Commentary: "Evolutionary course of the femoral head osteonecrosis: Histopathological - radiologic characteristics and clinical staging systems".

Osteonecrosis of the femoral head (ONFH) is a common and recalcitrant ischemic orthopaedic disorder, which occurs frequently in young and middle-aged population. ONFH results from primitive vascular problems, including disruption of microcirculation of the osteochondral complex in the femoral head. Based on the imaging characteristics, different clinical staging systems have been developed to evaluate the severity of ONFH, which is important for making treatment strategy [1,2]. However, patients classified with the same severity stage, especially in the peri-collapse stage, usually showed different prognosis after similar joint-preserving surgeries. The unusual phenomenon may be attributed to the limitations of the current imaging classification systems, which might underestimate the severity of the disease and ignore the personalized features of different patients, especially when referring to the early imaging stages.

In a recent review paper of Dr. CQ Zhang's group, they presented the etiology and pathogenesis of ONFH [3]. They also described the imaging features and current staging classification systems of ONFH. More importantly, they detailed the histopathological and microstructural alterations of the necrotic femoral head, and provided an overview of their essential contribution to ONFH progression. Given the current discordance between the imaging severity and underlying histopathological alterations, more studies on the relationship between imaging and histopathological/microstructural features are required to further improve the current classification systems of ONFH. These pathology-based studies could help advance treatment options for ONFH and serve as important references for performing joint-preserving surgeries.