Synovial rupture of the knee joint.

1. Twenty-two cases of synovial rupture of the knee have been studied. This condition may complicate any chronic synovitis of the knee in which a tense intra-articular effusion is subjected to increased tension during flexion and extension of the joint. 2. Two types of rupture have been seen; a herniation of the synovial membrane into the popliteal fossa and down the leg, and an acute synovial tear with extravasation of joint contents between the muscle planes of the calf. 3. The diagnosis of this condition, the differentiation of the types of rupture and their treatment are discussed. 4. The acute rupture usually responds to simple bed-rest; the large synovial herniations often need removal and repair of the posterior capsule.