Locomotion and lower-limb prosthetics.

One of the principal activities of the members of the Biomechanics Laboratory during the past two decades has been the study of human locomotion . A major objective of these studies has been the accumulation of data that might be used in the design and construction of improved prosthetic and orthotic devices . The investigations have included electromyograms of the phasic action of muscles, forceplate recordings of floor reactions in both normal subjects and amputees, recordings of angular displacements and angular accelerations using a variety of techniques, and measurements of metabolic energy expenditures of normal subjects and subjects with various encumbrances, such as loads applied to certain segments of the body or devices to immobilize certain major joints . Amputees wearing various types of protheses have been evaluated by a variety of techniques . Some of the material obtained from these studies has been published in journals, reported at various scientific meetings, or preserved in technical reports with limited distribution. When the vast amounts of data are reviewed, two facts are evident. First, the major displacements of the hip, knee, and ankle are grossly similar in all people and clearly are the result of our bipedal orthograde type of locomotion . Second, the variations in the less apparent movements are great, for example, in the horizontal rotations of the pelvis, thigh, and shank and the motions of the ankle and intrinsic articulations of the foot. These latter movements play a major role in determining the unique characteristics of an individual 's gait which enable one to recognize a friend walking even at a distance . Furthermore, these individual differences may be of great importance in orthopedic surgery and in the proper prescription of new prosthetic and orthotic devices. Despite the wide range of anatomic variations which exist and disabilities which may be involved, there is in most individuals a remarkable