[Villonodular synovitis--a rare condition causing intermittent locking of the knee]

Two patients with intermittent locking, mimicking a meniscal lesion or a loose body and with a palpable tumour in the knee joint are described. X-ray examinations were normal. Athroscopy revealed pedunculated tumours in both knees. The tumours were removed arthroscopically in one patient and by an arthrotomy in the other patient. The histological diagnosis was localized villonodular synovitis (giant-cell tumour) in both patients. This is a benign but very rare condition.