Snapping knee caused by intra-articular tumors.Arthroscopy. 2003 Mar; 19(3):E21.A
Locking of the knee can present with no history of antecedent injury. We identified impingement of intra-articular tumors in 2 cases. Intra-articular tumors are relatively rare. Mechanical symptoms were present in both cases. On physical examination, there was a palpable mass at the medial region of the patellofemoral joint. The interior had been replaced mainly by amorphous necrotic tissue. The definite diagnosis of a soft-tissue mass of the knee could not be made on histologic examination.