Partial joint resurfacing implant, instrumentation and method

Abstract

A partial resurfacing implant for use in repairing an articular cartilage defect site that includes a top articulating portion having a top surface that is configured with at least one radius of curvature to approximate the surface contour of the articular cartilage surrounding the defect site. The implant also includes a supporting plate that has a top surface and a bottom surface. The top surface is attached to the top articulating portion by a locking mechanism. The bottom surface of the supporting plate is constructed to facilitate the insertion of the implant into the defect site. Extending from the bottom surface of the supporting plate is at least one implant fixation portion. The at least one implant fixation portion is integrally connected to and is oriented about normal relative to the bottom surface. A method of repairing an articular cartilage defect with the partial joint resurfacing implant is also disclosed.

1 . An implant for repairing an articular cartilage defect site, the implant comprising:
 a top articulating portion; and   a supporting plate, the supporting plate comprising a top surface and a bottom surface, wherein the top surface of the supporting plate is coupled to the top articulating portion and the bottom surface of the supporting plate being configured to facilitate insertion into the articular cartilage defect site.   
     
     
         2 . The implant of  claim 1 , wherein the top articulating portion further comprises a top surface, the top surface having a first radius of curvature with the first radius of curvature being selected to approximate the surface contour of the articular cartilage surrounding the defect site. 
     
     
         3 . The implant of  claim 1 , wherein the top articulating portion further comprises a top surface, the top surface being planar to approximate the surface contour of the articular cartilage surrounding the defect site. 
     
     
         4 . The implant of  claim 1 , wherein the top articulating portion is fabricated from a lubricious and hydrophilic polymer. 
     
     
         5 . The implant of  claim 4 , wherein the lubricious and hydrophilic polymer is a polysaccharide treated thermoplastic polymer. 
     
     
         6 . The implant of  claim 1 , wherein the top articulating portion is fabricated from a polymer selected from the group consisting of polyesters, perfluorinated hydrocarbons, acrylates, polyamides, polycarbonates PEEK, epoxy resins, polysiloxanes and hydrogels. 
     
     
         7 . The implant of  claim 2 , wherein the top surface further comprises a second radius of curvature, wherein the first radius of curvature is greater than or equal to the second radius of curvature, with the first and second radius of curvatures being selected to approximate the surface contour of the articular cartilage surrounding the defect site. 
     
     
         8 . The implant of  claim 1 , wherein the implant further comprises a locking mechanism to mechanically interlock the top articulating portion to the supporting plate. 
     
     
         9 . The implant of  claim 8 , wherein the locking mechanism comprising at least one of a channel disposed on the top surface of the supporting plate, a snap-fit interlock between the top articulating portion and the top surface of the supporting plate and a durable adhesive disposed between the top surface of the supporting plate and the top articulating portion. 
     
     
         10 . The implant of  claim 9 , wherein the at least one channel is configured as at least one of a dovetail and a key-lock slot. 
     
     
         11 . The implant of  claim 1 , wherein the implant has a cross-sectional shape, the cross-sectional shape being one of a circle, an oval, a rectangle, an oblong or a polygonal shape, wherein the cross-sectional shape of the implant is configured to fit within the articular cartilage defect site. 
     
     
         12 . The implant of  claim 1 , wherein the supporting plate further comprises at least one implant fixation portion, the at least one implant fixation portion being integrally connected to and extending away from the bottom surface of the supporting plate. 
     
     
         13 . The implant of  claim 12 , wherein the at least one implant fixation portion comprises a lower stem, the lower stem being configured as at least one of a cylindrical post, a tapered post, a peg and a polygonal dowel to facilitate insertion into the articular cartilage defect site. 
     
     
         14 . The implant of  claim 13 , wherein the lower stem further comprises a proximal cylindrical section and distal bone fixation section, wherein at least two barbs project away from an outer surface of the distal bone fixation section, the barbs being configured to inhibit motion of the implant following implantation in the articular cartilage defect site. 
     
     
         15 . The implant of  claim 12 , wherein the bottom surface of the supporting plate and the at least one implant fixation portion is coated with a material for facilitating bio-ingrowth between the implant and the articular cartilage defect site. 
     
     
         16 . The implant of  claim 15 , wherein the material is at least one of hydroxyapatite, calcium phosphates, calcium sulfates, BMP, and a growth factor. 
     
