Patent Publication Number: US-2023145300-A1

Title: Modular stemless implants for arthroplasty implant systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure claims priority to U.S. Provisional Application No. 63/278,232, filed on Nov. 11, 2021, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     This disclosure relates to the field of arthroplasty, and more particularly to arthroplasty implant systems that include modular implants capable of establishing a stemless convertible platform for interfacing with articular implants. 
     Many bones of the human musculoskeletal system include articular surfaces. The articular surfaces cooperate to facilitate different types and degrees of joint movement. The articular surfaces can erode or experience bone loss over time due to repeated use or wear, thereby causing joint instability and pain. 
     Arthroplasty is an orthopedic surgical procedure performed to repair or replace joints that exhibit degenerative bone deficiencies. Bone deficiencies may occur along the articular surfaces of bone. Some arthroplasty procedures utilize one or more implants to repair the articular surfaces. 
     SUMMARY 
     This disclosure relates to arthroplasty implant systems and methods designed for restoring functionality to a joint. The arthroplasty implant systems may include an implant assembly that includes a stemless convertible implant. 
     An exemplary humeral implant assembly for an arthroplasty implant system may include, inter alia, an articular implant, and a modular stemless implant adapted to establish a convertible platform for receiving the articular implant. The modular stemless implant includes a thread configured to engage cortical and/or cancellous bone of a bone and a flange sized to engage a cortical rim of the bone. 
     In a further embodiment, the articular implant is an anatomic articular implant that includes a convex articular surface. 
     In a further embodiment, the articular implant is a reverse articular implant that includes a concave articular surface. 
     In a further embodiment, the articular implant includes a spacer that is coupled to the stemless implant and a liner that is coupled to the spacer. The liner includes a concave articular surface. 
     In a further embodiment, the spacer is coupled to the stemless implant by a C-ring. 
     In a further embodiment, the stemless implant is comprised of a polyether ether ketone (PEEK) material 
     In a further embodiment, the modular stemless implant includes a receiving cavity adapted to receive the articular implant, and the receiving cavity extends inwardly from a rim to a floor of a rounded base of the modular stemless implant. 
     In a further embodiment, the thread is circumferentially disposed about a radially outer surface of a cylindrical shaped body of the modular stemless implant. 
     In a further embodiment, the flange is removably connectable to the cylindrical shaped body. 
     In a further embodiment, an outer diameter of the flange is greater than an outer diameter of the cylindrical shaped body at a tip of the thread. 
     In a further embodiment, the cylindrical shaped body includes a plurality of pockets adapted to facilitate bony ingrowth. 
     In a further embodiment, the flange includes a plurality of suture eyelets that are each configured to receive a thread-like material. 
     An exemplary arthroplasty implant system may include, inter alia, a two-piece modular threaded cup having a cylindrical shaped body and a flange that is removably connectable to the cylindrical shaped body. A thread may be provided on the cylindrical shaped body. The thread is configured to engage cortical and/or cancellous bone of a bone, and the flange is configured to engage a cortical rim of the bone. 
     In a further embodiment, the flange is a separate component from the cylindrical shaped body to establish the two-piece modular design of the threaded cup. 
     In a further embodiment, the threaded cup embodies an inlay design that establishes a convertible platform for receiving an articular implant. 
     In a further embodiment, the flange is provided on a first side of the cylindrical shaped body and a rounded base is provided on a second side of the cylindrical shaped body. 
