Abstract:
A method for implanting a reverse modular humeral implant into a humerus that includes a natural humeral shaft and a natural humeral head. The implant includes a humeral stem implantable into the natural humeral shaft, and an adapter couplable to the humeral stem, the adapter including an anchoring projection configured to be coupled to a convex bearing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/089,004 filed on Nov. 25, 2013, which is a continuation of U.S. patent application Ser. No. 13/115,548 filed on May 25, 2011, now U.S. Pat. No. 8,591,591. The entire disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a humeral prosthesis for total shoulder joint replacement and generally includes a prosthetic coupling mechanism, an annular spring member, and a prosthetic head which replaces a portion of the humeral joint. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     It is not uncommon for the exterior surface of the humeral head to be damaged or defective. Conventionally, a variety of humeral head resurfacing implants exist for repairing humeral head surfaces. While conventional humeral head resurfacing implants are suitable for their intended uses, such implants are subject to improvement. 
     Conventional humeral implants fail to accommodate patients having inadequate skeletal structure during an impact situation. Specifically, conventional implants do not permit relative movement between the components or the absorption of impact energy. These impacts are often off axis and have complex loading parameters. 
     To overcome these deficiencies, reverse shoulders using a glenosphere have been used. These reverse shoulders may be susceptible to impacts when a patient inadvertently falls, impacting the prosthetic. Thus, there is a need for a humeral implant that permits proper articulation dynamics, while accepting impact loads. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. Various aspects of the teachings provide a modular humeral implant and associated kit and method for implantation into a shoulder joint that includes a natural humeral shaft and a natural humeral head and glenoid. 
     A modular reverse shoulder prosthetic is taught. The reverse shoulder prosthetic can have a glenoid tray configured to be implanted into a resected glenoid. The tray can have an opposed bearing mounting surface defining a coupling taper therein. A bearing coupling member is provided which is configured to engage the bearing mounting surface. A depending spring member is provided that is configured to be disposed radially about the bearing coupling member. The spring is coupled to a glenosphere bearing and the tray or the coupling member. 
     According to alternate teachings, the shoulder prosthetic can have a glenoid tray configured to be implanted into the resected glenoid. The tray can have a glenoid interface surface with a depending coupling stem and an opposed bearing mounting surface. The bearing mounting surface defines a coupling aperture having a coupling taper. A spring member is first disposed within a cavity defined by the glenoid tray, and is coupled to a glenosphere and defines an aperture which can annularly accept a bearing coupling member. The bearing coupling member is disposed within the spring member aperture. 
     According to alternate teachings, the glenoid tray can define a glenoid tray spring coupling ledge configured to annularly support the spring member when the bearing coupling member is engaged with the spring and the glenoid tray. The glenosphere head member is translatable with respect to the bearing coupling member. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a cross-sectional view of a humeral implant according to the present teachings; 
         FIG. 2  is an exploded view of an alternate reverse humeral implant according to the present teachings; 
         FIGS. 3A-3C  are side exploded views of a humeral implant subassembly using the coupling mechanism, spring, and tray according to the present teachings; 
         FIG. 4  is an assembled view of the prosthetic according to the prosthetic of  FIG. 3A ; 
         FIG. 5  represents an assembled view of the prosthetic of  FIG. 3B ; 
         FIG. 6  represents an assembled view of the prosthetic of  FIG. 3C ; 
         FIG. 7  represents an alternate glenosphere prosthetic; and 
         FIG. 8  represents an alternate glenospherical prosthetic. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
       FIG. 1  represents a cross-sectional view of the shoulder system  29  according to the present teachings. The system  29  utilizes the glenoid coupling member or glenoid tray  20  to couple a shoulder bearing  23  to the prepared glenoid. Disposed within the glenoid tray  20  is the shoulder bearing  23  having a mounting interface surface  24  and concave bearing surface  25 . The concave bearing surface  25  is configured to interface with the articulating surface of a humeral prosthetic  27 . The mounting interface surface  24  can have an intermediate depending piston  26 . The intermediate depending piston  26  can be fixed to mounting interface surface  24  or, as described below, to the glenoid tray  20 . 
     Operably disposed between the shoulder bearing  23  and the glenoid tray  20  is an annular spring member  35 . The spring member  35  functions to couple the bearing  23  to the glenoid tray  20 . In this regard, the spring member  35  functions to limit or constrain movement of the shoulder bearing  23  with respect to the glenoid tray  20 . Additionally, the spring member  35  functions to absorb impacts or forces applied onto the bearing surface  25 . The annular spring member  35  has a first end fixably coupled to an aperture  28  formed within the glenoid tray  20 . At its second end, the spring member  35  is fixably coupled to an aperture  30  formed on the interface side of the bearing  23 . 
