The effects of fibular and talar displacement on joint contact areas about the ankle.

The purpose of this study was to advance prior techniques and studies regarding the effects of fibular and talar displacement of contact areas of the tibio-talar joint. Type IV supination external rotation injuries were experimentally created on five fresh cadaveric specimens. Tibio-talar contact and peak pressures were measured using Fuji pressure-sensitive film with the talus in a neutral position and then displaced 1, 3, 4, 5, and 8 mm laterally as well as a repeat measurement following reduction and plate fixation. Results demonstrated a 50% reduction in contact area with only 1 mm of talar displacement along with a linear increase in average peak pressures. Reapproximation of the fibular osteotomy with a plate and rereduction of the talus allowed for return to normal pretesting contact areas. This study confirms prior studies demonstrating the significance of 1 mm of talar displacement in regards to marked reduction in contact area of the tibio-talar joints. In addition, restoration of the normal anatomy and fixation of the osteotomy allows for return of normal contact areas.