Mobile Prosthesis for Interpositional Location Between Bone Joint Articular Surfaces and Method of Use

Abstract

A biocompatible prosthetic device comprising a thin low friction spacer for location to overlie a bone member in an interpositional location between opposed bone joint articular surfaces. The prosthesis is preferably a thin spacer with at least one low friction surface, the spacer being adapted for location about a bone member in an interpositional location between opposed bone joint articular surfaces preferably about a margin of articular cartilage of a bone member's condyle, preferably without any modification of the articular surface of the condyle. One preferred use of a prosthesis is in a human temporomandibular joint as a thin cap-like member fitted closely over the mandibular condyle to be disposed intermediate of the mandibular condyle and the mandibular fossa of the temporomandibular joint.

1 . A method of modification of an orthopaedic joint joining a first bone member to a second bone member within a mammalian body to provide a resultant modified joint including a spacer member.
 the first bone member having a contiguous outer surface which engages with a contiguous outer surface of the second bone member in normal movement of the joint,   the joint is a diarthrodial joint in which the contiguous outer surfaces comprise contiguous bony surfaces on each of the first bone member and second bone member which are each covered with articular cartilage forming the respective contiguous outer surface of the first bone member and second bone member,   the contiguous bony surfaces on each of the first and second bone members are surfaces which are in contact during normal movement of the joint,   the first bone member having an adjacent outer surface adjacent to the contiguous outer surface of the first bone member which adjacent outer surface is not normally in contact with the second bone member during movement of the joint,   the contiguous outer surface of the first bone member forms a convexly rounded outer surface over a bulbous end of the first bone member joined to the first bone member by a neck of a reduced circumference than a larger circumference of a portion of the bulbous end, the neck comprising the adjacent outer surface,   the spacer member consisting of a thin sheet member having a smooth continuous inner surface and a smooth continuous outer surface and a thickness between the inner surface and the outer surface in the range of 0.0005 inches to 0.01 inches,   the sheet member selected from a sheet of metal and a sheet member comprising a composite of plastic or polymer materials with metal providing the inner and outer surfaces as metal,   the sheet member comprising a cap-like member with an opening defined within an edge of the sheet member,   the method comprising coupling the sheet member to the first bone member with the inner surface of the sheet member to overlie the contiguous outer surface of the first bone member with the sheet member disposed in between the outer surface of the articular cartilage of the first bone member and the outer surface of the articular cartilage of the second bone member.   
     
     
         2 . A method as claim in  claim 1  wherein the method including:
 (a) passing the bulbous end of the first bone member through the opening of the cap-like member to locate the cap-like member over the bulbous end with the edge disposed circumferentially around the neck, 
 (b) securing the sheet member about the neck with a circumferential ligature which extends circumferentially around the neck about the sheet member where the sheet member extends circumferentially about the neck, 
 (c) securing a first fastener member to the neck of the first bone member, 
 (d) coupling the circumferential ligature to the first fastener member to limit relative rotation of the opening of the cap-like member about the neck, and 
 (e) reducing a circumferential extent of the opening proximate the edge about the neck and maintaining the circumferential extent of the opening reduced with a circumferential ligature. 
 
     
     
         3 . A prosthesis for use in an orthopaedic joint to join a first bone member to a second bone member within a mammalian body to provide a resultant modified joint,
 the first bone member having a contiguous outer surface which engages with a contiguous outer surface of the second bone member in normal movement of the joint,   the joint is a diarthrodial joint in which the contiguous outer surfaces comprise contiguous bony surfaces on each of the first bone member and second bone member which are each covered with articular cartilage forming the respective contiguous outer surface of the first bone member and second bone member, and the contiguous bony surfaces on each of the first and second bone members are surfaces which are in contact during normal movement of the joint, wherein:   the prosthesis comprising a spacer member consisting of a thin sheet member having an inner surface and an outer surface and a thickness between the inner surface and the outer surface not greater than 0.01 inches,   the sheet member consisting of a sheet-like substrate carrying as each of the inner surface and the outer surface a layer of metal,   the inner surface of the spacer member conforming to the shape of the outer surface of the articular cartilage of first bone member,   the sheet member adapted to be disposed in between the contiguous outer surface of the first bone member and the contiguous outer surface of the second bone member with the inner surface of the sheet member overlying the contiguous outer surface of the first bone member in engagement therewith and with the outer surface of the sheet member facing the outer surface of the articular cartilage of the second bone member in engagement therewith,   the inner surface of the sheet member having a coefficient of friction sufficiently low to facilitate relative movement of the inner surface of the sheet member and the articular cartilage forming the contiguous outer surface of the first bone member in engagement with the inner surface of the sheet member, and   the outer surface of the sheet member having a coefficient of friction sufficiently low to facilitate relative movement of the outer surface of the sheet member and the articular cartilage forming the contiguous outer surface of the second bone member in engagement with the outer surface of the sheet member,   characterized in that the contiguous outer surface of the first bone member forms a convexly rounded outer surface over a bulbous end of the first bone member joined to the first bone member by a neck of a reduced circumference smaller than a larger circumference of a portion of the bulbous end,   the sheet member comprising a cap-like portion with an opening defined by an edge of the sheet member, wherein the inner surface of the sheet member over the cap-like portion is generally concave, the outer surface of the sheet member over the cap-like portion is generally convex, and wherein the prosthesis being changeable from an opened to a closed position and wherein:   in the closed position of the prosthesis, the cap-like portion adapted to overlie the bulbous end with the opening about the neck, in which closed position the opening has a circumference which corresponds to the circumference of the neck.   
     
