An overuse injury characterized by a dull pain felt at the kneecap. Patellofemoral pain syndrome is most common among runners who overtrain and who continue to train through injuries (see also pain cycle). The pain tends to worsen when ascending or descending stairs, and when running downhill. Typically, the knee stiffens when trying to straighten it after sitting for prolonged periods (the so-called theatre sign). The pain is thought to arise from nerve fibres in the subchondral bone of the patella or from inflammation of the synovial membrane. Patellofemoral pain syndrome is often confused with chondromalacia patellae, but in the syndrome there is no softening of the articular cartilage. Flat feet, hyperpronation, femoral anteversion, high Q-angle, and weakness and tightness in the quadriceps, hamstrings, and calves are often associated with the syndrome. Treatment of patellofemoral pain syndrome varies. It includes rest from running, ice-treatment, anti-inflammatories, correction of anatomical defects, exercises that strengthen the muscles around the knee, and stabilization of the kneecap with a knee brace. Sometimes knee surgery is required to relieve the pain. A key feature of rehabilitation is strengthening the vastus medialis (obliquus) muscle by suitable static muscle actions (isometric contractions).
Subjects: Sports and Exercise Medicine.