INFLUENCE OF OBESITY IN EARLY OUTCOME OF HIP REPLACEMENTS.

Abstract

Introduction: Obesity is detrimental to the health of an individual, however does a high body mass index (BMI) actually determine post operative morbidity following hip replacement surgery?

Methods: 550 consecutive primary hip replacement patients were included in this study. Patients were followed up at four weeks, six weeks and one year following surgery. Any complication that the patient had was recorded and listed either as local or general. The complications were further sub divided into minor and major depending on the risk they posed to the patient or the joint.

Results: The average BMI of our patients was 28.3 (4.3). 56 (10%) patients had a complication following hip replacement surgery. The group who did not have any complications had an average BMI of 28.13 (SD=4.6) while the group who sustained complications had an average BMI of 29.46 (SD=5.8) with a p value of 0.104 (Student t-test). When BMI was grouped in values of 5 starting from < 25 and ending with > 35 the p value was 0.029 (chi square test). Odds ratios for grouped BMI varied from 0.086–1.61(95% CI 1.01–1.08) (p=0.086). Odds ratios for individual surgeons ranged from 0.96–2.41 (p=0.024)

Discussion: When we looked at the overall BMI there was no significant difference between the group who had a complication and the group who did not have a complication, however when the BMI was split into groups those patients in group 30–34 and 35+ experienced a higher rate of complications. The final odds of BMI was 1.05 (1.01,1.09). There was a higher complication rate in the groups other than the ideal BMI of 25–29, and even a fall in BMI caused an increase in the complication rates.

Conclusions: Obese individuals are at a higher risk of developing a complication following surgery, however the operating surgeon also has an influence on the complication rate following hip replacements.