Osteonecrosis of the femoral head in post-COVID-19 patients: a retrospective comparative study

The COVID-19 pandemic has claimed many lives and continues to impact individuals through post-COVID-19 conditions. Osteonecrosis of the femoral head (ONFH) is increasingly recognized as a major post-COVID-19 complication, yet most studies are limited to case reports and small series. This study aimed to evaluate COVID-19-related factors potentially contributing to ONFH development in post-COVID-19 patients.

A retrospective analysis was conducted on 84 patients with ONFH and a confirmed history of COVID-19. Baseline characteristics were collected, and patients were categorized into the following groups for comparative analysis: (1) vaccinated vs. unvaccinated, (2) unilateral vs. bilateral ONFH, (3) dexamethasone (DEX) and methylprednisolone (MPS) vs. DEX therapy, and (4) Association Research Circulation Osseus (ARCO) stage 2 vs. stage 3. Group differences and associations were analyzed.

The DEX and MPS-treated group had a greater extent of COVID-19 lung involvement compared to the DEX-treated group (59.2% vs. 36.3%, p = 0.002), as well as longer hospital stays in both general ward (14.2 days vs. 10.6 days, p = 0.018) and ICU (5.4 days vs. 3 days, p = 0.017). The DEX and MPS-treated group also had a longer duration of steroid therapy (19.3 days vs. 12.3 days, p < 0.001) and received higher DEX-equivalent cumulative steroid doses (380 mg vs. 125 mg, p < 0.001). Notably, ONFH symptoms developed earlier in the DEX and MPS-treated group compared to the DEX-treated group (7.5 months vs. 12 months, p = 0.004). Multivariable logistic regression analysis identified cumulative steroid dose as the sole predictor of ONFH severity (OR: 1.015, 95% CI: 1.001-1.028, p = 0.032), with ARCO stage 3 patients receiving higher cumulative steroid doses than stage 2 patients (240 mg vs. 126 mg, p = 0.018).

Our study demonstrated that cumulative steroid dose is the primary determinant of ONFH severity in post-COVID-19 patients. Additionally, combined use of corticosteroids may accelerate the onset of ONFH, highlighting the need for cautious steroid management in COVID-19 patients.