A dynamic cadaver model of the stance phase of gait: performance characteristics and kinetic validation.

Abstract

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: Typical biomechanical investigations of cadaver feet simply place a static load on the tibia. The present system was designed to better simulate the changing in-vivo loading environment of the foot and ankle during gait. METHODS: The device mimics the behavior of the tibia, foot, and ankle from heel-strike to toe-off by reproducing the physiologic actions of five extrinsic foot muscles and physiologic motion at the proximal tibia. To verify its utility, cadaver gait simulations were conducted while measuring applied muscle forces, ground reaction forces, and plantar pressures. RESULTS: Dynamic muscle forces were consistently delivered to within 10% of pre-programmed values. Dynamic measurements of ground reaction forces and plantar pressure were similar to those measured in healthy human subjects. Peak vertical (y), foreaft (x) and medio-lateral (z) forces were 110, 18, and 4% of body weight respectively. Compressive force in the tibial shaft reached 410% of body weight. RELEVANCE: Cadaver studies have greatly enhanced our understanding of normal and pathologic foot function, but are often limited by over-simplified loading conditions. The apparatus presented here accurately reproduces the in-vivo loading environment and provides a powerful investigational tool for the study of foot and ankle function. With this device, musculoskeletal structures can be examined in detail under biomechanical conditions similar to those they experience in life.