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1407 E. Michigan Ave., Jackson 517-784-1142 770 Riverside Ave., Suite 101, Adrian 517-263-3310
CHAPTER I - How We Walk
ON NATURAL FEET. - No two persons walk exactly alike. Everyone carries his mannerisms in his steps. The way in which he lands on his heel, rolls on the sole, lifts on the ball, throws himself to the right or the left, the uniformity and regularity of each joint’s action, the angle at which the hip is checked, the range of articulation permitted in the knee and the angular motion of the ankle, - all form a part of his individuality and make it possible to distinguish a friend from a stranger long before his features have come within the reach of vision. All sorts of forces – heredity, early habits, occupation, disease, injuries, and age – influence the movements of the leg and foot. A man in good health walks differently from an invalid, a farmer can be distinguished from a merchant, a bookkeeper from a railroad conductor, the sprightliness of youth, the infirmities of age are reflected in every step that is taken. Yet there are certain facts connected with walking that are common to all and which can be ascertained by observation and study. These facts are so universal that they become laws governing locomotion; they form a necessary part of the limb-maker’s education, and unless he is familiar with them and applies them thoughtfully to the construction of artificial limbs, he is not competent to work out the problems that are continually arising.

As this work is designed as a text-book on artificial limbs, it is essential, at the outset, to present the cardinal facts relating to natural walking, in order that the application of them to artificial aids may be clearly understood and appreciated.

Kinetoscopic photography affords the most valuable aid to an investigation of the actions of the knee and ankle joints when performing their functions. It shows that when a man walks slowly, say two miles an hour, the knee flexes but slightly and the ankle considerably. When walking three miles an hour, the knee joint acts through a greater range and the ankle joint through a lesser one. When walking moderately fast, say four miles an hour, the knee action becomes considerable and the ankle action scarcely perceptible. When walking rapidly, say five miles an hour, the knee action is increased and the ankle becomes practically rigid. When running the knee increases its activity, and the ankle reverses its action and throws the man forward by the ball of the foot.

The ratio that exists between the range of motion of the knee and that of the ankle is in proportion to the speed with which one moves. An impulse is had to walk slowly or rapidly, or to change from one gait to another. The proper muscles and tendons instantly respond to the mind, and the required speed is attained. If the co-operation between the mind and muscles be disrupted the person becomes a paralytic and his steps are unreliable. The same may be said of a person walking on an artificial leg with ankle motion that is not under control.

Three miles an hour is the ordinary gait of a person occupied in commercial life. Successive photographs of a man with natural legs, walking at this gait, show that there is but very little motion in the ankle joint; and limited as that motion is, it is of a character that cannot be imitated by mechanical means. The walker throws his left foot forward, barely touching the heel to the ground, as shown in Cut A 1; instantly the right foot under control of the tendo-Achilles extends and the heel is raised from the ground, throwing the weight of the body on the ball, supplying the impetus that urges the body forward. As the body is carried forward, the ball of the left foot reaches the ground at about the time the body is vertically over it, as shown in Cut A 2. At this point the right foot is in the act of leaving the ground, and, as shown in Cut A 3, is passing the left which, still being flat on the ground, performs no function, except that of supporting the body, as shown in Cut A 4. The right leg is carried a little further forward when a slight amount of flexion is admitted in the left ankle joint, as shown in Cut A 5. But this is for a very brief period, as Cut A 6 shows that the tendo-Achilles instantly contracts and the foot extends and the entire body is lifted and thrown on the ball, and when the weight of the body is placed on the heel of the right foot, there is a slight flexion in the knee joint which permits the sole to reach the ground. At this time, the knee joint of the left is flexed and the foot of that leg is raised, as shown in Cut A 7, and when the weight of the body is practically over the right foot the knee is extended, so as to support the weight securely, as shown in Cut A 8.

A study of these successive photographs shows that in making a complete step the soles of both feet are not on the ground at the same time, and at times when the weight of the body is placed equally on each foot, the heel of the advanced foot and the toes of the rear foot are only those parts that are on the ground. It also shows that propulsion is obtained by rising on the ball of the rear foot.

ON ARTIFICIAL FEET WITH ANKLE JOINTS. - Similar photographs of a man walking with one or a pair of artificial legs with ankle joints set to act at a constant range of motion, show that he walks fairly well at a slow gait, but at a speed of three or more miles an hour his step becomes perceptibly awkward, and the effort required to overcome the too liberal motion in the ankle is fatiguing. So far as the knee joint is concerned the motions of the artificial and natural legs are approximately the same, but the motions of the ankles are very different. The sole of the foot is flat on the ground for a considerably longer period with the artificial ankle joint than with the natural. As the walker advances and strikes the heel of the artificial foot on the ground, almost immediately the front of the foot drops and the entire sole rests on the ground and remains there during the interval through which the body is passing over it.

Having made plan the movements of the natural foot in walking, and contrasted them with the movement of the artificial foot articulating at the ankle, we now propose to carry the contrast to the spring-mattress rubber foot attached rigidly to the leg socket.

ON SPRING-MATTRESS RUBBER FEET WITHOUT ANKLE JOINTS. - As the walker advances on the rubber foot he touches the heel to the ground. He applies his weight, and the sponge rubber in the heel compresses sufficiently to allow him to roll on the bottom of the foot; the moment the body is carried a little in advance, he rises on the ball very much the same as he does on the natural foot. There is no effort required to lift on the ball, as the weight of the body, being in advance of its center of gravity, overcomes that apparent obstruction; not a muscle or tendon is brought into play; the weight of the body does the entire work.

These studies and comparisons of the movements in walking bring out very clearly the essential fact that with the artificial ankle joint the interval that the plantar surface rests on the ground is very much greater than that of the natural foot, while with the sponge rubber spring-mattress foot it is approximately the same, and, by compelling the walker to rise on the ball, produces a very natural action, giving greater assistance in walking and dispensing with a vast amount of mechanism.

It is apparent also that the value of mental force in controlling the actions of the natural ankle joint cannot be overestimated. When these forces become inert, as they necessarily do in artificial joints, the embarrassments that follow are the same as with paralytics, locomotor ataxia, etc. The injured are obliged to walk cautiously, the affected foot is placed almost entirely by the sense of sight, and the step is made with meditation and progress must necessarily be slow.

If an artificial leg with ankle articulation be applied to a person who desires to walk at a gait faster than two miles an hour, he will find himself not only greatly hindered, but required to put more energy into the natural foot and leg in order to overcome the influence of the articulating ankle in retarding his progress. The rubber foot without ankle joint will assist rather than hinder rapid walking, and will not hinder slow walking when desired.

Comment from follow-up survey
Thanks so much for the brace it really decreases the pain!