Patellofemoral arthritis, also known as patellofemoral tenderness, is not an academic diagnosis that accurately reflects patellofemoral cartilage and patellofemoral joint pathology. The so-called patellofemoral joint is the contact surface between the cartilage on the inner surface of the patella and the cartilage of the femoral talus. The pathogenesis is as follows: 1. Developmental problems. Mainly in women of yellow ethnicity, there is a higher chance of patellar hypertelorism, knee valgus (increased Q angle of the knee joint), medial femoral muscle hypoplasia, underdevelopment of the femoral epicondyle and patellar typing type 2-5, etc. The end result is a poorly matched patellofemoral joint, resulting in unbalanced medial and lateral contact of the patella during movement on the femoral cartilage, with the patella skewed to the lateral side and only the lateral half of the patella working. The medial half carries less weight, and under the same conditions, such people are prone to patellofemoral joint cartilage problems. 2, occupational factors or inappropriate sports. Beach volleyball, mountain climbing and other sports, if engaged in for a long time, will cause the patellofemoral joint cartilage wear more than the ability to repair, just like the squat training you do. 3, trauma is also a factor in the development of the disease. As for the examination, it is mainly the clinical examination of the doctor, the front and side films of the knee joint and the CT of the knee joint at 30 degrees of flexion are sufficient, the MRI of the knee joint is not very helpful for the etiology of the disease, as for the treatment, the first is the etiological treatment, that is, the removal of the factors causing the poor patellofemoral joint match, such as the adjustment of the patellar motion trajectory, followed by the repair of the cartilage, including chondroplasty or microfracture techniques. The second is cartilage repair, including chondroplasty or microfracture techniques, and other adjunctive treatments such as cartilage nutritional drugs and anti-inflammatory and analgesic treatments.