     
         4 . A prosthesis as claimed in  claim 3  wherein the neck of the first bone member comprising a non-contiguous surface of the first bone member adjacent the articular cartilage on of the first bone member which non-contiguous surface is not normally in contact with the second bone member during movement of the joint. 
     
     
         5 . A prosthesis as claimed in  claim 4  wherein the cap-like portion of the sheet member conforms to the shape of the outer surface of the articular cartilage of first bone member and is sized so that when coupled to the first bone member the cap-like portion permits marginal movement of the sheet member relative the outer surface of the articular cartilage of the first bone member without displacement from engagement with the outer surface of the articular cartilage of the first bone member. 
     
     
         6 . A prosthesis as claimed in  claim 3  including a circumferential ligature engaging the sheet member about the opening of the cap-like portion to reduce and maintained reduced the circumferential extent of the opening about the neck. 
     
     
         7 . A prosthesis as claimed in  claim 6  including:
 a plurality of eyelet openings through the sheet member circumferentially about the opening spaced from the edge, 
 the circumferential ligature passing through the eyelet openings circumferentially about the opening, 
 the circumferential ligature having a circumferential extent which is sufficiently large to permit passing of the bulbous end of the first bone member through the opening of the cap-like portion to locate the cap-like portion over the bulbous end with the edge disposed circumferentially around the neck, 
 the circumferential ligature has its ends secured together to maintain the opening in the circumference of the closed position of the prosthesis. 
 
     
     
         8 . A prosthesis as claimed in  claim 7  wherein the circumferential ligature is selected from the group consisting of an elongate string member, an elongate strap member and an elongate wire member. 
     
     
         9 . A prosthesis as claimed in  claim 3  wherein the sheet member selected from the group consisting of: a sheet of metal and a sheet member comprising a composite of plastic or polymer materials with metal providing the inner surface and the outer surface as metal, and a sheet of metal. 
     
     
         10 . A prosthesis as claimed in  claim 3  wherein the thickness between the inner surface and the outer surface selected from the group of (a) less than 0.005 inches, (b) in the range of 0.001 inches to 0.01 inches, and (c) in the range of 0.0005 inches to 0.01 inches. 
     
     
         11 . A prosthesis as claimed in  claim 3  wherein:
 the inner surface of the sheet member is smooth to facilitate relative movement of the inner surface of the sheet member and the articular cartilage forming the contiguous outer surface of the first bone member in engagement with the inner surface of the sheet member and to resist bonding of the articular cartilage forming the contiguous outer surface of the first bone member to the inner surface of the sheet member, and 
 the outer surface of the sheet member is smooth to facilitate relative movement of the outer surface of the sheet member and the articular cartilage forming the contiguous outer surface of the second bone member in engagement with the outer surface of the sheet member and to resist bonding of the articular cartilage forming the contiguous outer surface of the second bone member to outer surface of the sheet member. 
 
     
     
         12 . A prosthesis as claimed in  claim 3  wherein the thickness between the inner surface and the outer surface is a constant thickness. 
     
     
         13 . A prosthesis as claimed in  claim 3  wherein the orthopaedic joint is the orthopaedic temporomandibular joint connecting the mandible bone to the temporal bone at the side of the skull, and the first bone member is the condyle of the mandible bone. 
     
     
         14 . A prosthesis as claimed in  claim 3  wherein metal is selected from the group consisting of tantalum, zirconium, titanium and alloys thereof. 
     
     
         15 . A prosthesis as claimed in  claim 3  wherein:
 the neck of the first bone member comprising the non-contiguous surface of the first bone member adjacent the articular cartilage on of the first bone member which non-contiguous surface is not normally in contact with the second bone member during movement of the joint, 
 the sheet member adapted for coupling to the first bone member with the inner surface of the sheet member to overlie both the contiguous outer surface of the first bone member and the adjacent non-contiguous surface of the first bone member, 
 the sheet member comprising the closed cap-like portion and a circumferential neck coupling portion, the coupling portion including an opening through the coupling portion defined by an edge of the sheet member, the coupling portion extending circumferentially about the opening between the opening and the cap-like portion, 
 the cap-like portion overlies in the closed position of the prosthesis the bulbous end with the coupling portion and its opening about the neck, in which closed position the opening has a circumference which corresponds to the circumference of the neck.