SHOULD TOTAL HIP ARTHROPLASTY HAVE A BMI CUTOFF? A SINGLE-SURGEON COHORT STUDY

Introduction High BMI is a growing issue for the NHS, with 30% of adults living with obesity. While obesity is known to be associated overall with increased co-morbidity, as regards total hip arthroplasty (THA), it is not clearly established that obesity results in poor surgical or functional outcomes. Despite this, some trusts have looked to establish an arthroplasty BMI cutoff. We aimed through a single surgeon cohort study to establish if increased BMI led to any increase in complications or revision rate. Methods A retrospective review was conducted of 850 THAs performed by a single consultant, with patients stratified into morbidly obese (MO); BMI 40–45, and non-obese (NO); 20–29. Patients BMI 30–39 were excluded to allow a clearer analysis. Revisions, complication rate, Oxford Hip Score (OHS), and component size was compared. Results Revision rate between groups was comparable (3.5% MO, 1.6% NO), with no significant statistical difference (p=0.32), as was complication rate (2.6% MO, 3% NO, p=1). Improvement in OHS between the groups was equal (+26) at 1 year. As regards components, mean stem size was equal, while cup size was marginally larger in the MO group (54 vs 52mm). Discussion This study indicates comparable rate of revision and complications in morbid obese vs non obese patients, while demonstrating equivalent PROMS improvements. Implant median sizes were not grossly different, so not suggesting mal positioning in MO patients. This work indicates, discriminating for THA as regards BMI up to 45, is not justified, similar to previous reported literature for TKR.