TIBIOTALAR CONTACT AREA AND PRESSURE DISTRIBUTION - THE EFFECT OF MORTISE WIDENING AND SYNDESMOSIS FIXATION

An unconstrained cadaver ankle model was designed to reevaluate the ef fect of ankle mortise widening and syndesmotic fixation on the load-be aring characteristics of the tibiotalar joint, Tibiotalar contact area , centroid shift, and mean contact pressure were quantified using a pr essure-sensitive film technique, Six fresh-frozen below-knee amputatio n specimens were axially loaded with 500 N in three positions: neutral , 10 degrees of dorsiflexion, and 20 degrees of plantarflexion. The ti biotalar contact area and centroid position for each specimen in its i ntact state were first determined and then compared with values obtain ed after syndesmotic fixation, mortise widening of 2 and 4 mm, and dee p deltoid ligament transection, Syndesmotic fixation significantly dec reased joint contact area but did not consistently affect centroid pos ition, However, unlike earlier studies, which used more constrained an kle fracture models, mortise widening with or without deltoid rupture was not found to significantly affect contact area, centroid position, or joint contact pressure, When statically loaded, the talus moved to its position of maximal congruence in the mortise, rather than displa cing laterally along with the lateral malleolus.