Claims
- 1. A non-constrained total joint system for effecting an articulation between first and second adjacent resected bony shafts, the system comprising:
- A. a first component formed of non-plastic biocompatible material and including:
- (a) a first stem configured to be received in the end of said first bony shaft;
- (b) a convex bearing surface, said convex bearing surface extending up to 180.degree.; and
- (c) means, including a non-bearing intermediate portion interposed between said first stem and said convex bearing surface, for fixedly attaching said convex bearing surface transversely to said first bony shaft, said non-bearing intermediate portion comprising a cylindrical portion adjacent to said first stem and a frustro-conical portion adjacent to said convex bearing surface, said frusto-conical portion providing for sufficient clearance for articulation of the joint system and protecting said convex bearing surface against possible boney overgrowth;
- B. a second component, including:
- (a) a second stem adapted to be received in the end of said second bony shaft;
- (b) a receptacle portion attached to said second stem; and
- (c) an intermediate insert formed of a biocompatible plastic, fixedly disposed in said receptacle portion, said insert including a concave bearing surface conforming to said convex bearing surface and of an area significantly less than the area of said convex bearing surface.
- 2. The system of claim 1 wherein said frustro-conical portion manifests an angle that is no greater than the tangent to said convex bearing surface at the juncture of said convex bearing surface and said frustro-conical portion.
- 3. A non-constrained total joint system for effecting an articulation between first and second adjacent resected bony shafts, the system comprising:
- a first component composed of a unitary, non-plastic biocompatible material and formed as an integral head and rearwardly projecting first stem, said first stem configured to be received in the end of said first bony shaft, said head having a convex bearing surface having a large major radius of curvature relative to a diameter of said head and approximating that of the anatomic articulating surface and extending up to 180.degree., said head further having a non-bearing intermediate portion interposed between said first stem and said convex bearing surface to offset said convex bearing surface from the end of said first bony shaft by a distance which provides sufficient clearance for articulation of the joint system and protecting said convex bearing surface against possible boney overgrowth;
- a second component, including an integral receptacle portion and a rearwardly projecting second stem, said second stem configured to be received in the end of said second bony shaft, said receptacle portion being substantially cylindrically shaped with an outer first beveled surface and receiving an intermediate insert formed of a biocompatible plastic, fixedly disposed within said receptacle portion, said insert including a concave bearing surface conforming to said convex bearing surface and of an area significantly less than the area of said convex bearing surface, said intermediate insert projecting beyond said receptacle portion and having a second beveled surface intersecting with said concave bearing surface and substantially forming an extension of said first beveled surface and protecting said concave bearing surface against possible boney overgrowth.
- 4. The non-constrained total joint system of claim 3 wherein said intermediate insert is formed of ultrahigh molecular weight polyethylene.
- 5. The non-constrained total joint system of claim 4 wherein said integral receptacle portion and said second stem are formed of titanium.
- 6. The non-constrained total joint system of claim 5 wherein said first component is formed of cobalt chrome.
- 7. The non-constrained total joint system of claim 3 including means for effecting a snap fitting of said intermediate insert in said receptacle portion.
- 8. The non-constrained total joint system of claim 3 wherein said first and second stems have a generally rectangular cross-section.
- 9. The non-constrained total joint system of claim 3 wherein the surface of said first beveled surface is at an angle within the range of 20.degree. to 35.degree. relative to the axis of said receptacle portion.
- 10. The non-constrained total joint system recited in claim 3 wherein said major radius of curvature is in the range of from approximately 7 to 17 mm and said distance is in the range of from approximately 0.5 to 1.5 mm.
- 11. A non-constrained total joint system for effecting an articulation between first and second adjacent resected bony shafts, the system comprising:
- a first component composed of a unitary, non-plastic biocompatible material and formed as an integral first head and rearwardly projecting first stem, said first stem configured to be received in the end of said first bony shaft, said head having a convex bearing surface having a large major radius of curvature relative to a diameter of said head and approximating that of the anatomic articulating surface and extending up to 180.degree., said head further having a non-bearing intermediate portion interposed between said first stem and said convex bearing surface to offset said convex bearing surface from the end of said first bony shaft by a distance which provides sufficient clearance for articulation of the joint system and protecting said convex bearing surface against possible boney overgrowth;
- a second component, including a second head attached to a rearwardly projecting second stem, said second stem configured to be received in the end of said second bony shaft, said second head being substantially cylindrically shaped with an outer beveled surface, said second head including a concave bearing surface formed of a biocompatible plastic conforming to said convex bearing surface and of an area significantly less than the area of said convex bearing surface, said beveled surface intersecting with said concave bearing surface and protecting said concave bearing surface against possible boney overgrowth.
- 12. The non-constrained total joint system of claim 11 comprising means for fixedly attaching said concave bearing surface to said second stem including a base formed of a non-plastic biocompatible material integral with said second stem, and having a recessed portion configured to receive at least a portion of said biocompatible plastic therewithin.
- 13. The non-constrained total joint system of claim 12 wherein said biocompatible plastic is ultrahigh molecular weight polythylene.
- 14. The non-constrained total joint system of claim 11 wherein said outer beveled surface is frustro-conical.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No. 07/720,709 filed Jun. 25, 1991, now abandoned.
US Referenced Citations (6)
Continuations (1)
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Number |
Date |
Country |
Parent |
720709 |
Jun 1991 |
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