The more common cause of knee pain and discomfort when playing ball is meniscal injury, or local muscle ligament or soft tissue injury, or degenerative osteoarthritis or synovitis of the knee. If the meniscus is damaged, a positive McKay test on physical examination can determine the extent of meniscal damage by MRI of the knee. If it is considered to be degenerative osteoarthritis, the knee x-ray can be completed and the corresponding follow-up treatment can be done according to the examination results. If the meniscus injury is not severe, conservative treatment can be chosen by avoiding sports and excessive knee flexion for the time being. In case of severe meniscal injury, arthroscopic surgery may be considered.