Device for uniting the thigh and lower leg

Abstract

A device comprising an upper joint member having a portion to be secured to the thigh, a lower joint member having a portion to be secured to the lower leg, and an intermediate joint member uniting the upper and lower joint members by an upper pin and lower pins pivotably at upper and lower two positions.

Description

The present invention relates to improvements in a device for uniting the thigh and the lower leg together, more particularly to improvements in knee prosthesis and knee joint brace for uniting the thigh and the lower leg together.

The natural knee joint is adapted for smooth articulation by virtue of special mode of sliding contact between the distal end of the femur and the proximal end of the tibia which have unique surfaces respectively. It is well known that the knee motion is not a simple uniaxial motion.

However, conventional devices for joining the thigh and the lower leg together, whether knee prostheses or knee joint braces, are of such construction that the upper and lower joint elements to be fixed to the thigh and the lower leg respectively are pivotably united together only at one position by one pin. Consequently, the known devices give a uniaxial motion as entirely distinct from the actual knee motion, resulting in serious objections during walking or when the knee is stretched or flexed as will be described below.

With knee prostheses heretofore proposed, the motion of extension and flexion always takes place about only one support point without permitting the displacement of the support point, so that the motion lacks comfort and smoothness and involves extreme difficulties. In addition, the body movement is unnatural and unsightly. The known devices furthermore require a strong muscular power for extension and flexion, hence unapplicable to those who have a weak muscular power, and are unserviceable over a prolonged period of time inasmuch as the anchorage of the device to the support bones is subject to loosening. Thus the conventional devices have found applications only to extremely limited kinds of pathologic changes and are generally of poor practical value. For the same reasons, knee joint braces so far have the serious drawback of being unable to properly follow the motion of the actual knee joint, failing to alleviate the load on the knee joint to any significant extent. When worn, they produce abrasion in the skin due to the reciprocal frictional contact with the thigh and the lower leg and are therefore unapplicable continuously.

A main object of this invention is to provide a mechanism for uniting the thigh and the lower leg together by upper and lower pins so as to unite them at two positions, i.e. at the upper and the lower and to thereby render them pivotably movable in the same manner as the natural joint.

Another object of this invention is to provide a device which incorporates the mechanism to unite the thigh and lower leg together and by which the motion of actual knee joint can be reproduced accurately to assure knee extension and flexion with comfort and smoothness, the device therefore being operable very satisfactorily where hardly any muscular power is available, free of loosening at its anchorage to the support bone, serviceable over a long period and applicable to a wide variety of pathologic changes.

Still another object of this invention is to provide a knee joint brace which incorporates the above-mentioned muchanism to unite the thigh and the lower leg together and which is capable of following the motion of the natural joint properly, making it sure to mitigate the load on the knee joint and assuring continuous use without causing skin abrasion where the brace is applied.

According to this invention there is provided a device comprising an upper joint member, a lower joint member disposed under the upper member and an intermediate joint member interposed between the upper and lower joint members, the upper joint member having an upper portion to be secured to the thigh and a lower pin bearing portion, the lower joint member having a lower portion to be secured to the lower leg and an upper pin bearing portion, the bearing portion of the upper joint member being pivotably engaged with the lower ends of the intermediate joint member by lower pins, the bearing portion of the lower joint member being pivotably engaged with the upper end of the intermediate joint member by an upper pin, whereby the thigh and lower leg can be united together pivotably at two positions, i.e., at the upper and the lower.

By securing the upper joint member to the thigh and the lower joint member to the lower leg, the thigh and the lower leg can be united together by upper and lower pins pivotally at two positions, i.e., at the upper and the lower, with the result that the pivotal motion takes place about two support points in the joint which are displaceable as desired in the same manner as the actual knee joint motion.

Accordingly, the joint mechanism of this invention, when embodied as a knee prosthesis, assures reproduction of the actual knee joint motion to permit trouble-free and smooth extension and flexion of the knee and satisfactory application where hardly any muscular power is available. Since the present prosthesis is serviceable over a prolonged period of time free of loosening at its anchorage to the support bone, it has the great advantage of being applicable to a wide variety of pathologic changes.

