Abstract:
A multi-piece prosthetic component for use in joint arthroplasty which is adapted to be implanted into a joint and engaged by a joint socket. The modular prosthetic component includes body which is at least partially implantable within a bone, said body having an external surface. A mechanism for coupling soft tissue to the exterior surface of the implant is provided. The mechanism has an attachment mechanism which is operable to prevent movement of the soft tissue attachment mechanism with respect to the body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a method and apparatus for use in orthopedic surgery and, more particularly, to a method and apparatus for providing a prosthesis having a modular soft tissue coupling mechanism. The soft tissue coupling mechanism is a member configured to be optionally coupled to the implant and has a fixation flange capable of being coupled to soft tissues. 
     2. Discussion of the Related Art 
     It is generally known in the art to provide prostheses that replace or reinforce various portions of bone during an orthopedic surgical procedure. However, the current prior art prostheses along with the associated surgical components and instruments utilized during orthopedic surgery suffer from many disadvantages. 
     For example, because the extent of degradation is not always evident until during the surgery; extensive bone resection may be necessary. Additionally, etiologies such as bone tumors or those requiring revision of an implanted joint require significant bone removal which may remove soft tissue fixation sites. In these cases, soft tissue fixation to the prosthesis may or may not be necessary. To provide for soft tissue attachment, some replacement joint components provide an integral flange configured to accept soft tissue attached to a lateral surface of the prosthetic replacement joint head. These fixed fixation flanges, however, may not provide the proper locational adaptivity needed during the orthopedic surgical procedure and leave the surgeon with little or no options as to soft tissue attachment. 
     What is needed then is a prosthesis and associated surgical components for use in orthopedic surgery which does not suffer from the above-mentioned disadvantages. This in turn, will provide a prosthesis which is stable and secure and increases the overall flexibility for a surgeon to fix soft tissues. It is, therefore, an object of the present invention to provide such a prosthesis and associated surgical components for use in orthopedic surgery. 
     SUMMARY OF THE INVENTION 
     In accordance with the teachings of the present invention, an apparatus and method for providing a prosthetic having a modular soft tissue attachment mechanism is disclosed. The apparatus and method employs a modular soft tissue attachment mechanism for use during the orthopedic surgical procedure. 
     In one embodiment, an orthopedic implant has a body that is at least partially implantable within a bone. A mechanism for coupling soft tissue to the body is provided. The mechanism for coupling soft tissue to the body has an attachment mechanism operable to prevent movement of the coupling mechanism with respect to the body. 
     In another embodiment, a humeral prosthetic having an articulating head is presented. The humeral prosthetic has a base member defining a fixation surface which is coupled to the head. A soft tissue fixation member has a coupling mechanism, which functions to couple the soft tissue fixation member to the fixation surface. A locking mechanism is provided which prevents movement of the soft tissue fixation mechanism with respect to the base member. 
     In another embodiment, a modular replacement joint component is used for joint arthroplasty such that a replacement joint component is adapted to be implanted into a bone and engaged by a socket portion of the replacement joint component. The replacement joint component includes a head member having a first articulating surface and a second medial surface, which is opposite to the first articulating surface. The first articulating surface is adapted to engage the articulating surface of the a socket portion and the second medial surface is adapted to engage a second fixation component. The fixation component has a first surface adapted to be secured to the lateral surface of the head member and a second surface. The base member extends from the second medial surface such that the base member provides a fixation surface. A soft tissue fixation member, is coupled to the base member. The soft tissue fixation member has an exterior flange having a soft tissue coupling member. 
     A method for implanting an orthopedic devise is further disclosed. The method includes selecting an appropriately sized implant. Next, a determination is made if soft tissue fixation to the implant is necessary. Should it be necessary to couple soft tissue to the implant, a soft tissue fixation mechanism is attached to the implant. The implant is subsequently implanted. 
