Single-cell RNA sequencing reveals distinct immunometabolic and osteogenic states across etiological subtypes of human osteonecrosis of the femoral head

Abstract Background Osteonecrosis of the femoral head (ONFH) is a progressive skeletal disorder with heterogeneous etiologies, among which alcohol exposure and glucocorticoid use are major non-traumatic causes. However, the cell-type-resolved microenvironmental alterations underlying different etiological subtypes remain incompletely defined. Results Here, we performed single-cell RNA sequencing of human femoral head tissues from alcohol-associated ONFH (ALC-ONFH), glucocorticoid-associated ONFH (GC-ONFH), and femoral neck fracture controls, generating a transcriptomic dataset comprising 77,993 high-quality cells. Integrated bioinformatic analyses revealed marked differences in osteogenic potential, immune-metabolic states, and signaling microenvironments between the two ONFH subtypes. ALC-ONFH was characterized by a prominent inflammatory stress microenvironment and limited osteogenic reparative responses. By contrast, GC-ONFH showed osteogenic reparative cell programs accompanied by hypoxia-adapted cell states and lactate-metabolism-related molecular signatures. Computational analyses further suggested divergent cell-state dynamics and distinct putative signaling axes, including OSM-centered inflammatory signaling in ALC-ONFH and TNF/RANKL-related bone-remodeling signaling in GC-ONFH. Tissue immunostaining for HIF-1α, LDHA, PKM2 and MCT4 supported the enrichment of hypoxia-glycolysis-lactate-transport signatures within GC-ONFH lesions. Conclusions Together, this study provides a public human single-cell transcriptomic resource for ONFH and identifies etiology-linked cellular and molecular features. These findings suggest that alcohol-associated and glucocorticoid-associated ONFH are associated with distinct inflammatory and metabolic remodeling programs, offering candidate signatures for future etiology-stratified studies and functional validation.