Prosthesis for Movably Couplings os Metacarpale I of a Hand to a Second Metacarpal Bone and a Combination of a Prosthesis and a Fastening Means

Abstract

The invention relates to a prosthesis for movably coupling os metacarpale I of a hand to a second metacarpal bone of the hand, which prosthesis includes a first and a second element. The first element includes a first attachment member, which first attachment member is configured for attachment to os metacarpale I, and the second element comprises a second attachment member, which second attachment member is configured for attachment to the second metacarpal bone, which first and second element are movable relative to each other. The second metacarpal bone is os metacarpale II of the hand and the second attachment member is configured to be arranged from the radial side of os metacarpale II. The invention also relates to a combination of a prosthesis according to the invention and at least one fastening means.

Claims

1. A prosthesis for movably coupling os metacarpale I of a hand to a second metacarpal bone of the hand, which prosthesis comprises a first and a second element, wherein the first element comprises a first attachment member, which first attachment member is configured for attachment to os metacarpale I, and the second element comprises a second attachment member, which second attachment member is configured for attachment to the second metacarpal bone, which first and second element are movable relative to each other, and wherein the second metacarpal bone is os metacarpale II of the hand and the second attachment member is configured to be arranged from the radial side of os metacarpale II.

2. The prosthesis according to claim 1, wherein the second attachment member comprises a plate, which plate corresponds on a first side with the curved shape of the radial outer side of os metacarpale II of the hand.

3. The prosthesis according to claim 2, wherein the plate comprises at least one fastening hole for receiving a fastening means such as for instance a screw, pin or peg, and wherein the at least one fastening hole is continuous and extends to the first side.

4. The prosthesis according to claim 3, wherein at least one of the at least one fastening hole is provided with first locking means, such as for instance internal screw thread or a relief structure, for the purpose of anchoring a fastening means to the plate with angular stability relative to the plate.

5. The prosthesis according to claim 2, wherein the plate comprises at least one fastening pin, which at least one fastening pin extends from the first side and is configured to attach the plate to os metacarpale II.

6. The prosthesis according to claim 1, wherein the second attachment member comprises an intramedullary rod, which intramedullary rod is elongate and is configured for intramedullary insertion, via the joint surface of os metacarpale II and the trapezium, into the medullary cavity of os metacarpale II.

7. The prosthesis according to claim 6, wherein the intramedullary rod is curved, and wherein the curvature corresponds with the curvature of the medullary cavity of os metacarpale II.

8. The prosthesis according to claim 6, wherein the intramedullary rod is provided at least partially with a hydroxyapatite coating.

9. The prosthesis according to claim 6, wherein the intramedullary rod comprises at least two fixing holes for the purpose of anchoring the intramedullary rod in the medullary cavity of os metacarpale II with angular stability, wherein the at least two fixing holes are arranged at right angles relative to the longitudinal axis of the intramedullary rod and wherein the respective axes of the fixing holes are arranged at an angle greater than 5° relative to each other, preferably at an angle of between 450 and 135°, preferably at an angle of 90°.

10. The prosthesis according to claim 1, wherein the second element also comprises a third attachment member configured for attachment to os trapezoideum of the hand.

11. The prosthesis according to claim 1, wherein the first element is coupled to the second element by a ball-and-socket joint.

12. The prosthesis according to claim 11, wherein the ball-and-socket joint comprises a first part, which first part comprises an at least partially cup-shaped cavity and which first part is arranged on the first element, and wherein the ball-and-socket joint comprises a second part, which second part comprises an at least partially spherical ball, which second part is arranged on the second element and wherein the spherical part of the ball is arranged rotatably in the cavity.

13. A combination of a prosthesis according to claim 4, and at least one fastening means, such as an at least partially hydroxyapatite-coated peg, wherein the at least one fastening means is elongate and is provided on or close to a first outer end with second locking means for the purpose of anchoring the at least one fastening means with angular stability in at least one of the at least one fastening hole provided with first locking means, and is configured at a second outer end for attachment of the plate to os metacarpale II by means of a form-fitting connection.

14. The prosthesis according to claim 3, wherein the plate comprises at least one fastening pin, which at least one fastening pin extends from the first side and is configured to attach the plate to os metacarpale II.

15. The prosthesis according to claim 4, wherein the plate comprises at least one fastening pin, which at least one fastening pin extends from the first side and is configured to attach the plate to os metacarpale II.

16. The prosthesis according to claim 7, wherein the intramedullary rod is provided at least partially with a hydroxyapatite coating.

17. The prosthesis according to claim 7, wherein the intramedullary rod comprises at least two fixing holes for the purpose of anchoring the intramedullary rod in the medullary cavity of os metacarpale II with angular stability, wherein the at least two fixing holes are arranged at right angles relative to the longitudinal axis of the intramedullary rod and wherein the respective axes of the fixing holes are arranged at an angle greater than 5° relative to each other, preferably at an angle of between 450 and 135°, preferably at an angle of 90°.

18. The prosthesis according to claim 8, wherein the intramedullary rod comprises at least two fixing holes for the purpose of anchoring the intramedullary rod in the medullary cavity of os metacarpale II with angular stability, wherein the at least two fixing holes are arranged at right angles relative to the longitudinal axis of the intramedullary rod and wherein the respective axes of the fixing holes are arranged at an angle greater than 5° relative to each other, preferably at an angle of between 450 and 135°, preferably at an angle of 90°.

