Artificial Skeletal Joint

Abstract

A pair of skeletal members, such as a tibia and a femur, are connected together by a ball and socket type assembly comprising said artificial joint. The ball of the assembly is secured to one of said skeletal members which shifts relative the other skeletal member in an anterior-posterior direction as the ball rotates. A follower supported from the ball against the exterior of the socket cams the ball from a first chamber to a connected second chamber in the socket, the follower being secured to the other skeletal member to produce the relative shifting of said members.

Description

FIELD OF THE INVENTION

The present invention relates to articulated skeletal joints. More particularly the invention relates to a skeletal joint prosthesis. Specifically, the invention relates to a prosthetic knee and the like.

BACKGROUND OF THE INVENTION

Ideally an artificial skeletal joint of the type comprehended by this invention would restore a full range of natural movement between the skeletal parts connected thereby. And while heretofore known joints have been used markedly to improve function of natural body parts which have become disabled in consequence of damage resulting from either natural or unnatural causes, wanting has been an ideal articulation.

It is an object of the present invention to provide an improved artificial skeletal joint.

It is another object of the present invention to provide an improved artificial knee.

It is a further object of the invention to provide improved rehabilitation for damaged skeletal parts.

It is an additional object of the invention to simulate a full range of natural movements between skeletal parts which are articulated with an artificial joint.

It is an additional object of the invention to simulate a full range of natural knee movements between a tibia and femur with an artificial knee.

SUMMARY OF THE INVENTION

To achieve the foregoing, and other objects of the invention which will become apparent from ensuing description, in accordance with the present invention, an artificial skeletal joint comprises a first member having a chamber with a pair of sections. The first member is adapted for securance to a first skeletal component. A second member is adapted for securance to a second skeletal component; and it has an element which is movably disposed in said chamber. Camming means are adapted to shift the element from one of said sections to the other thereof and thereby to relatively shift said skeletal members.

BRIEF DESCRIPTION OF THE DRAWINGS

In the ensuing detailed description, reference is had to the accompanying drawings in which:

FIG. 1 is an exploded view in perspective of one embodiment of said invention, natural skeletal parts being shown in phantom;

FIG. 2 is a vertical sectional view of said embodiment in a laterally extending plane; and

FIG. 3 is a vertical sectional view of said embodiment in an anterior-posterior plane, an alternate condition of said embodiment being shown in dashed lines.

DETAILED DESCRIPTION OF THE INVENTION

Referring now more particularly to the drawings, shown is a complete prosthesis or artificial skeletal joint 10 for articulating a pair of skeletal components and in which natural articulation has become impaired. The exemplary skeletal components are, respectively, a tibia 12 and a femur 14. Accordingly, joint 10 is an artificial knee, though the invention is by no means limited to a prosthesis for replacing damaged knees; and it comprises a tibial member or component 16 and a femoral member or component 18.

Tibial component 16 comprises bone anchoring means herein shown as a connector or bone broaching part or stem 20. It is elongated for securance to tibia 12 in the marrow channel of which it is adapted to engage. An integral flange 22 secured from a joint proximate end of stem 20 has a flat bone proximate surface 24. Said surface is adapted for rigid securance, by, for example, a suitable biologically inert adhesive, to prepared surface 26 which has been suitably flattened on the joint proximate end of the tibia by an appropriate tool (not shown). A part, ball or head 28 is carried from one end of a neck 30 which is secured from said flange distal to its connection from the tibia. The proportioning and arrangement of the parts is such than an extension of the longitudinal axis of the stem is diametric of ball 28.

Femoral component 18 comprises bone anchoring means herein shown as a connector or bone broaching part or stem 32. It is elongated for securance to femur 14 in the marrow channel of which it is adapted to engage. A casing or socket 34 which is rigidly secured from a joint proximate end of said stem has a flat bone proximate external surface 36. The latter is adapted for rigid securance by, for example, a suitable biologically inert adhesive, to a prepared surface 38 which has been suitably flattened on the joint proximate end of the femur by an appropriate tool (not shown).

Socket 34 is defined by a wall and has therein a chamber 40. The wall of the socket also has six sides including surface 36. The other five sides are as follows: opposed lateral sides 42 and 44 (FIG. 2), an anterior aspect 46 (FIG. 3), a posterior aspect 48, and a bone distal side or bottom 50. A slot 52 extending through the bottom 50 and the posterior aspect of the socket connects chamber 40 to the exterior thereof.

Chamber 40 has a pair of communicating sections or compartments 54 and 56, the sections being arranged in anterior-posterior operative alignment within the socket and having a combined anterior-posterior length of about 3 radii of ball 28. Each section has a radius of curvature substantially equal to the radius of curvature of the ball, with posterior chamber 56 being slightly upwardly offset from anterior chamber 54 when the parts are oriented for use (FIG. 3).

Ball 28 is disposed in the chamber 40 and the parts are proportioned such that neck 30 is wholly disposed in slot 52 with the tibial distal surface 58 of flange 22 engaged against the exterior surface of the socket adjacent slot 52. The width of the slot is such that opposed lateral sides of the neck are engaged by the bottom ends 60 and 62 (FIG. 2) of sides 42 and 44 while its length may be about 4 radii of ball 28. Thereby, though the ball is restrained from angular movement about its X axis (by ends 60 and 62), it is able to rock about Y and Z axes. In the exemplary embodiment the ball has an angular range of about 130.degree. about the Z axis with motion thereabout limited by engagement of neck 30 with the anterior end 64 (FIG. 3) and posterior end 66 of slot 52.

