Evans JT, Mouchti S, Blom AW, et al. - Given revision estimates in all body mass index (BMI) groups below the recognized threshold, no proof of elevated mortality, and difference in change in Oxford Knee Score (OKS) below the minimal detectable change (MDC), This large national registry demonstrates no evidence of poorer outcomes in patients with high BMI. This research does not demonstrate rationing of total knee replacement (TKR) based on elevated BMI.

• Researchers examined 493,710 TKRs implanted between 2005 and 2016 to explore the proportion of patients that died within 90 days, how many implants needed revising (redo surgery) after 10 years, and the changes between preoperative and 6-month postoperative Oxford Knee Score (OKS).

• Between 2005 and 2016, there does not seem to be any data to support clinically relevant worse outcomes following TKR for patients with a raised BMI in the NJR.

• These outcomes do not suggest a restriction of referral for knee replacement based on BMI alone.

• It seems that even though some individuals with increased BMI are at risk of poorer outcomes, the outcomes remain acceptable by contemporary standards, and the selection process of orthopedic surgeons is effective at distinguishing the correct patients to operate on at a population level.

• In overweight and obese patients, the relative improvement in OKS was lower than those with “normal” BMI, but the difference was below the minimal detectable change (MDC; 4 points).

• Missing BMI especially in the early years of data collection and a potential selection bias effect of surgeons selecting the fitter patients with raised BMI for surgery were the main limitations.