Patent Publication Number: US-9844439-B2

Title: Multiple bearing humeral prosthesis

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/632,199 filed 1 Oct. 2012, now issued as U.S. Pat. No. 9,084,680, which claims the benefit of U.S. Provisional Application No. 61/543,477, filed on 5 Oct. 2011. The entire disclosures of the above identified applications are incorporate herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a modular prosthesis, and particularly to a humeral prosthesis including a plurality of bearings operable to interconnect with a single shell in a humeral prosthesis. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Articulating regions of the anatomy can include areas where two bone sections move relative to one another. For example, a humerus can provide a region for articulation with a glenoid bearing. The articulating region, however, can become injured or worn, and can therefore be replaced with various prostheses. Prostheses can replace the glenoid, the humeral head, various other portions of the humerus, or combinations thereof (see  FIG. 1 ). The replacement of both the glenoid and the humeral head is generally referred to as a total joint replacement. 
     The total joint replacement of the glenoid and the humeral head requires a bearing or articulating surface for both the humeral head and the glenoid. The articulating surfaces are generally positioned relative to the various portions of the remaining natural anatomy in a substantially fixed manner. Materials must be selected for the bearing surfaces for various purposes, and are dependent upon patient defined parameters such as age, musculature, or expected activity level. 
     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. 
     A prosthesis to replace a portion of the anatomy, such as the humerus can include a first portion, such as a cup or shell, that can be fixed to, for example, a resected humerus. The humerus can be prepared in any appropriate manner to receive fixation of the cup. The prosthesis can include a second portion, such as a concave bearing or convex bearing, which can be positioned relative to the shell to provide a bearing surface to articulate with a glenoid prosthesis. It will be understood, however, that a selected bearing component can be provided to articulate or provide a bearing surface relative to a natural glenoid. 
     The prosthesis system can include a single shell that can be interconnected with two or more bearing members. The bearing members can include various characteristics or material selections, such as a polymer bearing and a metal bearing. The polymer bearing can provide a relatively soft surface for a member to bear against. The metal bearing, relative to the polymer bearing, can provide a substantially hard or tough surface to bear against. The different bearing materials can also include different connection portions to interconnect with the shell. The shell can include connecting regions to connect with the multiple bearing members, including both convex and concave bearing members. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The present teachings will become more fully understood from the detailed description, the appended claims and the following drawings. The drawings described herein are for illustrative purposes only of selected embodiments, and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  represents a humeral prosthesis according to the prior art; 
         FIG. 2  represents a humeral prosthesis according to the present teachings; 
         FIG. 3  represents a total shoulder prosthesis according to one embodiment of the present teachings; 
         FIG. 4  represents a reverse shoulder prosthesis according to an alternate embodiment of the present teachings; 
         FIGS. 5 and 6  represent views of a humeral prosthesis according to an alternate embodiment of the present teachings; 
         FIG. 7  represents an alternate humeral prosthesis according to the present teaching; 
         FIGS. 8 and 9  represent sectional views of various embodiments according to the present teachings; 
         FIGS. 10-12  represent stem coupling mechanisms according to the present teachings; and 
         FIG. 13  represents an alternate humeral prosthesis according to the present teachings. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. Although various embodiments are discussed below, including exemplary materials, it will be understood that any appropriate materials or combinations may be selected for use with the kits and/or assemblies of the present teachings. Exemplary 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, systems and/or methods, to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that exemplary embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
       FIG. 2  represents one example of a humeral prosthesis  20  according to the present teachings. As will be discussed in greater detail below, the humeral prosthesis embodiments disclosed herein can be included in a kit, such as a humeral implant kit, for use in a partial or total shoulder joint replacement. According to various embodiments, the kits can include various humeral components of differing sizes and configurations, such as humeral shells, bearings and coupling members, to accommodate partial and total shoulder joint replacements, including reverse shoulder prosthesis configurations. 