     In a further embodiment, a receiving cavity extends inwardly from a rim of the cylindrical shaped body to a floor of the rounded base, and the floor establishes an inner surface of the rounded base. 
     In a further embodiment, at least one engagement opening is formed through the rounded base. 
     In a further embodiment, an outer diameter of the flange is greater than an outer diameter of the cylindrical shaped body at a tip of the thread. 
     In a further embodiment, the cylindrical shaped body includes a plurality of pockets adapted to facilitate bony ingrowth. 
     In a further embodiment, the flange includes a plurality of suture eyelets that are each configured to receive a thread-like material. 
     In a further embodiment, an inserter system includes a drive shaft configured to engage the cylindrical shaped body of the threaded cup and a cage assembly configured to engage the flange of the threaded cup. 
     In a further embodiment, the drive shaft includes an inner shaft having a threaded distal tip for engaging an engagement opening of the cylindrical shaped body, and the cage assembly includes a mounting leg having a tapered tooth configured to engage a tapered slot of the flange. 
     An exemplary surgical method may include, inter alia, preparing a bone for receiving a threaded cup, positioning a flange of the threaded cup against a cortical rim of the bone, and screwing a cylindrical shaped body of the threaded cup through the flange and into the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a humeral implant assembly of an arthroplasty implant system. 
         FIG.  2    illustrates another exemplary humeral implant assembly of an arthroplasty implant system. 
         FIG.  3    is an exploded view of an exemplary threaded cup of a humeral implant assembly. 
         FIG.  4    is a cross-sectional perspective view of the threaded cup of  FIG.  3   . 
         FIG.  5    illustrates multiple flange options that may be provided for the threaded cup of  FIG.  3   . 
         FIG.  6    illustrates a flange of the threaded cup of  FIG.  3    engaging a cortical rim of a bone. 
         FIG.  7    illustrates various details associated with a circumferential thread of the threaded cup of  FIGS.  3 - 6   . 
         FIG.  8    schematically illustrates an exemplary surgical method for performing a shoulder arthroplasty procedure. 
         FIG.  9    illustrates a humeral implant assembly that includes a threaded cup. 
         FIG.  10    is an exploded view of the humeral implant assembly of  FIG.  9   . 
         FIG.  11    is a cross-sectional view of the humeral implant assembly of  FIG.  9   . 
         FIGS.  12 A and  12 B  illustrate a spacer of another exemplary humeral implant assembly. 
         FIG.  13    illustrates a liner of the humeral implant assembly of  FIG.  9   . 
         FIG.  14    illustrates another exemplary liner of the humeral implant assembly of  FIG.  9   . 
         FIG.  15    illustrates an inserter system for implanting a threaded cup. 
         FIG.  16    is an exploded view of the inserter system of  FIG.  15   . 
         FIG.  17    is a cross-sectional view of the inserter system of  FIG.  15   . 
         FIG.  18    illustrates select portion of the inserter system of  FIG.  15   . 
         FIG.  19    illustrates additional select portions of the inserter system of  FIG.  15   . 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure describes arthroplasty implant systems and methods for restoring the functionality of a joint. The arthroplasty implant systems may include implants capable of establishing a stemless convertible platform for interfacing with articular implants. 
     In some implementations, the arthroplasty implant systems of this disclosure may include a modular threaded cup having a cylindrical shaped body and a flange that is removably connectable to the cylindrical shaped body. A thread may be provided on the cylindrical shaped body. The thread is configured to engage cortical and/or cancellous bone of a bone, and the flange is sized to engage a cortical rim of the bone. These and other features of this disclosure are further detailed below. 
