Snapping Biceps Femoris Tendon.

A 23-year-old male active duty soldier presented with a biceps femoris tendon snapping over the fibular head with flexion of the knee beyond 90°. Surgical release of anomalous anterolateral tibial and lateral fibular insertions provided relief of snapping with no other repair or reconstruction required. The soldier quickly returned to full running and active duty. Snapping biceps femoris tendon is a rare but potential cause of pain and dysfunction in the lateral knee. The possible anatomical variations and the cause of snapping must be considered when determining the operative approaches to this condition.