The invention is characterized by cam means being a cam and follower. The cam is comprised of the exterior surface of socket 34 marginal to slot 52. The follower is comprised of the portion of the surface 58 of flange 22 which is adapted to engage said cam, said follower and cam being fashioned such that as ball 28 is rocked about the Z axis between a position in which tibia 12 and femur 14 are aligned (solid line of FIG. 3), and a position corresponding to maximum flexion (dashed line of FIG. 3), the ball will be cammed between compartments 54 and 56 of chamber 40.

End 60 of illustrated joint 10 is adapted as a motion constraint normally provided by the lateral collateral ligament in a leg. End 62 similarly is adapted as a restraint in lieu of the medial collateral ligament. Likewise, end 64 is adapted to replace the action of the corresponding anterior cruciate ligament. Thusly, the subject prosthesis enables movement of skeletal parts more closely simulating a natural condition than has been attainable by using heretofore known appliances.

As many modifications in the described construction could be conceived, and as many changes could be made therein without departing from the spirit and scope of the claims, it is intended that all matter contained in the accompanying specification shall be considered as illustrative only and not in a limiting sense.

Claims

I claim:

1. An artificial skeletal joint comprising: a first member adapted for securance to a first skeletal component and having a chamber with a pair of operably associated sections;

a second member having a first part disposed in said chamber for movement about a pair of orthogonal axes and a second part adapted for securance to a second skeletal component, and

means arranged externally of said chamber for shifting said first part between said sections as said first part moves about one of said axes.

2. A combination according to claim 1 wherein said first part is a head and said shifting means includes a camming element rigidly secured to and movable about a pair of orthogonal axes with said head.

3. A combination according to claim 1 wherein said shifting means comprises a cam on said first member and a follower connected to said second member and engaged with said cam externally of said chamber and continuously during shifting.

4. A combination according to claim 3 wherein said first member is a socket and said cam comprises an external surface of said socket.

5. An artificial skeletal joint comprising:

a first member adapted for securance to a first skeletal component and having a chamber with a pair of operably associated sections;

a second member having a part adapted for securance to a second skeletal member and a ball arranged for angular movement in said chamber about a pair of axes in a three planar coordinate system;

means for shifting said ball between said sections; and

means for restraining movement of said ball about the third of said axes.

6. An artificial skeletal joint comprising:

a first member adapted for securance to a first skeletal component and having a chamber with a pair of operably associated sections, said first member having a slot providing a passage from said chamber to the exterior;

a second member having a part adapted for securance to a second skeletal component and a ball arranged for angular movement in said chamber about first and second orthogonal axes, said part having a portion disposed outside said first member and a neck arranged for movement longitudinally of said slot, said neck connected to said ball for angular movement about one of said axes as it moves longitudinally of said slot about the other of said axes; and a camming element rigidly secured to said outside portion for shifting said ball between said sections in response to angular movement of said neck longitudinally of said slot.

7. An artificial skeletal joint comprising:

a socket;

a spherical ball having orthogonal axes and arranged for movement in said socket;

means for anchoring said ball and said socket on a pair of skeletal components for articulation thereof;

said socket having a chamber therein and a slot providing passage from said chamber to the exterior for connecting said ball to said ball anchoring means;

said chamber having a pair of adjacent sections providing a pair of seats proportioned for enabling angular movement of said ball about said axes in each of said sections; and

means for lineally shifting said ball between said sections at any angular aspect of said ball about one of said axes as said ball is moved angularly about the other of said axes.

8. An artificial skeletal joint comprising:

a socket, said socket having a chamber therein and a slot providing passage from said chamber to the exterior;

a ball arranged for movement in said socket, said chamber having a pair of adjacent sections providing a pair of seats proportioned for enabling angular movement of said ball in said chamber;

means for anchoring said ball and said socket on a pair of skeletal components for articulation thereof, said anchoring means including a first connector associated with said socket and adapted for connection to one of said skeletal components and a second connector associated with said ball and adapted for connection to the other of said skeletal components; and

cam means for shifting said ball from one of said sections to the other as said ball is moved angularly, said cam means including a part rigidly carried with said second connector for engaging said socket as said connectors are moved angularly, each relative to the other thereof, to shift said ball.

9. A combination according to claim 8 characterized by a neck through said slot for connecting said second connector to said ball, and wherein said socket has an external cam fashioned surface, said part being a follower disposed in engagement with said surface.

10. A combination according to claim 9 wherein said chamber sections are operably aligned and said slot is elongated in the direction of alignment and proportioned for enabling said neck to shift longitudinally therein as said ball moves angularly.

11. A combination according to claim 9 wherein said socket has a bone distal side and a pair of opposed sides integral with and extending boneward from said bone distal side, said slot extending through said bone distal side and through one of said opposed sides.

12. An artificial knee according to claim 11 wherein said opposed sides have an anterior-posterior relationship, said socket being further characterized by a pair of spaced apart lateral sides having bone distal ends limiting said slot to prevent rotation of the ball about a first of its axes in a three dimensional system.

13. An artificial knee according to claim 12 wherein said socket is proportioned for enabling said ball to rock about a second of said axes in each chamber section.

14. An artificial knee according to claim 13 wherein said slot has opposed ends spaced apart, each from the other thereof, a distance such that said ball can rock about the third of said axes about 130.degree. as it shifts between said sections.

15. An artificial skeletal joint comprising:

a rockable member with orthogonal axes;

a socket having chamber sections, said rockable member proportioned for angular movement about both of said axes in each of said chamber sections; and

means for lineally shifting said rockable member between said chamber sections in response to its angular movement about one of said axes.

16. An artificial knee according to claim 15 wherein said socket has means comprised of at least one prosthetic ligament.

17. A combination according to claim 15 wherein said shifting means is operative upon angular movement of said rockable member about one of said axes at each angular aspect about the other of said axes.