GSTM1 and avascular necrosis: They observed characteristic metabolite changes (biosynthesis of guanine, L‐glycine and adenosine) and decreased CRLF1 (cytokine receptor-like factor 1) and GSTM1 activities in tissues attached to explanted artificial hip specimens, compared to 8 controls who received primary total hip replacement due to avascular necrosis of femoral head or femoral neck fracture.