       FIG.  1    illustrates an arthroplasty implant system  10  that includes a humeral implant assembly  12 . The humeral implant assembly  12  may be implanted within a humerus  14  of a shoulder joint to aid in reconstructing the native articular surface of the humerus  14  and/or restoring the functionality (e.g., range or motion, stability, etc.) of the shoulder joint. Although not shown, the arthroplasty implant system  10  could additionally include a glenoid implant assembly that is configured to interface with the humeral implant assembly  12  for restoring functionality to the shoulder joint. Moreover, although the teachings of this disclosure are described with specific reference to the shoulder joint, this disclosure is not intended to be limited to any particular joint of the human musculoskeletal system and could be applicable to other joints, such as the hip joint, for example. 
     The humeral implant assembly  12  may include a threaded cup  16  and an anatomic articular implant  18 A (see  FIG.  1   ) or a reverse articular implant  18 B (see  FIG.  2   ). The anatomic articular implant  18 A may be utilized in combination with the threaded cup  16  for performing anatomic total shoulder arthroplasty procedures, and the reverse articular implant  18 B may be utilized in combination with the threaded cup  16  for performing reverse shoulder arthroplasty procedures. In reverse shoulder arthroplasty procedures, the reconstituted humerus  14  provides the socket portion and the glenoid (not shown) provides the ball portion of the ball-and-socket joint, which is the opposite of the native anatomy. The anatomic articular implant  18 A may include a convex articular surface  20 A, and the reverse articular implant  18 B may include a concave articular surface  20 B. The articular surfaces  20 A,  20 B are configured to interface with the native glenoid or a glenoid implant assembly of the arthroplasty implant system  10 . 
     In some implementations, the threaded cup  16 , the anatomic articular implant  18 A, and the reverse articular implant  18 B may be provided together as part of a surgical kit. The surgical kit could additionally could multiple sizes of each of the threaded cup  16 , the anatomic articular implant  18 A, and the reverse articular implant  18 B. 
     In the illustrated embodiment, a humeral head of the humerus  14  has been resected, and thus the native articular component of the humerus  14  is removed in order to prepare the humerus  14  for receiving the humeral implant assembly  12 . After the humerus  14  has been appropriately prepared, the threaded cup  16  may be screwed into a metaphysis  22  of the humerus  14 . In an embodiment, the threaded cup  16  is a stemless implant of the humeral implant assembly  12  and therefore lacks a stem that extends into a diaphysis  24  of the humerus  14 . The threaded cup  16  may be configured to establish a convertible platform for receiving either the anatomic articular implant  18 A or the reverse articular implant  18 B. The anatomic articular implant  18 A or the reverse articular implant  18 B may be mounted to the threaded cup  16  for assembling the humeral implant assembly  12 . 
     The threaded cup  16  of the humeral implant assembly  12  is further illustrated in  FIGS.  3 ,  4 , and  5    (with continued reference to  FIGS.  1  and  2   ). In an embodiment, the threaded cup  16  is constructed of a titanium material. In another embodiment, the threaded cup  16  may be made of a material that has an elastic modulus that is relatively close to that of cortical bone, such as polyether ether ketone (PEEK), for example. Other materials for constructing the threaded cup  16  could alternatively be utilized within the scope of this disclosure. 
     The threaded cup  16  may include a cylindrical shaped body  26  and a flange  28 . In this embodiment, the threaded cup  16  embodies a two-piece modular design in which the flange  28  is removably connectable to the cylindrical shaped body  26 . 
     The cylindrical shaped body  26  may extend between a rim  25  located at a top or proximal side of the cylindrical shaped body  26  and a rounded base  30  located at a bottom or distal side of the cylindrical shaped body  26 . The rim  25  may thus be located on an opposite side of the cylindrical shaped body  26  from the rounded base  30 . 