     With additional reference to  FIG. 3 , the humeral prosthesis  20  can include a stem  22  coupled to a head coupling member  24  and a first bearing member  26 . In one embodiment, the head coupling member  24  can define a generally spherical or cylindrical coupling aperture  27  forming a void or passage  76 . Defined within the head coupling member  24  can be a shell  25 , which can define the coupling aperture  27 . The coupling aperture  27  can include a defined interior coupling groove  30 . An apical location  21  of the shell  25  can define a coupling mechanism used to couple the stem  22  to the head coupling member  24 . 
     The interior coupling groove  30  can be configured to couple the first bearing member  26  to the head coupling member  24 . As best seen in  FIGS. 2, 5 and 6 , the first bearing member  26  can have a convex or concave articulating bearing surface  40  and an opposite coupling side  42 . The coupling side  42  can define an exterior coupling groove  31 , which can interface with a coupling member or snap-ring  61  to fix the first bearing member  26  to the head coupling member  24  via a ringlock connection. Additionally, the coupling side  42  can have a convex surface configured to interface with the spherical or cylindrical coupling aperture  27 . The coupling side  42  can have a polymer exterior surface, or can have a metallic exterior sleeve or layer  46 , as will be discussed in greater detail herein. The first bearing member  26  can be formed of a substantially hard or rigid material, including ceramic, UHMWPE material, metal or metal alloys. 
     The ringlock connection, such as in the RingLoc® humeral implant sold by Biomet, Inc. of Warsaw, Ind., USA, can offer a substantially fixed position of the first bearing member  26  in both an axial position and rotational position relative to the shell  25 . The ringlock can have tabs to facilitate coupling the snap-ring  61  into the coupling or ringlock grooves  30 ,  31 . 
     As best seen in  FIGS. 2-3 , the first bearing member  26  includes the first articulating bearing surface  40 , which can have a first radius of curvature. The opposite coupling side  42  of first bearing member  26  can have a convex curved coupling or exterior surface  62  having a second radius of curvature which is less than the first radius of curvature. The convex curved coupling surface  62  can be a sphere (e.g.,  FIGS. 2, 3 and 6 ) or an exterior surface of a cylinder (e.g.,  FIG. 5 ), as will be discussed below in greater detail. The exterior coupling groove  31  can be defined at a location between the articulating bearing surface  40  and the coupling side  42 . 
     The coupling surface  62  of first bearing member  26  can be configured to cooperate with an interior surface  38  of coupling aperture  27  of shell  25 . The interior surface  38  of the shell  25  can be provided in any appropriate manner, such as substantially highly polished or substantially smooth. The interior surface  38  can contact exterior surface  62  of the coupling side  42  of the first bearing member  26  substantially tightly or with any appropriate gaps. The interior surface  38  can contact the exterior surface  62  completely or in part, according to various embodiments. 
     As best seen in  FIG. 3 , the radius of curvature of the bearing surface  40  can conform to the radius of curvature of an articulating surface  68  of a glenoid prosthesis  70 . The glenoid prosthesis  70  can have a traditional concave bearing surface for a shoulder replacement, or in a reverse shoulder arrangement  72  (discussed below in greater detail with reference to  FIG. 4 ), can have a convex bearing surface. The glenoid prosthesis  70  can be coupled to a glenoid using fixed or removable pegs  75 . 
     With reference to  FIG. 4 , the shell  25  can accommodate provisions for a reverse shoulder bearing configuration  72 . In this regard, the shell  25  can be used to couple intermediate coupling members  32  and  34 , which can be used to couple a second bearing  26 ″ having a concave articulating bearing surface  40  defined thereon. Coupling member  32  can have a curved coupling surface  62  defined on the coupling side  42 , which can interface with the interior surface  38  of the coupling aperture  27  of shell  25 . Intermediate coupling member  32  can be coupled to the shell  25  using the snap-ring  61  in a similar manner as discussed above for first bearing member  26 . Intermediate coupling member  32  can also have a locking taper  37  defined therein. 
