P122. Comparing long term deformity correction and other outcomes between single level circumferential XLIF and MI-TLIF: a retrospective review with 5-year minimum follow up

Abstract

<h3>BACKGROUND CONTEXT</h3> XLIF with percutaneous pedicle screw fixation (circumferential XLIF) and MI-TLIF are two commonly used minimally invasive approaches to the lumbar spine. Because of its lateral approach, traditional XLIF is blocked to the L5-S1 disc space by the iliac crest. Studies that have compared these two techniques typically do not account for this limitation and, furthermore, tend to not restrict their analysis by number of levels operated on. Additionally, studies evaluating long term (>5-year) outcomes of these techniques are less numerous. Therefore, this study aims to compare the clinical and radiological outcomes of single level circumferential XLIF and MI-TLIF exclusively at the L4-L5 disc space. <h3>PURPOSE</h3> To compare the clinical and radiological outcomes of single level XLIF and MI-TLIF at L4-L5. <h3>STUDY DESIGN/SETTING</h3> Retrospective comparative study. <h3>PATIENT SAMPLE</h3> A total of 108 total patients (75 MI-TLIF and 33 circumferential XLIF) that underwent single level surgery at L4-L5 at a single institution from 2008 to 2015 with a minimum of 5-year follow up. <h3>OUTCOME MEASURES</h3> 1) Patient demographics: age, sex, BMI, length of follow up; 2) rate of complications requiring a return to the OR (RTO); 3) Radiographic outcomes: graft subsidence, final anterior and posterior disc height (ADH and PDH); 4) Patient outcome scores: Oswestry Disability Index (ODI), Visual Analogue Scale (VAS). <h3>METHODS</h3> A retrospective review was performed to identify all patients between 2008-2015 who underwent circumferential XLIF or MI-TLIF with a minimum followup of 5 years. Demographic data, complication-related data, radiographic outcomes and patient outcome scores were recorded and compared between cohorts. Standard binominal and categorical comparative analyses were performed. <h3>RESULTS</h3> A total of 108 patients were included for analysis (75 MI-TLIF and 33 circumferential XLIF). Mean age (53.5 MI-TLIF and 53.9 XLIF), BMI (32.3 MI-TLIF and 31.4 XLIF), and length of follow up (90 months MI-TLIF and 103 months XLIF) were similar between cohorts. Overall RTO rate was found to be statistically similar between groups at 16.0% (95% CI, 9.24-26.07) in the MI-TLIF group and 6.1% (95% CI, 0.68-20.60) in the XLIF group. Final ADH was 9.03±1.10 mm in the MI-TLIF group and 12.3±2.60 mm in the XLIF group (p < 0.0001). Final PDH was 9.97±1.96 mm for MI-TLIF and 7.12±2.2 mm for XLIF (p < 0.0001). Average DH was 9.50±1.59 mm and 9.71±2.41 mm for the MI-TLIF and XLIF groups, respectively (p=0.593). Change in ODI and VAS scores at final follow up were similar between MI-TLIF and XLIF groups (p=0.629 for ODI and p=0.322 for VAS). <h3>CONCLUSIONS</h3> This long-term comparative study demonstrates similar clinical and radiological outcomes between single level MI-TLIF and circumferential XLIF at the L4-L5 level. As expected, MI-TLIF had significantly greater long-term improvement in posterior disc height and XLIF had significantly greater improvement in anterior disc height. However, average disc height was found to be similar between groups. This suggests that although MI-TLIF and circumferential XLIF lead to equivalent long-term improvement at the L4-L5 level, choosing one's approach based on the anterior versus posterior disc anatomy of the patient may enhance patient outcome. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.