INTRAARTICULAR CONTACT STRESSES WITH SIMULATED ANKLE MALUNIONS

Peak contact stresses were evaluated in a human cadaver ankle model of ankle fracture malunion. In one set of experiments, changes in peak c ontact stresses were evaluated for ankles loaded with lateral displace ments of the talus and fibula of 1, 2, 3, and 4 mm. In a second set of experiments, peak contact stresses were evaluated after removal of po sterior malleolar fragments. Peak contact stresses were concentrated o ver the anterior medial talar dome in normal specimens, and in specime ns with stimulated malunions. There were relatively low stresses benea th the medial malleolus. Peak stresses for ankles without talar displa cements ranged from 1.9 MPa to 12.4 MPa (eliminating one disparate spe cimen). There was no increase in peak stresses with lateral displaceme nts of the talus or with removal of posterior malleolar fragments. The fact that peak stresses with simulated ankle malunions were not eleva ted suggests that factors other than the magnitude of normal contact s tresses are of greater importance in the pathogenesis of posttraumatic arthritis.