     Use of the present invention provides an apparatus and method for providing a prosthetic having a modular soft tissue attachment mechanism for use during an orthopedic surgical procedure. As a result, the aforementioned disadvantages associated with the currently available prostheses and associated surgical components have been substantially reduced or eliminated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Still other advantages of the present invention will become apparent to those skilled in the art after reading the following specification and by reference to the drawings in which: 
         FIG. 1  is an exploded view of the prosthetic component according to the teachings of the preferred embodiment; 
         FIGS. 2   a – 2   b  are views of a bone fixation member of humeral component of  FIG. 1 ; 
         FIG. 3  represents a base member according to the teachings of the present invention; 
         FIGS. 4–8  are alternate embodiments for a soft tissue fixation member of the humeral component of the present invention; 
         FIG. 9  represents the prosthetic according to the present invention implanted within a skeletal structure; 
         FIG. 10  represents an alternate embodiment of the present invention; 
         FIG. 11  represents an alternate base member according to the teaching of the present invention; 
         FIG. 12  represents an alternate soft tissue fixation member according to the teaching of the present invention; 
         FIGS. 13   a – 13   b  represent the interaction of the soft tissue fixation member of  FIG. 12  with the base according to  FIG. 11 ; 
         FIGS. 14 and 15  represent the application of the present invention to a femoral implant; and 
         FIG. 16  represents cross-sectional views of implanted humeral components of the present invention and its fixation to soft tissue. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments concerning an apparatus and method for providing a prosthesis having a modular soft tissue attachment mechanism is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Moreover, while the present invention is discussed in detail in relation to a shoulder joint and a hip joint replacement, the present invention is not limited to only these procedures. For example, any type of orthopedic surgical procedure that replaces or reinforces bone may employ the present invention. 
       FIG. 1  depicts components used in a shoulder arthroplasty of the current invention. As shown, a modular humeral component  31  has a base member  32  and a head member  33 . The base member  32  is configured to be coupled to a fixation stem  34  which is used to attach the humeral component  31  to a resected bone  36  of the humerus  38  by way of a Morse type taper  39  or any other attachment mechanism (see  FIG. 9 ). If a total shoulder arthroplasty is performed, a glenoid component  40 , shown in  FIG. 9 , is first implanted into the scapula  42  using techniques well known in the art. The glenoid component  40  is preferably of the type disclosed in U.S. Pat. No. 5,800,551, which is hereby incorporated by reference, or any other suitable conventional glenoid component. The humeral component  31  is designed to allow rotational and transitional movement of the head member  33  with respect to the glenoid component  40 . 
       FIG. 1 , shows a humeral head  33  which mates through a humeral body component  35  to the base member  32  by way of a Morse type taper  39  or any other appropriate attachment mechanism. It should be noted that a surgical kit of the components would contain numerous head members  33 , each having a varied radius of curvature, diameter, and height to allow a surgeon to optimize joint movement. Additionally, a surgical kit would contain the instruments needed for implantation (described later). 
       FIGS. 2   a  and  2   b  depict fixation stems  34  according to the teachings of the present invention.  FIG. 2   a  discloses a conventional fixation stem which will be mounted to the base member  32  via a Morse type taper  39 . The Morse type taper  39  is disposed upon a shelf member  40  which functions as an interface surface to a resected bone (as described below). Alternatively, as depicted in  FIG. 2   b , the fixation stem  34  can be integral to the base member  32 . Particularly, the stem  34  is disposed perpendicularly to the surface  50  of the base member  32 . In this configuration, however, the surface  50  must be configured so as to allow the interior bore  56  of the soft tissue fixation mechanism  53  to be disposed about the base member  32 . 
       FIG. 3  depicts the base member  32  of one embodiment of the current invention. The base member  32  is defined by a shelf member  44 , which may function as an impaction surface. The shelf member  44  can have at least one mating member  48  for engaging the humeral body component  31 . It is preferred that the mating member  48  be a defined Morse type taper  39  or other suitable attaching mechanism. In addition to the mating member  48 , each base member  32  has or is coupled to a fixation stem  34  disposed on the lower lateral surface  50 . The fixation stem  34  is generally perpendicular to the lower lateral surface  50 , and can be a male or female Morse type taper. A cylindrical outer surface  46  of the base member  32  is defined between the shelf member  44  and the flat lower lateral surface  50 . Optionally, disposed about the base member  32  is soft tissue fixation mechanism  53 . Soft tissue fixation mechanism  53  is a cylindrical tube having an inner surface  54 , which defines the inner bore  56  and an exterior surface  63 . 
     The humeral body component  31 , stem  34 , base member  32 , and soft tissue fixation mechanism  53  is made of bio-compatible materials such as, without limitation, titanium, titanium alloys, surgical alloys, stainless steels, bio-compatible ceramics, and cobalt alloys. Optionally, the base member  32  can additionally be made of materials such as biocompatible ceramics and resorbable and non-resorbable polymers and other anticipated bio-compatible metallic or polymeric materials. Should the base member  32  be made of non-metallic components, a fastener may be needed to couple the body  31  to the base member  32 . Additionally, the fixation mechanism  53  can be an allograft material. 
