There are several possible causes of knee pain after a long squatting time: first, patellofemoral arthritis, patellofemoral arthritis is a chronic inflammation of the joint between the patella and the femur of the knee joint, resulting in knee pain after a long squatting time, then the knee X-ray, nuclear magnetic examination for diagnosis and treatment; second, meniscal damage, meniscal damage or tears in the posterior horn of the meniscus. If the meniscus is damaged or torn, it can compress the posterior horn of the meniscus and cause knee pain after squatting for a long time, so we need to perform the relevant meniscus MRI for diagnosis and treatment; third, synovitis, patients with synovitis can also show symptoms of knee pain after squatting for a long time, so we need to perform the relevant physical examination and examination to exclude other diseases for diagnosis; fourth, osteoarthritis, patients with osteoarthritis can also show symptoms of knee pain after squatting for a long time. Fourth, osteoarthritis, patients with osteoarthritis can also have symptoms of knee pain after squatting for a long time, then we need to carry out X-ray and nuclear magnetic examination of the knee joint for diagnosis and treatment.