Inclusion Criteria:  Inclusion criteria:  Age <40. Normal strength line of lower limbs: no valgus or varus feet (HKA <±5°)  Exclusion Criteria:  Combined patella dislocation and medial retinacular injury. Have a history of knee surgery, knee injury and fracture. Complicated cruciate ligament injury and medial and lateral collateral ligament injury. Combined knee osteoarthritis. Complicated with rheumatism, rheumatoid arthritis and other types of arthritis Patellar bisection, trochlear dysplasia Gouty arthritis and hyperuricemia of the knee Complicated meniscus injury of degree III or above Incorporating lateral discoid meniscus