Functional and Perioperative Outcome of Transforaminal Lumbar Interbody Fusion as it Relates to Patient Body Mass Index

Presented at SMISS Annual Forum 2014
By Reginald Q. Knight MD, MHA
With Scott Grainger BS, RN,

Disclosures: Reginald Knight MD, MHA B; Stryker Spine, Vertebral Technology Inc, Vertera Spine. C; Stryker Spine, Vertebral Technology Inc, Vertera Spine. D; Vertebral Technology Inc, Vertera Spine, Gerstner Medical. Scott Grainger BS, RN None,

Introduction:
Degenerative conditions of the lumbar spine frequently occur in patients with large body mass indexes. MIS is reported to reduce complications and improve patient function regardless of patient size.

Aims/Objectives:
Our study will evaluate a consecutive series of patients undergoing TLIF for degenerative conditions and the impact of patient size on functional outcome and perioperative demographics.

Methods:
From January 2011 through May 2014 28 patients were treated with MIS TLIF through a 22 millimeter tubular retractor using intradiscal horizontally assemble cage and percutaneous pedicle-rod instrumentation. 19 consecutive patients with primary lumbar spondylosis or spondylolisthesis form the study cohort. Chart and radiographic review were performed under IRB sanctioning. Sagittal and coronal reconstructed lumbar CT scans are obtained at 10 months. Oswestry, VASB and VASL data was collected prep, 1, 4, 10 and 24 months postop. Patients were stratified on basis of BMI (normal less than 25, overweight from 25 to 29, obese from 30 to 39 and morbidly obese 40 or above). Statistical analysis via Student t-test with less than 0.05 as significant.

Results:
Cohort means of age (54 years), BMI (31.1 - normal = 5 patients, overweight = 7, obese = 3, morbidly obese = 4), estimated blood loss (144cc), operative time (279min), fluoroscopy time (161sec), length of stay (2.4days), and followup (19mos) were documented. Levels fused include L4-5 (15) and L5-S1 (9). 4 patients (3 normal BMI, 1 obese) experienced a complication without required re-operation. All patients with adequate follow-up (12/19) obtained 10 month CT scans. All indicated solid bony fusion. Overall functional outcome was significantly improved (VASB pre 70, 24 months 38; VASL pre 64, 24 months 33; ODI pre 54, 24 months 41). Intergroup-BMI analysis on basis of demographics or functional outcome did not indicate any significant differences based on BMI.

Conclusions:
Obesity is a condition facing spine surgeons on a daily basis. Treatment options include minimally invasive techniques such as TLIF. Our data indicates BMI as a singular perimeter does not negatively impact preoperative demographics, complications, fusion rate or functional outcome.