Abstract:
A glenoid component used for shoulder arthroplasty is adapted to be implanted into a scapula and engaged by a head of a humeral component. The glenoid component includes a body having a first articulating surface and a second medial surface opposite to the first articulating surface. The first articulating surface is adapted to engage with a humeral head. A plurality of fixed pegs each have a first end adapted to engage a cavity formed in the scapula and a second end extending from the medial surface. A central peg fixation mechanism is provided that is configured to couple an optional central fixation peg to the medial surface.

Description:
FIELD 
       [0001]    The present disclosure relates to a prosthetic device and, more particularly, to a modular glenoid prosthetic. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. A natural shoulder joint may undergo degenerative changes due to a variety of etiologies. When these degenerative changes become so far advanced and irreversible, it may ultimately become necessary to replace a natural shoulder joint with a prosthetic shoulder joint. When implantation of such a shoulder joint prosthesis becomes necessary, the natural head portion of the humerus can be resected and a cavity is created in the intramedullary canal of the host humerus for accepting a humeral component. The humeral component includes a head portion used to replace the natural head of the humerus. Once the humeral component has been implanted, the glenoid cavity positioned at the lateral edge of the scapula may also be resurfaced and shaped to accept a glenoid component. The glenoid component generally includes an articulating surface which is engaged by the head portion of the humeral component. 
         [0003]    It is generally known in the art to provide a shoulder joint prosthesis having a glenoid component, as discussed above. However, the current prior art glenoid components along with the associated surgical components and instruments utilized during shoulder arthroplasty suffer from many disadvantages. 
         [0004]    For example, since the glenoid component is subject to various types of loading by the head portion of the humeral component, the glenoid component must offer a stable and secure articulating surface. To achieve this, some glenoid components provide pegs that are inserted and cemented into holes bored into the glenoid cavity. However, such existing pegged glenoid components also exhibit several disadvantages. For example, some of the pegged glenoid components utilize up to five pegs to stabilize and secure the glenoid component to the scapula. Such glenoid components increase the amount of bone tissue removed, while also increasing the labor and complexity of the shoulder arthroplasty. Other pegged glenoid components may offer one or two larger diameter pegs that reduce the complexity of the shoulder arthroplasty. However, the larger diameter pegs also requires excess bone tissue to be removed that may not be practical in some patients. Furthermore, the use of one or two pegs may potentially reduce overall stability of the glenoid component, similar to a keeled glenoid. 
         [0005]    Additionally, most prior art glenoid components only rely on the keel or pegs to secure the glenoid component to the scapula, via a cement mantle. These systems are typically rigid in fixation methods. In this regard, the prior art systems fail to provide a selection of coupling mechanisms which may best be used to address varying degenerative changes or specific muscular needs of a patient. 
         [0006]    What is needed then is a glenoid component and associated surgical components for use in shoulder arthroplasty that does not suffer from the above-mentioned disadvantages. This in turn, will provide a glenoid component which is stable and secure, reduces the overall amount of bone tissue required to be removed, reduces inventory, reduces the overall surgical time and complexity, increases overall medial surface area, enhances and increases attachment strength and adaptivity without increasing overall peg diameter, provides a fully enhanced coupling mechanism and increased overall stability, and provides increased tensile and shear strength. It is, therefore, an object of the present invention to provide such a glenoid component and associated surgical components for use in shoulder arthroplasty. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the teachings of the present invention, an apparatus and method for shoulder arthroplasty is disclosed. The apparatus and method employs a glenoid component and other associated surgical components for use in the shoulder arthroplasty. In this regard, the glenoid component is adapted to be implanted into a scapula at the glenoid fossa or cavity and engaged by a head portion of a humeral component. 
         [0008]    In one embodiment, a glenoid component is used for shoulder arthroplasty such that the glenoid component is adapted to be implanted into a scapula and engaged by a head of a humeral component. The glenoid component includes a body having a first articulating surface and a second medial surface opposite to the first articulating surface. The first articulating surface is adapted to be engaged by the head of the humeral component and the second medial surface is adapted to be secured to the scapula. A plurality of fixed pegs are provided, each having a first end adapted to engage a cavity formed in the scapula and a second end extending from the medial surface. A central peg fixation mechanism is provided that is configured to couple a central fixation peg to the medial surface. 
         [0009]    In another embodiment, a system for use during shoulder arthroplasty is provided. The system has a glenoid component adapted to be implanted into a scapula and engaged by a head of a humeral component. The glenoid component includes, a body having a first spherical articulating surface and a second medial surface. The first spherical articulating surface is adapted to permit rotational movement of the head of the humeral component. A plurality of fixed coupling pegs are provided having a first end adapted to engage a cavity formed in the scapula. The medial portion has a central stem fixation mechanism, and a depending central stem. 
