The effect of weight compared to BMI on patient reported outcomes at long term follow up of primary total hip arthroplasty

Abstract

IntroductionObesity has been linked to the development of osteoarthritis meaning that a large portion of arthroplasty patients are overweight or obese. Whilst the short-term complications associated with obesity are well described there is a paucity of evidence on the effect of weight compared to BMI for long term functional outcomes of total hip replacements (THR). The aim of this study was to investigate the influence of BMI and weight on long-term patient reported outcome measures following primary THR. Methods846 patients who underwent primary THR at the Royal Adelaide Hospital between 2000 and 2009 had a pre-operative height and weight recorded. Patient reported outcome measures (PROMs) were completed at 1, 5 and greater than 10 years follow-up. Categorical comparison of PROMs was performed for patients in weight categories of 0–65 kg, 65–80 kg, 80–95 kg, 95–110 kg and >110 kg; and BMI categories as per the WHO Classifications. ResultsThere was no difference in absolute or change in PROMs for any weight category. BMI did not have an effect on the change in (HHS), however there was a statistically significant decrease in absolute (HHS) values at 1 and 5 years with increasing obesity. 65 patients underwent revision within the first ten years. ConclusionThe results from this study confirm for the first time that there was no impact of weight or BMI on the change in long-term PROMs of THR. There remains a need for larger registry studies to investigate the effect of weight and BMI on long-term patient outcomes and revision rate.