US3086521A

US3086521A - Lower leg brace

Info

Publication number: US3086521A
Application number: US87417A
Authority: US
Inventors: Desai Shrikant; William H Henderson; Charles W Radcliffe
Original assignee: University of California
Current assignee: University of California
Priority date: 1961-02-06
Filing date: 1961-02-06
Publication date: 1963-04-23
Anticipated expiration: 1980-04-23

Description

April 23, 1963 s. DESAI ETAL 3,086,521

LOWER LEG BRACE Filed Feb. 6, 1961 2 Sheets-Sheet 1 INVENTORS 47 SHRIKANT DESAI I W LLIAM H. HENDERSON /I f 48 BY CH R DCLIFF s 16 '56. 5 KHZ/1y Ap 1963 s. DESAI E'I 'AL 3,086,521

LOWER LEG BRACE Filed Feb. 6, 1961 2 Sheets-Sheet 2 INVENTORS, SHRIKANT DEsAI WILLIAM HENDERSON H BY CHARLES w. (LII-Z5 AID.

United States Patent 3,086,521 LOWER LEG BRACE Shrikant Desai, Berkeley, William H. Henderson, Pacifica, and Charles W. Radcliffe, Lafayette, Calif., assignors to 'ghe Regents of the University of California, Berkeley,

Filed Feb. 6, 1961, Ser. No. 87,417 '7 Claims. (Cl. 12880) This invention relates to bracing devices for human limbs and more particularly it relates to an improved leg brace of the below-knee or short-leg type.

The major objective of the present invent-ion is to provide a greatly improved leg brace that not only affords adequate support for disabled or paralyzed human limbs, but which also provides for the normal articulation of the foot about its natural anatomical axes and which overcomes many serious deficiencies of prior art braces.

The leg-bracing problem, viewed from the standpoint of the necessary or desirable performance of the bracing device, may be generally stated as being that of: first, providing adequate support or stability for the disabled or paralyzed limb; secondly, providing simultaneously for the freedom of movement of the foot about its natural anatomical axes so that it can be positioned properly to perform a share of the body supporting function, and so that it can aid mobility during walking or articulation of the limb; and thirdly, of providing for the application of external forces to replace the loss of muscle power or to overcome an imbalancing of muscle forces about the various joints. The various forms of lower-leg brace-s usedprior to the present invention failed to provide these necessary prerequisites for proper bracing because they did not provide a means to compensate for the complex anatomical structure of the human leg, ankle and foot, the bones of which constitute the links of an internal mechanical system. For example, the lower-leg braces heretofore used provided articulation of the foot about only one mechanical axis, and thus limited the foot to movement about only one anatomical axis. One serious disadvantage with this arrangement was that the wearer of the brace, being restricted by the brace to a movement having but a single degree of freedom, could not manipulate his foot to assume a proper position of alignment with the supporting bones of the leg below the hip. Thus, in walking with such braces, the major portion of the body weight often had to be supported by the arms instead of the legs and this resulted in serious fatigue and discomfort. It also put greater stress on the bracing components which thus had to be relatively large to provide the necessary strength .and rigidity.

Another problem which arose as a result of the aforementioned lack of articulation about the natural joint axes, was that of compensating for abnormal muscle imbalance about certain joint axes which often occurs in leg paralysis cases. The braces heretofore used did not provide for movement about both of the major anatomical joints in the ankle and foot and thus they did not provide .a means to supply forces to overcome abnormal twisting of the foot due to such muscle defects. For example,

the lower-leg braces heretofore used had no means of serious (lllfiCllltlCS during walking since it prohibited the foot from positioning itself with respect to the leg bones in order to support the weight of the body.

Still another problem with leg braces of the prior art "ice I was a tendency for the brace members to shift their position during movement of the leg, thus causing chafing or constriction of the leg where the brace cuff was attached to the leg. This problem primarily arose from the fact that the mechanical axis of the brace was not aligned with the anatomical axis of the equivalent joint. For example, during walking, the misalignment of the mechanical and anatomical ankle axis caused movement of the brace cuff along the leg which resulted in chafing and discomfort to the brace wearer. In severe cases, additional accessory straps were often required to maintain the brace in position.

The present invention solves the aforementioned problems and overcomes the disadvantages of prior art lowerleg braces by providing a lower-leg brace having a novel combination of elements arranged toprovide two axes of articulation, thus forming an external mechanical bracing system which affords the equivalent movement of the internal anatomical system. The brace components are arranged in a novel manner so that the two mechanical axes of movement become substantially aligned with the ankle axis and subtalar axis of the foot when the brace is properly attached to the wearer. Our invention also provides means for overcoming muscle imbalance, when necessary, by application of a tension means to counteract abnormal rotation about a particular joint axis. Thus, the invention provides for the maximum utilization of available musculature consistent with maximum mobility.

In summarizing the objects of the invention, one important object is to provide a lower-leg brace which not only provides adequate support to a disabled or paralyzed limb but which is compatible with the kinematics of the human anatomical foot structure and thus affords the full freedom of articulation of the foot about its natural anatomical axes.

Another object of the invention is to provide a brace that will counteract abnormal unbalancing muscle forces in the partially paralyzed human foot to hold the foot in a desired position during walking.

Another object is to provide a brace that will provide a movement around mechanical axes coincident with the principal anatomical axes of the subtalar and ankle joints when the brace is attached to the wearer.

Another object is to provide a lower-leg brace that eliminates restriction to movement about the natural anatomical axes of the foot and is simple and light in con struction.

Another object of the invention is to provide a leg brace that is inexpensive to manufacture.

Another object is to provide a brace which is readily adaptable to the statistical average foot configuration.

Another object of the invention is to provide a lowerleg brace that enables articulation of the foot about both the ankle and subtalar axes by means of an external mechanical system that presents a minimum of visible mechanical linkage on the leg and foot of the wearer.

Other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a view in side elevation of the leg brace according to the present invention;

FIG. 2 is a view in perspective showing a skeletal structure of a human foot and indicating the major joints and axes of articulation of the foot about the leg bones;

FIG. 3 is a view in rear elevation of the leg brace shown in FIG. 1;

FIG. 4 is a bottom view of the leg brace shown in FIG. 3 with the heel of the shoe removed to show the heel plate;

FIG. 5 is an enlarged fragmentary view showing the heel plate connected to the bearing assembly on the yoke;

FIG. 6 is an enlarged fragmentary view in side elevation and in section taken along the line 6-6 of FIG. 3 and showing the hinged connection between the yoke and a side bar;

FIG. 7 is an enlarged fragmentary view in end elevation of the side bar shown in FIG. 6.

The present invention provides a bracing device that not only furnishes full support to a disabled leg but also solves the problem of providing an external mechanical system which affords normal articulation of the foot about the natural joint axes. A leg brace 10 according to the principles of the present invention, is shown in FIG. 1, and comprises a base or heel plate 11 preferably fixed to the sole 12 of a shoe 13 worn on the disabled leg. A rearwardly extending portion of the heel plate 11 forming a bearing support 14 extends beyond the rear end of the shoe 13. Attached to the bearing support 14 by means of a heel bearing assembly 15 is a U-shaped yoke member '16. The bearing assembly 15 is adapted to provide rotation of the yoke member 16 about a shaft 17 fixed to the bearing support 14. The axis of the shaft 17 is fixed at a predetermined angle relative to the heel plate 11, so that it is substantially aligned with the axis of the subtalar joint of the bracewearers foot when positioned within the shoe 13. The

ends

18, 19 of the U-shaped yoke member 16 are hingedly attached to two supporting

side bar members

20 and 21 which extend upward from the yoke 16 generally parallel to the leg shank where they are connected to a cuff assembly 22 having a strap 23 that enables the cuff to be tightened around the leg, preferably just below the knee.

