Elbow prosthesis

Abstract

A humeral component, forming a first articulating surface, and an ulnar component forming a second articulating surface adapted to be disposed around a part of the first articulating surface and to pivot about its longitudinal axis. This ulnar component is provided with structure for mounting a locking element which forms a third articulating surface extending the second and adapted likewise to be disposed around a part of the first surface. These mounting structure comprise guiding structures adapted to cooperate with complementary structure provided on the locking element in order to guide this element in translation with respect to the ulnar component, up to a position where blocking structure provided respectively on the locking element and on the ulnar component may be employed to immobilize this element on this component, these blocking structure being able to be employed only in this position.

1. Elbow prosthesis comprising a humeral component, forming a first articulating surface, and an ulnar component forming a second articulating surface adapted to be disposed around a part of said the first articulating surface and to pivot about a longitudinal axis of said the first articulating surface, said the ulnar component being provided with means for mounting a locking element which forms a third articulating surface extending said the second articulating surface and adapted likewise to be disposed around a part of said the first articulating surface, wherein said the mounting means comprise guiding means adapted to cooperate with complementary means provided on said the locking element in order to guide said the locking element in translation with respect to said the ulnar component, up to a position where blocking means provided respectively on said the locking element and on said the ulnar component may be employed to immobilize said the locking element on said the ulnar component, said the blocking means being able to be employed only in this position. 
     
     
       2. The prosthesis of  claim 1 , wherein said the blocking means comprise comprises a screw and a complementary tapping provided respectively on said the locking element and on said the ulnar component, or vice versa, the direction of relative translation between said the locking element and said the ulnar component as imposed by said the guiding means being non-parallel to the longitudinal axis of said the tapping and/or of said the screw. 
     
     
       3. The prosthesis of  claim 1 , wherein said the guiding means comprise comprises at least one element in relief projecting with respect to a principal part of said the ulnar component, while the complementary means provided on said the locking element are adapted to interact with said the locking element in relief by cooperation of shapes. 
     
     
       4. The prosthesis of  claim 3 , wherein said the locking element in relief is a nose, while said the complementary means comprise comprises a fork of which two branches define therebetween a volume for receiving and for slide of said sliding the nose. 
     
     
       5. The prosthesis of  claim 1 , wherein said the guiding means and said the blocking means are arranged in the vicinity of two opposite edges of said the second articulating surface, while said the complementary means and the blocking means provided on said the locking element are arranged on two opposite edges of said the locking element. 
     
     
       6. The prosthesis of  claim 1 , wherein said the blocking means comprise comprises a screw and a tapping, which are complementary and respectively provided on said the locking element and on said the ulnar component, or vice versa, and means are provided for blocking said the screw in rotation. 
     
     
       7. The prosthesis of  claim 6 , wherein the piece against which the head of said screw bears, is provided with a tab foldable into configuration of blocking of said head. 
     
     
       8. The prosthesis of  claim 7 , wherein the head of said screw is of polygonal profile, with faces whose width is greater than the width of said foldable tab. 
     
     
       9. The prosthesis of  claim 6 , wherein the head of said screw is of non-circular section, while the piece against which said head bears, forms a space for receiving said head, with contact between the surface of said piece and the outer surface of said head. 
     
     
       10. The prosthesis of  claim 9 , wherein said head is provided with catch elements adapted to penetrate superficially in the surface of said piece. 
     
     
       11. The prosthesis of claim 6, wherein when a head of the screw bears against the ulnar component, the ulnar component is provided with a tab foldable into a configuration capable of blocking the head, and wherein when the head of the screw bears against the locking element, the locking element component is provided with a tab foldable into a configuration capable of blocking the head. 
     
     
       12. The prosthesis of claim 11, wherein a head of the screw has a polygonal profile having faces with widths greater than a width of the tab. 
     
     
       13. The prosthesis of claim 6, wherein a head of the screw is of non-circular section, wherein when the head of the screw bears against the ulnar component, the ulnar component forms a space for receiving the head with contact between a surface of the ulnar component and an outer surface of the head and wherein when the head of the screw bears against the locking element, the locking element forms a space for receiving the head with contact between a surface of the locking element and an outer surface of the head. 
     
     
       14. The prosthesis of claim 6, wherein a head of the screw is provided with catch elements adapted to penetrate superficially in the surface of either the ulnar component or the locking element, whichever the head bears against. 
     
