Abstract:
An implant assembly for re-establishing a glenohumeral joint between scapula and humerus bones. A substantially spherical shaped element is adapted to being mounted a reconditioned glenoid cavity defined in the scapula and exhibits a second convex exterior surface projecting from the bone surface. A receiver component has a base with a first convex bone contacting surface adapted to being mounted to a reconditioned humeral head associated with the humerus, the receiver component exhibiting a second convex exterior surface projecting away from the bone surface and exposing a concave profile exhibiting only a rim edge therebetween at an outer exposed seating end of said second convex surface for supporting the components in inter-articulating fashion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application is a Division of application Ser. No. 13/592,738 filed on Aug. 23, 2012. Application Ser. No. 13/592,738 claims the benefit of U.S. Provisional Application 61/526,388 filed on Aug. 23, 2011. Application 13/592,738 claims the benefit of U.S. Provisional Application 61/526,404 filed on Aug. 23, 2011, the contents of which are incorporated herein in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to a shoulder implant assembly and, more specifically, to a multi-component implant assembly incorporating a ball and a receiver mounted to first and second shoulder joint defining bones. An optional third substantially spherical shaped and intermediate defining component establishes dual and spaced apart universal and articulating surfaces with the fixedly mounted ball and receiver providing evenly distributed wear profiles for increased useful life of the implant, as well as relieving associated ligament tension. 
       BACKGROUND OF THE INVENTION 
       [0003]    The prior art discloses various types of artificial implants, such as replacing damaged natural joint constructions including those for the shoulder. Examples of these include each of the modular humeral head resurfacing system of Winslow et al., U.S. 2006/0009852 and U.S. 2005/0107882, each of which incorporates a two piece humeral component for use in joint arthroplasty which is adapted to be implanted into a joint and engaged by a likewise implanted socket component. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention discloses an implant assembly for re-establishing a glenohumeral joint between a scapular and humerus. The implant includes a ball adapted to being mounted to a reconditioned glenoid cavity defined in the scapula. A receiver is adapted to being mounted to a reconditioned humeral head associated with the humerus. 
         [0005]    The substantially spherical shaped element is interposed between the ball and receiver and establishes first and second articulating surfaces. A concave recess is defined in an exposed face of the ball for seating in articulating fashion a portion of the spherical element. 
         [0006]    A concave recess is defined in the spherical shaped element for seating in articulating fashion an exposed portion of the scapula mounted ball. Each of the ball, spherical element and receiver is constructed of an alternating material including at least one of a polymer, polymer composite, metal, metal composite or polymer/metal admixture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Reference will now be made to the attached drawings, when read in combination with the following detailed description, wherein like reference numerals refer to like parts throughout the several views, and in which: 
           [0008]      FIG. 1  is an assembled view of a yet further mortified shoulder implant assembly exhibiting only first and second scapula and humerus mounted components and eliminating the inter-disposed and supported spheroid shaped component; and 
           [0009]      FIG. 2  is an exploded view of the arrangement of  FIG. 1  and better depicting the inner concavity profile defined in the humerus mounting receiver and for seating the ball mounted in the scapula; and 
           [0010]      FIGS. 3-5  depict a series of supporting Prior Art illustrations of a human anatomical shoulder joint, and for which the multi-component assembly provides an in situ and reconditioned implantation option. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]    As will be described in additional detail with reference to the succeeding variants, the present invention discloses a multi-component shoulder implant assembly for providing an in-situ and reconditioned installation option which is an improvement over other conventional joint implant installations. 
         [0012]    Prior to describing in detail the configuration of the multi-component shoulder implant depicted in  FIGS. 1-2 , a Prior Art depiction of an anatomically correct human shoulder is shown in  FIGS. 3-5  and which includes three bones consisting of the clavicle (collarbone)  1 , the scapula (shoulder blade)  2 , and the humerus (upper arm bone)  3 , as well as associated muscles, ligaments and tendons (see in particular  FIGS. 4 and 5 ). The articulations between the bones of the shoulder collectively make up the shoulder joints where the humerus  3  attaches to the scapula  2 . 
         [0013]    An abbreviated and incomplete description of the scapula further includes, at strategic locations a coracoid process  4  and spine connected acromion  5 , in the proximity of which is configured the glenoid cavity  6 . The humerus  3  terminates, in relevant part, at an upper end located humeral head  7  ( FIG. 4 ) which generally seats via an interposed bursa  8  ( FIG. 3 ). 
         [0014]    The three joints of the shoulder further include each of the glenohumeral, acromioclavicular and sternoclavicular joints. The glenohumeral joint, see as identified at  9  in  FIG. 5 , is the main joint of the shoulder and the generic term “shoulder joint” usually refers to this ball and socket joint that allows the arm to rotate in a circular fashion or to hinge out and up away from the body. 
