BIOMECHANICAL EFFECTS OF INTERNAL-FIXATION OF THE DISTAL TIBIOFIBULARSYNDESMOTIC JOINT - COMPARISON OF 2 FIXATION TECHNIQUES

This biomechanical study compares two methods of internal fixation of the tibiofibular syndesmosis used in Weber type C malleolar fractures of the ankle. The transverse syndesmotic 3.5-mm screw was compared wit h two 1.5-mm Kirschner wires introduced obliquely across the distal ti biofibular syndesmosis. The influence of implants on distal tibiofibul ar joint motion and contact characteristics of the intact ankle joint were determined. Up to 1.25 mm of lateral displacement and 2-degrees o f external rotation of the lateral malleolus during uninjured ankle do rsiflexion was recorded. Both techniques stabilized the injured syndes motic joint and limited its normal motion during flexion and extension of the ankle. Pressure distribution displaced laterally in internally stabilized ankles compared with intact specimens, regardless of the t ype of fixation used. Therefore, both techniques alter joint biomechan ics equivalently compared with the intact ankle.