THE OUTCOME OF LUMBAR DISCECTOMY IN THE OBESE

Abstract

The recent NICE guidelines on management of osteoarthritis outline weight loss as first line treatment in degenerative joint disease in the obese. There is little data surrounding the effects of obesity on the outcomes in spinal surgical interventions. Intervertebral discectomy is one treatment for prolapse of a lumbar vertebral disc. We aim to investigate the effect of obesity on outcomes for discectomy.

Demographic details including age, sex, weight and BMI were recording with a pre-operative Oswestry Disability Index (ODI). The fat thickness was measured at L5/S1 using calibrated MRI scans. Outcome measures included complications, length of surgery and change in ODI at 1 year following surgery. Obesity was defined as a body mass index of over 30. The units Serial patients undergoing discectomy were recruited into the study. Patients with bony decompression, instrumentation, revision surgery or multilevel disease were excluded.

Fifty patients with a single level uncomplicated disc prolapse were entered into the study. Sixteen patients had a BMI over 30 and so were obese, whilst 34 had a BMI of less than 30. The mean pre-operative ODI was 46.5 in the obese group and 52 in the normal group this difference was not significant (p> 0.05). The mean post operative ODI was statistically improved in the high BMI group at 28 (18.5 point improvement) and 25.2 (29.1 point improvement) in the normal group. The ODI improvement was significantly better in the low BMI group (p=0.036). There was no significant difference in operative time (p=0.24). Only a single patient had a complication (dural leak), so no valid comparison could be made.

The outcomes of spinal surgery in the obese are mixed.

We found no increase in the complication rate or intra-operative time associated with an increased BMI. However, the improvement in ODI was significantly better in the normal BMI group.