Arthroscopic internal marsupialization of meniscal cysts.

Meniscal cysts begin with extrusion of synovial fluid through a tear of the meniscus, enlarging probably as a result of a one-way valve effect of the tear flap. We describe a technique of arthroscopic internal marsupialization of meniscal cysts with or without meniscectomy. A 5 mm channel was created in the capsule adjacent to the cyst arthroscopically for decompression of the cyst into the joint, thus equalising pressures between the cystic and intra-articular compartments. Only unstable meniscal tears were debrided down to a stable rim while intact meniscii or stable tears were left alone. Eight patients with MRI confirmed atraumatic medial or lateral meniscal cysts underwent surgery. At a mean follow-up of 39.1 months (12-94 months, S.D. 26.4), Tegner scores averaged 5.1 (3-8, S.D. 2.1) and Lysholm scores averaged 94.4 (85-100, S.D. 5.4). No cyst recurred. Arthroscopic internal marsupialization effectively decompresses meniscal cysts and prevents their recurrence, while preserving meniscal tissue and minimising arthrosis of the knee joint.