     The locking taper  37  can be configured to engage a corresponding locking taper  39  that can be defined on coupling member  34 . Additionally, a second locking taper  41  can be defined by a portion of coupling member  34 , and can be configured to engage a locking taper  43  defined in the bearing  26 ″. 
     The glenoid portion of the reverse shoulder bearing configuration  72  can include an intermediary member  48  coupled to the glenoid with a plurality of fasteners  49 . Fasteners  49  can be the same as, or different from the fasteners  75  shown in  FIG. 3 . The intermediary member  48  can have provisions to accept various sized convex bearings  100 , as shown in  FIG. 4 . These convex bearings  100  can have a male locking taper  50  configured to engage a female taper  51  defined in the intermediate member  48 . In the exemplary configuration illustrated, the bearings  100  can define a female taper  96  configured to be coupled to a male taper  98  defined about the female taper  51 . An articulating surface  68  of the bearing  100  can be configured to rotatably engage bearing surface  40  of second bearing  26 ″. 
     With continuing reference to  FIG. 4  and additional reference to  FIGS. 6 and 9 , the coupling aperture  27  can function to fix an alternative first bearing member  26 ′, shown in the form of a concave bearing cup  80 , to the head coupling member  24 . The alternative first bearing member  26 ′ can be formed of any appropriate materials, such as polymers including ultra-high molecular weight polyethylene (UHMWPE) or polyetheretherketone (PEEK). As will be discussed in greater detail below, the alternative first bearing member  26 ′ can include a concave articulating bearing surface operable to articulate with a selected member, such as a natural glenoid or a prosthesis glenoid implant. 
     As shown in  FIG. 6 , the alternative first bearing member  26 ′ or bearing cup  80  can include an outer lip  82  which can bear against an exterior bearing ledge  84 . The bearing cup  80  can have an extended portion  85  in the form of a cylindrical member  86 , which can lead to a concave articulating surface  89 . Similar to first bearing member  26 , the snap-ring  61  can fixedly hold the bearing cup  80  or alternative first bearing member  26 ′ relative to the shell  25 , at least in an axial position. In this regard, the bearing cup  80  can include an external groove  79  similar to exterior coupling groove  31  of first bearing member  26 , as shown for example in  FIG. 6 . The exterior groove  79  can align with the interior groove  30  of shell  25  when the first bearing member  26 ′ is positioned in coupling aperture  27 , as also shown in  FIG. 6 . In particular, an external surface  88  of the first bearing member  26 ′ can engage the interior surface  38  of the coupling aperture  27  of shell  25  and the snap-ring  61  can couple bearing  26 ′ to shell  25  in a similar manner as first bearing member  26  discussed above. 
     The alternative first bearing member  26 ′ can also include any appropriate size for positioning in the shell  25 . The first bearing member  26 ′ can be selected to include the concave articulation surface  89  for articulation relative to the reverse glenoid implant configuration  72  shown in  FIG. 4 . In this particular configuration, the first bearing member  26 ′ can be configured to replace the intermediate coupling members  32  and  34  and the second bearing member  26 ″ shown in  FIG. 4 , such that the concave articulation surface  89  of the alternative first bearing member  26 ′ engages the articulation surface  68  of the convex bearing  100 . In this regard, the curvature of the articulation surface  68  can be configured to mate with the curvature of the articulation surface  89  of the first bearing member  26 ′. 
     Optionally, as seen in  FIG. 9 , the alternative first bearing member  26 ′ or bearing cup  80  can be incorporated fully within the shell  25 . For example, a first exterior wall portion  120  of the alternative first bearing member  26 ′ can engage a substantially hemispherical or semispherical inner wall  112  of the shell  25 . The first bearing member  26 ′ can also include an engagement flange  124  that is operable to engage an internal bearing region  104  of the shell  25 . The internal bearing region  104  can provide a ringlock connection. Optionally, the snap-ring  61  can also be used to couple first bearing member  26 ′ to shell  25 , as shown in  FIG. 9 . In this exemplary configuration of shell  25  and first bearing member  26 ′, grooves for receiving snap-ring  61  can be positioned relative to the outer lip  82  of bearing  26 ′ and the engagement flange  124  of shell  25 , as also shown in  FIG. 9 . 
