CA2831507C

CA2831507C - Brace

Info

Publication number: CA2831507C
Application number: CA2831507A
Authority: CA
Inventors: Bob Garrish
Original assignee: Spring Loaded Technology Inc
Current assignee: Spring Loaded Technology Inc
Priority date: 2013-10-31
Filing date: 2013-10-31
Publication date: 2021-08-17
Anticipated expiration: 2033-10-31
Also published as: CA3122981A1; CA2831507A1

Abstract

A brace for augmenting the extension of a limb. In a knee brace embodiment the brace comprises an upper arm for engaging against the femoral portion of a user's leg pivotally connected to a lower arm for engaging against the tibial portion of the user's leg. At least one compression element is fixed to one of the upper and lower arms. A substantially inelastic tensioning element such as a cord is affixed to the head through the compression element such that applying a tensile force to the cord compresses the compression element. The cord is affixed to the other arm over a tensioning member, so that applying a force to bend the knee brace to a flexed position tensions the cord and compresses the compression element. Upon removal of the flexing force the compression element applies a restoring force to urge the knee brace back to the extended position.

Description

BRACE
FIELD OF THE INVENTION
[0001] This invention relates to braces, and in particular a brace for supporting and/or assisting the extension of a limb.
BACKGROUND OF THE INVENTION

[0002] As is well known, a knee brace can perform a purely prophylactic function, or provide an assistive force that helps the user to extend their knee, or both. Knee braces can provide physical protection against injury, and may for example be used by athletes involved in high-risk sports where there is a relatively high susceptibility to sustaining a knee injury.

[0003] Many individuals suffer from knee problems, often due to a prior knee injury. Some such problems can significantly affect mobility and/or the ability to support the injured person. While corrective measures such as exercise and physiotherapy, or in more serious cases surgery, can assist in correcting or partially alleviating some knee problems, there remains a need in many cases for knee support and extension augmentation.

(0004] Particularly where there has been ligament damage, for example a tear or strain in the anterior cruciate ligament (ACL), medial collateral ligament (MCL) or lateral collateral ligament (LCL), a knee brace can be used to both provide support and enhance extension strength, and thus reduce the load on the injured knee.
Conventional knee braces that provide active assistance to knee extension are designed to yield when the knee is flexed, loading a torsion spring or compression spring in the process. The spring is loaded when the user bends their leg, and when extending their leg the spring unloads applying a force that augments the extension action. This also helps to support the user and prevent collapse if the injured knee buckles.

[0005] However, conventional springs do not provide sufficient force to significantly enhance knee extension or resist buckling of the knee. It would accordingly be advantageous to provide a mechanical substitute for a steel spring that is light-weight, and provides effective enhancement of the knee extension action in cases where strength enhancement is needed and resistance to buckling of the knee.
BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In drawings which illustrate by way of example only a preferred embodiment of the invention,

[0007] Figure 1 is a side elevation of an embodiment of a knee brace according to the invention with the brace in an extended condition.

[0008] Figure 2 is a side elevation of the knee brace of Figure 1 with the brace in a flexed condition.

[0009] Figure 3 is a side elevation of the compression element in the relaxed condition when the knee is extended.

[0010] Figure 4 is a side elevation of the compression element in the loaded condition when the knee is flexed.

[0011] Figure 5 is a front perspective view of a further embodiment of a knee brace according to the invention.

[0012] Figure 6 is a perspective view of a further embodiment of a knee brace according to the invention utilizing a liquid die spring compression element.

[0013] Figure 7 is an exploded view perspective of the liquid die spring in the knee brace of Figure 6.

[0014] Figure 8 is a cross-sectional side elevation of the compression element in the knee brace of Figure 6, in the relaxed condition when the knee is extended.
10015] Figure 9 is a cross-sectional side elevation taken opposite Figure 8, in the loaded condition when the knee is fully flexed.
[0016] Figure 10 is a schematic perspective view of an embodiment of the tensioning system having an ovate pivot.