     As best seen in  FIGS. 4–8 , the soft tissue fixation mechanisms  53   a–e  are configured to be annularly disposed about the cylindrical outer surface  46  of the base member  32 . The inner surface  54  is configured to have an attachment mechanism  55  disposed thereon. Optionally, this attachment mechanism  55  can take the form of a 6° included Morse type taper which couples to a Morse type taper  57  defined on the cylindrical outer surface  46  of the base member. The exterior surface  63  of the soft tissue fixation mechanism  53   a–f  define soft tissue fixation members  58 . As best seen in  FIG. 4 , the soft tissue fixation members  58  can take the form of a longitudinal flange  60 . The longitudinal flange  60  defines through suture bores  62  which function as sites for coupling soft tissue to the prosthetic. Alternately, the soft tissue fixation members  58  can take the form of multi-directional flanges  64  or as an attachable suture anchor attachment site. The use of a Morse type taper  55  to couple the soft tissue fixation member  58  to the base member  32  allows a physician to rotate at any desired location the location of the fixation flanges. 
       FIGS. 4–8  depict alternate embodiments of soft tissue fixation mechanism  53   a – 53   e . In this embodiment, the soft tissue fixation mechanisms  53   a – 53   e  are cylindrical members which define an interior bore  56 . The interior bore  56  defines an attachment mechanism  58 . Additionally, depending on the length of the soft tissue fixation mechanism  53   a–e , a through suture bore  62  can be defined. The attachment mechanism  55  is a female portion of a 6° Morse type taper. The 6° included Morse type taper couples to the 6° included Morse type taper defined on the exterior surface of base  32 . As can be seen in  FIGS. 4 ,  5 ,  6 , and  8 , the soft tissue fixation mechanism  53  has an exterior surface  63  which defines at least one soft tissue coupling flange  60 . This flange  60  is generally coaxial with the body of the implant and is generally parallel to the implant centerline. 
     As can be seen in  FIGS. 7 and 4 , the flange  64  can also be configured so as to define a plane perpendicular to the centerline of the base member  32 . Each flange  64  defines at least one through suture bore  62  or slot which is used to couple the soft tissue to the soft tissue fixation mechanism  53   a –e. It should be noted that each soft tissue fixation mechanism  53   a – 53   e  can have a plurality of flanges  64  and  60 . While through suture bores  62  are shown for use to couple the soft tissue, those skilled in the art will recognize other structures such as keyed slots and channels and angled flange members can be used to accept sutures and suture anchors. Additionally, wires, aortic graft, and tape can be used to fix the soft tissue. 
       FIG. 9  discloses the orthopedic implant  31  shown in  FIG. 1  disposed within a patient. Shown is the bone fixation stem  34  disposed within the medullary canal of the resected bone  36 . The stem  34  is coupled to the base member  32  via a Morse type taper  39 . Disposed about the base member  32  is the soft tissue fixation mechanism  53   a . As can be seen, the mounting flange  60  can be rotated about the base member  32  to fix extensor and abductor soft tissue to the prosthetic  31 . In situations where the flexor abductor must be fixed to the prosthetic, a soft tissue attachment mechanism such as the one shown in  FIG. 4  can be used. 
       FIG. 10  discloses an alternate view of the present invention. Shown is a soft tissue fixation mechanism  53   f  disposed between a humeral head  33  and a humeral head base  35 . As with the soft tissue fixation members depicted in  FIGS. 4–8 , it is envisioned that the soft tissue fixation mechanism  53   f  can have either longitudinal or transverse mounting flanges. 
     As shown in  FIGS. 11–15 , the attachment mechanism  55  need not be a Morse type taper.  FIGS. 13   a  and  13   b  show the attachment mechanism  55  being tapered key slots  66  which couple to a locking flange  68  disposed on the base member  32 . It is envisioned that as few as one and as many as sixteen tapered key slots  66  can be disposed on the inner surface  54  of the soft tissue fixation member  53 . Base members, as disclosed in  FIG. 11 , would be used in situations where maximum rotational torque may be applied by the soft tissue to the prosthetic. In this regard, while a Morse type taper fixation is usable in a humeral prosthetic, a key/slot configuration may be necessary for a higher rotational stability. 
       FIG. 11  defines base members  32  having the shelf member  44  and a cylindrical outer surface  46 . Additionally shown is a channeled outer surface  68  for mating the base member  32  to the soft tissue fixation members  58 . The base members  32  and soft tissue fixation members  58  are depicted in  FIGS. 13   a  and  13   b  and are shown mated. As can be seen, locking flange  68  is disposed on the inner surface  54  of the soft tissue fixation member  58 . This locking flange  68  is coupled to a channel formed on the exterior surface of the base  32 .  FIG. 13   b  shows the rotation of the soft tissue fixation members  58  about the base member  32 , which allows the physician to regulate or adjust the location of the optional fixation flange. 
     The method for implanting the humeral component  30 , along with associate surgical components utilized will now be described with reference to  FIG. 16 . The head of the humerus  38  is resected using a saw, then planed flat. With the resected bone  36  of the humerus  38  exposed, an appropriately sized implant is chosen for insertion into the medullary canal of the humerus. 
