Snapping knee syndrome caused by semitendinosus and semimembranosus tendons. A case report.

We report the case of a 24-year-old female triathlon athlete with a snapping syndrome of both the distal semimembranosus and the semitendinosus tendon which has not been described so far. The semitendinosus tendon was harvested whereupon snapping has diminished. Tenoscopy and digital palpation showed the semimembranosus tendon to cause the snapping, as well. A careful step-by-step release of the anterior insertion of the tendon was performed with the result of a snapping-free range of motion of the patient's knee.