         [0015]    As is best depicted in the prior art view of  FIG. 4 , associated types of joint cartilage include articular cartilage located on the ends of the bones and which allows the bones to glide and move on each other and labrum cartilage located in the shoulder. In combination, the shoulder as constructed exhibits sufficient mobile for undertaking a wide range of actions of the arms and hands as well as being sufficiently stable as to allow for actions such as lifting, pushing and pulling. This compromise between mobility and stability results in a large number of shoulder problems not faced by other joints such as the hip. 
         [0016]    With reference now to the embodiments of the invention set forth in  FIGS. 1-2 , and for purposes of ease and clarity of illustration, a simplified depiction is shown of the glenohumeral joint established between the scapula  2  and humerus  3  and in which all ligaments, muscles and tendons are removed. In each instance, and prior to installation of the multi-component implant assembly (such as occurring after significant degradation of the natural glenohumeral joint or in other instances in which an accident or other traumatic incident has resulted in significant damage), an initial (in situ) surgical reconditioning procedure is employed of the opposing joint defining surfaces established by the humeral head  7  and the glenoid cavity  6 . This includes employing relevant surgical drilling and shaping instruments (also not shown) in order to prepare the joint defining locations of the bones for subsequently attaching selected components associated with the implant assembly and as will now be described. 
         [0017]    The above stated, and referring initially to each of  FIGS. 1 and 2 , a pair of assembled and exploded views, both generally at  10 , are depicted of a shoulder implant assembly for installation within reconditioned and opposing end locations of the patient&#39;s scapula  2  (represented by reconditioned profile  12 ) and humerus (further represented by reconditioned profile  14 ), and as is best shown in the exploded view of  FIG. 2 . The implant assembly  10  includes, collectively, a stem supported and substantially semi-spherical component, also termed a ball element having a main convex surface  16  defining an annular perimeter with a reverse convex bone contacting surface  17  which is mounted within the reconditioned recess  12  of the scapula glenoid cavity. 
         [0018]    A further receiver component includes a convex bone contacting surface (see at  18 ), a stem mounting portion  20  projecting from a lower end location of the bone contacting surface  18 . The receiver component exhibits a substantially spherical shape with a main convex surface (see at  21  and which likewise defines an annular or perimeter boundary with the convex bone contacting surface  18 ). 
         [0019]    A reduced dimension concave profile  22  is configured at an outer exposed seating end of the main convex surface  21  of the receiver component, the concave profile  22  exhibiting only a rim edge therebetween at an outer exposed seating end of the main convex surface  21  and is sized for seating directly the convex profile of the pseudo spherical ball element  16  (see again  FIG. 2 ) in order to define an articulating relationship between the components  16  and  18 . As further shown in  FIG. 2 , an axis  24  extending through a center location of the stem mounting portion  20  extends at a non collinear angle relative to a further axis  26  extending through the receiver component at a midpoint location of the concave profile  22  (such as in particular depicted as a substantially right angle). 
         [0020]    The ball element  16  and receiver component  18  are each constructed of any suitable material including any type of plastic, metal or admixed composite. While not limited to any specific variant, the material selection for these components can alternate between any suitable material (e.g. heavy duty, wear resistant and sanitary polymeric, polymeric composite, surgical steel/aluminum, other metal or metal composite, as well as plastic/metal admixture. 
         [0021]    The exploded view of  FIG. 2  better depicts the configuration of the ball element  16 , such as exhibiting an outwardly semi-spherical or convex exhibiting end face on a surface thereof, and with a reverse extending stem  28  which seats within a hidden recess configuration (not shown) established within the reconditioned innermost profile  12  of the scapula glenoid cavity, the stem portion  20  of the receiver component  18  seating within a like configured inner most recess configuration established within the corresponding humeral head reconditioned profile  14 . In a typical surgical procedure, a medical bonding cement or other suitable fastener/adhesive (not shown) is employed for anchoring the ball element  16  and receiver component  18  to the respective bone  2  and  3  ends, it being further understood that the configuration of these elements is capable of being reversed (e.g. the ball element  16  mounting to the humeral head and the receiver component  18  to the scapula glenoid cavity). 
         [0022]    Referring again to the existing arrangement of ligaments, tendons and muscles depicted in the Prior Art views of  FIGS. 3-5 , these provide the anchoring/seating support for retaining the articulating relationships established between the ball element  16  and receiver component  18 , it further being understood that the components are capable of being retrofit installed within the reconditioned bone ends of the patient without the necessity of the ligaments and tendons being severed of otherwise impacted, thereby enhancing the universal motion profile afforded by the design and likewise reducing recovery time for the patient. As previously described, the ability to segment the articulating motion of the gleno-humeral joint into a pair of spaced articulating surfaces serves to both enhance artificial joint mobility as well as to more evenly distribute an associated wear profile of the joint, thereby increasing expected life of the assembly. 
         [0023]    Having now described our invention, other and additional preferred embodiments will become evident to those skilled in the art to which it pertains, and without deviating from the scope of the appended claims.