         [0010]    In another embodiment, a method for implanting a medical device is disclosed. A glenoid prosthetic having a plurality of fixed pegs and a center fixation peg coupling mechanism is provided. The method includes machining a scapula to form a resected glenoid. A plurality of fixed peg accepting holes are machined in the resected glenoid. Further, the scapula is machined to form a center fixation peg coupling member accepting aperture. The physician will then determine if a center fixation peg is needed. If a center peg is required, a center peg is coupled to a glenoid prosthetic. A central peg accepting aperture is optionally machined into the resected glenoid. The prosthetic is then coupled to the resected glenoid either with or without the attached central stem. 
         [0011]    Use of the present invention provides an apparatus and method for shoulder arthroplasty, and specifically, a glenoid component and associated surgical components for use in shoulder arthroplasty. As a result, the aforementioned disadvantages associated with the currently available glenoid components and associated surgical components for shoulder arthroplasty have been substantially reduced or eliminated. 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. 
     
    
     
       DRAWINGS 
         [0012]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0013]      FIG. 1  represents an exploded view of a modular glenoid according to the present teachings of the present disclosure; 
           [0014]      FIG. 2  represents a second glenoid according to the present teachings; 
           [0015]      FIGS. 3A and 3B  represent perspective and side views of the glenoid according to  FIG. 1 ; 
           [0016]      FIGS. 4A and 4B  represent perspective and side views of the glenoid according to  FIG. 2 ; 
           [0017]      FIGS. 5A and 5B  represent alternate perspective and cross-sectional views according to the present teachings; 
           [0018]      FIGS. 6A-6E  represent perspective views of various stems usable in the glenoids shown in  FIGS. 1-4B ; 
           [0019]      FIGS. 7A-7C  represent various drive mechanisms; 
           [0020]      FIGS. 8A-8E  represent cross-sectional views of the stems shown in  FIGS. 6A-6E ; 
           [0021]      FIGS. 9-12  represent perspective views of the preparation of the glenoid to accept the prosthetic shown in  FIGS. 1-8E ; 
           [0022]      FIG. 13  represents the implantation of the glenoid shown in  FIG. 1 ; 
           [0023]      FIG. 14  represents a side cross-sectional view of a glenoid according to the present teachings implanted into a resected glenoid; and 
           [0024]      FIG. 15  represents a system of modular glenoid components according to the present teachings. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0026]    Referring generally to  FIGS. 1 and 2  which represent perspective views of the modular glenoid component according to the teachings of the present application. Shown is a glenoid prosthetic  20 . The glenoid prosthetic  20  has a first side  22  having a generally spherical articulating surface  24  and a second coupling side  26 . The spherical articulating surface  24  is adapted to permit rotational and translational movement of the head of the humeral component (not shown) or natural humerus. The coupling side  26  can include one or more fixed coupling stems  28  that are configured to couple the glenoid to a plurality of apertures defined within a resected glenoid. 
         [0027]    The coupling stems  28  can be configured to include a first superior fixed peg  28  and a pair of second inferior fixed pegs  28 , each fixed peg  28  positioned on the coupling side  26  to form the corners of a triangle and, preferably, an isosceles triangle. The coupling stems  28  can take on various forms. In this regard, the fixed stems  28  can have a relatively smooth profile which define annular and/or longitudinal grooves  33 . As described below, the grooves  33  can be configured to accept bone cement to fixably couple the peg to apertures  35  defined within a resected glenoid  37 . As shown in  FIG. 2 , the fixed glenoid stems  28  can have a plurality of aperture engaging flanges  31 . Defined on the flanges  31  can be a plurality of grooves  39 . These grooves  39  can be co-axial with grooves  33  defined by the stem  28 . 
         [0028]    As best seen in  FIGS. 3A-3B , the coupling side  26  of the glenoid  20  also defines a central stem coupling mechanism  34 . The coupling mechanism  34  is configured to removably and selectively couple a central fixation peg  48  to the coupling side  26 . This mechanism can define male or female threaded portions which interface with the central stem  48 . As shown, the coupling mechanism  34  can define a threaded coupling aperture  36  within a generally cylindrical body  38 . As shown in  FIGS. 4A-5B , this cylinder can have a flat or curved exterior surface. In this regard, it is envisioned the exterior surface can be tapered to transition into the coupling side  26 . Disposed within the body  38  can be an internally threaded bushing  40 . Defined on an exterior surface of the bushing  40  are optional coupling flanges  42  that are configured to couple the bushing  40  to the cylindrical body  38 . This bushing can be coupled to the glenoid during a molding process, or the bushing can be press-fit into the coupling side  26 . 