[0017] Figure 11 is a schematic perspective view of an embodiment of the tensioning system having a circular pivot mounted eccentrically.
[0018] Figure 12 is a schematic perspective view of an embodiment of the tensioning system having an elongated pivot.
[0019] Figure 13 is a side elevation of a further embodiment of the invention in an extended position.
[0020] Figure 14 is a side elevation of the embodiment of Figure 13 in a flexed position.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The invention will be described in the context of a knee brace for humans.
However, it will be appreciated that the principles of the invention apply equally to braces for other human body appendages and to braces for animals including (without limitation) horses, dogs and cats.
[0022] The invention thus provides a brace for augmenting extension of a joint, in the embodiment shown a user's knee, comprising an upper arm having an engaging portion for engaging against the user's leg above the knee, and an attachment portion, a lower arm having an engaging portion for engaging against the user's leg below the knee, and an attachment portion, the lower arm attachment portion being pivotable relative to the upper arm attachment portion, and at least one compression element disposed in fixed relation to at least one of the upper and lower arms, and a substantially inelastic tensioning element affixed to the other of the upper and lower arms over at least one tensioning member such that applying a force to bend the knee brace to a flexed position loads the compression element, and upon removal of the flexing force the compression element applies a restoring force to urge the knee brace back to the extended position.
[0023] A preferred embodiment of a knee brace 10 for augmenting extension of a user's knee 6 is illustrated in Figures 1 and 2 by way of example. The knee brace 10 conventionally comprises an upper arm 12 having an engaging portion 12a for engaging against the femoral portion 2 of a user's leg, for example the front of the femoral portion 2 as illustrated, and an attachment portion 12b; and a lower arm 14 having an engaging portion 14a for engaging against the tibial portion 4 of the user's leg, for example the rear of the tibial portion 4 as illustrated, and an attachment portion 14b. The upper arm 12 is formed with a contour that comfortably engages against the user's quadricep 2, which may be padded for additional comfort, and may be secured to the leg by a top strap 20 and an upper cruciate strap 22 as is conventional. The lower arm 12 is formed with a contour that comfortably engages against the user's calf 4, which similarly may be padded for additional comfort, and may be secured to the leg by a bottom strap 24 and optionally a lower cruciate strap (not shown).
[0024] The lower arm attachment portion 14b is pivotally connected to the upper arm attachment portion 12b as at pivots 16, 17. Each pivot 16, 17 is rotationally affixed to a connecting element such as a gusset 18 (best seen in Figure 5) so that the upper and lower arms 12, 14 can pivot relative to the gusset 18, and thus relative to each other. As shown in Figures 1 and 2, when the knee brace is in position the pivots 16, 17 are disposed on either side of the leg along the axis of rotation of the knee 6, and the arms 12, 14 freely pivot relative to one another as the knee 6 flexes and extends. In use the brace 10 is positioned so that the two pivots 16, 17 are aligned with the two pivot points in the knee 6. In other embodiments the arms 12, 14 may be geared to each other, or otherwise coupled by a linkage such that they rotate together.
[0025] The knee brace 10 illustrated applies a force to assist the user in extending the knee 6 when the knee 6 has been flexed. As illustrated, this restoring force is supplied by a tensioning system comprising at least one compression element 30 fixed to at least one of the upper and lower arms 12, 14. In the preferred embodiment a compression element 30 is fixed to each of the upper and lower arms 12, 14.
[0026] The compression element 30 comprises a rigid base 32, in the embodiment shown in Figures 1 to 4 a hollow cylinder having a floor 32a and a wall 32b.
The compression element 30 may be formed integrally with the arm 12, 14 as shown, or may be a separate component which is bolted, riveted or otherwise fastened to the exterior surface of the arm 12 or 14. Figure 5 for example illustrates an embodiment of the knee brace 10 utilizing compression members 40 having a generally rectangular cross-section, fixed within openings 29 in the upper and lower arms 12, 14.
100271 The compression element 30 further comprises an elastomeric element 34 seated against the floor 32a of the base 32, and a rigid head 36 spaced from the floor 32a of the base 32 and overlaying the elastomer 34. The base 32 and head 36 may for example be composed of metal or a rigid plastic strong enough to withstand the force of the elastomer 34 when under compression, as described below. The elastomer may for example be a block of polyurethane, preferably having a hardness in the range of 25 to 70 Shore D, most preferably in the range of 30 to 60 Shore D, and thus being compressible to a desired extent depending upon the degree of extension augmentation required for a particular application or individual.
00281 The elastomer 34 is essentially sandwiched between the floor 32a of the base 32 and the head 36. It is possible to form the base 32 as a floor only, without the wall 32b, which would still allow for the compressive loading of the compression element 30 in the manner described below. However, providing a rigid wall 32b to contain the elastomer 34 advantageously increases the compression resistance of the elastomer 34, because the wall 33b prevents the elastomer 34 from expanding laterally as the head 36 is drawn toward the base 32 in the manner described below. Also, forming the base 32 as a container is beneficial aesthetically and keeps the elastomer clean.
Further reduction of the compressibility of the elastomer 34 may be achieved by intermixing elastomeric elements with incompressible elements such as metal washers, for example by separating the elastomer block into pieces and interspersing metal washers between the elastomer pieces.
100291 A flexible tensioning element such as a substantially inelastic cord 38 is fixed to the head 36 through the elastomer 34 and the base 32, as best seen in Figures 3 and 4. Applying tensile force to the cord 38 draws the head 36 toward the base 32 to compress the elastomer 34. The cord 38 may be retained through the head 36 by a washer 36a crimped or clinched to grasp the end of the cord 38. Alternatively, the head 36 may be formed around the cord 38, or any other suitable manner of engagement of the cord 38 to the head may be used.