     [moss] The flange  28  may be removably connected to the rim  25  of the cylindrical shaped body  26 . For example, the rim  25  of the cylindrical shaped body  26  may include a tapered outer circumferential surface  27 , and the flange  28  may include a tapered inner circumferential surface  29 . The tapered inner circumferential surface  29  may be configured to engage the tapered outer circumferential surface  27  via an interference fit to connect the flange  28  to the cylindrical shaped body  26 . In an embodiment, the tapered outer circumferential surface  27  and the tapered inner circumferential surface  29  taper in a proximal-to-distal direction. 
     A receiving cavity  32  of the threaded cup  16  may be configured to receive and secure either the anatomic articular implant  18 A or the reverse articular implant  18 B to the threaded cup  16 . The receiving cavity  32  may be circumscribed by the flange  28  and the cylindrical shaped body  26 . The receiving cavity  32  may extend inwardly from the rim  25  to a floor  34  of the rounded base  30 . The floor  34  may establish an inner surface of the rounded base  30 . 
     The receiving cavity  32  may provide an inlay design in which a majority of the threaded cup  16  (with the exception of the flange  28 ) is disposed inside the humerus  14  post implantation. In this way, the connection between the threaded cup  16  and the articular implant  18 A,  18 B is also inlaid rather than exhibiting an onlay design. 
     A thread  36  may be circumferentially disposed about a radially outer surface  38  of the cylindrical shaped body  26 . The thread  36  may be a self-tapping thread configured to allow the threaded cup  16  to be screwed into the humerus  14 . The thread  36  may be configured such that either a clockwise rotation or a counterclockwise rotation functions to advance the threaded cup  16  into the humerus  14 . 
     In an embodiment, an outer diameter D 1  of the flange  28  is greater than an outer diameter D 2  (defined here at a tip of the thread  36 ) of the cylindrical shaped body  26  (see, e.g.,  FIG.  4   ). The outer diameter D 1  of the flange  28  may be sized to enable the flange  28  to engage a cortical rim  40  (see, e.g.,  FIG.  6   ) of the humerus  14 . Engaging the cortical rim  40  in this manner may provide additional fixation support and load the proximal portion of the humerus  14  more favorably. 
     Moreover, the outer diameter D 2  may be sized such that the thread  36  is positioned in relatively close proximity to cortical bone  42  of the humerus  14  once the threaded cup  16  is inserted therein (see, e.g.,  FIG.  6   ). Fixating the threaded cup  16  with the thread  36  as close to the cortical bone  42  as possible may provide improved initial and long-term fixation as compared to “press-fit” implant designs. The thread  36  may thus engage cortical bone  42 , cancellous bone  43 , or both. 
     The cylindrical shaped body  26  may further include an inner diameter D 3 . The inner diameter D 3  may establish a cup size of the threaded cup  16 . The inner diameter D 3  may be less than both the outer diameter D 1  and the outer diameter D 3 . 
     The actual dimensions of the outer diameter D 1  of the flange  28 , the outer diameter D 2  of the cylindrical shaped body  26 , and the inner diameter D 3  of the cylindrical shaped body  26  may vary depending on the size of the patient, among other factors. The surgical kit referenced above could include threaded cups having multiple combinations of flange  28  outer diameter sizes and cylindrical shaped body  26  inner diameter sizes. Multiple exemplary sizes of flanges (identified as  28 - 1  to  28 -N, where “N” is any number) that could optionally be utilized with the cylindrical shaped body  26  of the threaded cup  16  are illustrated in  FIG.  5   . 
     Table 1 below illustrates exemplary sizes of threaded cups  16  that could be provided as part of the surgical kit. The listed sizes are exemplary only and thus intended to be non-limiting. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Exemplary Sizes of Threaded Cup 16 
               
