Biomechanical comparison of prophylactic medial malleolar fixation in total ankle arthroplasty

The purpose of this study was to compare the biomechanical properties of two common forms of prophylactic fixation of the medial malleolus during total ankle arthroplasty (TAA). Ten matched pairs of cadaveric lower extremities were fixed with a single cannulated cortical screw or a one-third tubular plate after preparation for TAA. Ten unmatched single cadaver lower extremities were used as the control. A transverse load was applied to the medial malleolus. Bone mineral density, peak loads at fracture, and fracture pattern were noted. There was no statistically significant difference in peak load to failure between either fixation cohorts or between the fixation cohort and the control cohort. There was a moderate positive correlation between bone mineral density and peak load for all three experimental groups. The peak load was significantly (p = .035) increased in male cadavers. Fractures occurred almost exclusively at the apex of the tibial and malleolar cuts with a vertical fracture pattern.