Obesity is a major challenge in healthcare, and it is well known that it is associated with problems such as heart disease, diabetes and some types of cancers. Operating on people who are markedly overweight presents the orthopaedic surgeon with a number of problems, and we often advise patients to lose as much weight as they can before surgery. The main difficulties are related to the surgical approach to the hip, and the risk of excessive blood loss and infection. A careful assessment of the risks and benefits of surgery will help the surgeon and patient to decide whether or not to proceed to surgery. A recent study of  3290 patients undergoing hip replacement in Canada has helped to inform this process. The authors found that:

‘While the pre- and post-operative scores were lower for the group classified as morbidly obese, the overall change in outcome scores suggested an equal if not greater improvement compared with the non-morbidly obese patients. The overall survivorship and rate of complications were similar in the BMI groups although there was a slightly higher rate of revision for sepsis in the morbidly obese group.

Morbid obesity does not affect the post-operative outcome after THR, with the possible exception of a marginally increased rate of infection. Therefore withholding surgery based on the BMI is not justified.’

The last sentence is interesting because some commissioners of healthcare are using BMI (Body Mass Index) to ration services. This debate will continue as resources become increasingly squeezed in the future.