Background: A 36-year-old woman presented to the orthopedic department with painful impairment of the left knee. The pain to the medial side of the knee and locking of the knee joint had started after a distortion of the knee during a game of soccer 2 weeks earlier. On clinical exami - nation, the left knee showed a flexion/extension range of 110/0°. On palpation and rotation of the knee joint, the patient experienced pain in the medial compartment of the knee. The anterior drawer test was slightly positive (+1); examinations of the other ligaments of the knee were negative.