Plica Syndrome

A plica is a thin wall of fibrous tissue that are extensions of the synovial capsule of the knee. During fetal development, the knee is divided into three (3) separate compartments. As the fetus develops these compartments develop into one large protective cavity (synovial membrane). The majority of people have remnants of these three cavities referred to as a plica. Most often the plica is on the medial (inside) of the knee at the level of the medial femoral condyle. Most individuals are not adversely affected by the presence of plicas.

The plica only becomes a problem when the knee is irritated, causing an inflammation in the synovial sack. When the synovium is inflamed, the area of the plica becomes thicker. This thickened area then begins to catch on the femur as the knee moves. This in turn keeps the plica inflamed resulting in a viscous cycle.

The plica can be located anywhere in the knee. The exact symptoms will be determined by the plica’s location. The most common location is along the medial (inside) side of the knee. The plica can tether the patella to the femur, be located between the femur and patella, or located along the femoral condyle. Regardless of location the pain is due to the plica catching or being pinched between the patella and femur. If the plica connects the patella to the femoral condyle, symptoms will mimic patello-femoral syndrome.

With out a complete clinical examination, the plica may be missed, resulting in an inappropriate rehabilitation plan. For example, if the patella is tethered by the plica, the clinician may design a rehab plan to address a patello-femoral disorder. This may only exacerbate the condition. If the plica is truly tethering the patella, the rehab should focus on decreasing the inflammation, and increasing the overall strength of the quad muscles.

Treatment of Plica Syndrome

The first concern is to decrease the inflammation of the synovial capsule. This can be attacked with numerous methods. First, the orthopaedic surgeon may prescribe a non-steroidal anti-inflammatory medication. Examples of these medications are Motrin®, DayPro®, Naprosyn®, Celebrex®, and Indocin®. These medications act systemmically to slow the inflammation process. Theraputic exericses and modalities may also be used to treat the plica. To attack the inflammation, modalities such as iontophoresis (utilizing low intensity electric current to transport medications through skin), phonophoresis (using ultrasound to transport medications through skin), and ice are most commonly utilized.

Rehabilitative exercises should be instituted when the inflammation has been controlled and pain levels are falling. These exercises should focus on increasing overall quadriceps, hamstring, and calf strength., as well as increasing overall muscular flexibility. Examples of appropriate exercises are: pain-free squats that progress to one-leg squats, side step-ups, closed chain terminal knee extension, and applicable sport-specific exercises. Care should be taken to avoid deep squats as this can increase pain and inflammation.

The exercises should be performed utilizing PRE (progressive resistance exercises) principles, gradually increasing load and intensity as pain and inflammation allows.

Case Study

An 18 year old male football player presents with a history suspicious of a medial meniscal tear. This was confirmed by MRI. Surgery was performed to repair the medial meniscal tear. Upon arthroscopic evaluation the plica was found. The MRI did not visualize the plica. This plica was located on the medial synovial lining, running superiorly into the suprapatellar pouch. As can be seen in the picture, the plica is distending the synovial lining into the knee joint. The picture on the left shows the same view of the knee with the plica removed. Notice that the synovial lining is no longer pulled into the joint. The torn meniscus was also addressed.

The athlete was seen in the training room for 5 total visits in a two week span. Treatment emphasized basic quadriceps strength and range of motion. Following his 10 day post-op physician’s visit, the athlete was released to normal strength training (10 day gradual return to previous routine) in the weight room.