The membrane that covers the knee joint has a fold known as a plica. The average person has four plica in each knee. The plica in the center of the knee can occasionally become irritated from being overused. The symptoms of plica syndrome include discomfort, edema, and instability.
Mesenchymal tissue that develops in the knee throughout the embryological stage of development is essentially what makes up a plica. The resorption of this plica is facilitated by the movements of the foetus inside the uterus. However, the cavitation of the knee joint is frequently partial in many people because the mesenchymal tissue is not completely resorbed. The prevalence of plica is thought to be around 50% of the population.
Causes
The onset of pain is often insidious, but may be related to:
- Fall or injury.
- Overuse of the knee, especially those involving climbing stairs, biking, or jumping.
Symptoms
- Joint instability
- Painful going up or down stairs.
- Pain from squatting, bending or standing
- Knee may lock up, give way, get stuck or make a popping noise.
Physical tests
Inspect the knee for tenderness. In the case of a pathological medial plica, the tenderness is localized to the medial aspect of the patella. When the knee is flexed, a pathological plica can be palpated as a thickened band. Place the knee in flexion at 90°, then extend the knee. In the presence of a pathological plica, a popping sound may occur at approximately 60° of flexion. Other conditions, such as patellofemoral disorders, may present with similar symptoms and should be excluded.
