Patellofemoral arthritis is the most common cause of anterior knee pain in young adults, especially in young athletes, and is thus mostly a unicompartmental lesion. The typical presentation is anterior knee pain with activity, especially during stairs, climbing or rising from a seated position, but often not during walking on level ground. The etiology includes mechanical or kinematic abnormalities such as patellar subluxation due to tension in the lateral patellar support band and abnormal patellar trajectory; patellofemoral joint trauma, often osteochondral injury; and primary cartilage degeneration. These lesions eventually lead to degeneration of patellofemoral cartilage and produce symptoms. The treatment of unicompartmental arthritis of the patellofemoral joint is more complex than that of other intercompartmental arthritis, with varying outcomes reported in the literature. It is important to standardize its treatment and evaluation. We treated patients with patellofemoral arthritis aged <50 years with a stepwise surgical treatment strategy based on the Outerbridge classification of arthroscopic cartilage degeneration. Among them, grade I-II cartilage degeneration was treated with cartilage preservation surgery such as arthroscopic parapatellar lateral support band release, cartilage revision and radiofrequency therapy; grade III cartilage degeneration and grade IV lesions with cartilage defect range <1 cm were treated with cartilage repair surgery including autologous chondrocyte transplantation and mosaic bone cartilage transplantation; grade IV lesions with cartilage defect range >1 cm were treated with patellofemoral arthroplasty. Postoperative follow-up showed significant improvement in WOMAC score, Lysholm score and KSS score after surgery, and there were no complications such as infection and loosening during the follow-up period. In young people with patellofemoral arthritis, early surgical intervention is required, and a stepwise surgical treatment strategy has better results. The earlier the lesion, the more reliable the outcome.