Abstract:
A reverse modular humeral implant for implantation 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 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/009,896 filed on Jan. 20, 2011. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a humeral prosthesis for total shoulder joint replacement and generally includes a prosthetic humeral stem, a bearing coupling mechanism, and a prosthetic head which replaces a portion of the humeral joint. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    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. 
         [0005]    Conventional humeral implants fail to accommodate patients having inadequate skeletal structure needed during a revision procedure. 
         [0006]    Specifically, conventional implants do not permit articulation between the implant and the concave undersurface of the coracoacromial arch of the scapula, the coracoacromial arch being a structural component of the shoulder comprising the coracoacromial ligament, coracoid process, and acromion. Thus, there is a need for a humeral implant that permits revision of the articulation surface to allow proper articulation dynamics. 
       SUMMARY 
       [0007]    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 humerus that includes a natural humeral shaft and a natural humeral head. 
         [0008]    A modular reverse shoulder prosthetic for a revision procedure 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 aperture therein. The aperture has a first portion with a first internal diameter and a second portion with a second internal diameter, the second internal diameter being larger than the first diameter, wherein the first portion can be disposed between the second portion and the bearing mounting surface and wherein a locking surface can be defined at an interface between the first and second portions. A bearing coupling member is provided which is configured to engage the bearing mounting surface, the bearing coupling member can have a coupling flange extending generally perpendicular therefrom. The flange can have a depending locking member configured to be disposed through the first portion and into the second portion of the coupling aperture and to engage the locking surface. The mounting portion having a bearing coupling side can have a coupling taper configured to mate to a corresponding taper on a bearing member. 
         [0009]    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 therein. The coupling aperture can have a first portion with a first internal diameter and a second portion with a second internal diameter. The second internal diameter can be larger than the first diameter, and the first portion can be disposed between the second portion and the bearing mounting surface. A locking surface can be defined at the interface between the first and second portions. The bushing member is first disposed within the glenoid tray, and defines an aperture having a plurality of generally planar bearing surfaces defining a bushing member bearing ledge. A bearing coupling member is disposed within the bushing member. 
         [0010]    The bushing member can have a planar interface surface configured to engage the bearing mounting surface. The bearing mounting surface can have a coupling flange extending generally perpendicular therefrom. A bearing coupling member can be disposed therein. The bearing coupling member can have a bearing coupling side having a coupling surface configured to mate to a corresponding surface on a bearing member. 
         [0011]    According to alternate teachings, the bearing coupling member can define a bearing coupling member coupling ledge configured to slidably engage the bushing member bearing ledge when the bearing coupling member is engaged with the bushing and the glenoid tray. The bearing coupling member is translatable with respect to the bushing. 
         [0012]    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 
         [0013]    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. 
           [0014]      FIG. 1  is a view of a humeral implant according to the prior art; 
           [0015]      FIG. 2  is an exploded view of a reverse humeral implant according to the present teachings; 
           [0016]      FIGS. 3 a -3 c    are end views of the coupling member, bushing, and tray according to the present teachings; 
           [0017]      FIGS. 4 a -4 d    are side exploded views of a humeral implant subassembly using the coupling mechanism, bushing, and tray according to the present teachings; 
           [0018]      FIG. 5  is an assembled end view of the coupling mechanism and tray according to the present teachings in an engaged position; and 
           [0019]      FIGS. 6-9  represent cross-sectional views of a revision procedure. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0021]      FIG. 1  represents a shoulder prosthetic system according to the prior art. Shown is a coupling, bearing or glenoid tray  20  having a dependent stem  21  and fixation edge  22 . Disposed within the glenoid tray  20  is a polymer glenoid  23  having a mounting interface  24  and concave bearing surface  25 . The concave bearing surface  25  is configured to interface with the articulating surface of a humeral prosthetic  26 . Generally, the concave bearing surface  25  is configured to interface with a humeral prosthetic. 
         [0022]    The humeral prosthetic has a stem  27  which can be coupled to the medullary canal of a resected humerus  28 . Alternatively, a short stem head prosthetic can be used. As further described below, the prosthetic system can at least be partially removed in a revision procedure.  FIG. 2  represents an exploded perspective view of the reverse shoulder system  29  according to the present teachings. The reverse shoulder system  29  utilizes the glenoid tray  20  to couple a reverse shoulder head member  30  to the prepared glenoid after a traditional glenoid member has been removed in a revision procedure. 
         [0023]    As described below, the head member  30  is coupled to the glenoid tray  20  using an intermediary or bearing coupling member  31 . Disposed about the bearing coupling member  31  is a polymer sleeve, bushing member or bushing  32 , which can be coupled to the bearing coupling member  31  and the glenoid tray  20 . The bearing coupling member  31  is non-rotatably fastened to the glenoid tray  20  using a fastener  35 . In this regard, the bearing coupling member  31  has a generally cylindrical coupling flange  37  which is inserted into a bore  36  defined within the glenoid tray  20 . The bushing  32  engages the fixation edge  22  to prevent rotation of the bearing coupling member  31 . 
         [0024]    The fastener  35  can be used to fixably couple the bearing coupling member  31  to the glenoid tray  20 . The polymer bushing  32  defines an interior coupling bore  40  defining at least one flat bearing surface  39 . Optionally, the interior coupling bore  40  can define four intercepting flat bearing surfaces which form a square or a rectangle. The interior coupling bore  40  radially supports the bearing coupling member  31  on a pair of parallel sides. As described below, the bearing coupling member  31  is slid along the axis  42  of the interior coupling bore  40  to move the locking member or coupling flange  37  from an unengaged to an engaged position. 