     Once the proper sized implant is chosen, the resected bone  36  of humerus  38  is optionally reamed using a reamer shaft with the driver. Upon rotating the surface of the reamer, the resected bone  36  of the humerus  38  is prepared to mate or conform with the shape of the fixation stem  34  of the base member  32 . 
     Once the inside surface of the resected bone  36  of the humerus  38  has been prepared, the stem  34  can be inserted into the medullary canal. Prior to insertion, a decision is made whether soft tissue fixation to the implant is necessary. Should it be necessary, a soft tissue fixation mechanism  53  is disposed about the base member  32 . The soft tissue fixation mechanism  53  is rotated into position and fixed to the base member  32  in its proper orientation. It is envisioned that fixation stem  34  of the base member  32  can be forced into the medullary canal to displace the bone material. Optionally, the medullary canal can also be reamed to a larger interior diameter to accept the stem  34  without displacement of the bone material. 
     The modular nature of the humeral component  30  of the present invention allow a set of various types of both replacement base members  32 , humeral body components  31 , and stems  34  to be formed. In using such a set, a surgeon can interoperatively choose the appropriate base member depending on the patient&#39;s particular condition. Additionally, the surgeon can then choose from a set of head members  33 , which both have the proper articulating surface radius and a proper coupling to the humeral body component  31 . 
       FIGS. 14 and 15  show the soft tissue fixation member according to the present invention used in a hip implant.  FIG. 14  depicts an exploded view of an implant having a head portion  70  with a neck  72 . Additionally, the prosthetic has base portion  74  and a femoral stem  76 . Under normal conditions, the femoral prosthetic  69  can be assembled without the use of a soft tissue fixation mechanism  53   g . Soft tissue fixation mechanism  53   g  is shown having an interior locking mechanism  78  taking the form of a tapered flange  80 . The tapered flange  80  is configured so as to be lockably positioned within a channel  82  disposed on an exterior surface  84  of the base portion  74 . As can be seen, the soft tissue fixation mechanism  53   g  is rotatable about the base portion  74 , allowing the soft tissue coupling flange  86  to be rotationally positioned in any location about the centerline of the implant. 
       FIG. 15  depicts the soft tissue fixation mechanism  53   g  according to the teachings of the present invention disposed about the hip prosthetic. In this configuration, the head  70  is disposed within the acetabulum. The neck  72  is coupled to the base portion  74  and the base portion  74  is coupled to the stem  76  using a standard locking Morse type taper  88 . 
       FIG. 16  depicts the coupling of soft tissue to varying flanges  60  and  64  of the prosthetic. Generally, the implant will be implanted into the medullary canal of the resected bone  36  prior to the coupling of the soft tissue  90  to the soft tissue fixation mechanism  53   a . As can be seen, the soft tissue  90  is coupled to the soft tissue attachment mechanism via standard sutures  92  or suture anchors, while the attachment mechanism can take the form of a threaded fastener or appropriate adhesive. 
     While the soft tissue attachment mechanism is shown throughout the application as a cylindrical tube disposed about a implant positioned within an intermedullary canal, it should be noted that the soft tissue fixation member  53  can further take the form of a plate coupled to either a cylindrical or flat baseplate member. In this regard, the soft tissue fixation mechanism  53  can take the form of a plate member capable of accepting a suture or suture anchor. Additionally, the prosthetic need not be associated with a joint, e.g. an intercalary member. 
     Additionally, the soft tissue fixation mechanism  53  can be adjustably positioned on the prosthetic in one or more fixation areas. In this regard, multiple soft tissue fixation mechanisms can be located on multiple locations of a single implant. While the soft tissue fixation mechanism  53  is shown on a modular prosthetic, those skilled in the art will recognize that only the soft tissue fixation mechanism  53  need be modular and that the soft tissue fixation mechanism  53  can be fixed to a single piece prosthetic device. 
     The description of the invention is merely exemplary embodiments in the present invention. One skilled in the art would readily recognize from such discussion and from accompanying drawings and claims that various changes, modifications, variations may be made therein without the spirit and scope of the invention. For example, while the soft tissue fixation mechanism  53  is shown being coupled to a humeral or femoral implant, the soft tissue fixation mechanism  53  can equally be applied to other joint implants such as, but not limited to, knees and elbows, and for whole bone replacement. Additionally, while the base member is shown being disposed outside of an intermedulary canal, it is possible to position at least a portion of the base member  32  within a bone structure. Further, while the fixation members are shown as transverse and longitudinal flanges, they can equally be positioned in any direction, or can take the form of a depression within the surface of the soft tissue fixation mechanism exterior.