     It is envisioned the intermediate depending piston  26  fixed to the mounting interface surface  24  can be slidably accepted by the cylindrical aperture  32  defined within the glenoid tray  20 . The intermediate depending piston  26  and cylindrical aperture  32  can be sized and toleranced so that the interface between the intermediate depending piston  26  and aperture  32  functions as a fluid damper. The aperture  32  can be formed in a tray coupling stem  33 . 
     The coiled spring member  35  can define a central through bore  31  which annularly surrounds the intermediate depending piston  26 . It is envisioned that the spring member  35  can be positioned within a cavity defined by a fixation edge  22  of the glenoid tray  20 . Alternatively, the spring member  35  may be incorporated into a cavity (not shown) defined by the bearing  23  mounting interface surface  24 . In addition, the spring member  35  may be sized and configured to be located within the cylindrical aperture  32  in order to impart force upon the intermediate depending piston  26 . 
     As shown in  FIG. 2 , a glenosphere head  40  can be coupled to the glenoid tray  20  using a bearing coupling member or intermediary coupling member  41 . Disposed about the intermediary coupling member  41  is a spring member  35 , which can be coupled between the intermediary coupling member  41  and the head  40 . The coupling member  41  is non-rotatably, but floatably disposed within the glenoid tray  20  using, by way of non-limiting example, the coupling taper  42 . In this regard, the coupling taper  42  is inserted into a bore defined within the glenoid tray or support structure  20 . 
     The head  40  is configured to be coupled to a cup member bearing  44  fixed to the stem  45 . As further described below, the head  40  is coupled directly to the glenoid tray  20  or to the glenoid tray  20  through the intermediary coupling member  41  using the spring member  35 . The spring member  35  is fixably or rotatably coupled to the head  40  and the intermediary coupling member  41 . The taper  42  is configured to loosely couple to a taper in the head  40 . In this regard, the taper  42  can be a non-locking taper. 
       FIGS. 3A and 3B  represent exploded cross-sectional views of the shoulder components according to the present teachings.  FIG. 3A  depicts the components shown in  FIG. 1 . As shown, the spring coupling apertures defined by the bearing  23  or the glenoid tray  20  can be generally parallel to the interface surfaces of both the bearing  23  and the glenoid tray  20 . 
       FIGS. 3B and 3C  represent reverse shoulder components having an intermediary coupling member  41 . The intermediary coupling member  41  has a head bearing surface  50  which is translationally coupled to a corresponding surface  51  defined within the head. The head bearing surface  50  is configured to transfer applied loads onto the head bearing surface  50  through the coupling member  41  and into the glenoid tray  20 . The head bearing surface  50  can be a non-locking taper  53  or a spherical bearing surface  54 . 
     The coupling member  41  has an exterior surface  46  having a generally fixed radius of curvature about the centerline defining the coupling member  41 . The spring coupling member  35  generally can present one and a half rotations which has a cross-sectional area smaller than the cross-sectional area of the head  40 . As shown in  FIGS. 3B and 3C , the ledge portion  52  of the head  40  is configured to annularly enclose the spring member  35 . 
       FIGS. 4-6  represent cross-sectional views of the implantation of the shoulder components shown in  FIGS. 1-3C . After the resection of the glenoid, an aperture  63  can be formed within the glenoid to accept a tray coupling stem  33 . After coupling the glenoid tray  20  to the resected glenoid, the spring member  35  can be coupled to the glenoid tray  20  or the coupling member  41 . 
     After coupling the spring member  35  to the glenoid tray  20  or the coupling member  41 , the coupling member  41  (if used) can be coupled to a coupling taper defined in the glenoid tray  20 . The second end  34  of the spring member  35  can then be coupled into the spring coupling aperture  49  formed in the mating surface of the head  40 . 
     As shown in  FIG. 7 , the glenoid tray  20  can be flexibly coupled to the head  40 . In this regard, the coupling member  41  can be fixably coupled to the head  40  by the coupling surface  53 . The coupling member  41  has a flat surface  56  which slidably interfaces with a planar interface surface  39 . The floating head  40  and coupling member  41  are movably fixed to the glenoid tray  20  through the spring member  35 . As with all of the examples, the head can be moveable with respect to the glenoid tray, the bearing coupling member, or a portion of the spring when the head is subjected to forces. 
     As seen in  FIG. 8 , the head  40  can be coupled directly to the glenoid tray  20  using only the coupling spring member  35 . As described above, the coupling spring can be fixably coupled at the coupling apertures. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.