Bilateral symptomatic snapping biceps femoris tendon due to fibular exostosis.

We present an unusual case of an athletic 17-year-old male cyclist with bilateral chronic dislocating biceps femoris tendons. On flexion of the knee, the biceps tendon subluxed over a large exostosis, creating a snapping sound. Snapping of tendons is common around the hip, ankles, shoulder, and elbow, but rare at the knee. When it does occur, snapping about the knee can be due to discoid meniscus, rheumatoid nodules, synovial plicae, iliotibial band syndrome, congenital snapping knee, and snapping tendons. Research revealed only 5 previous cases due to subluxation of the biceps femoris tendon. The case we present is the only one due to an exostosis, as well as the only one that required bilateral surgical repair. The patient presented when his pain became significant enough to interfere with his ability to continue competitive cycling.