     
       15. An elbow prosthesis comprising:
 a humeral component comprising a first articulating surface having a curved and concave generatrix and a first longitudinal axis;   an ulnar component comprising a first guide portion and a second articulating surface adapted to be disposed around a portion of the first articulating surface and to pivot about the first longitudinal axis;   a locking element comprising a second guide portion and a third articulating surface that extends an arc length of the second articulating surface and is adapted to extend around a portion of the first articulating surface,   the first and second guide portions of the ulnar component and the locking element, respectively, forming a complementary guide structure including an extension adapted to be slidingly received within a projecting element in a complementary fit such that the complementary guide structure imposes sliding translation of the locking element relative to the ulnar component along a direction of slide; and   a fastening structure adapted to immobilize the locking element with respect to the ulnar component when the locking element and the ulnar component are engaged.   
     
     
       16. The elbow prosthesis of claim 15 wherein the first articulating surface comprises a component attached to a humeral stem. 
     
     
       17. The elbow prosthesis of claim 15 wherein the humeral component comprises:
 a stem adapted to be inserted in a medullary canal of a humerus; and   a member adapted to abut against an external surface of the humerus.   
     
     
       18. The elbow prosthesis of claim 15 wherein the second and third articulating surfaces comprise similar cross-sectional profiles. 
     
     
       19. The elbow prosthesis of claim 15 wherein the second and third articulating surfaces comprise low-friction linings. 
     
     
       20. The elbow prosthesis of claim 15 wherein the second and third articulating surfaces comprise a material adapted to engage a first articulating surface, wherein the first articulating surface is formed of metal. 
     
     
       21. The elbow prosthesis of claim 15 wherein the second and third articulating surfaces combine to surround the first articulating surface. 
     
     
       22. The elbow prosthesis of claim 15 wherein the guide structure translates the locking element relative to the ulnar component. 
     
     
       23. The elbow prosthesis of claim 15 wherein the guide structure comprises a direction of assembly that is non-parallel to a longitudinal axis of the fastening structure. 
     
     
       24. The elbow prosthesis of claim 15 wherein the locking element and the ulnar component are engaged when the second articulating surface abuts with the third articulating surface. 
     
     
       25. The elbow prosthesis of claim 15 wherein the first guide portion of the ulnar component is located at a first edge of the second articulating surface and at least a portion of the fastening structure is located at a second edge of the second articulating surface. 
     
     
       26. The elbow prosthesis of claim 15 wherein the fastening structure comprises a first hole in the locking member that is aligned with a second hole in the ulnar component only when the locking member is in the engaged position. 
     
     
       27. The elbow prosthesis of claim 11 comprising a member adapted to prevent rotation of a fastener in the fastening structure once the locking element is in the engaged position. 
     
     
       28. An elbow prosthesis comprising:
 a humeral component comprising a first articulating surface having a curved and concave generatrix and a first longitudinal axis;   an ulnar component comprising a guide element and a second articulating surface adapted to be disposed around a part of the first articulating surface and to pivot about the longitudinal axis;   a locking element comprising a nose and a third articulating surface that extends an arc length of the second articulating surface and is adapted to extend around a portion of the first articulating surface, the nose being complementary to the guide element such that the guide element is adapted to slidingly receive the nose within the guide element and impose sliding translation of the locking element along a direction of slide relative to the ulnar component; and   a fastening structure adapted to immobilize the locking element with respect to the ulnar component.   
     
     
       29. An elbow prosthesis comprising:
 a humeral component comprising a first concave articulating surface with a first longitudinal axis;   an ulnar component comprising a second articulating surface adapted to be disposed around a part of the first concave articulating surface and to pivot about the longitudinal axis, the ulnar component comprising at least one hole adapted to receive a fastener;   a locking element comprising a third articulating surface that extends an arc length of the second articulating surface and is adapted to extend around a portion of the first articulating surface, the locking element comprising at least one hole adapted to receive a fastener; and   a guide structure comprising a projecting element and an extension adapted to be received within the projecting element in a complementary fit to impose a direction of slide of the locking element relative to the ulnar component, wherein the projecting element is located on one of the ulnar component and the locking element and the extension is located on the other of the ulnar component and the locking element, and further wherein the hole in the locking member is substantially aligned with a hole in the ulnar component only when the locking member is fully engaged with the ulnar component.   
     
     
       30. An elbow prosthesis comprising:
 a humeral component comprising a first curved articulating surface including a first longitudinal axis;   an ulnar component comprising a second articulating surface adapted to be disposed around a portion of the first curved articulating surface and to pivot about the longitudinal axis;   a locking element comprising a third articulating surface that extends an arc length of the second articulating surface and is adapted to extend around a portion of the first articulating surface;   a guide structure comprising a nose and a fork adapted to receive the nose within the fork to impose a direction of slide between the ulnar component and the locking element, wherein one of the nose and the fork is located on the ulnar component and the other of the nose and the fork is located on the locking element; and   a fastening structure adapted to immobilize the locking element with respect to the ulnar component, wherein the guide structure comprises a direction of assembly that is non-parallel to a longitudinal axis of the fastening structure.