I. Main criteria 1. Clinical symptoms, signs and history: arthralgia mainly in the groin and hip and thigh areas, limited internal rotation of the hip joint, history of hip trauma, history of corticosteroid application, history of alcoholism. 2.X-ray changes: femoral head collapse without joint space narrowing; sclerotic zone with demarcation in the femoral head; subchondral bone with transverse X ray zone (crescent sign, subchondral fracture). 3.Nuclear scan shows a cold zone in the hot zone within the femoral head. 4, T1-weighted phase of MRI of the femoral head shows banded low signal (banding type) or T2-weighted phase with bilinear sign. 5. Bone biopsy shows more than 50% osteocyte vacuolation sockets in bone trabeculae and involvement of multiple adjacent bone trabeculae with bone marrow necrosis. Secondary criteria 1. X-ray shows collapse of the femoral head with narrowing of the joint space, cystic degeneration or speckled sclerosis in the femoral head, and flattening of the outer upper part of the femoral head. 2.Nucleotide bone scan shows cold or hot areas. 3, MRI shows a band type with homogeneous or heterogeneous low signal intensity without T1 phase. The diagnosis can be confirmed if two or more major criteria are met. One major criterion is met, or the number of positive secondary criteria is ≥4 (including at least one positive radiographic change).