Did the COVID-19 Pandemic Coincide with an Increase in Osteonecrosis as Indication for Total Hip Arthroplasty in Older Patients?

INTRODUCTION: Osteonecrosis of the femoral head is a common indication for total hip arthroplasty (THA). It is unclear to what extent the COVID-19 pandemic has impacted its incidence. Such data may be important as, theoretically, the combination of microvascular thromboses seen in patients who have COVID-19 and corticosteroids as a COVID-19 treatment option may increase the risk of osteonecrosis. We aimed to 1) assess recent osteonecrosis trends and 2) investigate if a history of COVID-19 diagnosis is associated with osteonecrosis. METHODS: This retrospective cohort study utilized a large national database, identifying elective THA cases between 2016 and 2021. Here, osteonecrosis incidence in 2016 to 2019 was compared to 2020 to 2021. Secondly, utilizing a cohort from April 2020 through December 2021, we investigated whether a prior COVID-19 diagnosis was associated with osteonecrosis. For both comparisons, Chi-square tests were applied. RESULTS: Among 1,127,796 THAs performed between 2016 and 2021, we found an osteonecrosis incidence of 1.6% (n=5,812) in 2020 to 2021 compared to 1.4% (n=10,974) in 2016 to 2019; P<0.0001. Furthermore, using April 2020 to December 2021 data from 248,183 THAs, we found that osteonecrosis was more common among those who had a history of COVID-19 (3.9%; 130 of 3,313) compared to patients who had no COVID-19 history (3.0%; 7,266 of 244,870); P=0.001). CONCLUSION: Osteonecrosis incidence was higher in 2020 to 2021 compared to previous years and a previous COVID-19 diagnosis was associated with a greater likelihood of osteonecrosis. These findings suggest a role of the COVID-19 pandemic on an increased osteonecrosis incidence. Continued monitoring is necessary to fully understand the impact of the COVID-19 pandemic on THA care and outcomes.