To lose weight or to weight the loss? Insights into the use of the body mass index in preoperative assessment before major orthopaedic surgery.

The ERAS (Enhanced Recovery After Surgery) guidelines in major orthopaedic surgery do not address the issue of managing excess body weight in patients scheduled for hip and knee replacement or lumbar fusion. This aspect is relevant to practice due to the increasing number of obese individuals and to some evidence suggesting higher complication rates in patients with excess weight. There is a debate on whether obesity defined by the body mass index, i.e. the ratio of weight to squared height, can guide surgical eligibility and whether losing excess weight preoperatively can actually lead to better outcomes. In this practice development article, we explore opposing perspectives on the value of a high BMI as an indicator of increased preoperative risk and discuss the potential consequences of losing weight prior to a major orthopaedic surgery. The aim is to promote a conscious management of individuals with excess body fat based on the patient's overall health rather than BMI alone. In the absence of strong evidence on what is best to do, it is reasonable to suggest that any prehabilitation initiatives should not focus on a rigid weight loss mandate but on a multidisciplinary, multimodal, and personalised approach that does not necessarily include a reduction in body weight.