Bisphosphonates for Post-COVID Osteonecrosis of the Femoral Head: Medical Management of a Surgical Condition

COVID-19 infection can cause long-term effects, cumulatively known as long COVID syndrome. One such sequela is osteonecrosis of the femoral head (also called avascular necrosis of the femoral head, or AVNFH). On the basis of our 20-year experience in using bisphosphonate therapy in the successful management of osteonecrosis, we conducted the present study to evaluate the efficacy of the therapy in the management of post-COVID osteonecrosis of the femoral head. In addition, we aimed to evaluate the cumulative dosage of corticosteroids and the duration between the commencement of corticosteroids and the development of osteonecrosis in COVID-19 survivors. METHODS: This was a retrospective evaluation of 48 patients (88 hips) diagnosed with osteonecrosis of the femoral head at a tertiary care center after COVID-19 infection between September 2020 and May 2021. Patients received intravenous zoledronic acid (5 mg) at the initiation of therapy and oral alendronate (35 mg) twice weekly, and were followed for a minimum of 6 months. Clinical evaluation was conducted using a visual analog scale (VAS) for pain and the Harris hip score (HHS). Radiographic evaluation was performed to assess the progression of the disease and collapse of the femoral head. RESULTS: At a mean follow-up of 10 months, 84 (95.5%) of the hips showed good clinical outcomes, and only 4 (4.5%) of the hips required surgical intervention. The mean VAS pain score and HHS improved at 6 weeks and steadily improved on subsequent follow-ups. In 16 (18%) of the 88 affected hips, radiographic progression was observed. The mean dose of corticosteroids administered to the patients to manage COVID-19 infection was 841.3 mg of prednisolone equivalents. The mean duration between the commencement of corticosteroid therapy and the development of osteonecrosis was 179 days. CONCLUSIONS: Post-COVID osteonecrosis appears to be more aggressive, with COVID-19 itself contributing to its etiopathogenesis in addition to corticosteroids. However, it can be diagnosed by magnetic resonance imaging (MRI) in symptomatic patients and then effectively treated medically, especially if detected in the early stages. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.