Cirrhosis is a risk factor for total hip arthroplasty for avascular necrosis

Background and purpose — There are limited data on risk factors for avascular necrosis of the hip, but cirrhosis has been proposed as a risk factor. We examined the association between cirrhosis and incidence of total hip arthroplasty for avascular necrosis. Methods — We used nationwide healthcare data to identify all Danish residents diagnosed with cirrhosis in 1994–2011, and matched them 1:5 by age and sex to non-cirrhotic reference indi- viduals from the general population. We excluded people with a previous total hip arthroplasty, a previous hip fracture, or a previous diagnosis of avascular necrosis. We used stratifi ed Cox regression to estimate the hazard ratio (HR) for cirrhosis patients relative to reference individuals, adjusting for potential confound- ers. We used the cumulative incidence function to compute 5-year risks. Results — We included 25,421 cirrhosis patients and 114,052 reference individuals. Their median age was 57 years, and 65% were men. 45 cirrhosis patients and 44 reference individuals underwent total hip arthroplasty for avascular necrosis. Cirrho- sis patients’ HR for a total hip arthroplasty for avascular necrosis was 10 (95% CI: 6–17), yet their 5-year risk of avascular necrosis was only 0.2%. For the reference individuals, the 5-year risk was 0.02%. Interpretation — Cirrhosis is a strong risk factor for avascular necrosis of the hip, but it is rare even in cirrhosis patients.