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Plica syndrome occurs when an otherwise normal structure in the knee becomes a source of knee pain due to injury or overuse.

Plica Syndrome

Plica is a term used to describe a fold in the lining of the knee joint. Imagine the inner lining of the knee joint as nothing more than a sleeve of tissue. This sleeve of tissue is made up of synovial tissue, a thin, slippery material that lines all joints. The synovial sleeve of tissue has folds of material that allow movement of the bones of the joint without restriction.


Four plica synovial folds are found in the knee, but only one seems to cause trouble. This structure is called the medial plica. The medial plica attaches to the lower end of the kneecap and runs sideways to attach to the lower end of the thighbone at the side of the knee joint closest to the other knee.

Plica Syndrome


A plica causes problems when it is irritated. Over time the plica can be irritated by certain exercises, repetitive motions, or kneeling. Activities that repeatedly bend and straighten the knee, such as running, biking, or use of a stair-climbing machine, can irritate the medial plica and cause plica syndrome.

If the knee is injured, the plica and the synovial tissue around the plica can swell and become painful. The initial injury may lead to scarring and thickening of the plica tissue later. The thickened, scarred plica fold may be more likely to cause problems later.

Plica Syndrome


The primary symptom of plica syndrome is pain. There may also be a snapping sensation along the inside of the knee as the knee is bent, due to the rubbing of the thickened plica over the edge of the thighbone. If the plica has become severely irritated, the knee may become swollen. Pain from plica syndrome usually occurs when the knee is straightened from a flexed or bent position to a straight position.

Plica Syndrome


History and Physical Exam

Diagnosis begins with a history and physical exam. The examination will try to determine where the pain is located and whether or not the band of tissue can be felt. X-rays will not show the plica. X-rays are mainly useful to determine if other conditions are present if there is not a clear-cut diagnosis.

Radiological Tests

If there is uncertainty in the diagnosis or if other injuries are suspected, an MRI may be suggested. The MRI (magnetic resonance imaging) uses magnetic waves to show the soft tissues of the body. This test does not require any needles, X-rays or special dye and is painless. A CAT scan may also be used to see whether the plica has become thickened. Most cases of plica syndrome will not require special tests such as the MRI or CAT scan. A plica band can not always be seen on a MRI or CAT scan.

Diagnostic Tests

If the history and physical examination strongly suggest that a plica syndrome is present, arthroscopy may be suggested to confirm the diagnosis and treat the problem at the same time. Arthroscopy is an operation that involves inserting a small fiber-optic TV camera into the knee joint, allowing the orthopedic surgeon to look at the structures inside the knee to determine whether the plica is inflamed.


Most people with plica syndrome get better without surgery. The primary treatment goal is to reduce inflammation. This may require limiting activities like running, biking, or using the stair-climbing machine.

Conservative Treatment

Most people with plica syndrome get better without surgery. The primary treatment goal is to reduce inflammation. This may require limiting activities like running, biking, or using the stair-climbing machine.


If conservative treatments fail, surgery may be suggested. Usually, an arthroscope is inserted into the knee joint through one-quarter inch incisions. Once the plica is located, small instruments are inserted through another one-quarter inch incision to cut away the plica tissue and remove the structure. The area where the plica is removed heals back with scar tissue.

Plica Syndrome


Following surgery, you will be referred to a physical therapist. Your first few rehabilitation sessions are designed to ease pain and swelling and help you begin gentle knee motion and thigh tightening exercises. Patients rarely need to use crutches after this kind of surgery.

As symptoms of swelling and pain are controlled, the focus of exercise is to get the quadriceps muscle moving again. Patients usually start with isometric exercises to tighten the front thigh muscle, advancing to straight-leg lifts. Muscle stimulation may be needed at first if the quadriceps muscle is sluggish. This technique uses electrical current passed though electrodes placed on the skin over the muscle.

As the program evolves, more challenging exercises are chosen. Patients do exercises that mimic familiar activities like squatting down, lunging forward, and going up or down steps. These exercises are designed to help keep pressure off the kneecap while getting a challenging workout for the leg muscles. Your therapist will work with you to make sure you are not having extra pain in your knee during the exercises. You may be shown stretches for the soft tissues along the edge of the kneecap as well as muscle stretches for the hamstrings, quadriceps, and calf muscles.

The therapist’s goal is to help patients keep their pain under control, make sure they aren’t putting too much weight on the injury, and improve quadriceps muscle strength and knee range of motion. When patients are well underway, their regular visits to the therapist’s office will end. The therapist will continue to be a resource, but patients will be in charge of doing their exercises as part of an ongoing home program.

  • American Orthopaedic Society for Sports Medicine
  • American Association for Hand Surgery
  • American Academy Of Orthopaedic Surgeons
  • The American Board of Pediatrics
  • North American Spine Society
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