A DYNAMIC CADAVER MODEL OF THE STANCE PHASE OF GAIT - PERFORMANCE-CHARACTERISTICS AND KINETIC VALIDATION

Objective. This study was undertaken to evaluate the performance of a new dynamic laboratory model of the stance phase of gait. Design. Five cadaver feet were repetitively tested in the apparatus. Background. T ypical biomechanical investigations of cadaver feet simply place a sta tic load on the tibia. The present system was designed to better simul ate the changing in-vivo loading environment of the foot and angle dur ing gain. Methods. The device mimics the behavior of the tibia, foot, and ankle from heel-strike to toe-off by reproducing the physiologic a ctions of five extrinsic foot muscles and physiologic motion at the pr oximal tibia. To verify its utility, cadaver gait simulations were con structed while measuring applied muscle forces, ground reaction forces , and plantar pressures. Results. Dynamic muscle forces were consisten tly delivered to within 10% of pre-programmed values. Dynamic measurem ents of ground reaction forces and plantar pressure were similar to th ose measured in healthy human subjects. Peak vertical (y), fore-aft (x ) and medio- lateral (z) forces were 110, 18, and 4% of body weight re spectively. Compressive force in the tibial shaft reached 410% of body weight. Relevance Cadaver studies have greatly enhanced our understan ding of normal and pathologic foot function, but are often limited by over-simplified loading conditions. The apparatus presented here accur ately reproduces the in-vivo loading environment and provides a powerf ul investigational tool for the study of foot and ankle function. With this device, musculoskeletal structures can be examined in detail und er biomechanical conditions similar to those they experience in life. (C) 1998 Elsevier Science Ltd. All rights reserved.