19. A combination of a prosthesis according to claim 5, and at least one fastening means, such as an at least partially hydroxyapatite-coated peg, wherein the at least one fastening means is elongate and is provided on or close to a first outer end with second locking means for the purpose of anchoring the at least one fastening means with angular stability in at least one of the at least one fastening hole provided with first locking means, and is configured at a second outer end for attachment of the plate to os metacarpale II by means of a form-fitting connection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] These and other features of the invention are further elucidated with reference to the accompanying drawings.

[0050] FIG. 1 shows a perspective view of a first embodiment of the prosthesis according to the invention.

[0051] FIG. 2 shows a perspective view of a first embodiment of the prosthesis according to the invention, placed in a hand.

[0052] FIG. 3 shows a perspective view of a second embodiment of the prosthesis according to the invention.

[0053] FIG. 4 shows a perspective view of a third embodiment of the prosthesis according to the invention.

[0054] FIG. 5 shows a perspective view of a third embodiment of the prosthesis according to the invention, placed in a hand.

DESCRIPTION OF THE INVENTION

[0055] In the figure description os metacarpale I and os metacarpale II are designated as respectively MC1 and MC2.

[0056] FIG. 1 shows a first embodiment of a prosthesis 1 according to the invention. Prosthesis 1 has a first element 2 with a first attachment member 3. Second element 4 has a second attachment member 5 in the form of an elongate plate. Continuous fastening holes 6, 7 are arranged evenly in the plate for the purpose of receiving fastening means. The curvature of the plate is clearly visible, wherein the curvature of the plate corresponds on the mounting side, also referred to as first side, to the slightly concave form of the radial side of MC2. The curvature of the mounting side of the plate thus corresponds at least to the curvature of the radial side of MC2 in the coronal plane. When second attachment member 5 is attached to MC2, the mounting side or first side will have an ulnar orientation. The side 8 of second attachment member 5 lying opposite thereto has a radial orientation.

[0057] The distal end 9 of the second element ends close to a fastening hole 7. Arranged close to proximal end 10 of the second element is a partially spherical head 11 which forms a ball-and-socket joint with the cup arranged in second element 2.

[0058] FIG. 2 shows a first embodiment of the prosthesis 1 according to the invention, placed in a hand 12. First attachment member 3 is arranged in the proximal end 13 of MC1 14. Os trapezium has already been removed. The second attachment member 5 is attached to MC2 15 by means of fastening means 16, 17 arranged in fastening holes 6, 7. It can be clearly seen in the partly cut-away MC2 15 that the bicortical screws 17 connect the second attachment member 5 fixedly to the radial side of MC2 15. A pin 16 is arranged in the most proximally situated fastening hole 6. It is clearly visible that prosthesis 1 provides for diversion of the forces via MC2 15 and os trapezoideum 18 in proximal direction 19, designated with arrow 19. The distal direction 20 is designated with arrow 20.

[0059] FIG. 3 shows a second embodiment of the prosthesis 31 according to the invention. The first element of the prosthesis is not shown in this figure. The second element 34 has a second attachment member 35, in which continuous fastening holes 37 are arranged evenly for the purpose of receiving fastening means. The continuous fastening holes 37 are arranged at the distal end 39 of the second attachment member 35. Also arranged toward the proximal end 40, on which the ball head 41 of the ball-and-socket joint is also arranged, is a fastening pin 42. This fastening pin 42 forms a whole with the second element 34.

[0060] FIG. 4 shows a third embodiment of the prosthesis 51 according to the invention. Prosthesis 51 has a first element 52 with a first attachment member 53. Second element 54 has a second attachment member 55 in the form of an intramedullary rod 62. Arranged in the intramedullary rod 62 are optionally continuous fixing holes 56, 57 for receiving fastening means. Fixing holes 56, 57 are arranged at an angle relative to each other. In the shown embodiment the fixing hole 56 close to distal end 59 of second element 54 and the fixing hole 57 lying adjacently thereof in the direction of proximal end 60 form an angle of about 90° with each other in more or less parallel planes, as seen from the longitudinal axis of the elongate intramedullary rod 62.

[0061] FIG. 5 shows a third embodiment of the prosthesis 51 according to the invention, placed in a hand 82. The first attachment member 53 is arranged in the proximal end 83 of MC1 84. Os trapezium has already been removed. The second attachment member 55 in the form of intramedullary rod 62 is arranged in the medullary cavity 86 of MC2 85 through insertion via the radial side of MC2 85, through the joint surface 87 situated between MC2 85 and the already removed os trapezium. In the partially cut-away MC2 85 it is clearly visible that the intramedullary rod 62 follows the internal curvature of medullary cavity 86, whereby rotation is already prevented. Fixing screws 67, which are arranged at an angle relative to each other, fix the intramedullary rod 62 relative to MC2 85 with angular stability. Alternatively, bolts and blind fixing holes can also be used for the fixing. The proximal 19 and distal 20 directions are designated with arrows 19, 20.