Pain behind the knee, specifically at the back of the leg behind the knee, can be caused by several conditions:
- Hamstring injury: Straining or tearing the hamstring muscle can cause pain behind the knee and difficulty bending it, often due to overstretching or sudden forceful movements.
- Popliteal cyst (Baker’s cyst): This is a fluid-filled swelling in the shallow pit behind the knee, often linked to arthritis or cartilage injuries. It can cause swelling and sometimes pain, especially if it bursts.
- Meniscus tear: The menisci are cartilage pads in the knee that can tear from injury or wear and tear, causing pain behind the knee, especially when bending or twisting.
- Posterior cruciate ligament (PCL) injury: The PCL connects the thigh to the shin bone and can be injured by a blow to the bent knee or overstretching, causing pain behind the knee, especially when kneeling or going downhill.
- Osteoarthritis: Degeneration of the knee cartilage causes pain and stiffness behind the knee, often worsening with weight-bearing and improving with rest.
Other less common causes include vascular issues like venous malformations, nerve entrapment, or deep vein thrombosis (which requires urgent medical attention if there is calf swelling and tenderness). Symptoms vary by cause but may include swelling, stiffness, difficulty bending the knee, a popping sensation, or a feeling of the knee catching or locking. If the pain is accompanied by swelling, redness, warmth, or calf tenderness, or if it persists, it is important to seek medical evaluation to determine the exact cause and appropriate treatment
