Patellofemoral problems in runners.

Unlike twisting and cutting sports, in which there are torsional forces placed on the knee, distance running involves straight line motion. The biomechanics of running usually insure a relatively smooth tracking of the patella in the femoral groove, so it is rare for a runner to experience an acute traumatic injury of the joint. Since such injuries are rare, this article concentrates on stress-related patellofemoral syndromes that are seen in runners.