Gut microbiota and avascular necrosis: a scoping review of current evidence and knowledge gaps

Avascular necrosis (AVN), also known as osteonecrosis, is a progressive condition characterized by ischemic bone death, most commonly affecting the femoral head. Its etiology is multifactorial and includes corticosteroid exposure, alcohol use, trauma, hematological disorders, and systemic inflammatory conditions. However, in a substantial proportion of cases, the underlying mechanisms remain poorly understood. The gut microbiota has emerged as a key regulator of systemic inflammation, immune responses, metabolic homeostasis, and vascular function. Alterations in gut microbiota composition (dysbiosis) have been implicated in a wide range of musculoskeletal, inflammatory, and metabolic disorders. Increasing evidence suggests that microbiota-derived metabolites, immune modulation, and gut–vascular interactions may contribute to bone homeostasis and microcirculatory integrity, which are central to the pathophysiology of avascular necrosis. To date, evidence linking gut microbiota and avascular necrosis appears scattered across experimental, clinical, and translational studies, with no comprehensive synthesis of existing knowledge. A scoping review is therefore appropriate to map the available evidence, clarify how the gut microbiota–AVN relationship has been investigated, and identify key knowledge gaps to guide future research. The objective of this scoping review is to systematically map and summarize the existing evidence on the relationship between gut microbiota and avascular necrosis, and to identify gaps in current knowledge.