     
         17 . A partial resurfacing implant for repairing a cartilage defect site, the implant comprising:
 a top articulating portion having a top surface being configured with at least one radius of curvature to approximate the surface contour of the cartilage surrounding the defect site; and   a supporting plate, the supporting plate comprising a top surface and a bottom surface, wherein the top surface of the supporting plate is coupled to the top articulating portion and the bottom surface of the supporting plate being configured to facilitate insertion into the cartilage defect site.   
     
     
         18 . The partial resurfacing implant of  claim 17 , wherein the top articulating portion is fabricated from a hydrophilic polymer. 
     
     
         19 . The partial resurfacing implant of  claim 18 , wherein the hydrophilic polymer is a polysaccharide treated thermoplastic polymer. 
     
     
         20 . The partial resurfacing implant of  claim 17 , wherein the top articulating portion is fabricated from a polymer selected from the group consisting of polyesters, perfluorinated hydrocarbons, acrylates, polyamides, polycarbonates PEEK, epoxy resins, polysiloxanes and hydrogels. 
     
     
         21 . The partial resurfacing implant of  claim 17 , wherein the implant further comprises a locking mechanism to couple the top articulating portion to the supporting plate. 
     
     
         22 . The partial resurfacing implant of  claim 21 , wherein the locking mechanism comprising at least one of a channel disposed on the top surface of the supporting plate, a snap-fit mechanical lock between the top articulating portion and the top surface of the supporting plate and a durable adhesive disposed between the top surface of the supporting plate and the top articulating portion. 
     
     
         23 . The partial resurfacing implant of  claim 22 , wherein the at least one channel is configured as at least one of a dovetail and a key-lock slot. 
     
     
         24 . The partial resurfacing implant of  claim 17  wherein the implant has a cross-sectional shape, the cross-sectional shape being one of a circle, an oval, a rectangle, an oblong or a polygonal shape, wherein the cross-sectional shape of the implant is configured to fit within the cartilage defect site. 
     
     
         25 . The partial resurfacing implant of  claim 17 , wherein the supporting plate further comprises at least one implant fixation portion, the at least one implant fixation portion being integrally connected to the bottom surface of the supporting plate. 
     
     
         26 . The partial resurfacing implant of  claim 25 , wherein the at least one implant fixation portion extends in a perpendicular direction from the bottom surface of the supporting plate. 
     
     
         27 . The partial resurfacing implant of  claim 25 , wherein the at least one implant fixation portion comprises a lower stem, the lower stem being configured as at least one of a cylindrical post, a tapered post, a peg and a polygonal dowel to facilitate insertion into the cartilage defect site. 
     
     
         28 . The partial resurfacing implant of  claim 27 , wherein the lower stem comprises a proximal cylindrical section and distal bone fixation section, wherein at least two barbs project away from an outer surface of the distal bone fixation section, the barbs being configured to inhibit motion of the implant following implantation in the cartilage defect site. 
     
     
         29 . The partial resurfacing implant of  claim 25 , wherein the bottom surface of the supporting plate and the at least one implant fixation portion is coated with a material for facilitating bio-ingrowth between the implant and the cartilage defect site, the material is at least one of hydroxyapatite, calcium phosphates, calcium sulfates, BMP, and a growth factor. 
     
     
         30 . A method of repairing an articular cartilage defect site, the method comprising:
 surgically creating an opening in the articular cartilage defect site;   employing a partial resurfacing implant, the implant comprising:   a top articulating portion; and   a supporting plate, the supporting plate comprising a top surface and a bottom surface, wherein the top surface of the supporting plate is coupled to the top articulating portion and the bottom surface of the supporting plate being configured to facilitate insertion into the articular cartilage detect site; and   implanting the partial resurfacing implant into the opening, wherein the supporting plate is inserted into the opening with the top articulating portion and adjacent articular cartilage being positioned tangential to each other to facilitate motion over the defect site.   
     
     
         31 . The method of  claim 30 , wherein the surgically creating an opening further comprises employing a drill guide to form a pilot hole in the defect site, the pilot hole being oriented substantially normal to the articular cartilage defect site. 
     
     
         32 . The method of  claim 30 , wherein the surgically creating an opening further comprises cutting damaged articular cartilage from the articular cartilage defect site. 
     
     
         33 . The method of  claim 30 , wherein the surgically creating an opening further comprises enlarging the pilot hole to accommodate the implant. 
     
     
         34 . The method of  claim 30 , further comprising the step of inserting a trial implant within the articular cartilage defect site to confirm the sizing and final positioning of the partial resurfacing implant.