Further when embodied as a knee joint brace, the present joint mechanism properly follows the motion of the actual knee joint, making it sure to lessen the load on the joint and to render the brace bearing part free from skin abrasion, hence serviceable continuously with safety.

For a better understanding of the present invention, a detailed description will be given below with reference to accompanying drawings, in which:

FIG. 1 is an exploded perspective view showing an embodiment of the joint mechanism of the invention as it is applied to knee prosthesis;

FIG. 2 is a rear view of the same as it is assembled;

FIG. 3 is a side elevation of the same;

FIG. 4 is a view illustrating the same in a flexed state;

FIG. 5 is a front view partly in vertical section showing an embodiment of the joint mechanism of this invention as it is applied to knee joint brace;

FIG. 6 is a side elevation of the same;

FIG. 7 is a perspective view showing the same in a flexed state with part omitted; and

FIG. 8 is an enlarged view in section showing the pivotally movable portion of the same.

The knee prosthesis embodying this invention is molded of hard plastic, metal or like material which is inactive in vivo.

An upper joint member A is in the form of a casing-like frame 1 which is open at its bottom and at least one side for housing an intermediate joint member. The upper joint member A comprises a securing portion including a projection 3 projecting from the upper face of the upper wall 2 of the frame 1 to be anchored in the distal end of the femur, a bearing portion including a pair of recesses 5 and 5 formed in the under faces of the opposite side walls 4 and 4 of the frame 1 and defining semicircular surfaces, and a front wall 6 of the frame 1.

The lower joint member B comprises a securing portion including a projection 8 projecting from the under face of a disc 7 to be anchored in the proximal end of the tibia, a bearing portion including a recess 10 formed in the upper face of a support 9 extending upward from the plate 7 and having a semicircular surface, and a stopper in the shape of a stepped portion 11 formed in a lower front part of the support 9.

The intermediate joint member C comprises a pin 13 connecting the upper ends of legs 12 and 12 spaced apart by a required distance and pins 14 and 14 in alignment with each other and extending outward from the lower ends of the legs 12 and 12, the intermediate joint member C being in the form of a crank.

The upper pin 13 of the intermediate member C is fitted in the semicircular recess 10 in the lower joint member B, and the lower pins 14 and 14 of the intermediate joint member C are fitted in the semicircular recesses 5 and 5 in the upper joint member A, whereby the upper and lower joint members A and B are united together for pivotal movement about the upper and lower pins 13 and 14, i.e., at two positions of the lower and the upper.

According to the foregoing mode of embodiment of this invention, the projection 3 of the upper join member A is anchored in the distal end of the femur where the disabled joint element has been removed, and the projection 8 of the lower joint member B anchored in the proximal end of the tibia from which the disabled joint element has been removed. When thus installed in place to unite the thigh and the lower leg together, the present device achieves excellent effects as described below.

The uppper and lower pins 13 and 14 which unite the thigh and the lower leg together pivotably provide two support points for the knee motion which can be displaced as desired as illustrated in FIG. 4 permitting smooth and trouble-free extension and flexion of the knee in the same manner as the actual knee motion without requiring hardly any muscular power, hence applicable where almost no muscular power is available. The stable performance of the device eliminates an objectionable eccentric load acting on the portions where the projections 3 and 8 of the joint members A and B are anchored in the support bones, rendering the anchors free of loosening to assure trouble-free use over a long period of time. The ability to simulate the actual knee motion renders the device applicable to a wide variety of pathological changes.

The securing portions or anchorages for the upper and lower joint members A and B in the foregoing embodiments need not necessarily be in the form of projections 3 and 8 but may alternatively be coarse-surfaced portions or planer surfaces insofar as the device can be secured to the upper and lower support bones.

The knee joint brace shown in FIGS. 5 to 8, another embodiment of the present invention, has the following construction.

