Knee Brace

Abstract

A knee brace for support and protection of a knee joint comprises inner and outer bracing structures, each comprising two substantially rigid generally planar and elongated arms. Upper securing means secures one arm of each bracing structure parallel to the wearer's upper leg above the knee for movement with the upper leg and limited motion parallel to the upper leg, and lower securing means secures the other arm of each bracing structure parallel to the wearer's lower leg below the knee for movement with the lower leg and limited motion parallel to the lower leg. Each bracing structure has a first arm bifurcated to provide two generally parallel plate portions; the second arm has an end portion received between the plate portions for articular motion of the second arm relative to the first arm within a plane parallel to the planes of the plate portions; the plate portions prevent motion of the second arm out of the plane. The articular motion is determined by the normal flexion and extension of the wearer's knee and comprises any combination consistent therewith of rotation of the second arm about any axis through the first arm bifurcated end and the second end portion and normal to the plane, and translation of the second arm as a whole with respect to the first arm in any direction within the plane.

Description

This invention relates to knee braces.

The knee-joint has been described as a hinge joint, but it is really of a much more complicated character. It must be regarded as consisting of three articulations, of two different kinds. The first kind is a condyloid articulation; in this form of joint, an ovoid articular surface, or condyle, is received into an elliptical cavity in such a manner as to permit flexion, extension, abduction, adduction, and circumduction, but no axial rotation. The second kind of articulation involved is arthrodial; this is a joint which permits only gliding movement. It is formed by the apposition of plane surfaces, or one slightly concave, the other slightly convex, the amount of motion between them being limited by the ligaments or osseous processes surrounding the articulation.

The knee-joint is made up of two condyloid joints and a third joint, partly arthrodial, but not completely so, since the articular surfaces are not mutually adapted to each other, so that the movement is not a simple gliding one. The principal movements that take place at the knee-joint are flexion and extension. The movements of flexion and extension at this joint differ from those in a typical hinge joint, such as the elbow, in that the axis around which motion takes place is not a fixed one but shifts forward during extension, as a gliding movement is superposed on the rolling, and shifts backward during flexion.

Persons who have sustained knee injuries, who have had operations to remove cartilage, or who have weak knee joints from causes such as arthritis need protection principally against lateral motion of the knee, that is, motion transverse to the plane of flexion and extension. Such motion may be the result, for example, of a blow to the side of the knee. At the same time, a suitable knee brace should not interfere with the normal flexion and extension of the leg. The brace should protect the knee against sidewise motions during both flexion and extension; this means that the bracing structure should continue to lie parallel to the parts of the leg above and below the knee joint in all positions of the joint and that the intersection of the separate parts of the brace structure should remain substantially at the knee.

Many previous knee brace and protection devices have been simple hinged structures or structures pivotable about a fixed point, which cannot move parallel to the complex motion of the knee joint. As a result, while such structures may lie parallel to the leg while it is extended, as the leg is flexed the bracing structure fails to follow the motion accurately and at greatest flexion the portions of the brace will not lie parallel to the limb, the intersection being displaced from the joint to such a distance as to offer no support or protection against sidewise displacement of the joint.

It is accordingly a major object of this invention to provide a knee brace that is capable of substantially following the actual motion of the knee, so that the bracing portions remain in protective position with respect to the joint during flexion as well as extension.

It is a further object to provide such a brace that is adapted for comfortable wear, is easily secured and removed, and is readily adjustable to the shape and size of the wearer's leg.

It is another object to provide such a brace that does not interfere with normal extension and flexion of the wearer's leg, while preventing sidewise motion of the knee joint whether the leg is flexed or extended.

The knee brace of the invention includes a bracing structure comprising a first substantially rigid generally planar and elongated arm bifurcated at one end to provide two generally parallel plate portions, and a second substantially rigid generally planar and elongated arm, having an end portion received between the plate portions for sliding articular motion of the second part relative to the first arm coplanar with the plate portions. The plate portions substantially prevent motion of the second arm in any other plane.

In preferred embodiments, a knee brace for support and protection of a knee joint comprises inner and outer bracing structures, each comprising two substantially rigid generally planar and elongated arms. Upper securing means secures one arm of each bracing structure parallel to the wearer's upper leg above the knee for movement with the upper leg and limited motion parallel to the upper leg, and lower securing means secures the other arm of each bracing structure parallel to the wearer's lower leg below the knee for movement with the lower leg and limited motion parallel to the lower leg. Each bracing structure has a first arm bifurcated to provide two generally parallel plate portions; the second arm has an end portion received between the plate portions for articular motion of the second arm relative to the first arm within a plane parallel to the planes of the plate portions; the plate portions prevent motion of the second arm out of the plane. The articular motion is determined by the normal flexion and extension of the wearer's knee and comprises any combination consistent therewith of rotation of the second arm about any axis through the first arm bifurcated end and the second arm end portion and normal to the plane, and translation of the second arm as a whole with respect to the first arm in any direction within the plane.

