ACP5 and osteonecrosis: Using pathological and immunohistochemical staining, tartrate-resistant acid phosphatase (TRAP) staining, quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR), micro-computed tomography (micro-CT), and Western blotting, we assessed the change in bone microstructure, micromechanical strength of bone trabeculae, and activation of osteoblasts and osteoclasts in different areas of femoral head specimens that had undergone osteonecrosis.