         [0025]      FIGS. 3 a -3 c    represent end views of the glenoid tray  20  and associated bushing  32 . Shown are snapped ends  46  which rotationally lock both the glenoid bearing or bushing into the glenoid tray  20 . As best seen in  FIGS. 3 a    and  4 , the glenoid tray  20  defines a central coupling bore  47 . The coupling bore  47  has a first portion  49  having a first diameter, and a second portion  50  having a second diameter. The second portion  50  defines a locking surface  51  configured to interface with a coupling flange of the bearing coupling member  31 . 
         [0026]      FIGS. 4 a -4 d    represent exploded views of alternate mechanisms for coupling the bearing coupling member  31  to the glenoid tray  20 . While similar, each coupling mechanism has different advantages. As shown in  FIGS. 4 a  and 4 b   , the bearing coupling member  31  can be coupled through the interior coupling bore  40  defined in the bushing  32 . The coupling flange  37  can take the form of a cylinder or coupling taper. Additionally, the-fastener  35  can be used to couple the bearing coupling member  31  to the glenoid tray  20 . 
         [0027]    As shown in  FIGS. 4 c  and 4 d   , the bearing coupling member  31  can be coupled through the interior coupling bore  40  defined in the bushing  32  and into the first and second portion of the bore  36 . The coupling flange  37  takes the form of a cylinder coupling flange. The coupling flange  37  has a depending flange  53  configured to interface with the locking surface  51 . The coupling flange  37  is centered at a location generally offset on a first side from the centerline of the bearing coupling member  31 . The bearing coupling member  31  defines a throughbore  38  generally offset on a second opposed side from the centerline of the bearing coupling member  31 . The fastener  35  can be passed through the throughbore  38  and at least partially into the first portion of the coupling bore to couple the bearing coupling member  31  to the glenoid tray  20 . 
         [0028]    As best seen in  FIG. 5 , the coupling mechanism depending flange  53  is configured to interface with the locking surface  51 . The flange  53  is configured to fit through the smaller diameter first portion  49  of the coupling bore  47 . It, therefore, has a cross-sectional area and geometry which allows its transfer from a first non-engaged position to an engaged position after the depending flange is passed through into the second portion  50 . This engagement releasably locks the bearing coupling member  31  to the glenoid tray  20 . The addition of the fastener through the offset throughbore  38  locks the coupling member in place. It is envisioned the coupling member can have either male or female locking tapers or an exterior coupling taper  43  to couple the head member  30  to the glenoid tray  20 . 
         [0029]      FIGS. 6-8  depict side exploded views of a procedure to couple the interface coupling system to the glenoid tray  20 . In this regard, it is envisioned that the glenoid tray  20  could have been previously coupled to the glenoid in a traditional arthroplasty (see  FIG. 1 ).  FIG. 6  depicts the glenoid tray  20  coupled to a prepared glenoid. Shown is the central coupling bore  47  with associated first and second portions  49  and  50 . 
         [0030]    As shown in  FIG. 7 , after the bushing  32  is coupled to the glenoid tray  20 , the bearing coupling member  31  is positioned though a bushing aperture or bore  41  in contact with a bearing surface of the glenoid tray  20 . Defined about the external periphery of the bearing coupling member  31  can be a cutout or ledge portion configured to interface with a ledge defined within the bushing aperture or bore  41  of the spacer member. 
         [0031]    The coupling flange  37  has an exterior surface having a generally fixed radius of curvature about the centerline defining the body. The coupling flange  37  generally can present a one-half cylinder which has a cross-sectional area smaller than the cross-sectional area of the coupling bore  47  in the glenoid tray  20 . The flange extended ledge portion  52  extends generally perpendicular to a centerline defining the extending ledge portion  52 . As shown in  FIGS. 7 and 8 , the ledge portion  52  is configured to interface with the locking surface  51 . 
         [0032]    The reverse shoulder prosthetic can have a glenoid tray  20  configured to be implanted into a resected glenoid. The glenoid tray  20  can have a glenoid interface surface  60  and an opposed bearing mounting surface  61 . The bearing coupling member  31  can have a planar interface surface  63  configured to engage the bearing mounting surface  61 . 
         [0033]    Shown in  FIG. 8 , the bushing  32  defines bushing bore  41  having a plurality of generally planar bearing surfaces which define a bushing member bearing ledge  68 . The bearing coupling member  31 , disposed within the bushing  32 , has a planar interface surface  69  configured to engage the bearing mounting surface  61 . The bearing coupling member can be translated with respect to the glenoid tray  20 . The bearing coupling member  31  can be translatable with respect to the glenoid tray  20  from an unlocked position to a locked position. The bearing coupling member  31  is translatable with respect to the glenoid tray in a direction parallel to the bearing mounting surface from a first unlocked position ( FIG. 7 ) to a second locked position ( FIG. 8 ). 
         [0034]    As best seen in  FIG. 9 , a head  30  can be coupled to the exterior coupling taper  43  formed on the bearing coupling member  31 . It is envisioned that the interfering ledges can hold the bushing  32  in place against the glenoid tray  20  and the bushing  32  inhibits rotation of the bearing coupling member  31 . 
         [0035]    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. 
         [0036]    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. 
         [0037]    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. 
         [0038]    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. 
         [0039]    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. 
         [0040]    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.