Aggressive Presentation and Rapid Progression of Osteonecrosis of the Femoral Head After COVID-19.

Background: We aim to report the consecutive patients diagnosed with osteonecrosis of femoral head (ONFH) following recovery from COVID-19 disease and elucidate the unique features of ONFH associated with COVID-19.

Methods: Consecutive 22 patients (39 hips) recovered from COVID-19 and presented with ONFH from November 2020 to October 2021 were included. All the patients received corticosteroids as a supportive treatment during COVID-19. Patients were classified into two types based on the type of presentation, namely classic ONFH and rapidly destructive coxarthrosis (RDC) depending on radiographs, MRI, inflammatory markers and hip aspiration findings. Harris hip score was used to evaluate the functional outcome before and after treatment.

Results: The mean time to diagnose of ONFH from the onset of hip symptoms was 39.3 days (range 10-90 days). The average duration of onset of hip symptoms after COVID 19 infection was 7.5 months (range 3 - 11 months). The average cumulative dose of methylprednisolone equivalent was 811 mg (range 200-2100 mg) and the average duration of steroid intake was 2.8 weeks. There was significant elevation in the inflammatory markers in RDC group compared to classic ONFH ( < 0.05). The Harris hip score improved from 63.6 ± 23.2 at presentation to 82.6 ± 9.6 after treatment ( < 0.05). Three patients had features of RDC. Among the three patients with RDC, two patients had rapid progression of ONFH and underwent total hip arthroplasty (THA). The third patient is awaiting a THA.

Conclusion: ONFH after COVID-19 can have a varied presentation. While the most common presentation is like classical ONFH, some patients can have an acute and aggressive presentation with rapid destruction. They have features like elevated serological markers and extensive periarticular bone and soft tissue edema. A low cumulative dose of steroids in our patients suggests that the COVID-19-associated vasculitis may play a role in the pathogenesis of ONFH.