            
           
           
               
               
            
               
                 OD of 
                 ID of Threaded Cup 16 
               
            
           
           
               
               
               
               
               
               
            
               
                 Flange 28 
                 30 mm 
                 33 mm 
                 36 mm 
                 39 mm 
                 42 mm 
               
               
                   
               
               
                 41 mm 
                 ● 
                   
                   
                   
                   
               
               
                 43 mm 
                 ● 
               
               
                 45 mm 
                 ● 
                 ● 
               
               
                 47 mm 
                 ● 
                 ● 
                 ● 
               
               
                 49 mm 
                 ● 
                 ● 
                 ● 
               
               
                 51 mm 
                 ● 
                 ● 
                 ● 
                 ● 
               
               
                 53 mm 
                 ● 
                 ● 
                 ● 
                 ● 
               
               
                 55 mm 
                 ● 
                 ● 
                 ● 
                 ● 
                 ● 
               
               
                   
               
            
           
         
       
     
     The flange  28  of the threaded cup  16  may be either circular or elliptical shaped. However, the actual shape of the flange  28  is not intended to limit this disclosure. 
     The flange  28  may include a plurality of anti-rotation tabs  35 . The anti-rotation tabs  35  may protrude from a distal-facing surface  37  of the flange  28 . The anti-rotation tabs  35  may be impacted into bone (e.g., the humerus  14 ) for preventing the flange  28  from rotating within the bone. 
     A plurality of suture eyelets  44  may extend through the flange  28 . The suture eyelets  44  may be configured to receive a thread-like material, such as a suture  46  (see  FIG.  4   ). The suture  46  may then be utilized to assist with tying tissue (e.g., subscapularis muscle, supraspinatus muscle, etc.) to the humerus  14  in the area around the flange  28 . 
     One or more cutouts or interruptions  48  may be formed in the rim  25  of the cylindrical shaped body  26  of the threaded cup  16 . The interruptions  48  are sized to receive mating features of a wedge/spacer (not shown) that may be utilized in combination with the threaded cup  16  for reducing laxity between the threaded cup  16  and the articular implant  18 A,  18 B. The mating features of the wedge/spacer may engage walls of the rim  25  that delineate the interruptions  48  to prevent rotation of the wedge/spacer relative to the threaded cup  16 . 
     One or more engagement openings  50  may be formed through the rounded base  30  of the threaded cup  16 . The engagement openings  50  may be configured to receive additional mating features of the wedge/spacer. The engagement openings  50  may be threaded round openings, for example. 
     The rounded base  30  may include one or more additional engagement openings  52  formed therethrough. The engagement openings  52  may be configured to receive mating features of an inserter device that can be utilized to implant the threaded cup  16  within the humerus  14 . The engagement openings  52  may be oblong or round, for example. 
     The threaded cup  16  may additionally be equipped with a plurality of pockets  54 . In some implementations, the pockets  54  may be formed in the radially outer surface  38  of the cylindrical shaped body  26  at a location just inward or distal of the rim  25 . The pockets  54  may facilitate bony ingrowth post-insertion. Alternatively or additionally, a porous coating could be applied to select portions of the cylindrical shaped body  26  for facilitating bony ingrowth. In yet another embodiment, a surface finish of the thread  36  may be grit blasted to promote bony ingrowth. The pockets  54  may be oblong shaped, in an embodiment. 
       FIG.  7    illustrates additional details associated with the thread  36  of the threaded cup  16 . The thread  36  may include design characteristics such as a thread pitch  60 , a thread angle  62 , a thread tip width  64 , a thread root width  66 , a thread depth  68 , and a thread root radius  70 . Table 2, provided below, illustrates exemplary design characteristics of the thread  36 . The disclosed design characteristics are intended to be exemplary only, and thus other thread specific formulations are contemplated as within the scope of this disclosure. In this disclosure, the term “about” means that the expressed quantities or ranges need not be exact but may be approximated and/or larger or smaller, reflecting acceptable tolerances, conversion factors, measurement error, etc. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Exemplary Design Characteristics of Thread 36 
               
            
           
           
               
               
               
            
               
                   
                 Thread Property 
                 Dimension 
               
               
                   
                   
               
               
                   
                 Thread Pitch 
                 About 2.70 mm 
               
               
                   
                 Thread Angle 
                 About 40° 
               
               
                   
                 Thread Tip Width 
                 About 0.19 mm 
               
               
                   
                 Thread Root Width 
                 About 0.83 mm 
               
               
                   
                 Thread Depth 
                 About 2 mm 
               
               
                   
                 Thread Root Radius 
                 About 0.20 mm 
               
               
                   
                   
               
            
           
         
       
