This condition, which is commonly known as BREAST STROKERS SYNDROME, can occur in patients of all ages. Despite the connotation of BREAST STROKERS a plica syndrome is not necessarily associated with swimming, although most patients partake in sporting activities.

The drawing emphasises the different types of plicae within the knee cavity. The supra patellar plica is generally called 'Septum' whilst the inferior plica is described as the Ligamentum Mucosum. The medial plica is most commonly involved in causing problems and represents about 85% of all plica syndromes (from Oliver Schindler 'Synovial Plicae of the Knee' Current Orthopaedics 2004)

Synovial plicae are soft tissue folds, which naturally occur in the knee. They represent embryological remnants, which date back to a time when our knees were divided into several separate compartments. These folds can have various sizes and patients with larger folds are generally more prone to develop a so-called Plica Syndromeh. The condition is most common in patients who partake in activities, which involve repetitive exercises such as running, athletics, field sports etc. Often a sudden step-up in activity level creates an inflammatory reaction in these folds caused by mild to moderate impingement between the condyle and the patella. Patients usually complain of dull discomfort across the antero-medial aspect of the knee, which occurs several minutes into the activity and may linger on for hours. Swelling and effusion are no regular features. Localised tenderness and a 'moving strand' of tissue can often be detected when the examiner places his thumb onto the medial condyle whilst asking the patient to perform half-squats.

An inflamed an enlarged medial plica usually impinges onto the inner aspect of the patello-femoral joint between 15 to 30 degrees of knee flexion.

The condition is caused by repetitive impingement of the medial or supra-patella plica across the femur at various degrees of flexion. Once the plica is inflamed it may thicken and bowstring. This may take several months during which symptoms will gradually increase. If such a situation arises, it is difficult to treat with conservative measures. An intra-plical injection can be attempted but has only limited success, especially if symptoms have been present for more than six months. In chronic cases, arthroscopic plica excision remains the treatment of choice.

View of an impinging medial plica viewed arthroscopically. In knee extension the plica bowstrings across the medial femoral condyle. In flexion, the plica wraps around the edge of the condyle. Surface damage affecting both patella and femur are clearly demonstrated.

Chronic impingement of a medial or supra-patellar plica is thought to be responsible for initiating surface degeneration, which may subsequently lead to the development of osteo-arthritis. In patients with localised uni-compartment wear, a thickened plica is often found in close proximity of the lesion. Such specimens are then excised when joint replacement surgery is performed.