IL6 and osteonecrosis: Interestingly, a recent study of specimens from patients with non-traumatic ONFH also found that the main macrophage subset in the osteonecrosis area had the M1 phenotype, the local microenvironment was enriched with IL-1β and IL-6, and the ratio of M1 to M2 macrophages was significantly increased as osteonecrosis progressed (35).