Cirrhosis is a risk factor for total hip arthroplasty for avascular necrosis: A Danish nationwide cohort study

Deleuran, Thomas; Overgaard, Søren; Vilstrup, Hendrik; Jepsen, Peter

The mechanisms behind the association between cirrhosis and AVN are unclear. Cirrhosis patients suffer from coagulopathy, endothelial dysfunction, and chronic infl ammation (Albillos et al. 2014 , Iwakiri and Groszmann 2007 , Søgaard et al. 2009 ). Endothelial dysfunction has been linked to glucocorticoid-induced AVN (Chen et al. 2013), but chronic infl ammation may be more important for development of AVN (Morse et al. 2013 ). Interleukin-33, a T-lymphocyte activator, has been linked to both cirrhosis and AVN (Marvie et al. 2010 , Zheng et al. 2014 , and cirrhosis patients' hyperdynamic circulation facilitates diffusion of proinfl ammatory cytokines and endotoxins throughout the body (Lee et al. 1996) . Hence, even though the exact mechanisms remain unclear, the pathophysi- total hip arthroplasty for AVN and also the strength of the association between cirrhosis and total hip arthroplasty for AVN. Thus, bias is unlikely to explain the strong association between cirrhosis and AVN. Incomplete confounder control could possibly have led us to overestimate the effect of cirrhosis on the rate of total arthroplasty for AVN. We were able to adjust for conditions that predispose to AVN and for indicators of smoking and treatment with corticosteroids, but our use of hospital diagnoses to identify confounders would probably underestimate their prevalence. Our results were unaltered when we performed a supplementary analysis aimed at minimizing the effect of alcohol intake. Still, we cannot rule out the possibility that some of the association was caused by alcohol intake and other confounders, but we believe that it is unlikely that the strong association was entirely the result of confounding.