Automatic Locking Orthotic Knee Device

The present invention relates generally to joints for strap-on orthotic knee devices. More particularly, this invention relates to joints which allow the user freedom to extend and bend the knee normally when load is not applied to the joint, to automatically lock the joints when load is applied thereto, and to automatically unlock the joints when load is removed therefrom.

The prior art abounds with strap-on orthotic knee devices to be worn by persons recuperating from surgery or injuries to the knees. Most of the prior art devices include a strap-on thigh engaging section and a strap-on leg engaging section connected by a pair of tang in clevis joints which permit the user the freedom to extend and bend the knee over a full range. One currently available strap-on orthotic knee device incorporates tang in clevis joints with automatically engaging locking devices which snap in at full extension of the knee joint and requires the manual disengagement of the locking device by means of a finger loop to allow bending of the joint.

The prior art strap-on orthotic knee device with the automatically engaging locking device has two major drawbacks or disadvantages. The first drawback or disadvantage is due to the fact that the locking, while automatic, can occur only when the user has achieved full extension of the knee. This creates a safety hazard and causes accidents in that the user may not be able to fully extend the knee before loading (placing weight on) the leg, which could cause the knee to fold uncontrollably, and permit the user to fall. The second drawback or disadvantage relates to the manual operation required to disengage or unlock the joint, which operation is cumbersome in that the user must have a free hand to devote to the control loop and could discourage the user from the therapeutic bending of the knee.

The present invention overcomes the disadvantages, drawbacks or deficiencies of the prior art devices in that it provides a rapid, automatic, locking and unlocking of the joint according to the load being carried by the joint. The joint of the present invention automatically locks when weight is applied thereto, even when the knee is slightly bent, thus allowing the joint to remain free to rotate when unloaded, to permit more freedom of motion and mobility to the user. The rapid, automatic, loading and unloading of the joint prevents accidents and encourages the user to exercise the knee to rehabilitate same.

Accordingly, it is an object of the present invention to provide a new and improved tang in clevis joint for strap-on orthotic knee devices which incorporates locking and unlocking structure which is rapid and automatic in operation and prevents the unwanted folding of the joint.

It is a further object of the present invention to provide a rapid and automatic locking and unlocking tang in clevis joint for strap-on orthotic knee devices which prevents accidents, encourage exercise by the user, and aids in the rehabilitation of the injured knee.

It is still a further object of the present invention to provide a tang in clevis joint for strap-on orthotic knee devices which automatically locks and unlocks the knee to allow the free rotation of the knee and the locking of the knee as desired.

Other aspects, objects and advantages of this invention will become apparent to those skilled in the art to which this invention pertains from a study of the preferred embodiment as set forth in the specifications, drawings and the appended claims.

In accordance with the present invention, a tang in clevis joint is provided which ca be incorporated in newly manufactured conventional strap-on orthotic knee devices or for replacing such tang in clevis joints in the conventional strap-on orthotic knee devices. Two such tang in clevis joints are normally incorporated in conventional strap-on orthotic knee devices, one on each side of the knee with each being connected to a thigh engaging section and a leg engaging section.

The tang in clevis joint of the present invention allows the user the freedom to extend and bend the knee normally when n load (weight) is applied to the knee and to automatically lock the knee when the user transfers weight (load) to the knee. This locking feature prevents the user's damaged knee from bending uncontrollably when weight is applied to the knee and is effective over a range of motion from fully extended to the order of forty-five degrees (45.degree.) of bend in the joint. The locking and unlocking of the joint is silent and allows the user greater mobility and safety.

The tang in clevis joint of the present invention includes first and second clevis plates, a tang assembly and a spacer plate sandwiched and secured between the clevis plates. Each clevis plate includes a bevelled serrated upper section. A bevelled shoe is secured to the tang in close proximity to the bevelled serrated upper section of the clevis plates. A coiled spring mounted within an oblong bore of the tang normally urges (when no weight is applied to the joint) the shoes secured to the tang out of engagement with the serrated upper section of each clevis plate to allow rotation of the tang relative to the clevis plate. When weight (load) is applied to the joint, the load compresses the coiled spring, the serrations on each clevis plate dig into the bevelled shoes secured to the tang to prevent relative movement between the tang and clevis plates. A shoulder is provided on each of the tang and the spacer plate to prevent overextension of the joint.

FIG. 1 is a perspective, partially broken-away, view of the prior art orthotic knee brace and joints.

FIG. 2 is an exploded, perspective, view of the automatic orthotic knee joint of the present invention.

FIG. 3 is a perspective view of an assembled orthotic knee joint of the present invention.

FIG. 4 is a perspective view of a tang assembly for the orthotic knee joint of the present invention.

Referring to the drawings, FIG. 1 is illustrative of a prior art orthotic knee brace 10 comprising a thigh engagement section 12, tang in clevis joints 14, and a leg engagement section 16. The upper portion of each tang in clevis joint 14 is connected to the lower end of a first pair of struts or arms 13 by any suitable means such as two screws or rivets 15 extending through bores (not shown) in struts or arms 13 with the upper end of each strut or arm 13 being connected to the lower portion of the thigh engagement section 12 by any suitable means (not shown) such as adhesives, screws or rivets. The lower portion of each tang in clevis joint 14 is connected to a second pair of struts or arms 17 by any suitable means such as two screws or rivets 19 extending through bores (not shown) in struts or arms 17 with the lower end of each strut or arm 17 being connected to the upper portion of leg engagement section 16 by any suitable means (not shown) such as adhesives, screws or rivets. The tang in clevis joint 14 in one prior art orthotic knee brace 10 incorporates an automatically engaged locking device (details not shown) which snaps in at full extension of the leg and requires the manual disengagement of the locking device to allow bending of the knee.

