Brief outline of knee plica (Synovial plica)

The plica is a thin fibrous membrane that is left over from the fetal knee development. This plica once divided the knee into three separate compartments during fetal development but then became a part of the knee structure as the compartments became one protective cavity. When friction or a pinching between the femur and patella occurs, the plica may become inflamed, causing it to thicken, which in turn causes more friction, creating a vicious cycle. This is common when the knee is flexed and placed under stress.

Cause of knee plica (Synovial plica)

Trauma to the flexed knee. Repetitive stress, especially with medial weight bearing such as in cycling.

Signs and symptoms of knee plica (Synovial plica)

Pain. Tenderness over the plica.

Complications if left knee plica (Synovial plica) unattended

The plica will continue to become inflamed and limit flexion activity in the knee if the condition is left unattended. The pain may also cause a change in gait or running form that could lead to other overuse injuries.