     
     The thread pitch  60  may be a variable pitch. In an embodiment, the variable pitch increases in a direction that extends from the proximal side of the threaded cup  16  toward the distal side of the threaded cup  16 . In another embodiment, the variable pitch increases in a direction that extends from the distal side of the threaded cup toward the proximal side of the threaded cup  16   
     The thread  36  may be a single lead thread, a double lead thread, or a triple lead thread. The thread lead may be modified to control the amount of turns it takes to seat the threaded cup  16  within bone 
       FIG.  8   , with continued reference to  FIGS.  1 - 7   , schematically illustrates a surgical method  75  for performing a shoulder arthroplasty procedure. The surgical method  75  may include implanting the threaded cup  16  during the shoulder arthroplasty procedure. However, other joints could be repaired or replaced using a similar procedure to the one described below. It should further be understood that the surgical method  75  could include a greater or fewer number of steps, and that the steps could be performed in a different order within the scope of this disclosure. 
     The method may begin at block  77  by preparing the humerus  14  for receiving the threaded cup  16 . Preparing the humerus  14  may include resecting the humeral head of the humerus  14 , preparing a cavity within the resected humerus for receiving the cylindrical shaped body  26 , etc. 
     Next, at block  79 , the flange  28  may be positioned onto the humeral cut plate. The cylindrical shaped body  26  of the threaded cup  16  may be then be screwed into the prepared humerus  14  at block  81 . The cylindrical shaped body  26  may be screwed through the opening of the flange  28  and down into the humerus  14  until the rim  25  sits just proud of the cortical rim  40 . 
     Once implantation is complete, the thread  36  of the threaded cup  16  may engage the humerus  14  near the cortical bone  42 , and the flange  28  may load against the cortical rim  40 . The thread  36  may therefore engage the cortical bone  42 , cancellous bone  43 , or both. 
     Finally, at block  83 , an articular implant  18 A,  18 B may be connected to the implanted threaded cup  16 . The threaded cup  16  therefore establishes a convertible platform for interfacing with either anatomic articular implants or reverse articular implants. 
     Referring now to  FIGS.  9 ,  10 , and  11   , the threaded cup  16  may be utilized as part of a humeral implant assembly  99  of an arthroplasty implant system. In addition to the threaded cup  16 , the humeral implant assembly  99  may include a spacer  78  and a liner  80 . Together, the spacer  78  and the liner  80  may establish an articular implant  82  of the humeral implant assembly  99 . 
     In this embodiment, the articular implant  82  is a reverse articular implant. Therefore, the liner  80  may include a concave articular surface  84 . However, anatomic articular implants are also contemplated within the scope of this disclosure (see, e.g.,  FIG.  1   ). 
     The threaded cup  16  may include one or more engagement openings  91  formed in the rounded base  30 . The engagement openings  91  may accommodate de-rotation pegs  93  of the spacer  78  (or of the liner  80  if the spacer  78  is not used) for rotationally stabilizing the spacer  78  relative to the threaded cup  16 . 
     A C-clip  86  may be used to couple the spacer  78  to the threaded cup  16 , and the liner  80  may be coupled to the spacer  78  by a taper connection or any other connection. The C-clip  86  may be accommodated within a circumferential groove  88  formed in the receiving portion  32  of the threaded cup  16 , and the C-clip  86  may be further accommodated within a circumferential groove  90  formed in the spacer  78 . 
     In an embodiment, the liner  80  includes a lock block  92 . The lock block  92  may be accommodated within a notch  94  formed in the spacer  78 . The lock block  92  is configured to prevent the C-clip  86  from deforming inwards and allowing the spacer  78  to disengage from the threaded cup  16 . 
     In another embodiment, the lock block  92  is provided by the spacer  78  (see, e.g.,  FIGS.  12 A and  12 B ). In this implementation, the lock block  92  may be translated between an open position ( FIG.  12 A ) in which the C-clip  86  is free to deform, and a locked position ( FIG.  12 B ) in which the C-clip  86  is prevented from deforming. The lock block  92  may move from the open position to the locked position in response to a force applied by the liner  80  as the liner is moved into coupling engagement with the spacer  78 . 
     In other implementations, the spacer  78  may be secured to the threaded cup  16  via a taper connection. In still other implementations, the spacer  78  may be eliminated from the humeral implant assembly  99 , and the liner  80  may be directly secured to the threaded cup  16 , such as via either a taper connection or a C-clip, for example. Thus, this disclosure is not intended to be limited to the exact implementations shown in  FIGS.  9 - 12 B . 
