Contact characteristics of the ankle joint. Part 1. The normal joint.

The contact characteristics of ankle joints in 18 fresh cadaver specimens were studied by using pressure-sensitive film to provide baseline information for subsequent studies of various pathologic ankle conditions. Specimens, consisting of the distal half of the tibia and fibula and the intact ankle and foot, were mounted in a materials testing system on a loading frame that allowed positioning in neutral, and 20 degrees of plantarflexion and dorsiflexion. An 800 N load (1 body weight) was axially applied to the specimens through the tibia with 10% of the total load distributed through the fibula. Transducers made of pressure-sensitive film were used to make a contact print and were scanned along with calibration strips to form a digital image. The image was analyzed quantitatively to determine total contact area, mean contact pressure, ratio of contact to plafond areas, and high pressure zone centroid location as a function of sagittal plane foot position in the normal ankle joint. The results demonstrated significant changes in ankle joint contact characteristics with different foot positions.