An upper joint member D comprises a securing portion and a pin bearing portion, the securing portion including a cylindrical cover 22 of a desired size to be fitted around the thigh and having free front ends 21 and 21 spaced apart by a required distance l in opposing relation to each other and a fastening string 23 extending between the opposing free ends 21 and 21 in engagement with hooks 21' thereon to reduce the distance l and to thereby fit the cover 22 intimately around the thigh, the pin bearing portion including connecting bars 24 and 24 vertically extending from the opposite sides of the cover 22 and formed with pin holes 25 in their lower ends respectively.

Similarly, a lower joint member E comprises a securing portion and a bearing portion. The securing portion includes a cylindrical cover 27 of a desired size to be fitted around the thigh and having free front ends 26 and 26 spaced apart by a require distance l' in opposing relation to each other and a fastening string 28 extending between the opposing free ends 26 and 26 in engagement with hooks 26' thereon to reduce the distance l' and to bring the cover 27 into intimate contact with the periphery of the lower leg. The bearing portion includes connecting bars 29 and 29 extending vertically from the opposite sides of the cover 27 and formed with pin holes 30 in their upper ends respectively.

An intermediate joint member F comprises a pair of short links 33 and 33 formed with pin holes 31 and 32 at their opposite ends respectively. Pins 34 and 34 are inserted into the holes 31 and 31 at the lower ends of the links 33 and 33 and into the holes 25 and 25 at the lower ends of the connecting bars 24 and 24 of the upper joint member D respectively to connect both the joint members D and E pivotably. Likewise, pins 35 and 35 are inserted into upper holes 32 and 32 in the links 33 and 33 and into the holes 30 and 30 at the upper ends of the connecting bars 29 and 29 of the lower joint member E to connect both the joint members E and F pivotably. In this way, the upper and lower joint member D and E are united together pivotably about the two upper and lower positions, i.e., about the pins 34, 34 and 35, 35 respectively.

To use the second embodiment of this invention described as a knee joint brace, the covers 22 and 27 of the upper and lower joint members D and E are fitted around and fastened to the thigh and the lower leg with the intermediate joint member F positioned at the opposite sides of the knee, whereby the following excellent effects and advantages will result.

The knee joint brace unites the thigh and the lower leg pivotably at the two upper and lower support points, which can be displaced as desired to produce a motion resembling the actual knee joint motion permitting the brace to properly follow the motion of the knee joint and making it sure to alleviate the load on the knee joint to achieve a remarkable efficacy in the remedy of the disabled knee joint. The above-mentioned ability of the present device to properly follow the knee motion serves to prevent the covers 22 and 27 from causing skin abrasion during extension, flexion and like knee motion while it is applied to the thigh and the lower leg. This ensures continuous use with safety.

The covers used as the joint members in this mode of embodiment must be made of a material having the desired body and soft feel and adapted for intimate contact. The connecting bars and links may suitably be made of a tough metal.

Although principal embodiments are given above, they are intended for illustrative purposes only and are not limitative in any way. One skilled in the art may be able to make various other alterations and modifications, which are to be included within the scope of this invention as set forth in the appended claims.

Claims

What I claim is:

1. A device for uniting the thigh and the lower leg to one another comprising a frame element forming an upper joint member, said frame element including an upper face to be secured to the distal end of the thigh and a pair of opposite side walls, the undersurface of each wall provided with a recess having a semicircular surface to form a pair of laterally spaced pin bearing portions, a lower joint member disposed beneath said upper joint member, said lower joint member including a bottom plate having an underface which is to be secured to the proximal end of the lower leg and an upper element extending upwardly from said bottom plate, said upper element having a recess formed in its upper edge, said recess having a semicircular surface and forming a centrally positioned pin bearing portion, an intermediate joint member positioned between said upper joint member and said lower joint member, said intermediate joint member having a configuration in the form of a crank and including a pair of laterally spaced vertically disposed leg portions, an upper, horizontally disposed pin portion connecting the upper end of each leg portion to one another, a lower, horizontally disposed pin portion extending outwardly from the lower end of each of said leg portions, each of said lower pin portions being fitted in the respective formed pin bearing portions of said formed upper joint member, and the upper pin portion of said intermediate joint member being fitted in the centrally positioned pin bearing portion of said lower joint member, thereby enabling the thigh and lower leg to be united pivotally at two upper and two lower positions.