs  342  radially positioned around the upper rim  329 . The tabs  342  can be generally raised relative to the upper rim  329 . The platform portion  326  can further define an inboard annular groove  346  formed around the bearing engaging surface  338 . The upper rim  329  can further include a slot  350 . In one example, the slot  350  can include a ledge or generally planar surface  354  that is transverse to a long axis of the stem portion  328 . The humeral tray  320  can have a bone engaging surface  344  having a porous coating. 
         [0057]    The bearing  322  will now be described in greater detail. The bearing  322  may be formed of polyethylene or other suitable bearing material. The bearing  322  can generally include an outer tray engaging surface  358  and an inner ball engaging surface  360 . An outboard annular groove  362  can be formed around the outer tray engaging surface  358 . The outer tray engaging surface  358  can have a generally planar surface, while the inner ball engaging surface  360  can be generally concave. A second inner locking portion  370  can be formed around a rim portion  372  of the bearing  322 . In the example shown, the second inner locking portion  370  is in the form of complementary notches  374  defined around the rim portion  372 . The first and second inner locking portions  340  and  370  can cooperatively mate in an assembled position ( FIG. 20 ), such that the tabs  342  nest with the notches  374  and, therefore, inhibit rotational motion of the bearing  322  within the humeral tray  320 . In the particular example shown, the amount of notches  374  equals the amount of tabs  342 . It is appreciated however, that in other examples, the notches  374  may outnumber the tabs  342 . 
         [0058]    The ring  24  used with the shoulder prosthesis assembly  312  is the same as described above with respect to the acetabular cup assembly  12 . Therefore, no further explanation of the ring  24  will be described. As explained, the ring  24  can be adapted to locate within the inboard annular groove  346  of the humeral tray  320 . In the locked position, the inboard annular groove  346  of the humeral tray  320  is operable to snapingly receive the ring  24  to secure the bearing  322  to the humeral tray  320 . Explained further, the ring  24  can be adapted to partially nest within the inboard annular groove  346  of the humeral tray  320  and, concurrently, partially nest within the outboard annular groove  362  of the bearing  322  in the locked position ( FIG. 20 ). The annular protrusion  84  of the ring  24  can nest within the second slot  352 . In this way, the ring  24  may be discouraged from rotating around the platform portion  326  of the humeral tray  320 . 
         [0059]    An exemplary method of removing the ring  24  and the bearing  322  from the humeral tray  320  using the removal tool  14  will now be described. With initial reference to  FIG. 21 , the humeral tray  320  is shown with the ring  24  nested within the inboard annular groove  346  of the humeral tray  320  and the bearing  322  secured within the bearing engaging surface  338  of the humeral tray  320  (locked position). As shown, a relief  376  formed in the bearing  322  can provide access to an upper surface of the ring  24  at the pair of fingers  82 . Also, notably, the slot  350  can be substantially aligned with and provides additional access to the fingers  82 . Once the ring engaging portion  110  of the removal tool  14  has been located atop the ring  24  at the fingers  82 , downward force may be applied by the removal tool  14  at the slit  80  of the ring  24 . The downward force of the removal tool  14  encourages the outwardly ramped surfaces  128  of the removal tool  14  to ride along the opposing surfaces of the slit  80  and, therefore, incrementally urge the ring  24  to spread radially outward toward an unlocked position (see also the discussion above related to  FIG. 4 ). It is appreciated that sufficient outward clearance exists in the inboard annular groove  346  of the humeral tray  320  to accommodate initial outward radial movement of the ring  24 . Once the ring  24  has flexed radially outward a predetermined amount, the ring  24  can be substantially displaced from the outboard annular groove  362  of the bearing  322 . 
         [0060]    With the ring  24  still in an outwardly flexed position, the removal tool  14  can then be tilted in a direction counter-clockwise, as viewed in  FIGS. 21 and 22 . As a result, the bearing engaging surface  120  of the distal end  94  of the removal tool  14  can engage the bearing  322  and exert a prying action (i.e., in a direction toward the rim portion  372 ) to further encourage the bearing  322  to remove from the humeral tray  320  (i.e., as illustrated in the sequence from  FIG. 21-23 ). It is important to note that the interaction of the removal tool  14  with the bearing  322  (i.e., at the bearing engaging surface  120 ) does not substantially deface the bearing  322 . 
         [0061]      FIG. 23  illustrates the exemplary reverse shoulder prosthesis assembly  312  cooperating with additional exemplary shoulder prosthesis components including a ball  382 , adapter  384 , a receiving member  386  and bone screws  388  for implanting relative to a glenoid cavity  390  of a scapula  392 . 
         [0062]    Turning now to  FIGS. 24-30 , a system  400  for replacing a portion of a shoulder joint according to additional features is shown. The system  400  can generally include the shoulder prosthesis assembly  312  and the removal tool  204 . Additional description of the removal tool  204  is explained above. As will be described, the removal tool  204  can be adapted to engage the ring  24  and operatively spread the ring  24  to an unlocked position, and subsequently lift the bearing  322  away from the humeral tray  320 . 
         [0063]    An exemplary method of removing the ring  24  and the bearing  322  with the removal tool  204  will now be described. With reference to  FIG. 24 , the shoulder prosthesis assembly  312  is shown with the ring  24  nested within the inboard annular groove  346  of the humeral tray  320 . The bearing  322  is not shown in  FIG. 25  for illustrative purposes but is shown installed in the locked position in  FIGS. 26 and 27 . As shown, the slot  350  can be substantially aligned with and provide additional access to the fingers  82 . 
         [0064]    Once the ring engaging portion  260  of the removal tool  204  has been located atop the ring  24  at the fingers  82 , downward force (as viewed in  FIG. 24 ) may be applied by the removal tool  204  at the slit  80  of the ring  24 . It is important to note that at this time, the bearing  322  is still in a nested position with the humeral tray  320  (as shown in  FIG. 29 ). The bearing  322  is shown slightly elevated in  FIG. 24  simply to illustrate the interaction between the tool  204  and the ring  24 . The downward force of the removal tool  204  encourages the outwardly ramped surfaces  264  of the removal tool  204  to ride along the opposing surfaces of the slit  80  and, therefore, incrementally urge the ring  24  to spread radially outward toward an unlocked position. It is appreciated that sufficient outward clearance exists in the inboard annular groove  346  of the humeral tray  320  to accommodate initial outward radial movement of the ring  24 . Once the ring  24  has flexed radially outward a predetermined amount, the ring  24  can be substantially displaced from the outboard annular groove  362  of the bearing  322 . 
         [0065]    With the ring  24  still in an outwardly flexed position ( FIG. 27 ), the removal tool  204  can then be translated upwardly (as illustrated in  FIGS. 28 and 30 ) along a longitudinal axis of the tool  204 . In one example, the removal tool  204  can be translated along an axis A that is substantially parallel to an axis B defined through the stem portion  328 . Explained differently, the tool  204  can be translated along the axis A in a direction that is substantially transverse to the upper rim  329 . During the upward translation, the engagement lip  270  engages an underside surface  380  of the bearing  322  to lift the bearing  322  away from the humeral tray  320  ( FIG. 30 ). It is appreciated that translation about the longitudinal axis of the tool  204  may be advantageous in such minimally invasive surroundings. In another example, the tool  204  may additionally or alternatively rotate about its longitudinal axis to provide a prying action to the bearing  322 . 
         [0066]    While the disclosure has been described in the specification and illustrated in the drawings with reference to various embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this disclosure, but that the disclosure will include any embodiments falling within the foregoing description and the appended claims.