[0030] The other end of the cord 38 is attached to the other arm 12 or 14.
In the preferred embodiment, a compression element 30 is fixed to both of the upper and lower arms 12, 14, which reduces the force required to achieve the same amount of compression when the knee is flexed, in comparison to using a single compression element 30.
[0031] The cord 38 is fixed between the two compression elements 30 such that it runs over a tensioning member, and is taut when the compression elements 30 are in the fully unloaded condition shown in Figures 1 and 3. In the embodiment shown pivots 16 and 17 form the tensioning member. The cord 38 may be retained about the pivots 16, 17 in any conventional fashion, for example the pivots 16, 17 may provide a circumferential slot through which the cord 38 runs as shown in Figure 5, or the cord 38 may be retained about the pivots 16, 18 by a housing or cap (not shown) which forms a channel preventing the cord 38 from slipping off of the pivots 16, 17 as tension is applied to the cord 38. Alternatively, a separate tensioning member such as a post or rivet (not shown) may be provided to retain an intermediate portion of the cord 38 near the front of the brace 10 around the region of the knee 6.
[0032] The cord is preferably composed of a polyethylene fibre, for example Honeywell Spectra (TM) high-strength light-weight polyethylene fibre, which has a very high tensile strength. This type of material also has a very low coefficient of friction, so it easily slides along the pivots 16, 17 without significant wear or resistance to the user's motion. Alternatively, the tensioning member may comprise rollers (not shown), if desired, to reduce friction. The pivots 16, 17 can be free-rotating, fixed to the gusset 18, or fixed to either or both of the arms 12,14 (and thus rotating with the arms 12, 14); and/or one or more separate wheels 56, 57 may be fixed to or near either or both of the pivots 16, 17 to form a tensioning member or tensioning members, for example as shown in Figure 11. There may be one or two pivots 16, 17. In embodiments where there are two cylinders 30, a single cord could be attached to both cylinders 30 or two cords 38 could be affixed to or near the gusset. In embodiments where there is one cylinder 30, the free end of the cord 38 can be attached to the gusset, the second pivot 16 or 17, or the other arm 12 or 14.

[0033] In use, the user affixes the knee brace 10 to their leg via straps 20, 22 and 24 in conventional fashion. With the knee 6 in the extended position shown in Figure 1, the compression elements 30 are in a relaxed condition with no compressive load on the elastomer block 34. When the user flexes their knee 6 to the flexed position shown in Figure 2, a force is applied to the tensioning cord 38 as the compression elements 30 are forced away from the tensioning member (pivots 16, 17). This tensions the cord 38, which draws on the head 36 of each compression element and compresses the elastomeric block 34, loading the compression elements 30, the compressive load increasing as the knee 6 is flexed. Upon removal of the flexing force the compression elements 30 release the stored energy and apply a restoring force to urge the knee brace 10 back to the extended position, augmenting the user's extension force.
[0034] Providing a compression element 30 on each of the upper and lower arms 12, 14 allows the compression elements 30 to be smaller (and therefore lighter), while still providing the required length of travel and recovery force needed to allow the user to fully flex and extend the knee. In a further embodiment illustrated in Figure 6, the compression element comprises a liquid die spring 60, illustrated in detail in Figures 7 to 9. The liquid die spring 60 relies on fluid compression to load the spring, and thus in this embodiment a single compression element can provide sufficient restoring force to assist with knee extension.
[0035] In the embodiment of Figure 6 the knee brace 50 comprises upper and lower arms 52, 54 pivotally connected at gusset 58 via respective upper and lower pivots.
The liquid die spring 60 illustrated comprises a housing 62 defining two liquid-filled cylinders 64 and a channel 66 sized to slidably receive a piston element 70, as best seen in Figures 8 and 9. The piston element 70 comprises a pair of piston heads 72 connected by a head bridge 74, and like the housing 62 is preferably cast or machined as an integral unit from 304 stainless steel, or chromed carbon steel, or another suitably strong, rigid material capable of withstanding the pressures experienced by the liquid die spring 60 in normal use. The free end of each piston head 72 extends through a hydraulic seal 76 at the opening of the respective cylinder 64, and intrudes slightly into its associated cylinder 64 when the spring 60 is in the rest (unloaded) condition shown in Figure 8.

