Patient: Male, 30 years old. Ten days ago due to work squatting time for a day, the next day when the knee joint bending obvious pain, after the successive aggravation, when bending pain intense back to bend pain relief, square no pain, but now the square kneecap has a bulging feeling no obvious redness and swelling. x-ray shows normal. The doctor said it was calcification of patellar osteoarthritis and suggested resting or doing magnetic resonance specific examination or playing glass needles. I want to know what the disease is, how it is caused, how to relieve and treat it, and how to prevent it in the future. The actual patellar cartilage chondromalacia is likely to be caused by squatting for a long time, the pressure on the patellofemoral joint surface, which leads to cartilage damage after a long period of time, now you should go up and down the stairs and squat less, you can do physical therapy and shine the light, intra-articular injection of sodium glass acid, oral glucosamine, etc.