CONTACT CHARACTERISTICS OF THE ANKLE JOINT .2. THE EFFECTS OF TALAR DOME CARTILAGE DEFECTS

Variations in ankle joint contact characteristics caused by articular defects of the talar dome were investigated in 14 fresh-frozen cadaver specimens using pressure-sensitive film. intact ankle and foot specimens were mounted in a materials tester on a loading frame which allowed positioning in neutral, and 20 degrees of dorsiflexion and plantarflexion. Joint contact prints were recorded while an 800 N load was axially applied through the leg. Specimens were randomly placed into two lesion groups: either anterolateral or posteromedial. During testing, each specimen had four concentrically placed lesions on the tatar dome, graduated in size. Following removal, the film transducers were digitized along with pressure calibration prints. The images were analyzed quantitatively to determine contact areas, mean contact pressures, ratio of to contact plafond areas, and high pressure centroid position as a function of lesion size and location. The results demonstrated significant changes in contact characteristics for larger lesions (greater than or equal to 7.5 x 15 mm) (P < 0.05). These findings suggest that determining the size of a lesion may assist in predicting the long-term outcome of ankles with cartilage defects.