     As best seen in  FIG. 5 , the shell  25  can optionally include a cylindrical coupling surface  83  configured to cooperate with a cylindrical coupling surface  102  of the first bearing member  26 . Optionally, the snap-ring  61  can be coupled to the shell  25  and the cylindrical surface  102  in the same manner as discussed above for the spherical coupling configuration of first bearing member  26 . As discussed above, the snap-ring  61  can be used to regulate rotation of the humerus with respect to the stem. As shown, the bearing  26  can have an articulating surface having a varying diameter or center of rotation. 
     As depicted throughout, the first bearing members  26 ,  26 ′ can include a metal coated or sleeved polymer. The metal coating or layer  46  can be a stamped or machined component. The first bearing member  26  can be insert molded or pressed into the metal layer or member  46 . The metal layer  46  can also define the coupling groove which facilitates the coupling of the bearing member  26  to the shell  25 , as shown for example in  FIGS. 5 and 6 . In addition, the alternative first bearing member  26 ′ can optionally include a metal coated or sleeved polymer layer, as shown for example in  FIG. 9 . 
     Briefly, the provision of the first bearing members  26 ,  26 ′ allows for a pre-operative or intra-operative selection of bearings for positioning within the shell  25 . In addition, or alternatively, the provision of the first bearing members  26 ′ that can engage the shell  25  can minimize the number of parts for a procedure. Each of a plurality of the first bearings  26 ,  26 ′ can also include different dimensions, such as an internal diameter, an external diameter, etc. 
     The shell  25  can also be provided in different sizes or configurations. For example, a diameter or height of the shell  25  can be altered based upon different portions that articulate with the first bearing members  26  and  26 ′, the size of the patient, or other appropriate considerations. The shell  25  defined by a shell wall portion or member can also be provided in multiple thicknesses. 
     As can be seen in  FIGS. 7 and 8 , a humeral assembly, according to various embodiments, includes the shell  25  relative to which the first bearing  26  can be positioned. As shown in  FIG. 7 , shell  25  can include a first thickness  54  that can be less than a second thickness  56 . Defined between these thicknesses can be bearing ledge  84 . The first and second thicknesses  54 ,  56  can also alter or change the dimensions of the snap-ring  61 . In this regard, it will be understood, however, that a system or kit of the shells  25  and the first bearing members  26 ,  26 ′ can include multiple sizes of the components included therein. 
     As also shown in  FIGS. 7 and 8 , a constraining ring  74  can be associated with the shell  25  and configured to cooperate with first bearing member  26  to retain bearing member  26  relative to shell  25 . The constraining ring  74  can include a groove  87  configured to receive a portion of snap-ring  61  when positioned in shell  25  relative to bearing ledge  84  and rim  71 . In this exemplary configuration, the snap-ring  61  can function to couple constraining ring  74  to shell  25  via the ringlock connection, which can thereby couple first bearing member  26  to shell  25 . 
     With additional reference to  FIG. 13 , an alternate humeral prosthesis  20  is shown in accordance with the present teachings. Humeral prosthesis  20  can include the shell  25  having a coupling arrangement  130  configured to receive a humeral tray  134 . As will be discussed below in greater detail, the humeral tray  134  can be configured to receive the first bearing member  26 , such as bearing  26  shown in  FIG. 5 , or an alternate first bearing member  138  shown in  FIG. 13 . 
