Popliteal fossa pain can have several causes: 1. osteoarthritis. Patients with osteoarthritis can involve the surrounding soft tissues and can cause pain in the popliteal fossa on the posterior side of the knee, which is diagnosed with a knee x-ray. 2. Meniscus injury. If there is damage to the posterior horn of the meniscus, the posterior popliteal fossa of the knee can be painful, especially when the knee is flexed and squatting. 3. Popliteal cysts. A popliteal cyst can cause pain in the popliteal fossa, mainly swelling and pain, and a cystic mass can be palpated, which should be diagnosed by ultrasound or MRI. 4. Bursitis of the popliteal fossa. The presence of bursae in the popliteal fossa, when there is chronic inflammation can appear pain in the popliteal fossa, which can be accompanied by signs and symptoms such as swelling and pressure pain in the posterior popliteal fossa, which should be diagnosed by relevant investigations and nuclear magnetic examinations.