     In an embodiment, the liner  80  is a metallic component (see  FIG.  13   ). In another embodiment, the liner  80  may include both a metallic portion  96  and a polymeric portion  98  (see  FIG.  14   ). The polymeric portion  98  may establish the concave articular surface  84  of the articular implant  82  and may be insert molded into a shell provided by the metallic portion  96 . 
       FIGS.  15 ,  16 ,  17 ,  18 , and  19   , with continued reference to  FIGS.  1 - 14   , illustrate an inserter system  100  for implanting the threaded cup  16  into the humerus  14 . The inserter system  100  may include a handle  102 , a drive shaft  104 , a cage assembly  106 , and a shaft assembly  108 . Each of these components and their respective functions are further described below. 
     The shaft assembly  108  may include an outer shaft  110  and an inner shaft  112 . The inner shaft  112  may be accommodated within a bore of the outer shaft  110  and may be secured in place relative to the outer shaft  110  by a pair of capture pins  114  (see  FIG.  18   ). 
     The inner shaft  112  may include a threaded distal tip  116  that may be screwed into the engagement opening  50  of the threaded cup  16  for attaching the inserter system  100  to the threaded cup  16 . A proximal tip  120  of the inner shaft  112  may include a hex tip design or any other connection suitable for attaching a peripheral component (e.g., a knob) to the inner shaft  112  for more easily screwing the inner shaft  112  into the threaded cup  16 . 
     The outer shaft  110  may include an outer thread  118  for securing the shaft assembly  108  to the cage assembly  106 . The outer thread  118  may be accommodated within a central threaded opening  122  of the cage assembly  106  (see  FIG.  19   ). The outer thread  118  and the central threaded opening  122  cooperate to maintain the threaded cup  16  recessed within the cage assembly  106  prior to insertion of the threaded cup  16  into bone. 
     The cage assembly  106  may include a proximal portion  124  that accommodates portions of the shaft assembly  108  and a distal portion  126  designed to interface with the flange  28  of the threaded cup  16 . For example, the distal portion  126  may include a plurality of mounting legs  128  that each include a tapered tooth  130  sized to engage a tapered slot  132  that may be formed through the flange  28 . The tapered slots  132  are additional openings that are separate from the suture eyelets  44 . Sutures (not shown) that are accommodated within the suture eyelets  44  may be routed through the flange  28 , then through slots  134  formed in the distal portion  126 , and then may be wrapped around one or more suture wrap blocks  136  that can be attached to the proximal portion  124  of the cage assembly  106 . 
     The handle  102  may include an outer grip  138  and an inner tube  140  that includes a proximal impaction face  142  and a distal connector  144 . The distal connector  144  may be connected to the proximal portion  124  of the cage assembly  106 , such as via a spring seal  146  (see  FIG.  17   ), for example. The proximal impaction face  142  may be exposed outside of the outer grip  138  and may be used for impacting the flange  28  onto the humerus  14 . For example, the proximal impaction face  142  may be impacted by a surgical mallet for driving the anti-rotation tabs  35  of the flange  28  into the humerus  14 , thereby securing the flange  28  in proper position at the cortical rim  40 . 
     The drive shaft  104  may be inserted through the inner tube  140  of the handle  102  for connection to the inner shaft  112  of the shaft assembly  108 . The drive shaft  104  may include a cannulation  148  for accommodating portions of the inner shaft  112 . The drive shaft  104  may connect to the inner shaft  112  using another spring seal  150  (see  FIG.  17   ), for example. 
     After unscrewing the outer shaft  110  of the shaft assembly  108  from the cage assembly  106 , the drive shaft  104  may be rotated in order to drive the threaded cup  16  into the humerus  14 . The threaded cup  16  is screwed through the opening of the flange  28  as the flange  28  is being held against the cortical rim  40  by the distal portion  126  of the cage assembly  106 . The various subcomponents of the inserter system  100  may then be removed from the threaded cup  16  and flange  28  to complete the procedure. 
     The exemplary arthroplasty implant systems of this disclosure employ modular stemless implants capable of establishing a convertible platform for interfacing with articular implants. The stemless implants may be configured as threaded cups that incorporate a modular flange (e.g., a circumferential ring/trunnion) that is adapted to rest atop the cortical rim of a resected bone in order to provide additional fixation support and load bone more favorably when implanted. The stemless implants may further provide inlaid designs that allow for inlay reverse prosthesis configurations. 
     Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
     It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should further be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
     The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.