X-ray staging of femoral head necrosis Stage I: normal X-ray performance Stage II: normal femoral head shape but obvious bone repair (cystic degeneration and osteosclerosis) Stage III: subchondral bone collapse (flattening of femoral head) Stage IV: joint space narrowing, joint collapse and secondary degeneration of acetabulum (cystic degeneration, marginal bone formation, cartilage destruction) Treatment options: Stage I: medullary core decompression Stage II: medullary core decompression, bone graft, g-metal implant Stage III: total hip replacement with biologic non-cemented prosthesis Stage IV: total hip replacement with biologic non-cemented prosthesis