Impact of COVID-19 on the Development of Femoral Head Avascular Necrosis: A Systematic Review

Background: COVID-19 has been linked to musculoskeletal complications, including femoral head avascular necrosis (AVN). Both COVID-19–related hypercoagulability and corticosteroid therapy have been proposed as contributing factors. This systematic review synthesizes current evidence on the occurrence, clinical characteristics, timing, and risk factors for femoral head AVN following COVID-19. Methods: A PRISMA-compliant systematic search of PubMed, Embase, and Scopus identified observational studies and case series (≥10 patients) reporting femoral head AVN in adults or adolescents with confirmed COVID-19. Data on epidemiology, symptom onset, imaging findings, and corticosteroid exposure were narratively synthesized due to heterogeneity. Results: Fifteen eligible studies described patients with post-COVID femoral head AVN. Symptom onset ranged from days to >12 months after infection. Early MRI often revealed asymptomatic or low-grade disease. Corticosteroid exposure was common and strongly associated with AVN severity; however, several studies reported AVN in patients without steroid use, whether this reflects an independent contribution of COVID-19 or unrecognized confounding cannot be determined from the available uncontrolled data. Higher cumulative steroid doses, severe pulmonary involvement, and elevated inflammatory markers were consistently linked to more advanced AVN stages. Conclusions: Femoral head AVN is an emerging post-COVID complication with variable timing and presentation. Corticosteroid exposure remains the principal risk factor; whether COVID-19 contributes independently of corticosteroids is unproven, and current evidence supports an association rather than a causal relationship. Awareness of this potential complication is warranted, although the role of early MRI screening remains to be established in prospective studies.