1, trauma – When the knee is knocked, the cartilage of the patella is directly or indirectly damaged, and the cartilage becomes inflamed and softened. 2, abnormal patellar development – some patients have a high or low patellar position, tilt, dislocation or subluxation, which can cause patellar instability, and the friction movement between the patella and femur is more intense than normal, and the cartilage of the patella will soften over time. 3, soft tissue inflammation of the knee joint – after inflammation of the synovial membrane around the joint, the composition of the synovial fluid will change and the content of some inflammatory factors will increase, resulting in the dissolution of cartilage, loss of elasticity and smooth surface, causing chondromalacia of the patella. Treatment of chondromalacia patellae: mainly rest, symptomatic, and if accompanied by synovitis and intra-articular effusion, oral anti-inflammatory and anti-swelling drugs are also required. Among the many non-steroidal anti-inflammatory drugs, drugs with little gastrointestinal irritation can be chosen for a period of time. Studies have found that the pressure on the surface of the patellar cartilage when climbing stairs is 3-5 times greater than when walking on flat ground. In outpatients, many middle-aged and elderly female patients are used to squatting on the floor to wipe the floor and choose vegetables, and some patients have developed the habit of climbing the stairs every day and climbing Fragrant Hill every week based on health care considerations. Although these exercises can exercise the body and improve cardiopulmonary function, they accelerate the degeneration of the knee joint, and can even cause arthritis and synovitis if the exercise is too frequent and too heavy.