What is a mucous membrane fold in the knee?
A mucosal fold in the knee refers to a protrusion of the mucosa that lines the inner surface of the knee. This mucous membrane is called synovia, while the occurrence of such a fold is known as plica syndrome. There are three major wrinkles in the knee (plica suprapatellaris, plica mediopatellaris and plica infrapatellaris).
These wrinkles are physiological. They are so-called reserve folds and actually recede over the course of life. In the case of plica syndrome, they increase in size for various reasons, so much so that they cause problems or become symptomatic.
Causes
The mucosal folds (plicae) should ideally recede completely. However, more than half of the adults still have these mucosal folds or remnants of them in their knees. If the knee is moved strongly and repeatedly, these mucous membrane folds can become irritated and become trapped.
The mucosal folds are also increasingly irritated in the case of an existing arthrosis of the knee. An incarcerated mucosal fold causes sudden pain in the affected knee. Patients also describe a feeling of being blocked and restricted in their knee, which they cannot and do not want to put full weight on the knee.
By loosening exercises and shaking the knee without much force and resistance, the blockage can often be released. In most cases, however, this one-time entrapment will not be the end. If this problem occurs regularly, there is probably an enlarged mucosal fold. In consultation and cooperation with a doctor, a therapy plan can be worked out to reduce the symptoms.
Associated symptoms
Typical symptoms are pain and swelling in the knee, which is located in the area of the kneecap. Patients describe that they perceive cracking and creaking noises in the knee during various movements – increasingly when bending. Furthermore, the range of motion of the knee is no longer fully usable and during movements (often while stretching) there is often a resistance to be overcome.
If the leg is shaken out, for example, the symptoms are often reduced or disappear. Affected persons also describe increased difficulties after prolonged sitting. The occurrence of pain on the inside of the knee when a mucosal fold is present indicates that the medial mucosal fold (plica mediopatellaris) is enlarged.
This fold lies partly behind, above and below, as well as to the side of the kneecap. If there is entrapment and friction in the middle area, the affected persons perceive pain on the inner side of the knee. The differential diagnosis of this pain should also include arthrosis and meniscus damage caused by malpositioning.
In the case of cartilage damage, an existing mucosal fold can cause increased pain. When the cartilage is worn or damaged, the mucosal fold rubs over the bone. This causes unpleasant pain during movements.
On the other hand, a chronically inflamed and enlarged mucosal fold can also cause cartilage damage. In the course of the inflammation, hardening and fibrosis of the mucosal fold occurs. This rubs against the cartilage and in the long term leads to inflammation and wear and tear.