In accordance with the principles of the invention, the lower-leg brace 10 shown in FIGS. 1-3 provides for normal movement of the foot relative to two major anatomical axes, and thus it comprises a novel solution to the leg bracing problem that provides many important advantages over prior art braces. To illustrate some of the problems solved by the invention, FIG. 2 shows the bones of a normal human foot and ankle which form an ankle joint 25 at the juncture of the tibia 26 and the fibula 27 with the surface of the talus 28. The axis of the ankle joint 25, indicated by line 29 extends through the ankle and is generally horizontal, thus providing the toe lifting movement of the foot. In the strict anatomical sense the ankle joint has actually two axes, one being called the dorsifiexion axis and the other, the plantar fiexion axis. To avoid complication, these separate axes are not shown in FIG. 2 but line 29 is shown as being their combined equivalent. The combined range of motions about two axes is approximately 50 to 62. When viewed from above along the tibia 26 when the foot is in the position of relaxed standing, the two axes are almost coincident, and when viewed from the front these axes form an angle of approximately 15 /2. With respect to the bracing problem, we have discovered that a single external brace axis can serve the function of the two anatomical ankle axes if the mechanical brace axis is located coincident to the average or combined equivalent of the two ankle axes represented by line 29 in FIG. 2. In locating the brace axis, we have also discovered that for the most satisfactory brace operation, the location of the mechanical ankle axis with respect to anatomical iankle axis must be more exact in the transverse plane than in the vertical plane, where a certain degree of latitude may be tolerated. This mechanical ankle axis is provided in our novel brace 10 by a pair of hinge pins '30 which provide the connections between the yoke 16 and the

side bars

20 and 21.

The second major joint of the human foot is the subtalar joint 32, which, as shown in FIG. 2, affords a sidewise tilting motion or a lateral adjustment to the foot. The motion of the foot about the axis of the joint 32, designated by the line 33, is purely rotational, and the range of motion is limited to about 24 to 27. The axis 33 is skewed to the ankle axis 29 and extends upward through the heel bone 36 at an angle to both the vertical and

longitudinal coordinate axes

34 and 35 of the foot as shown in FIG. 2. The subtalar joint 32 is extremely important to the leg bracing problem because it provides the means to position the foot properly during walking and standing in so that it can maintain its natural alignment with the upper leg and hip bones and their respective joints to thereby provide maximum support for the body. Without the capability of adjusting the foot position the proper alignment cannot be maintained in the braced lower limbs, and as a consequence the arms of the disabled person may be required to support the body weight during walking.

Describing now, the leg brace 10 in greater detail, FIG. 4 shows in plan view the heel plate 11 which is preferably attached by some suitable means such as rivets 40 to the sole 12 of the shoe 13. The heel plate 11, preferably formed from stainless steel, has essentially a T-shape and is mounted near the rear end of the sole 12 where it is normally covered by the heel 41 of the shoe 13. A transverse portion 42 of the T-shaped heel plate 11 extends across the sole 12 of the shoe 13 and has an integral turned down lug member 43 at each end thereof which extends over the edge of the sole 12. Extending rearwardly from the transverse portion 42 and along a line fixed at a predetermined angle to the centerline of the shoe 12 is an integral portion 44 of the heel plate 11. The portion 44 extends beyond the rear edge of the sole 12 and is bent upwardly at a fixed predetermined angle to form the bearing support 14. The short shaft member 17 is fixed to the bearing support 14 as shown in FIG. 5, by a flange 45 at its upper end which is welded to the bearing support 14. The lower end of the shaft 17 is internally threaded to receive an end screw 46 which retains the bearing assembly 15 and the attached yoke 16 to the bearing support 14 of the heel plate 11. The axis of the shaft 17 extends forward at an angle A to the heel plate 11 as shown in FIG. 1 and it also forms an angle B to the vertical coordinate 34 as shown in FIG. 3. The shaft axis is thereby located substantially coincident with the anatomical axis 33 of the subtalar joint 32 (FIG. 2) when the shoe 13 is placed on the foot. F or slight variations in the actual location of the subtalar joint axis for different persons, the position of the mechanical axis of the shaft 17 can be adjusted by varying the length of the rearwardly extending portion 44 of the heel plate 11 and its position on the shoe sole 12 and by varying the angle of the bearing support 14 relative to the plane of the heel plate 11 .The bearing assembly 15-, which may be of a standard commercially available type, comprises a housing 47 that is preferably welded to the yoke 16 and contains an outer ball bearing ring 48 fixed to the inner wall of the housing 47 and an inner ring 49 fixed to the shaft 17. Standard balls 56 positioned between the rings 48 and 49 afford low friction movement of the bearing assembly 15 and the yoke 16, about the shaft 17. It is apparent that other suitable forms of bearing means for providing the rotational movement of the yoke 16 relative to the heel plate 11 and the shoe 13 about an axis aligned with the anatomical axis of the subtalar joint of the foot on which the brace is worn, may be provided within the scope of the invention.

