Introduction: Obesity is increasingly prevalent in the United Kingdom. The consequences for daily practice and service provision in spinal surgery are uncertain. Some studies have demonstrated a correlation between Body Mass Index (BMI) and peri-operative complications, but others have shown none. We investigated the impact of BMI and posterior spinal fat content on peri-operative practice and complications in lumbar spine surgery.

Methods: 135 cases of lumbar spine surgery imaged and carried out at a single centre between October 2009 and 2010 were identified. Of these, 101 datasets including BMI were available for analysis. Patient demographics, co-morbidities, operative details, peri-operative complications and length of stay were recorded from case notes. Posterior spinal fat content was measured as the perpendicular distance from the skin to the spinous process at the level of pathology on T2 weighted MRI. Data was analysed using logistic multiple regression and contingency table analysis in the Minitab 13.1 statistics package.

Results: Mean BMI was 28.2 (SD 5.1) comprising 1 underweight (BMI <18.5), 31 normal weight (BMI 18.5-24.9), 33 overweight (BMI =25), 34 obese (BMI=30) and 2 morbidly obese patients (BMI=40). BMI correlated significantly with increasing length of stay after controlling for age, procedure and complication rate (coefficient 0.039, p 0.001), but posterior spinal fat content did not (p=0.057). Procedure (p=0.001) and complication rate (p<0.0005) also correlated strongly with length of stay. There was no significant effect of BMI or posterior spinal fat content on the incidence of peri-operative complications (p=0.374, p=0.205), operating time (p=0.462, p=0.865) or blood loss (p=0.732, p=0.820). Complication rate was 13% with 5 in the obese group, 6 in the overweight group and 3 in the normal weight group.

Conclusions: Obesity correlates with increased length of stay in spinal surgery. This is not associated with increased peri-operative complications, operating time or blood loss.

Patient Care: An understanding of the implications and risks, or lack thereof, of operating on obese patients will enable informed patient choice and surgical practice. An appreciation of the causes of increased length of stay should lead to improved efficency in the patient care pathway.

Learning Objectives: Participants should 1) Gain a further appreciation of the implications of operating on obese patients 2) Compare and contrast this cohort with their own experiences of the patient group

References: 1. Patel, N et al. Obesity and spine surgery: relation to peri-operative complications. 2007. J Neurosurg Spine. 6: 291–297. 2. Andreshak, TG et al. 1997. Lumbar spine surgery in the obese patient. 1997. Journal of Spinal Disorders. 10(5):376-379. 3. Yadla S et al. Obesity and spine surgery: reassessment based on a prospective evaluation of perioperative complications in elective degenerative thoracolumbar procedures. Spine J. 2010 Jul;10(7):581-7