Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Leg – Ankle
Reexamination Certificate
1996-08-27
2002-08-20
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Leg
Ankle
C623S052000
Reexamination Certificate
active
06436149
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a prosthetic device adapted for use on a lower extremity amputee. More particularly, the present invention is directed to an artificial ankle, and on a prosthetic leg device incorporating the ankle, that pivots to provide an amputee with an improved gait for running or walking. The present invention also enables a leg amputee to more easily ascend and descend staircases.
BACKGROUND OF THE INVENTION
Throughout modern human history, appropriate medical care sometimes has required amputation of a diseased or damaged limb. When a leg or portion thereof was amputated, often, the leg amputee was fitted with a prosthetic leg device so that the amputee could walk without the use of crutches or other aid devices. An early prosthetic leg device was simply a peg affixed to the remaining portion of the amputated leg of the amputee. Although effective, a “pegged” leg was not aesthetically pleasing.
Technological advancements of new materials enabled other types of prosthetic leg devices to be developed which were more aesthetically pleasing. Typically, these prosthetic leg devices included a calve portion, an ankle and a foot structure that simulated a human leg. Skillful fabrication of these prosthetic leg devices with advanced materials made them appear to be a real leg with a real foot structure. The advanced material which formed the anatomically-correct parts of the human body was either a plastic material or a rubber-like material having a color texture of human flesh. Now, a sock and footwear could be worn on the artificial foot to match the ones on the healthy foot so that the general public would be unable to visually determine that a person was an amputee.
Even though these new prosthetic devices appear generally life-like, several disadvantages remain. First, in order to assure proper balance,the lower leg portion below the “knee” is rearwardly offset from the upper leg portion above the “knee”. Therefore, when simply standing, the artificial foot is positioned to the side of and behind the real foot, that is, in a staggered orientation, which presents an unnatural appearance. More importantly, though, none of these devices could perform functionally as well as a human leg. Unlike the function of a healthy human ankle, the typical ankle of the prosthetic leg device is a rigid, 90-degree connection unable to provide any pivotal movement between the calve portion of the leg and the foot structure. To use prior art prosthetic leg devices, the amputee is required to angularly swing his/her amputated leg in an arcuate motion relative to his/her healthy leg when making a step with the prosthesis. This arcuate motion, although unnatural, is necessary so that the prosthesis can be lifted above the walking surface to avoid being dragged when stepping. This arcuate motion adds stress to the healthy knee, leg and ankle of the amputee that could result in chronic pain and further injury. Thus, a tradeoff occurs. For a more aesthetically-pleasing prosthetic leg device, the amputee must suffer pain and/or risk future damage to his/her healthy leg.
A normal gait cycle of a human being includes three general phases which are dorsiflexion, plantarflexion and “push-off”. Each of these phases is explained relative to an angular position, of the foot relative to a shin bone pivotally connected thereto by an ankle joint. The foot, of course, includes a heel disposed proximate to the ankle joint and a sole disposed distally to the ankle joint. The human foot is considered to be in a neutral position when it forms a 90-degree angle with the shin bone relative to a pivotal axis of the ankle joint. Dorsiflexion occurs when an acute angle is formed between the foot and the shin bone relative to the pivotal axis of the ankle joint. For example, dorsiflexion is best demonstrated during stepping as the heel on the foot of the advancing leg first contacts the walking surface immediately before the body weight of the amputee is transferred to the foot. Plantarflexion occurs when an obtuse angle is formed between the foot and the shin bone relative to the pivotal axis of the ankle joint. Plantarflexion is best demonstrated when the ankle of the advancing leg bends immediately after the heel contacts the walking surface so that both the heel and sole of the foot contact the walking surface in preparation of receiving the body weight of walking person. “Push-off” occurs as the trailing leg completes its step whereby the ankle joint becomes “locked” with the foot and shin bone in the neutral position so that the sole of the foot can propel the body weight of the walking person forward to transfer it onto the advanced leg.
Since prior art leg prosthetic devices are permanently fixed in the neutral position, effective “push off” occurs so that the amputee can complete his step and repeat his/her gait cycle. Unfortunately, none of the prior art prosthetic leg devices known to the present inventor provides dorsiflexion or plantarflexion. This lack of dorsiflexion and plantarflexion requires the amputee to swing the prosthetic leg outwardly in the arcuate fashion as described above when stepping. Furthermore, the lack of dorsiflexion and plantarflexion further hinders the amputee when ascending or descending stairs. With prior art prosthetic leg devices, an amputee is well advised to descend stairs one at a time by first lowering the prosthetic leg onto the next lower step before advancing the trailing healthy leg thereonto. Correspondingly, the amputee should ascend stairs one at a time by first raising the healthy leg on the step disposed immediately above before advancing the prosthetic leg thereon. It is extremely perilous for an amputee with a prosthetic leg to attempt to ascend or descend stairs by stepping on alternate steps with each leg. For example, descending stairs by an amputee with a prosthetic leg device in an alternating matter tends to thrust the amputee's body weight forward which could result in falling down the stairs. This thrusting effect is due to the absence of dorsiflexion.
Prior art prosthetic leg devices inhibit amputees from. participating in various sporting events which require running. Not only is it difficult, if not impossible, to run in a prior art prosthetic leg device but also the rigidity of construction provides limited shock absorption capabilities. Much of the induced shock is absorbed by the body of the amputee that, in turns, causes further stress on the amputee's body. Such rigidity also results in minimal flexibility of the prosthetic leg device. Again, the amputee's body must compensate for this lack of flexibility.
There is a need in the marketplace to provide an artificial ankle joint that can be used with a prosthetic leg device so that a foot structure thereof can pivot about pivotal axis relative to a prosthetic leg portion. There is a further need in the marketplace to provide an artificial ankle joint for a prosthetic leg device which can execute the three general phases of dorsiflexion, plantarflexion and “push-off” to simulate a gait cycle of a normally healthy human being. It would be advantageous if this prosthetic leg device could be used for walking and running as well as ascending and descending stairs. It would be further advantageous if this prosthetic leg device could absorb shock and be flexible so as to relieve the amputee's body from absorbing shock and compensating for any lack of flexibility. There is a need to provide with such an ankle joint, and to provide a prosthetic leg device with such an ankle joint which prosthesis is lightweight. The present invention satisfies these needs and provides these advantages.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and useful artificial ankle joint for use with a prosthetic leg device having a foot structure and a proximal end portion so that the foot structure can pivot about a pivotal axis relative to the proximal end portion of the prosthetic leg device.
Another object of the present invention
Henson Michael R.
Martin Timothy J.
Weygandt Mark H.
Willse David H.
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