The yoke 16 attached to the bearing assembly 15 is generally U-shaped as seen in FIG. 3, having a curved center portion 51 to provide ample clearance around the rear portion of the shoe 13 and upwardly extending

arms

52 and 53. The

yoke arms

52 and 53 extend upward and forward at an angle to the horizontal and each has a predetermined length so that the yoke ends 18 and 19 can be connected by the hinge pins 30 to the side bars 20 and 21 along an axis substantiallyialigned with the anatomical ankle axis 29 of the foot of the brace wearer. The hearing assembly is located on the center curved portion 51 of the yoke 16 and it fits around the shaft 17 so that the yoke 16 thus is rotatable about the subtalar axis 33 of the brace wearers foo-t when in the shoe 13.

The yoke 16 is preferably formed as an integral memher from some suitable material such as steel rod stock. In forming the yoke 16, each end 18- and 19 as seen in FIG. 16, is preferably flattened and then bored to provide a hole 55 for attaching the yoke 16 to the side bars and 21. Adjacent each of the holes 55- is a projection 56 and an accompanying notch 57 as shown in FIG. 6 which provides a seat or stop to limit the amount of movement of the yoke 16 with the side bars 20 and 21.

The side bars 20 and 21 may be formed from a suitable strong but light metal such as aluminum and they are preferably flat and thin in cross-section. The upper end 58 of each

side bar

20, 21 is fixed to a leather lined cull assembly 22 of the well known type having a strap 23 or some suitable means to hold the cuff 22 in position around the leg. At the lower end of each

side bar

20, 21 is a portion 59 of increased cross-sectional thickness and at the lowest extremity of each said portion 59 is a birfurca-ted section 69 having two forked

members

61 and 62 as shown in FIG. 7. One member 61 may be provided with a round hole 63 and the other member 62 may have a rectangular hole 64. Each flattened

end

18 and 19 of the yoke 16 is then adapted to fit, with easy sliding clearance, between the forked

members

61 and 62 of each

side bar

20 and 21, and a slot-headed pivot pin 39 is inserted through the bearing

hole

63 and 64 on each side bar and the hole 55 on the yoke ends 18 and 19 to provide the hinged connection between the side bars 20 and 21 and the yoke 16. A nut 31 retains each hinge pin in the hole 64. v

In the lower enlarged portion 59 of each

side bar

20, 21 is an internally seated spring 65 that prov-ides a pivotal force on the yoke 16 about the hinge pins 30 which, when applied through the heel plate 11 serves to lift the toe of the shoe 13 automatically during walking. In each

side bar

20, 21 as shown in FIG. 6, the spring 65 is located in a tubular passage 66 which extends upward at an angle through the enlarged portion 59 of each side bar. The upper end of the passage 66 is threaded and closed by a plug 67 which seats the spring 65. By adjusting the plug 67 in and out of the passage 66, a desired amount of spring force can be maintained. The lower end of the spring 65- bears against the ball member 68 which is retained at the lower end of the tubular passage 66. When the shoe 13 is in its normal level standing position, the notch 57 and projection 56 on the ends '18, 19 of the yoke 16 form a seat for the ball 68, thereby pressing against it and pushing it up into the passage 66 to compress the springs 65. Thus, in walking, when the standing pressure is released, the springs 65, pressing againt the ball 68 and thus against the yoke 16, rotate the yoke 16 about the ankle axis hinge pins 30 and lift up the toe of the shoe 13. This prevents toe dragging and greatly aids the walking process for those with disabled limbs.

