Optimization and application of a wrap-spring clutch to a dynamic knee-ankle-foot orthosis.

A dynamic knee-brace system (DKBS) has been designed which provides stance phase stability and swing phase freedom. A wrap-spring clutch controls knee flexion. Clutch optimization was performed minimizing clutch length.

Effect on gait using various prosthetic ankle-foot devices.

Five different commonly prescribed ankle-foot devices for below-knee prostheses were tested for effects on gait: SACH, SAFE, SEATTLE, SINGLE AXIS, and MULTIPLE AXIS. Subjective ratings by the amputees served to resolve which physical variables determined the preferred ankle-foot device. Ratings were related to age, body weight, length of residual limb, and ratio of stride frequency to stride length.

Load-bearing characteristics of polyethylene foam: an examination of structural and compression properties.

Cellular foams used in shoe insoles come in a variety of structural configurations differing with respect to cell geometry. The compression of a cellular foam depends on cell reticulation and size. Examination of the compression behavior of closed cell polyethylene foams revealed distinct time-and nontime-related properties that occur during static and cyclic loading.

Effect of velocity and SF/SL ratio on external work and gait movement waveforms.

Ten normal adult subjects were tested under a wide range of combinations of stride length and stride frequency. Both longitudinal and vertical accelerations of the body increased with velocity, while stride frequency to stride length ratio (SF/SL) had little effect. The peak-to-peak amplitude of the forward velocity (V) decreased with SF/SL, but at constant SF/SL remained essentially unchanged throughout the speed range from 0.

Analysis of below-knee suspension systems: effect on gait.

Seven different suspension systems for below-knee prostheses were tested on 20 adult, unilateral amputees. All subjects walked with a prosthesis. Gait was evaluated with regard to longitudinal and vertical accelerations of the body, forward velocity, axial (piston) movement of amputated limb in the socket, and knee movement.

Volume changes occurring in postoperative below-knee residual limbs.

Comparative maturation rates of 36 below-knee postoperative, healed amputation residual limbs were observed. Measured were the limb volumes and circumferences. Three methods of residual limb stabilization were employed: 1) elastic wrap; 2) plaster cast and pylon; and, 3) plastic laminate socket and pylon.

A technique for the display of joint movement deviations.

Detection of deviations in lower-limb joint movements derived during locomotion testing may be enhanced by displaying as a function of the gait cycle the algebraic difference between actual performance and a synthetic waveform. A synthetic waveform for a joint movement may be generated by applying Fourier series coefficients derived from a statistical treatment of test data characterizing the performance of normal healthy individuals walking at various velocities. Application of waveform specifics related to velocity yields a synthetic pattern serving as the criterion at the specific velocity demonstrated by a patient.