Synovial tissue lines the knee joint and produces fluid to lubricate the joint. Plica is a thickening of the synovium lining separating the knee joint into separate compartments. These thickenings form in the fetus and reduce in size to small sleeves or folds during the second trimester. Most of the time, these folds shrink or disappear. However, these folds remain very thick in some people and can irritate the knee joint. Could your knee pain be due to medial plica syndrome knee?

The knee has four plicae, but the medial plica causes most problems.

 

plica thickening knee joint

Diagnosis of plica syndrome 

Plica syndrome is the term used to describe irritation of the plica fold. Usually, plica is found inside the knee (medial plica), which is irritated and causes symptoms. Primarily, irritation occurs when the knee bends, so the plica gets caught between the knee cap and the top part of the knee joint.

Generally, irritation of the plica causes the following symptoms:

  • Knee pain on the inside of the knee with repeated bending, such as climbing stairs, cycling and running
  • tenderness and swelling over the inside plica
  • snapping or clicking when bending the knee
  • Sometimes, a fall on the knee can cause swelling in the medial plica and subsequent pain

Often, an X-ray is normal. Likewise, we can see a thickened inflamed plica on MRI or ultrasound, although not always.

Sometimes, a suprapatellar plica blocks the flow of knee fluid in the joint, leading to pressure in the top part of the knee joint. We think this knee pressure can compress the quadriceps tendon, leading to quadriceps tendonitis.

Plica or meniscal tear?: How to differentiate

It is essential to exclude other causes of pain at the front or inside of the knee, such as a torn meniscus, kneecap arthritis, or patellar tendonitis. For example, a meniscal tear presents with pain in the knee joint toward the back of the knee and when bending and rotating the knee. Moreover, kneecap arthritis presents with pain inside the patella and swelling in the knee joint.

Plica syndrome treatment 

Usually, we try simple treatments first, such as anti-inflammatory treatments. Ice, compression, and ibuprofen tablets are enough to help settle the inflamed plica tissue. Then, we recommend a rehab program to reduce pressure on the plica, such as taping, stretching, and strengthening exercises. One study found 90% effectiveness in managing plica syndrome with rehab. 

An ultrasound-guided cortisone injection might help reduce inflamed plica in cases that fail to settle. However, it is essential to direct the injection by targeting the inflamed tissue inside the knee. Sometimes, in cases of suprapatellar plica, the injection is directed to the top part of the knee.

Does keyhole surgery work for plica syndrome? Plica surgery success rate: 

 

knee arthroscopy

 

Keyhole surgery uses a small camera inside the knee joint to find and remove the inflamed plica tissue. Plica surgery success rate is high if the inflamed tissue is the cause of pain. Also, there are no known problems after removing a plica.

Moreover, in cases of a suprapatellar plica causing quadriceps tendonitis, removing this plica will also help the quadriceps tendonitis.

However, it is often tricky to diagnose plica syndrome, as we discussed. Also, surgery is not without risks, and the success rate can vary depending on whether plica syndrome is the only cause of knee pain. Most studies on plica surgery have been case series, which is lower level evidence and does not prove effectiveness.. 

You should be cautious about proceeding with surgery as the success rate is unpredictable. Therefore, we should only suggest surgery if other measures fail, including one or two cortisone injections into the plica.

Final word from Sportdoctorlondon about medial plica syndrome 

Overall, we think that plica syndrome is a rare cause of pain in the front of the knee pain. Most causes of pain at the front or inside of the knee are not due to plica syndrome. You need a good clinical assessment with imaging findings of an inflamed plica to increase your chances of making a correct diagnosis. Also, you should only consider surgery after rehab failure and one or two injections. Be wary of practitioners suggesting that surgery is easy and the only answer.

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Dr. Masci is a specialist sport doctor in London. 

He specialises in muscle, tendon and joint injuries.