         [0029]      FIGS. 6A-6E  represent perspective and side views of the optional central coupling stems  48 . Each of the central coupling stems  48  can have a threaded coupling member  50  which is configured to fixably interface the stem  48  with the threaded aperture  36  of the central coupling mechanism  34 . The stems  48  further have a bearing surface or shoulder  51  configured to interface with a bearing surface or base  53  on the central coupling mechanism  34 . Optionally, the stems  48  can have a textured coupling surface. 
         [0030]      FIG. 6A  represents a center peg  48  having a generally cylindrical fixation peg with an exterior powder metal coating.  FIGS. 6B-6D  represent central pegs having at least one aperture engaging flange. These flanges can either be used to interface with the interior of an aperture formed in the scapula or can be used to retain bone cement in the aperture.  FIG. 6E  represents a porous central peg having a stepped exterior surface. The stepped exterior surface has varying diameter portions. 
         [0031]    As shown, the central stem  48  can have various surface treatments. It is envisioned the stem can be formed of a biocompatible polymer, metallic or ceramic. Additionally, the central pegs can have surface treatment such as powder metal spray coating or other porous structures to facilitate the ingrowth of bone. As shown in  FIGS. 7A-7C , optionally, the stems  48  can have drive surfaces  57  defined on a surface of the stem  48 . These drive surfaces  57  can be a multi-faceted extension or a multi-faceted surface defined within a bore in the stem  48 . 
         [0032]    Shown in  FIGS. 8A-8E , the stem can have various cross-sections. In this regard, the diameters of the stems can vary along the length of the stems  48 . As shown in  FIGS. 6B-6D , the stems  48  can have various coupling flanges  55  incorporated thereon. These coupling flanges  55  can be configured to have an exterior diameter which is less than, equal to, or greater than the corresponding diameter of a portion of an aperture disposed in the resected glenoid  37 . Each of the stems  48  is configured to interface with a bearing surface on the central coupling mechanism  34 . 
         [0033]      FIGS. 9-13  represent the preparation and insertion of the glenoid  20  according to the teachings herein. As shown in  FIG. 9 , a second drilling guide  64  can be used to position a central pilot hole  67  into the surface  62 . After the preparation of a central guide hole  67 , as shown in  FIG. 10 , the surface of the glenoid  62  is prepared using a rotating rasp or file  52 . The scapula is then machined to form the resected glenoid  37 . Shown is a rotating rasp  52  used to prepare a planar or curved glenoid surface to mate with the coupling side of the prosthetic  20 . 
         [0034]    After the resection, a plurality of fixed peg accepting holes  59  are machined into the resected glenoid  37 .  FIG. 11  represents the use of a drilling guide  56  for the placement of holes within the resected glenoid  37 . In this regard, it is envisioned that the drilling guide  56  be used to position the apertures for the acceptance of the fixed stems  28 . As shown in  FIG. 12 , immediately about a central pilot hole, a surface  66  is prepared which is configured to accept the stem coupling mechanism  34 . The center stem accepting aperture can be formed either prior to or after the preparation of the surface  66  to accept the stem coupling mechanism  34 . At this point, the physician can determine if a central fixation peg  48  is needed. If the central peg  48  is needed, the physician will further determine a preferred central peg fixation surface and a preferred central peg fixation size. The appropriate peg  48  is then chosen and theadably coupled to the glenoid  20  so as to cause engagement of the stem bearing surface  51  with the bearing surface  53  on the central coupling mechanism  34 . 
         [0035]    As shown in  FIG. 13 , it is envisioned that bone cement or biological materials can be injected into the apertures defined within the resected glenoid  37 . These materials can be inserted into the holes configured to accept the fixed pegs or the central stem  48 . It is equally envisioned that the central stem  48  can be inserted into the aperture so as to form an interference fit between the central stem  48  and the aperture. With the appropriate coupling stem  48  fixed to the bushing within the coupling mechanism  34 , proper coupling of the glenoid  20  can occur. In this regard, the central stem  48  is threadably coupled to an aperture within the central stem coupling mechanism  34 . The fixed and central stems are positioned within the apertures to couple the glenoid member  20  to the resected glenoid  37 . 
         [0036]      FIG. 14  represents a cross-sectional view of an implanted glenoid  20 . Shown is the relationship between the articulating surface  24 , fixed stems  28 , and the central stem  48 . Optionally, the coupling side  26  can be bonded to the resected glenoid using bone cement and further can have surface treatments to facilitate bonding. Further shown is the central stem  48  in relation to the threaded aperture  36  of the central stem coupling mechanism  34 . 
         [0037]      FIG. 15  represents a system of prosthetic components as described above. Shown are various glenoid prosthetics  20  as well as various size and shaped central stem portions  48 . These stems  48  have various exterior surface treatments and configurations as well as varying lengths and diameters. It is envisioned that the system also includes the appropriate types of bone fixation cement, cutting members, cutting pattern guides, as well as humeral head and fixation stem prosthetics.