CONTACT STRESS DISTRIBUTIONS IN MALREDUCED INTRAARTICULAR DISTAL RADIUS FRACTURES

Residual articular incongruity of the distal radius following intraart icular fracture has been correlated with early osteoarthritis (OA) and a poor clinical outcome. We developed a simple in vitro fracture mode l of the distal radius to investigate the relationship between degree of articular incongruity and the resulting distribution of radiocarpal contact stress, Twelve fresh-frozen cadaver arms were dissected, pack ets of Fuji Pressensor film were inserted into the wrist, and the wris t was loaded through its flexor and extensor tendons. We created a sim ple intraarticular fracture that allowed controlled distal radius arti cular incongruity. Loading trials were performed for the intact distal radius, for a fully reduced case, and for step-offs of 0.4, 1, 2, and 3 mm. Mean contact stress was significantly greater than the anatomic ally reduced case at only 3 mm of step-off. Contact area was greater t han the anatomically reduced case at 0.4, 1, and 2 mm of step-off. The elevations in contact stress that we observed were only modest, sugge sting that other factors may be involved in the pathogenesis of radioc arpal OA in the presence of residual articular incongruity.