In daily life, we often hear middle-aged women complaining of weakness in their knees and disobedience in their legs, especially when walking upstairs. This phenomenon may be caused by chondromalacia patellae. The patella is triangular in shape, located in front of the knee, and is the main fulcrum of the lower limb extension muscles, forming the patellofemoral joint with the femur, which plays a role in protecting the knee joint. When the patella is softened, the force of lower limb straightening is weakened or disappears, and the knee joint is not protected in time, which will manifest as weakness of the thigh and knee pain, which is only sore at the beginning of the activity and feels comfortable after the activity. If the amount of activity is increased and the time is slightly longer, the pain is significantly worse and relieved after rest. Some patients can hear a creaking sound when extending and flexing the knee joint, and can feel pain when pressing with their fingers around the patella. If not actively treated, the lesion may extend to the entire knee joint, with atrophy of the quadriceps muscle, thinning of the thighs, and swelling of the fluid in the knee joint. The prevention and treatment of chondromalacia patellae can generally take the following three methods: firstly, non-surgical treatment can be used, and most of them can be cured. Do not over-activate the knee joint, and try to avoid knee extension and flexion activities and semi-squatting posture during weight-bearing. Second, strengthen the functional exercise of the quadriceps, such as lying flat on the bed, straightening the knee joint and repeatedly lifting the lower limb. Thirdly, patients can do ultrasonic physical therapy and topical pain relief cream to reduce intra-articular pressure, improve local blood circulation and promote trauma repair.