As mentioned previously, a serious problem heretofore occurred in prior art braces when an imbalance of muscle tension caused an unnatural and uncontrollable tilting force on the foot about the subtalar axis. This often resulted in improper foot alignment which prevented proper balance and support. The present invention solves this problem by first, providing the combination of the heel plate 11, the bearing assembly 15, and the yoke .16 which together provide for rotation of the foot about the anatomical subtalar axis. In addition, our invention provides a spring means 70, which may be attached at one end 71, as shown in FIG. 2, to an outer turned down lug 43 on the heel plate 11, and at the other end .to an attaching hole 72 near an

end

18 or 19 of the yoke 16. The spring '70 can be attached to either side of the shoe 13 to accommodate various muscle conditions in particular paralysis situation-s. Any suitable spring tension means equivalent to the spring 70 can be used, and the spring 70 can be easily attachable or removable whenever necessary.

In applying the brace 10 of the present invention to one requiring external leg support, the brace components may be formed and assembled, as described previously, so that the mechanical axes of movement of the brace are coincident with the anatomical axes of the brace wearer when the brace is properly attached to the wearer. The exact location of the anatomical axes can be ascertained by one of several methods which are not part of this invention. After assembly of the brace components the heel plate 11 is attached to the shoe 13 in the proper position so that whenever the brace is worn, the axis of the hinge pins 39 and the axis of the heel bearing shaft 17 are always automatically aligned with the normal foot axes when the foot is placed in the shoe. A significant feature of our invention is that its relative mechanical simplicity makes it easy to make an adjustment in the brace components such as relocation of the heel plate 11 on the shoe sole 12 or the angular orientation of the bearing support 14. Thus, the brace can be made compatible an individual wearers leg and foot, and with the exact location of this ankle and subtalar joint axes, and a few basic sizes can easily accommodate a large percentage of wearers.

In cases where only limited bracing is required, a brace having a

single side bar

20 or 21 with its ankle joint assembly and half of the yoke 16, could be made within the scope of the invention. The side bar and yoke portion could be located on the side of the leg requiring the bracing strength and a spring 70 could be attached in the aforementioned manner to correct the muscle imbalance around the subtalar joint.

From the foregoing, it is apparent that the present invention provides a significant advance in the vital field of limb bracing and prosthetics. During normal body movements the brace acts to provide constant support and proper positioning of the feet relative to the legs. The springs 65 acting around the ankle axis hinge pins 30 keep the toe lifted when Weight is removed during walking, and the leveling springs 70 keep the foot properly positioned so as to give support to the legs in the proper alignment therewith. With all bodily movements, the foot, though well supported, can move with the normal degree of freedom about both major foot and ankle joints.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest them-selves Without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

1. A brace for supporting the lower leg and the foot of a human by simultaneously providing free movement to the foot relative to the leg about its anatomical ankle and subtalar joints, said brace comprising: a shoe adapted to be worn on said foot; a mounting means fixed to said shoe; a yoke mean movably connected to said mounting means about a first predetermined axis substantially aligned with the anatomical axis of the subtalar joint of said foot Within said shoe; side bar means pivotally attached to said yoke means along a second predetermined axis substantially aligned with the anatomical axis of the ankle joint of the foot within said shoe, said side bar means extending upward adjacent said leg; and means fixed to said side bar means for attaching said brace to the leg.

2. A brace for supporting the lower leg and the foot of a human while simultaneously providing free movement of the foot relative to the leg about its anatomical ankle and subtalar joints, said brace comprising: a shoe means adapted to be Worn on said foot; a heel plate fixed to said shoe, said heel plate having an integral portion extending rearwardly the heel end of said shoe and forming a bearing support; a cylindrical shaft connected to said bearing support and positioned thereon with the axis of said shaft forming a predetermined angle with the plane of the heel plate and being substantially aligned with the anatomical axis of the subtalar joint of said foot in said shoe; a generally U-shaped yoke; 21 first bearing means on said yoke attached to said shaft for providing rotation of said yoke about said shaft; end members on said yoke extending upward from said curved center portion; a second bearing means connected to said end members; side bar means pivotally attached to said second bearing means, thereby providing for rotational movement of said yoke relative to said bar means about the axis of said pin means, said axis of said second bearing means being substantially aligned with said anatomical ankle axis said side bar means extending upward substantially parallel the side of said leg; and circular cuff means fixed to said side bar means and adapted to fit around the leg for attaching said brace to the leg.

