Hip Joint Contact Stress after Incongruent Reduction of Acetabular Fracture

The results of previous experimental studies indicate an important role of contact stress in postraumatic steoarthritis development. Therefore in this work, a mathematical model has been developed to calculate the contact stress distribution in a human hip joint after acetabular fracture. The model was used to simulate effects of various malreduced column, wall, and transverse acetabular fractures on the hip contact stress. The stress distribution was studied for offset incongruity where fracture fragment is displaced away from acetabular surface and step-off incongrity where fracture fragment protrudes into the joint space. It was shown that both step off and-offset incongruities considerably increase the peak contact stress. The contact stress increase is larger if the fractures are located in the superomedial region of the acetabulum. Estimated values of stress in the hip joint after trauma are in the range of values typical for dysplastic hips. Results support the theory that postraumatic arthrosis is induced by considerably elevated contact stresses due to changes in the joint mechanics.