Plica Syndrome Causes And Symptoms

Plica is a fold in the tissue that is present in several synovial joints in the body. The most common of these is the knee and the membrane that lines these joints creates the fluid that lubricates the synovial membrane. It is in this synovial membrane that the folds called plicae occur. They move normally within the knee during flexion and extension of the knee, issues can arise due to inflammation or irritation from overuse, causing knee pain. This is a relatively unknown source of knee pain, which people associate with other knee issues such as meniscus-related pain. Plica syndrome is not generally as serious as other knee issues, but it is important to know its causes and symptoms as it is an uncommon issue.

A plica is a band of thick, fibrotic tissue that is connected to the knee joint; it is also known as a ‘fold’ and is a common occurrence in the anatomy of the knee.¹ There are many plicae that are found around the knee these can be:

• Infrapatellar
• Suprapatellar
• Medial
• Lateral

These can all be present in an individual or a combination of any of them, as they develop during foetal development. The medial plica is the most likely to develop the symptoms of plica syndrome and therefore cause knee pain.

The medial plica is between the kneecap and the medial side of the knee (this is the side of the knee that is closest to the centre of the body).² 

Causes of Plica Syndrome

The plicae can become inflamed and irritated due to overuse or injury. The inflammation can occur due to friction against the kneecap or other bones of the knee. This inflammation can cause plica syndrome, which is the anterior knee pain that arises from the condition and reduces the ability to exercise or normal movement without pain. Anterior knee pain is pain which occurs in front of the knee.²  

Symptoms

Knee pain is a common symptom that will be the main marker noticed, however, there are several other symptoms that can occur. They are:

• Swollen Knee
• Clicking or Popping sound in knee
• Pain that worsens after climbing stairs or squatting
• Catching sensation after standing for long periods
• Feeling of instability on slopes or stairs
• Feeling swollen plica when pressing on kneecap¹

Irritation can be more common in those that have significant muscle imbalances around the knee and have less muscle tone in the quad. This imbalance or weakness can alter the knee’s ability to function normally causing the plica inflammation. Research suggests that prolonged knee flexion can cause pain and this can particularly be an issue during sleep.³ 

Many of the same symptoms occur with plica syndrome as those that arise when someone has a torn meniscus, the pain, swelling, and reduced mobility are characteristic of both. A medical professional would be able to differentiate between the two, likely through a physical checkup⁴ and some form of imaging; x-ray or Magnetic Resonance Imaging (MRI) to confirm the diagnosis.

Treatment

As with most injuries, rest and anti-inflammatory medicines (Ibuprofen) are the basic ways to combat the pain caused by plica inflammation.

Long-term, stretching and strengthening of the knee can reduce pain, Strengthening the muscles around the knee (quads and hamstrings) can help, and taking anti-inflammatory drugs and rest are all conservative treatments that should be attempted for roughly 3 months before more aggressive treatments should be considered.

More aggressive treatment can be attempted if strengthening and stretching shows no improvement in the symptoms.

The next stage includes a corticosteroid injection or in the most extreme cases surgery. Arthroscopy (keyhole surgery on joints) can be done to resect (remove) the medial plica.²

Summary

Plica syndrome is the anterior knee pain that arises due to inflammation or irritation of the synovial fibres that surround the knee, called ‘plica’. Due to overuse or injury, these plica can be irritated or inflamed, causing pain, swelling and reduced mobility that arise. This pain is similar to that of a meniscus tear and shares similar symptoms, through a basic physical a doctor can discern whether the patient is suffering from plica syndrome or a meniscus tear.

If plica syndrome is diagnosed, rest, stretching and anti-inflammatory medicine are conservative treatment methods that over a few months should reduce the pain and inflammation that is being suffered. If required more aggressive treatment can occur, with a corticosteroid injection or entirely removing the plica with keyhole surgery.

Avoiding movements that illicit pain is the best solution for resting and treating plica syndrome.