[0036] A flexible, non-elastic cord 78 is affixed to the head bridge 74 and slidably extends through the housing 62 between the two cylinders 64. The cord 78 is connected to any convenient point below the upper arm 52 that is fixed relative to the pivoting motion of the upper arm 52, in the example shown to the lower pivot 57 as illustrated in the embodiment of Figure 6. Thus, as the lower arm 54 pivots toward the upper arm 52 the piston element 70 is drawn toward the lower arm 54, forcing the piston heads 72 into the cylinders 64 and compressing the hydraulic fluid therein, loading the die springs 60. When the user extends their knee the die springs 60 apply a restoring force to assist the extension.
10037] Hydraulic fluid is compressible, but provides a very high resistance to compression. Accordingly, the piston heads 74 preferably have a very small diameter, which means a very small volume in comparison to the volume of the cylinder 64.
This allows for a full a compression full stroke of the piston element 70, to the point shown in Figure 9, before the hydraulic fluid is compressed to the point that the user's weight cannot overcome the compressive resistance of the die spring 60.
100381 The above embodiments provide relatively uniform linearly increasing compression and release curves, so that the same amount of strength is required to load the compression element 30 or 60 whether at the beginning or the end of the path of travel of the knee brace; and likewise the same amount of assistive force is provided by the compression element 30 or 60 whether at the beginning or the end of the path of travel of the knee brace. In all embodiments it is possible to change the load characteristics at different points along the path of travel of the knee brace, for example by mounting circular pivots 56, 57 (or 16, 17) eccentrically, as shown in Figure 11, or by using oblong or otherwise non-circular pivots 80, 82 or 84, 86, as shown respectively in Figures 10 and 12. In these embodiments, because the pivot rotates with the arm, the length of cord 78 which is drawn out of the compression element 60 over a given length of travel of the lower arm 54 relative to the upper arm 52 varies, depending upon the shape and position of the pivot at any specific point in the path of travel. Thus, in cases where a particular pathology may require a greater restoring force or lesser loading force at one or more specific points in the flexing cycle, the pivot can be designed to provide a non-linear force curve to accentuate assistance or reduce the force required for loading at the specific point or points.

[0039] Figures 12 and 13 illustrate an embodiment of the invention 10 having a single compression element 60 disposed on the upper arm 12. The cord 78 in this embodiment extends over pivot 92 affixing the upper arm 12 to the gusset 18, retained against dislodgement by a retaining wheel 94 which may be fixed or free-rolling. A
further pivot 90 affixing the lower arm 14 to the gusset 18 is ovate and oriented such that the resistance of the compression element 60 to flexing of the brace 10 increases as the angle between the arms 12, 14 diminishes.
[0040] Various embodiments of the present invention having been thus described in detail by way of example, it will be apparent to those skilled in the art that variations and modifications may be made without departing from the invention. The invention includes all such variations and modifications as fall within the scope of the appended claims.

Claims

I CLAIM:

1. A knee brace for augmenting extension of a user's knee, comprising an upper arm having an engaging portion for engaging against the user's leg above the knee, and an attachment portion, a lower arm having an engaging portion for engaging against the user's leg belovv the knee, and an attachment portion, the lower arm attachment portion being pivotable relative to the upper arm attachment portion, at least a first compression element comprising a liquid die spring comprising a housing defining at least a first liquid-filled cylinder and a first piston element having a piston head extending axially through a hydraulic seal into the first cylinder, wherein one of the first cylinder and first piston is disposed in fixed relation to at least one of the upper and lower arms and the other one of the first cylinder and first piston being movable relative to the one of the upper and lower arms, and a substantially inelastic tensioning element affixed to the moveable one of the first cylinder and the first piston and to the other one of the upper and lower arms over at least one tensioning element tensioning member and is configured so that when a flexing force is applied to pivot the upper arm relative to the lower arm to move the knee brace from an extended position to a flexed position tension is applied to the tensioning element thereby urging the first piston further into the first cylinder to compress the liquid within the first cylinder and load the liquid die spring, and wherein upon removal of the flexing force the compression element applies a restoring force to urge the knee brace back to the extended position.