Other objects, features and advantages will appear from the following description of a preferred embodiment of the invention, taken together with the attached drawings hereof, in which:

FIG. 1 shows two bracing structures according to the invention in place with respect to the extended leg of the wearer;

FIG. 2 shows the outer bracing structure in relation to the flexed leg of the wearer;

FIG. 3 is a perspective view of the inner bracing structure according to the invention;

FIG. 4 is a detail of a portion of FIG. 3;

FIGS. 5 and 6 are perspective views of the outer and inner aspects, respectively, of the knee brace of the invention, and

FIG. 7 is a longitudinal section through the knee brace, taken along the line 7--7 of FIG. 5.

Referring now to the drawings, and in particular to FIGS. 1-4, the knee brace of the present invention includes two bracing structures, each of which comprises two arms. The inner leg bracing structure 10 comprises a first rigid arm 12, generally planar and elongated, and bifurcated at one end to provide two generally parallel plate portions 14 and 16, joined by inner surface 32. A second rigid arm 20 is similarly generally planar and elongated and has an end portion 22 providing a front edge 21, and received between plate portions 14 and 16 of the first arm 12. Each arm of the bracing structure may desirably be ribbed for strength throughout all or a portion of its length, as at 24 and 26. End portion 22 of arm 20 is cut out to provide a slot 17 having curved front edge 18 and straight back edge 28. It is important that edge 18 be curved as shown, but edge 28 need not necessarily be straight. Plates 14 and 16 are desirably connected by rivet 30, but such connection is not essential to the function of the knee brace, as is discussed in what follows.

Arm 12 of inner leg bracing structure 10 is curved to conform to the contour of the inner leg below the knee, as shown in FIG. 1. As a result of this conformation, the bracing structure is in good contact with the leg, and any force acting sidewise on the leg is readily absorbed. Outer leg bracing structure 34 is similarly composed of a bifurcated lower arm 36 and an upper arm 38 joined to it in the same manner as that described for structure 10. However, lower arm 36 is not curved to conform to the leg but is straight.

Within the plane defined by plate portions 14 and 16, upper arm 20 may rotate about any axis that passes through plate portions 14 and 16 of lower arm 36 and that is normal to the defined plane; upper arm 20 may also be translated as a whole with respect to lower arm 36 in any direction within the defined plane. This combination of motions results in an arthromimetic articular motion of the two arms with respect to one another, providing a relative motion that closely parallels the natural action of the knee joint. Since the articular motion is not constrained to follow any defined path but is made up of any combination of rotation and translation, the action of the joint can accurately follow the action of the individual wearer's knee. The upper and lower arms of the bracing structure remain generally parallel to the upper and lower parts of the wearer's leg even at greatest flexion, and end 22 remains substantially adjacent the knee joint, continuing to provide protection against sidewise forces.

When the two bracing structures 10 and 34 are retained in the harness, to be described, the relative translational motion of the two arms is limited by the harness; rivet 30 and slot 17 are not in practice essential to the operation of the invention.

Referring now to FIGS. 5, 6 and 7, the two bracing structures 10 and 34 are retained in a harness to compose the knee brace 40 of the invention. Essentially, the harness provides an upper strap 42 and a lower strap 44 immovably secured with respect to inner leg bracing structure 10, and attachable to outer leg bracing structure 34. An elastic cuff and internal padding are provided for comfortable wear.

Upper arm 38 of outer leg bracing structure 34 is retained in a leather pocket 48, composed of inner layer 48-1 and outer layer 48-2; lower arm 36 is retained in leather pocket 46, composed of inner layer 46-1 and outer layer 46-2. These pockets are secured, as by switching at 50, to an electric cuff 52, composed preferably of a two-way stretch material. Outer layers 48-2 and 46-2 do not extend to cover the overlapping joint portion of arms 36 and 38; an outer cover 54 of elastic material is secured by stitching at 55, covering the joint of bracing structure 34, but leaving room for articular motion as described above of arm 38 relative to arm 36. Inner pocket layers 48-1 and 46-1 overlap under the joint of structure 34.

Elastic cuff 52 is desirably provided with a centered back hole 70, to prevent binding of the cuff material when the knee is flexed, and a centered front hole 72, to aid the wearer in centering the harness over the knee cap.

Two rigid posts 60 and 62 extend through outer layer 48-2 of pocket 48 and are thereby rigidly secured with respect to upper arm 38 of bracing structure 34. Similar posts 64 and 66 are provided for lower arm 36. Internal pads 67, 68 and 69 of foam rubber are provided within elastic covers 73, 74 and 75 adjacent the upper end of arm 38, the joint of bracing structure 34, and the lower end of arm 36 respectively.

Inner leg bracing structure 10 is retained in similar leather pockets 80 and 82, with outer elastic cover 84 and inner pads 86, 87 and 88. Upper strap 42 is placed between pocket 82 and cuff 52, and the stitching 90 secures both pocket and strap to the cuff; strap 42 is thus held in perpendicularly fixed relation to upper arm 20 of inner bracing structure 10. Similarly, lower strap 44 is held by stitching 92 in similarly fixed relation to lower arm 12.