     In one exemplary configuration, humeral tray  134  can include a body  142  defining a bearing coupling side  146  and an opposite shell coupling side  150 . The body  142  can define a recess  154  for receiving the coupling side  42  of the first bearing member  26  or  138 . The bearing coupling side  146  can also define an interior coupling groove  30  configured to receive the snap-ring  61 , as shown in  FIG. 13 . The shell coupling side  150  can include a coupling member  158  in the form of a tapered male projection or locking taper  162  configured to be received in a corresponding tapered female recess or locking taper  166  defined by shell  25 . 
     The first bearing member  138  and the humeral tray  134  can be formed of a suitable metallic material, such as cobalt chromium or titanium. In this exemplary configuration, the first bearing members  26  and  138  can include a polymeric sleeve  178  such that the sleeve  178  engages the tray and snap-ring  61  as shown in  FIG. 13 . The first bearing member  138  can also be formed to include an optional extension  184  extending from a perimeter of the bearing member  138 , as also shown in  FIG. 13 . The extension  184  can extend along an outer perimeter  188  of the humeral tray  134  and can provide increased bearing coverage. It should be understood that first bearing member  138  can be formed and/or utilized with or without the sleeve  178  and extension  184 . 
     Shown throughout the figures are prostheses and components for a humeral implant kit for positioning various prostheses in a shoulder joint. The kit can include a humeral component having a shell defining a bearing accepting aperture. As discussed above, the shell can include a shell wall that extends from a distal apex portion to a proximal rim defining an internal passage or aperture operable to receive bearing components. The shell wall can include an internal shell wall surface defining the internal aperture or void and an external shell wall surface operable to engage a resected head of the humerus. Defined in the interior surface is a snap-ring mechanism, which can include a groove formed in the apical wall at a position between the internal shell wall surface and the external shell wall surface configured to receive the snap-ring. 
     As discussed above, the kit can have coupling stems of various sizes which can be formed by the shell. Additionally, as shown in  FIGS. 10-12 , the coupling stems  22  can be coupled to the shell  25  using expandable mating tapers  125 . These tapers  125  can be split in a manner which allows expansion using an interference rotatable fastener  126 , as shown in  FIGS. 10-12 . 
     The bearing components provided in the kit can include the first bearing member  26 , and the alternative first bearing member  26 ′. As discussed above, the first bearing member  26  can define a concave articulating bearing surface and having a first bearing wall extending from a first bearing distal rim. The bearing wall can define a snap-ring connection mechanism configured to be aligned to the snap-ring mechanism associated with the shell. The first bearing member  26 ′ can define a convex articulating bearing surface and a second bearing coupling mechanism extending from a second bearing distal apex. In one exemplary configuration, the first bearing member  26  can have a rigidity that is greater than a rigidity of the first bearing member  26 ′, and the bearing members  26 ,  26 ′ can be formed of different materials. A snap-ring connection mechanism can be formed adjacent the second bearing distal rim and between the convex coupling mechanism and the convex articulating bearing surface. 
     In practice, a humeral shell  25  which conforms to the resected humerus can be selected by a treating physician. The selected shell  25  can include the first stem  22  with a first connection portion at the apical location of the shell  25 , and a second connection portion positioned at a second position relative to the shell  25 . Upon a determination by the treating physician of an appropriate system, the physician can select one of the first bearing members  26 ,  26 ′. The humeral head can be resected and the selected shell  25  with the associated stem  22  can be inserted into the prepared humerus. The selected bearing can be axially inserted within the shell  25 . The selected bearing can be connected with the second connection portion of the shell discussed above. 
     According to various embodiments, various bearings depicted throughout can engage other defined connection portions simultaneously or during or after implantation. Thus, one skilled in the art will understand that while discussion herein may be focused primarily upon connecting a bearing with the connection portion that a bearing can also be connected at various times of the procedure. The multiple connections can be provided for various reasons, such as securing the bearing at more than one location, guiding the bearing into an implantation position, reduction in manufacturing processes, etc. 
     These teachings are merely exemplary in nature, thus, variations that do not depart from the gist thereof are intended to be within the scope of the teachings. Such variations are not to be regarded as a departure from the spirit and scope of these teachings.