3. A brace for supporting the lower leg and the foot of a human while simultaneously providing free movement of the foot relative to the leg about its anatomical ankle and subtalar joints, said brace comprising: a shoe adapted to be worn on said foot; a heel plate fixed to said shoe, said heel plate having an integral portion extending rearwardly the heel end of said shoe and forming a bearing support; a cylindrical shaft connected to said bearing support and positioned thereon with the axis of said shaft forming a predetermined angle with the plane of the heel plate and being substantially aligned with the anatomical axis of the subtalar joint of said foot in said shoe; a generally U-shaped yoke; a first bearing means on said yoke attached to said shaft for providing rotation of said yoke about said shaft; end members on said yoke extending upward from said curved center portion; a second bearing means connected to said yoke end members; side bar means pivotally attached to said second bearing means, thereby providing rotational movement of said yoke relative to said bar means about the axis of said second bearing means, said axis of said' second bearing means being substantially aligned with said anatomical ankle axis, said side bar mean extending upward substantially parallel to the side of said leg; spring-loaded means in said side bar means engaging said yoke ends to bias said yoke in a predetermined direction relative to the side bar means to thereby automatically lift the toe of said shoe during walking; and cuff means fixed to the upper ends of said side bar means for attaching said brace to the leg.

4. A brace for supporting the lower leg and the foot of a human comprising: a shoe adapted to be worn on said foot; a heel plate fixed to said shoe, said heel plate having a transverse portion extending across the width of said shoe and a longitudinal portion extending beyond the rear end thereof to form a bearing support, said bearing support being located in a predetermined position slightly to one side of the longitudinal center line of said shoe; a yoke means rotatably attached to said bearing support on said heel plate, the axis of rotation of said yoke on said bearing mount being located in a predetermined position extending upward at an angle to said heel plate and through said shoe and thereby substantially aligned with the subtalar axis of said foot when in place within said shoe; side bar means pivotally attached to said yoke means on an axis substantially aligned with the ankle aXis of said foot when in place with said shoe, said side bar means extending upward along the side of said leg; and cuff means fixed to said side bar means for attaching said brace to said leg.

5. The brace as described in claim 4 including a tension means attached to one end of said transverse portion on said heel plate and to said yoke means to provide a stabilizing force for overcoming muscle imbalance in said foot.

6. A brace for supporting the lower leg and the foot of a human while simultaneously providing free movement of the foot relative to the leg about its anatomical ankle and subtalar joints, said brace comprising: a shoe adapted to be Worn on said foot; a heel plate fixed to said shoe, said heel plate having an integral portion extending rearwardly the heel end of said shoe and forming a bearing support; a cylindrical shaft connected to said bearing support and positioned thereon with the axis of said shaft forming a predetermined angle with the plane of the heel plate and being substantially aligned with the anatomical axis of the subtalar joint of said foot in said shoe; a generally U-shaped yoke; a first bearing means on said yoke attached to said shaft for providing rotation of said yoke about said shaft; end members on said yoke extending upward from said curved center portion; aligned second bearing means attached to said end members; side bar means connected to said second bearing means and thus pivotally attached to said yoke end members, and providing for rotational movement of said yoke relative to said side bar means about the axis of said second bearing, the axis of said second bearing means being substantially aligned 'with the anatomical ankle axis of the foot in said shoe means, said side bar means extending upward substantially parallel the side of said leg; spring means connected from said heel plate to said yoke to provide a biasing force on said yoke about its axis to counteract an imbalanced muscle force about said subtalar joint; and circular cuff means fixed to said side bar means and adapted to fit around the leg for attaching said brace to the leg.

