Suprapatellar plica

Anatomy of the suprapatellar plica

Commonly a supra patellar plica is a curved band along one wall of the capsule above the kneecap. Rarely it may reach right across as a full membrane from one side of the supra patellar pouch to the other, dividing it in two, sometimes with a little window in the middle.

How the suprapatellar plica causes symptoms

As a plica the suprapatellar plica is quite common, but as a symptomatic disorder it is actually quite rare. In disorders of the supra patellar plica patients may complain of pain in the area above the kneecap, generally related to a prior episode of blunt trauma to ths region.

Here the patella (kneecap) has been cut from its tendon and lifted up to show the region at the top of the joint. You can see the curved suprapatellar plica above the patella.	X-ray from the side showing the position (yellow arrow) of the suprapatellar plica. The plica may easily be missed on X-ray but may show up as a thin structure if there is fluid in the knee (which shows as white).	A traumatised and thickened SPP can get trapped between the femur and the quadriceps, where it can cause ongoing pain. Sometimes this is mistaken as quadriceps muscle or tendon injury.