[Intra-osseous and intra-articular cyst of the knee. Apropos of a case associated with osteochondritis dissecans].

Subchondral bone cyst, intraarticular synovial cyst, and osteochondritis dissecans arising together are analyzed: this association has so far not been reported. If we accept the theory of a mechanical origin for subchondral bone cysts (leakage of joint fluid or intrusion of the synovial membrane through a breach in the cartilage), then the osteochondritis certainly provided the port of entry that allowed formation of the intraosseous synovial cyst in this patient.