Breaststroker's knee: pathology, etiology, and treatment.
Twenty-three breaststroke swimmers (ranging in age from 6 to 30 years old) with painful knees were examined. Underwater movies of these swimmers were taken. Eighteen swimmers had tenderness under the medial facet of the patella and over the medial femoral intercondylar ridge. Five of these 18 swimmers also had tenderness along the tibial collateral ligament. Five swimmers had tenderness just along the tibial collateral ligament. The onset of knee pain usually occurred within 3 years of the swimmers' beginning the breaststroke. Initially, the knees were only symptomatic when the swimmers performed the whipkick. As the swimmer continued the breaststroke, in spite of discomfort, the knees became symptomatic during other athletic and nonathletic activity. Breaststroke who had been using the whipkick for more than 8 years had clinical evidence of patellofemoral osteoarthritis. The site of pain in the knee was related to the way in which the whipkick was performed. Breaststroke without knee pain used a whipkick with characteristics that were consistently different than those of the symptomatic swimmers. Treatment of breaststroke's knee should be directed toward correcting the swimmer's whipkick. This approach is most likely to be successful if applied as soon as the swimmer becomes symptomatic.