A comparison of the accuracy of several hip center location prediction methods

In 15 normal adults an advanced biomechanical analysis of walking patterns at slow, natural, and fast cadences showed that the ankle had two mechanical power phases: a negative work phase during weight acceptance, followed by a dominant burst of positive work at push-off. The knee had four power phases: a negative work phase at weight acceptance, a small positive work phase during mid-stance, a major negative work burst at push-off and early swing, and a final energy-absorbing phase at the end of swing. The power phases at the hip are quite irregular and somewhat lower than those at the knee and ankle. The dominant positive work burst by the plantarflexors drops as speed decreases, but less rapidly than the positive work by the knee muscles during midstance. The energy absorption by the quadriceps during weight acceptance decreases rapidly as speed decreases and at late stance decreases moderately. The energy absorption by the ankle plantarflexors during weight acceptance remains fairly constant at all walking speeds, and the absorption by the knee flexors at end of swing drops only slightly as cadence decreases.

Energy generation and absorption at the ankle and knee during fast, natural, and slow cadences.

Motor patterns in normal human gait are evident in several biomechanical and EMG analyses over the stride period. Some of these patterns are invariant over the stride period with changes of cadence, whole others are closely correlated with speed changes. The findings for slow, natural, and fast walking are summarized: 1. Joint angle patterns over the stride period are quite invariant, and do not change with cadence; 2. Moment of force patterns at the ankle are least variable and quite consistent at all speeds; 3. A recently defined support moment is quite consistent at all speeds. 4. Moments at the knee and hip are highly variable at all cadences but decrease their variability as cadence increases; 5. Mechanical power patterns at all joints show consistent timing over the stride period; 6. EMG profiles of 5 muscles show consistent timing over the stride, but the amplitude increases as walking speed increases. Arguments are presented to support the concept that walking speed is largely controlled by gain and that the timing of the motor patterns, which is extremely tightly synchronized with the anatomical position, is under major afferent control.

Biomechanical Motor Patterns in Normal Walking

Prediction of hip joint centre location from external landmarks

We have examined 40 normal subjects (20 men and 20 women) to determine the ideal range of motion required to perform activities of daily living. The amount of wrist flexion and extension, as well as radial and ulnar deviation, was measured simultaneously by means of a biaxial wrist electrogoniometer. The entire battery of evaluated tasks could be achieved with 60 degrees of extension, 54 degrees of flexion, 40 degrees of ulnar deviation, and 17 degrees of radial deviation, which reflects the maximum wrist motion required for daily activities. The majority of the hand placement and range of motion tasks that were studied in this project could be accomplished with 70 percent of the maximal range of wrist motion. This converts to 40 degrees each of wrist flexion and extension, and 40 degrees of combined radial-ulnar deviation. This study provides normal standards for the functional range of motion of the wrist.

Functional ranges of motion of the wrist joint

A cntical evaluation of an experimental study of locomotion should include a consideration of the following elements. First, why is such a study undertaken and of what use will be the information obtained from it? Second, what techniques may be utiiized, and what are the advantages, i i i t a tions, and shortcomings of the procedures employed? The final evaluation of an experimental procedure in respect to the abovementioned elements can only be reached after the techniques have been actually employed. Some of the techniques which we envisioned as yielding fundamental information have proved disappointing because of the failure to consider a11 factors before their employrnent. Other techniques which we felt would be of limited value were found to be singularly significant as a source of fundamental information. Because of our experience, we feel that a review of the techniques employed and a critical evaluation of the experimental procedures would prove of value to other investigators who might enter the field of human locomotion and assist in the interpretation of results from the work st i i i in progress. Remoias for the Study of Auman Locomoiion. The reasons for studying human locomotion may be divided into four main categories. (i) The orthopedic surgeon is called upon frequentiy to attempt surgical procedures in order to improve the function of the locomotor system in individuals who have suffered damage to it. This includes not only fractures, but damage to joints and muscles. T t is obvious that any attempted surgicai procedure with any hope of success must depend upon an accurate knowledge of the functions of the parts involved. (2) Tlie physiotherapist has definite need of similar information in order to provide adequate treatment and proper functional training of impaired parts. (3) ?%en portions of the locomotor system are irreparably injured, the surgeon must rely upon externa1 support. These supporting braces must be designed for the work demanded of them without restraining the remaining normal functions if they are to prove of value. (4) M'ith the loss of a part, as in the amputee, an attempt is made to replace the lost portion with a prosthesis. How poorly we have succeeded in duplicaiing nature is evidenced daily by the individual who is in contact with the amputee. It is apparent that any improvement, either in surgical and physiotherapeutic procedures, or in braces and prostheses, must depend upon better knowledge of the function of the locomotor system.

Howard D. Eberhart

Papers

An evaluation of experimental procedures used in a fundamental study of human locomotion.