Rattling of knee when squatting may be caused by physiological reasons, osteoarthritis, meniscus injury, gouty arthritis, bursitis, etc. 1. Physiological reasons: If the knee maintains a posture for a long time, or repeatedly performs the same action, it is easy to cause local muscle tension, causing bone friction to produce a ringing sound. 2. Osteoarthritis: degenerative changes in articular cartilage and osteophytes can easily cause localized pain in the knee joints, and joint effusion, joint deformity, accompanied by joint popping. 3. Meniscus injury: after the meniscus is damaged and squeezed in the process of knee squatting, the meniscus may be displaced, resulting in rattling. 4. Gouty arthritis: If the uric acid level of gout patients is not well controlled, stones may be formed in the knee joints, which may affect the movement of the bones in the process of squatting with knees bent, thus generating rattles. 5. Bursitis: If you suffer from bursitis under the patella, the knee joint may produce pain, swelling, and may be accompanied by joint popping. Causes knee squatting ringing more reasons, but also with fat pad inflammation, synovitis, chondromalacia patella, knee joint free body, patellar dislocation and other diseases. If accompanied by knee pain and other discomfort, it is recommended to promptly go to the hospital to identify the cause of the disease, under the guidance of the doctor standardized treatment.