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The synovial shelf syndrome.

VOL. 64-B. No. 4, 1982 475 Although the synovial shelf syndrome has come into prominence during the last decade with the wider use of the arthroscope, the anatomy of the synovial folds within the knee was described much earlier (Mayeda 1918 ; lino 1939). The medial synovial shelf, also known as lino’s band, Aoki’s ledge (Aoki 1973), the meniscus of the patella, the plica synovialis mediopatellaris and the plica alaris elongata, crosses the medial suprapatellar plica and runs in the coronal plane to be inserted in the infrapatellar fatpad. The medial shelf, which is present in 45 to 50 per cent of patients (Fujisawa, Jackson and Marshall 1976; Sakakibara 1976) is of variable width, and comes to lie in close contact with the medial femoral condyle when the knee is flexed beyond 30 degrees. Irritation of the medial synovial shelf can give rise to the “synovial shelf syndrome” or “plica syndrome”, the essential features of which are pain and tenderness in the line of the medial synovial shelf when the knee is flexed for long periods, without pain on patellofemoral compression (Fujisawa et al. 1976; Sakakibara 1976; Patel 1978). The pain may be so well localised that the patient points to the site of the shelf with the index finger when asked to indicate the painful area. The medial synovial shelf must be distinguished from the medial suprapatellar plica (Harty 1978 ; Patel 1978 ; Dandy 1981) which seldom causes symptoms unless it forms a complete suprapatellar membrane (Jackson and Dandy 1976). The medial synovial shelf has a lateral counterpart which is smaller, does not lie close to the lateral condyle, and is seldom the cause of symptoms. A fourth fold, the infrapatellar fold, is well described in standard anatomical texts (Gray’s Anatomy 1980) and runs from the infrapatellar fatpad to the apex of the intercondylar notch. The synovial shelf syndrome is usually found in adolescents during the adolescent growth spurt, and may follow a blow to the anteromedial aspect of the knee. Any generalised synovitis will lead to inflammation of the medial synovial shelf and the features described above are only suggestive of the synovial shelf syndrome if the rest of the knee is normal. This paper describes 67 knees in which the medial synovial shelf was either divided or excised, with special reference to the clinical features associated with a successful result and the indications for operation.