Many people have heard of arthritis, especially knee osteoarthritis, which is very common, and may be able to come up with some valuable suggestions for prevention or treatment. However, I wonder if you have heard of chondromalacia patella, and how much do you know about this disease? The so-called chondromalacia patella refers to the osteoarthropathy of the patellofemoral joint, which is formed when the cartilage surface of the patella is swollen, cracked, broken, eroded, and detached due to chronic injury and finally the cartilage of the femoral condyles, which is opposite to it, also undergoes the same pathologic changes. The cause of this disease may be related to the congenital abnormal development of the patella, long-term wear and tear of the knee joint, and the abnormal composition of synovial fluid. Chondromalacia patella is mainly manifested as follows: it is common in young people, especially in athletes, and it is more common in long-term wear and tear of the knee joint. Initially, it is infrapatellar pain, which is relieved after a little activity, aggravated after too much exercise, and disappears gradually after rest, showing fluctuating changes. Usually it is difficult to go up and down steps or suddenly weak and weak leg, even fall down. In addition, the edge of the patella is painful, and there can be friction sensation with pain when squeezing or pushing the patella in the knee-extension position. When osteoarthrosis of patellofemoral joint is formed in later stage, joint effusion may occur secondary to synovitis. Posterior patellofemoral pain, patellar grinding test and single leg squatting test cause posterior patellofemoral pain is an important basis for diagnosis. Attention should also be paid to check whether there is a combination of meniscus injury and traumatic arthritis, etc. X-ray examination: the gap between the patella and the femoral condyle can be seen to be narrowed in the late stage, and there can be osteophytes on the edge of the patella and the femoral condyle. Treatment is mainly non-surgical: braking, physiotherapy, anti-inflammatory, joint cavity closure can be used. Of course, the specific method should be decided by the doctor according to the individual situation.