2. The knee brace of claim 1 wherein the tensioning element is attached to the other of the upper and lower arms via a second compression element fixed to the other of the upper and lower arms, the second compression element comprising a second liquid-filled cylinder and a second piston element having a piston head extending axially through a hydraulic seal into the second cylinder.

3. The knee brace of claim 1 wherein the lower arm attachment portion and the upper arm attachment portion are pivotally connected to a connecting element.
Date Recue/Date Received 2020-10-21

4. The knee brace of claim 3 wherein the at least one tensioning member comprises at least one pivot connecting the upper arm or the lower arm to the connecting element.

5. The knee brace of claim 4 wherein the at least one pivot comprises a circumferential groove for retaining the tensioning element.

6. The knee brace of claim 4 wherein the at least one tensioning member comprises the at least one pivot connecting each of the upper arm and the lower arm to the connecting element.

7. The knee brace of claim 4 wherein the at least one pivot is mounted eccentrically.

8. The knee brace of claim 4 wherein the at least one pivot is non-circular.

9. The knee brace of claim 4 wherein the at least one pivot is free-rotating.

10. The knee brace of claim 4 wherein the at least one pivot is fixed in relation to one of the upper arm and the lower arm or a gusset joining the upper and lower arms together.

11. The knee brace of claim 6 wherein at least one wheel is affixed to or near the at least one pivot to form one or more tensioning members.

12. The knee brace of claim 2, wherein the tensioning element comprises a separate flexible element attached to the first cylinder and the second cylinder and affixed to or near the at least one pivot.

13. A brace for augmenting extension of a joint in a limb, comprising an upper arm having an engaging portion for engaging against the limb on one side of the joint, and an upper arm attachment portion, a lower arm having an engaging portion for engaging against the limb on the other side of the joint, and a lower arm attachment portion, the lower arm attachment portion being pivotable relative to the upper arm attachment portion, 4813-3712-0463, v. 1 Date Recue/Date Received 2020-10-21 at least one compression element disposed in fixed relation to at least one of the upper and lower arms, and at least a first compression element comprising a liquid die spring comprising a housing defining at least a first liquid-filled cylinder and a first piston element having a piston head extending axially through a hydraulic seal into the first cylinder, wherein one of the first cylinder and first piston is disposed in fixed relation to at least one of the upper and lower arms and the other one of the first cylinder and first piston being movable relative to the one of the upper and lower arms, and a substantially inelastic tensioning element affixed to the moveable one of the first cylinder and the first piston and to the other one of the upper and lower arms over at least one tensioning element tensioning member and is configured so that when a flexing force is applied to pivot the upper arm relative to the lower arm to move the brace from an extended position to a flexed position tension is applied to the tensioning element thereby urging the first piston further into the first cylinder to compress the liquid within the first cylinder and load the liquid die spring, and wherein upon removal of the flexing force the compression element applies a restoring force to urge the brace back to the extended position.

14. The brace of claim 13 wherein the tensioning element is attached to the other of the upper and lower arms via a second compression element fixed to the other of the upper and lower arms.

15. The brace of claim 13 wherein the lower arm attachment portion and the upper arm attachment portion are pivotally connected to a connecting element.

16. The brace of claim 15 wherein the at least one tensioning member comprises at least one pivot connecting the upper arm or the lower arm to the connecting element.

17. The brace of claim 16 wherein the at least one pivot comprises a circumferential groove for retaining the tensioning element.
4813-3712-0463, v. 1 Date Recue/Date Received 2020-10-21

18. The brace of claim 16 wherein the at least one tensioning member comprises the at least one pivot connecting each of the upper arm and the lower arm to the connecting element.

19. The brace of claim 16 wherein the at least one pivot is mounted eccentrically.

20. The brace of claim 16 wherein the at least one pivot is non-circular.

21. The brace of claim 16 wherein the at least one pivot is free-rotating.

22. The brace of claim 16 wherein the at least one pivot is fixed in relation to one of the upper arm and the lower arm or a gusset joining the upper and lower arms together.

23. The brace of claim 13 wherein at least one wheel is affixed to or near the at least one pivot to form one or more tensioning members.

24. The brace of claim 14 wherein the tensioning element comprises a separate flexible element attached to the first cylinder and affixed to or near the at least one pivot.
4813-3712-0463, v. 1 Date Recue/Date Received 2020-10-21