Hip Misalignment Cause of Knee Pain

Runners hurt their knees more often than they do any other part of their body. And the most common knee injury is patellofemoral pain syndrome (PFPS). Matt Fitzgerald, a training intelligence specialist for PEAR Sports, says that orthopedists used to believe that PFPS was associated with chondromalacia, or fissuring of the cartilage in the joint.

Following the demise of that premise, Fitzgerald said that medical professionals speculated that the primary cause of PFPS is improper tracking of the patella during running. He now says that recent research shows that the most common cause of PFPS is a genu valgum, or “knock knee” effect that is related to weakness in the hip musculature.

Fitzgerald explains it this way. “At the stance phase of running, when one foot is in contact with the ground, the muscles on the outside of the hip must become active to prevent the body from tipping toward the unsupported side. If those muscles are not able to do their job properly, the leg goes into genu valgum to compensate.”

The University of Calgary enlisted 25 runners to participate in a study. Fifteen of the runners had PFPS and 10 did not. For three weeks, those with the sore knees participated in exercises designed to strengthen their hip abductors. The 10 runners who were not injured did not.

At the end of the study the injured runners found that their strength had increased, stride-to-stride knee joint variability was reduced, pain was reduced and there was no observed change in knee genu valgum among the injured runners.

While the study was small, the investigators were encouraged to learn that strengthening exercises for the hip abductors can alter runners’ knee joint kinematics in a way that reduces strain on the knee during running.