The automatically locking tang in clevis knee joint 18 of the present invention is illustrated in its nonassembled or exploded condition in FIG. 2 and in its assembled condition in FIG. 3. Tang in clevis knee joint 18 comprises a first clevis plate 20, a second clevis plate 30, a tang assembly 39 (FIG. 4), and a spacer plate 80 secured together by bolts 74 and 76. Tang assembly 39 is secured together by bolts 72.

As best illustrated in FIG. 2, first clevis plate 20 includes two threaded bores 22, a threaded bore 24, three threaded bores 26, and a bevelled serrated, upper, surface 28. Second clevis plate 30 includes two unthreaded bores 32, an unthreaded bore 34, three unthreaded bores 36, and a beveled serrated, upper, surface 38. Tang assembly 39 includes a tang 40, two unthreaded bores 42, five threaded bores 44 extending through tang 40, an oblong slot 46, a bushing 47 and a coiled spring 49 for mounting within oblong slot 46, a shoulder 48, a first shoe 50 having five countersunk openings 52 therein, a second shoe 54 having five countersunk openings 56 therein, five screws 58 having threads 59 for mounting within countersunk bores 52 of first shoe 50 and engagement with threaded bores 44 in tang 40, five screws 60 having threads 61 for mounting within countersunk bores 56 in second shoe 54 and engagement with threaded bores 44 in tang 40, a first strap 62 having two threaded bores 64 and two threaded bores 66, a second strap 68 having two unthreaded bores 69 and two unthreaded bores 70, and a pair of allen head bolts 72 having threads 73 for insertion through unthreaded bores 69 in second strap 68, unthreaded bores 42 in tang 40, and threaded bores 64 in first strap 62 with threads 73 positively engaging the threads in threaded bores 64 to secure together the entire tang assembly 39. Spacer 80 includes three unthreaded bores 82 and a shoulder 83. First clevis plate 20 and second clevis plate 30 are secured to the tang assembly 39 and spacer 80 by three allen head bolts 76 having threads 77 which pass through the unthreaded bores 36 in second clevis plate 30, the unthreaded bores 82 in spacer 80 and the threaded bores 26 in first clevis plate 20 with the threads 77 of the allen head bolts 76 being in positive threaded engagement with threaded bores 26 in first clevis plate 20, and by allen head bolt 74 having threads 75 which pass through unthreaded opening 34 in second clevis plate 30, the opening in bushing 47 of tang assembly 39 and the threaded bore 24 in first clevis plate 20 with the threads 75 of bolt 74 in positive engagement with the threads of bore 24 in first clevis plate 20.

Each tang in clevis joint 18 of the present invention is assembled or connected to the lower end of one of the pair of struts or arms 13 (FIG. 1) extending from and connected to the thigh engagement section 12 of an orthotic knee brace 10 such as that illustrated in FIG. 1 by inserting the lower end of the appropriate strut or arm 13 into the space separating the upper end of straps 62 and 68 and inserting a threaded screw 15 through each unthreaded bore 70 in strap 68, each unthreaded bore (not shown) in the lower end of strut or arm 13, and into threaded engagement with a threaded bore 66 in strap 62. Each tang in clevis joint 18 of the present invention is assembled or connected to the upper end of one of the pair of struts or arms 17 (FIG. 1) extending from and connected to the leg engagement section 16 of an orthotic knee brace 10 such as that illustrated in FIG. 1 by inserting the upper end of the appropriate strut or arm 17 into the space separating the lower portion of clevis plates 20 and 30 and inserting a threaded screw 19 through each unthreaded bore 32 in clevis plate 30, each unthreaded bore (not shown) in the upper end of strut or arm 17, and into threaded engagement with a threaded bore 22 in clevis plate 20.

Clevis plates 20 and 30 are preferably made of a hard steel such as Crescent steel; main plate 40 of tang assembly 39 is preferably made of aluminum; and shoes 50 and 54 are preferably made of a soft brass; however, these elements could be made of other materials. The serrations 28 and 38 in first clevis plate 20 and second clevis plate 30, respectively, are preferably radially cut; however, the cuts could be other than radially. The bevelled surfaces of shoes 50 and 54 might also incorporate serrations or have other conventional material applied thereto if additional frictional engagement were deemed necessary or desirable between shoes 50 and 54 and the serrations 38 and 28, respectively, of clevis plates 20 and 30.

In operation, thigh engaging section 12 and leg engaging section 16 are strapped or fastened to the thigh and leg, respectively, by conventional straps (not shown) attached thereto. When weight or pressure is applied to a joint 18, spring 49 is compressed to allow the serrations 28 and 38 on clevis plates 20 and 30, respectively, to bite into the bevelled surfaces of shoes 50 and 54, respectively, and prevent relative, rotational movement between the clevis plates 20 and 30 and the main plate 40. When weight or pressure is relieved from the joint 18, spring 49 acting on the wall of oblong slot 46 forces the main plate 40 and its shoes 50 and 54 in an upward direction away from the serrations 28 and 38 to allow relative, rotational, movement between the clevis plates 20 and 30 and the main plate 40. When weight or pressure is released from joint 18, the shoulder 48 on main plate 40 and shoulder 83 on spacer 80 serve as a stop to prevent an overextension of the knee.

While the above description constitutes a preferred embodiment of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.