Knee pain going up and down stairs may be caused by chondromalacia patella, osteoarthritis of the knee joint, knee osteoarthritis and other factors. 1. Chondromalacia patella: if the patient’s knee is traumatized, resulting in chronic damage to the patellar cartilage surface degenerative changes may lead to chondromalacia patella, specifically manifested as infrapatellar or anterior side of the knee pain, pain in going up and down the stairs is obvious. 2. Knee osteoarthritis: if degenerative changes occur in the articular cartilage or soft tissue injuries around the knee, osteoarthritis of the knee joint may occur, if hyperplasia forms bone spurs, it will lead to difficulty in going up and down the stairs, and when going down the stairs, the knee is soft and prone to fall. 3. Knee osteoarthritis: If the patient’s knee is affected by trauma, cold and other factors may induce knee osteoarthritis, the initial symptoms are paroxysmal pain in the knee, pain when going up the stairs, and will become obvious when going down the stairs. If the patient has trouble going up and down the stairs and pain, may also be meniscus injury, if the pain is not relieved, should go to the hospital in time for examination and consultation.