General information
Like all joints, the knee joint is surrounded by joint mucosa (synovialis). It keeps the joint supple so that all movements can be performed without friction. The plica infrapatellaris describes a fold of this joint mucosa in the knee joint. The word “infrapatellaris” refers to the position of the fold below the patella. It is a continuation of the Hoffa fat body, which lies between the head of the tibia and the lower edge of the patella.
Anatomy
The plica infrapatellaris is a mucous membrane fold in the knee joint that consists mainly of connective tissue. The mucosal fold is sometimes also called the ligamentum mucosum. It is surrounded by several cell layers and is thus separated from the surrounding tissue.
It can occur in different variations and usually separates the knee joint into two chambers. However, it may also not be present at all. When it is applied, the plica is located in a bony depression below the thigh bone.
From this recess, known as the intercondylar femoral fossa near the anterior cruciate ligament, the mucosal fold extends to the anterior joint cavity and ends at the Hoffa fat body. In its course, the plica increases in width towards the front. In some cases, the plica infrapatellaris may be associated with further wrinkles of the joint mucosa.
Basically, the various mucosal folds are formed during embryonic development and recede as the process continues. In the embryo, the mucosal fold acts as a kind of septum, dividing the knee joint into two chambers. In adults, the fold is approximately 65% full and forms a gap at the rear edge, so that the lateral and central joint space are connected.
History
The plica infrapatellaris is located below the patella. It runs through the knee joint as an extension of the applied fat body, which is also located below the patella. It divides the knee joint into a lateral and central compartment, thus creating two chambers.
The plica begins in a bony depression and ends at the anterior fat body. In the course of its development, its width increases steadily. It is often connected to the other folds of the mucous membrane, the suprapatellar and mediopatellar plica.