Anatomy
The synovial cavity of the knee joint is lined with a very thin synovium (synovium). In the synovium, synovial folds (plica synovialis) can form in the 4 joint chambers: in the inner joint chamber (medial plica), in the outer joint chamber (lateral plica), in the upper joint chamber (suprapatellar plica) and anterior joint chamber (anterior plica).
In more than 50% of people, a mucosal fold (plica) is found in the inner joint space of the knee.
Cause of the problem
If there is a pinching or bleeding in the mucosal fold, it will become ‘inflamed’ (inflamed) and thickened, which can cause pain.
Symptoms
The mucosal fold in the medial compartment (medial plica) is by far the most common cause of symptoms. The symptoms are diffuse grinding pain at the front of the knee, swelling and pseudo-locking that can be confusingly similar to the symptoms of a meniscus lesion.
The pain is usually localised just inside the kneecap in front of the inside joint line. The pain often occurs suddenly with certain movements and may be accompanied by swelling in the knee.
If a flap of the mucosal fold becomes trapped, lockjaw-like symptoms can occur.
Examination
In mild cases, the diagnosis is made based on the clinical examination alone. Severe cases or cases that do not improve on treatment should be assessed by a professional to get the correct diagnosis and treatment.
Occasionally, you may feel a tender slipping string on the inside of the kneecap, but often general clinical examination is not sufficient. Arthroscopy (binocular examination of the joint) or MRI scans (especially if there is fluid in the knee) are often needed to make a diagnosis.
Treatment
Treatment includes relief from pain-inducing activity and gradual rehabilitation of the knee within the pain threshold. If the discomfort does not slowly subside, treatment can be supplemented with anti-inflammatory drugs (NSAIDs) or injection of adrenal cortex hormone into the mucosal fold or knee joint. If this does not help either, the mucosal fold can be removed by arthroscopy.
Rehabilitation, specific:
Weight-bearing on the knee can start as soon as the pain and swelling in the knee have subsided. In uncomplicated cases, it is often possible to resume full sports activity within a month. Exercise should not cause increasing swelling (or pain) in the knee.
Complications
If no progress is made before surgery, you need to consider whether the diagnosis is correct. This will often require additional examinations (X-ray, ultrasound or MRI scan).
In particular, the following should be considered:
