Osteonecrosis of the femoral head (ONFH) is a destructive degenerative disease that can develop into subchondral and articular facet cartilage collapse. Among proposed pathological mechanisms underlying ONFH, much attention has been paid to the theory of increased intraosseous pressure. The core of this theory is an unbalance in osteoblast and adipocyte differentiation of bone marrow mesenchymal stem cells (BM-MSCs). The occurrence and development of osteonecrosis has been related to abnormal metabolism and differentiation of BM-MSCs. Normal adult BM-MSCs can differentiate into adipocytes and osteoblasts to maintain normal physical status. In response to exogenous stimuli (for example, use of exogenous hormones or alcohol), the bone marrow microenvironment changes to allow more BM-MSCs to differentiate into adipocytes, leading to increased bone marrow cavity pressure, thereby inducing ischemic ONFH.