P116. Five-year minimum outcomes of MI-TLIF in obesity: a matched cohort analysis

Abstract

BACKGROUND CONTEXT Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is an established technique for the treatment of degenerative spine disease. However, obese patients increase the complexity of the MI-TLIF approach due to obstacles associated with increased body habitus, and there is conflicting evidence regarding postoperative outcomes after MI-TLIF in this population. PURPOSE To compare 5-year minimum postoperative outcomes in obese patients versus nonobese patients undergoing MI-TLIF through a matched-cohort analysis. STUDY DESIGN/SETTING Matched retrospective comparative study. PATIENT SAMPLE A total of 148 matched patients (74 obese, 74 nonobese). OUTCOME MEASURES 1) Patient demographics; 2) Perioperative data; 3) Revision rate; 4) Complications; 5) Radiographic outcomes: pelvic incidence-lumbar lordosis (PI-LL) mismatch, graft subsidence, fusion rate; 6) Patient reported outcome scores: Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS). METHODS A retrospective review of a single institution was performed to identify patients who underwent MI-TLIF with a minimum follow up of 5 years. Patients were divided into two cohorts: obese (BMI > 30 kg/m2) and non-obese (BMI < 30 kg/m2). Each cohort was matched for age, sex and levels operated. Revision rates and complications were compared. Radiographic outcomes and fusion rate were measured at final followup. Patient-reported outcomes and radiographic outcomes were recorded and compared. Standard binomial and categorical comparative analyses were performed. RESULTS There were 148 patients included and matched (74 obese, 74 nonobese). Mean follow-up time was similar between obese and nonobese groups at 90.9 and 94.2 months, respectively. Significance was found for average blood loss (127.8 mL obese and 37.8 mL nonobese, p <.001) between groups; 17.6% of obese patients required revision surgery compared to 16.2% of nonobese patients (p= 0.826). Both cohorts achieved a similar proportion of PI-LL mismatch correction (79.2% obese and 83.3% nonobese, p= 0.780). Graft subsidence rates at final follow-up were 8.1% and 5.4% in the obese and nonobese cohorts, respectively (p= 0.512). Mean change in functional outcome scores were similar between cohorts. CONCLUSIONS This long-term matched comparative study demonstrates similar clinical and radiological outcomes between obese and nonobese patients undergoing MI-TLIF. Obese patients were found to have significantly greater blood loss and operative time than nonobese patients, however, the true clinical impact of these differences was minor. Our findings suggest that MI-TLIF is an appropriate lumbar fusion technique for the obese patient with degenerative pathology of the lumbar spine. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is an established technique for the treatment of degenerative spine disease. However, obese patients increase the complexity of the MI-TLIF approach due to obstacles associated with increased body habitus, and there is conflicting evidence regarding postoperative outcomes after MI-TLIF in this population. To compare 5-year minimum postoperative outcomes in obese patients versus nonobese patients undergoing MI-TLIF through a matched-cohort analysis. Matched retrospective comparative study. A total of 148 matched patients (74 obese, 74 nonobese). 1) Patient demographics; 2) Perioperative data; 3) Revision rate; 4) Complications; 5) Radiographic outcomes: pelvic incidence-lumbar lordosis (PI-LL) mismatch, graft subsidence, fusion rate; 6) Patient reported outcome scores: Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS). A retrospective review of a single institution was performed to identify patients who underwent MI-TLIF with a minimum follow up of 5 years. Patients were divided into two cohorts: obese (BMI > 30 kg/m2) and non-obese (BMI < 30 kg/m2). Each cohort was matched for age, sex and levels operated. Revision rates and complications were compared. Radiographic outcomes and fusion rate were measured at final followup. Patient-reported outcomes and radiographic outcomes were recorded and compared. Standard binomial and categorical comparative analyses were performed. There were 148 patients included and matched (74 obese, 74 nonobese). Mean follow-up time was similar between obese and nonobese groups at 90.9 and 94.2 months, respectively. Significance was found for average blood loss (127.8 mL obese and 37.8 mL nonobese, p <.001) between groups; 17.6% of obese patients required revision surgery compared to 16.2% of nonobese patients (p= 0.826). Both cohorts achieved a similar proportion of PI-LL mismatch correction (79.2% obese and 83.3% nonobese, p= 0.780). Graft subsidence rates at final follow-up were 8.1% and 5.4% in the obese and nonobese cohorts, respectively (p= 0.512). Mean change in functional outcome scores were similar between cohorts. This long-term matched comparative study demonstrates similar clinical and radiological outcomes between obese and nonobese patients undergoing MI-TLIF. Obese patients were found to have significantly greater blood loss and operative time than nonobese patients, however, the true clinical impact of these differences was minor. Our findings suggest that MI-TLIF is an appropriate lumbar fusion technique for the obese patient with degenerative pathology of the lumbar spine.