April 21, 2006

Hip exercises aid common knee problem

By Amy Norton

NEW YORK -- People with chronic knee pain known as patellofemoral pain syndrome may find relief from exercises that strengthen and stretch the hip muscles, research suggests.

In a study of 35 adults with the condition, researchers found that when patients were able to increase their hip strength and flexibility through physical therapy, their knee pain significantly diminished.

Patellofemoral pain occurs under and around the kneecap, and often worsens after activity or long periods of sitting with the knees bent. As it moves, the kneecap tracks along the groove of the thigh bone, and incorrect alignment between these bones is thought to play a major role in patellofemoral pain.

Typically, therapy for patellofemoral pain focuses on the kneecap - akin to bringing the "train back on the track," explained Timothy Tyler, a physical therapist at Lenox Hill Hospital in New York City and the lead author of the new study.

In contrast, he told Reuters Health, exercises for the hip muscles - which stabilize the thighbone and pelvis - essentially "bring the track back to the train."

For their study, published in the American Journal of Sports Medicine, Tyler and his colleagues followed 35 patients who went through six weeks of physical therapy for patellofemoral pain. The regimen focused on strengthening and improving flexibility in various muscles that act on the hip.

Overall, the study found, the therapy was successful for two-thirds of the patients, and strengthening the hip flexors -- muscles that bring the thigh and torso toward each other - was a key to success.

Of the 26 knees that were treated successfully, strength in the hip flexor muscles improved by an average of 35 percent. On other hand, in all cases where patellofemoral pain did not improve, there was no gain in hip flexor strength.

Patients also benefited from boosting their flexibility -- namely, in muscles that flex the hip and in the iliotibial band, a long stretch of connective tissue that runs along the outer thigh, from the hip to just below the knee.

Tyler described the success rates in the study as "remarkable," and said the findings point to the importance of hip muscle function in patellofemoral pain. But right now, he noted, the typical physical-therapy prescription for the condition does not focus on the hip muscles.

"Hopefully, this will spread," Tyler said.

SOURCE: American Journal of Sports Medicine, April 2006.