7. A brace for supporting the lower leg and the foot of a human while simultaneously providing free movement of the foot relative to the leg about its anatomical ankle and subtalar joints, said brace comprising: a shoe adapted to be worn on said foot; a heel plate fixed to said shoe, said heel plate having an integral portion extending rearwardly the heel end of said shoe and forming a bearing support; a cylindrical shaft connected to said bearing support and positioned thereon with the axis of said shaft forming a predetermined angle with the plane of the heel plate and being substantially aligned with the anatomical axis of the subtalar joint of said foot in said shoe; a generally U-shaped yoke; bearing means on said yoke attached to said shaft for providing rotation of said yoke about said shaft; end members on said yoke extending upward from said curved center portion; rotatable connection means attached to said yoke end members; side bar means pivotally attached to said connection means, thereby providing rotational movement of said yoke relative to said bar means about the axis of said connection means, the axis of said connection means being substantially aligned with said anatomical ankle axis, said side bar means extending upward substantially parallel to the side of said leg; spring-loaded means in said side bar means engaging said yoke ends to bias said yoke in a predetermined direction relative to the side bar means to thereby automatically lift the toe of said shoe during walking; spring means connected from said heel plate to said yoke to provide a biasing force on said yoke about its axis to counteract an imbalanced muscle force about said subtalar joint; and cutr' means fixed to the upper ends of said side bar means for attaching said brace to the leg.

eferences on following page) 9 10 References Cited in the file of this patent 2,959,168 Shook Nov. 8, 1960 2,973,757 Katthoefer Mar. 7, 1961 UNITED STATES PATENTS OTHER REFERENCES Publication entitled New Horizons in Brace Research, copyright-ed 1949, page 7 employed; on file in Div. 55.

2,267,848 Taylor Dec. 30, 1941 2,516,872 Hauser :et a1. Aug. 1, 1950

Claims

3. A BRACE FOR SUPPORTING THE LOWER LEG AND THE FOOT OF A HUMAN WHILE SIMULTANEOUSLY PROVIDING FREE MOVEMENT OF THE FOOT RELATIVE TO THE LEG ABOUT ITS ANATOMICAL ANKLE AND SUBTALAR JOINTS, SAID BRACE COMPRISING: A SHOE ADAPTED TO BE WORN ON SAID FOOT; A HEEL PLATE FIXED TO SAID SHOE, SAID HEEL PLATE HAVING AN INTEGRAL PORTION EXTENDING REARWARDLY THE HEEL END OF SAID SHOE AND FORMING A BEARING SUPPORT; A CYLINDRICAL SHAFT CONNECTED TO SAID BEARING SUPPORT AND POSITIONED THEREON WITH THE AXIS OF SAID SHAFT FORMING A PREDETERMINED ANGLE WITH THE PLANE OF THE HEEL PLATE AND BEING SUBSTANTIALLY ALIGNED WITH THE ANATOMICAL AXIS OF THE SUBTALAR JOINT OF SAID FOOT IN SAID SHOE; A GENERALLY U-SHAPED YOKE; A FIRST BEARING MEANS ON SAID YOKE ATTACHED TO SAID SHAFT FOR PROVIDING ROTATION OF SAID YOKE ABOUT SAID SHAFT; END MEMBERS ON SAID YOKE EXTENDING UPWARD FROM SAID CURVED CENTER PORTION; A SECOND BEARING MEANS CONNECTED TO SAID YOKE END MEMBERS; SIDE BAR MEANS PIVOTALLY ATTACHED TO SAID SECOND BEARING MEANS, THEREBY PROVIDING ROTATIONAL MOVEMENT OF SAID YOKE RELATIVE TO SAID BAR MEANS ABOUT THE AXIS OF SAID SECOND BEARING MEANS, SAID AXIS OF SAID SECOND BEARING MEANS BEING SUBSTANTIALLY ALIGNED WITH SAID ANATOMICAL ANKLE AXIS, SAID SIDE BAR MEANS EXTENDING UPWARD SUBSTANTIALLY PARALLEL TO THE SIDE OF SAID LEG; SPRING-LOADED MEANS IN SAID SIDE BAR MEANS ENGAGING SAID YOKE ENDS TO BIAS SAID YOKE IN A PREDETERMINED DIRECTION RELATIVE TO THE SIDE BAR MEANS TO THEREBY AUTOMATICALLY LIFT THE TOE OF SAID SHOE DURING WALKING; AND CUFF MEANS FIXED TO THE UPPER ENDS OF SAID SIDE BAR MEANS FOR ATTACHING SAID BRACE TO THE LEG.