The upper and lower arms of bracing structures 10 and 34 are thus retained in the leather pockets of the harness and are prevented by the pockets from angular motions with respect to the wearer's legs; however, the arms are free to slide small distances longitudinally within the pockets, providing additional flexibility in following the action of the brace wearer's knee.

Upper strap 42 provides a back strap portion 94 with two rows of holes 96, and two front strap portions 98 and 100 each with a row of holes 102. To secure the knee brace 40, the wearer, after centering front hole 72 over the knee cap, brings back strap portion 94 around to outer bracing structure 34, and fastens the strap by inserting posts 60 and 62 through the particular holes 96 that provide a comfortable fit. The wearer then brings front strap portions 98 and 100 around and fastens them to posts 60 and 62. The divided nature of the front portion of strap 42 enables the strap to conform to the shape of the leg, which is generally conical rather than cylindrical, and prevents gaping of the strap. Lower strap 44 is similarly secured to posts 64 and 66. Two points of fixed location with respect to each arm are required to maintain the needed perpendicular connection and to prevent pivoting of the strap with respect to the arm, and to ensure that angular motion of the leg drags the arm along with it, preventing any angular shift of the bracing structure with respect to the leg.

In alternative embodiments, posts 60, 62, 64 and 66 and corresponding holes 96 and 98 could be replaced by other fastening means, such as strips of hook and pile fastener, buckles, ties, snaps or the like.

Claims

What is claimed is:

1. A knee brace for support and protection of a knee joint comprising

inner and outer bracing structures, each said bracing structure comprising two substantially rigid generally planar and elongated arms,

upper securing means securing one said arm of each said bracing structure parallel to the wearer's upper leg above the knee for movement with the upper leg and limited motion parallel to the upper leg,

lower securing means securing the other said arm of each said bracing structure parallel to the wearer's lower leg below the knee for movement with the lower leg and limited motion parallel to the lower leg,

each said bracing structure having a first said arm bifurcated to provide two generally parallel plate portions, and a second said arm having an end portion providing a smoothly curved edge, said end portion being received between said plate portions for articular motion of said second arm relative to said first arm within a plane parallel to the planes of said plate portions, said plate portions preventing motion of said second arm out of said plane,

said second arm end portion having a hemispheric slot having a curved front edge and a straight back edge and said first arm bifurcated end having a pin passing through said slot and connected said arms together, said slot being substantially larger than said pin diameter,

said articular motion being determined by the normal flexion and extension of the wearer's knee and comprising any combination consistent therewith of

rotation of said second arm about any axis through said first arm bifurcated end and said second arm end portion and normal to said plane, and

translation of said second arm as a whole with respect to said first arm in any direction within said plane.

2. A knee brace for support and protection of a knee joint comprising

inner and outer bracing structures, each said bracing structure comprising two substantially rigid generally planar and elongated arms,

upper securing means securing one said arm of each said bracing structure parallel to the wearer's upper leg above the knee for movement with the upper leg and limited motion parallel to the upper leg,

lower securing means securing the other said arm of each said bracing structure parallel to the wearer's lower leg below the knee for movement with the lower leg and limited motion parallel to the lower leg,

each said bracing structure having a first said arm bifurcated to provide two generally parallel plate portions, and a second said arm having an end portion providing a smoothly curved edge, said end portions being received between said plate portions for articular motion of said second arm relative to said first arm within a plane parallel to the planes of said plate portions, said plate portions preventing motion of said second arm out of said plane,

said knee brace further including an elastic cuff adapted to be worn adjacent the knee joint,

said upper and lower securing means including pockets secured to said cuff and retaining said arms to maintain said second arm end portion between said first arm plate portions and permitting limited translation of one arm relative to the other,

said articular motion being determined by the normal flexion and extension of the wearer's knee and comprising any combination consistent therewith of

rotation of said second arm about any axis through said first arm bifurcated end and said second arm end portion and normal to said plane, and

translation of said second arm as a whole with respect to said first arm in any direction within said plane.

3. The knee brace of claim 2 wherein

said pockets retaining said outer bracing structure upper and lower arms each have two attaching means spaced along said arm,

said upper securing means including an upper strap secured in perpendicularly fixed relation to said pocket retaining said inner bracing structure upper arm and removably securable in perpendicularly fixed relation to said pocket retaining said outer bracing structure upper arm,

said lower securing means including a lower strap secured in perpendicularly fixed relation to said pocket retaining said inner bracing structure lower arm and removably securable in perpendicularly fixed relation to said pocket retaining said outer bracing structure lower arm,

said upper strap providing a back portion removably securable to said two attaching means in said outer bracing structure upper arm pocket, and two front portions each removably securable to a said attaching means on said outer bracing structure upper arm pocket, and

said lower strap providing a back portion removably securable to said two attaching means on said outer bracing structure lower arm pocket, and two front portions each removably securable to said attaching means on said outer bracing structure lower arm pocket.