Does obesity affect long-term outcomes of extreme lateral interbody fusion with posterior stabilization?

Background Context: Obese patients can pose significant challenges to spine surgeons in lumbar fusion procedures. The increased risk of complications has led surgeons to be wary in pursing operative interventions in these patients. Since the advent of minimally-invasive techniques in lumbar fusion, surgeons are turning to these procedures in an attempt to minimize operative time, blood loss and overall cost. With an increased proportion of obese patients in the population, it is imperative to understand the long-term outcomes in these minimally-invasive approaches.
Purpose: The purpose of this study was to evaluate the long-term safety and efficacy of extreme lateral interbody fusion (XLIF) in the obese.
Study Design/setting: Retrospective cohort study.
Patient Sample: A total of 115 patients (53 nonobese and 62 obese) who underwent XLIF with a minimum of 5-year follow-up.
Outcome Measures: (1) Patient reported outcome scores: Visual Analog Scale (VAS) for back pain, Oswestry Disability Index (ODI), (2) Reoperation rate, (3) Pelvic incidence (PI)- Lumbar lordosis (LL) mismatch correction, (4) Graft subsidence and fusion rate METHODS: A retrospective review was performed to identify patients who underwent XLIF with percutaneous posterior stabilization since 2007 with a minimum follow-up of 5 years. Demographics including BMI were recorded and patients were subdivided into 2 cohorts: nonobese (BMI <30 kg/m ² ) and obese (BMI ≥30 kg/m ² ). Functional outcomes were assessed by comparing pre- and postoperative VAS and ODI scores. Reoperation rates were compared between cohorts. PI-LL mismatch was calculated from both pre- and postoperative radiographs. Rates of graft subsidence and fusion were measured at final follow-up.
Results: A total of 115 consecutive patients were included (53 nonobese and 62 obese) with a mean follow up of 95.3 months. Mean BMI was 25.3 in the nonobese group and 35.3 in the obese group (p<.001). There were more females in nonobese cohort. VAS scores decreased by a mean of 5.7 in the nonobese cohort, and 5.4 in the obese cohort (p=.213). ODI improvement was also similar between the groups. 5.6% of nonobese patients required reoperation compared to 9.6% of obese patients (p=.503). Graft subsidence rates at final follow-up were 5.66% and 8.06% for the nonobese and obese groups, respectively (p=.613). Rates of successful fusion were 96.23% and 98.39% for the nonobese and obese groups, respectively (p=.469). Both cohorts achieved a similar proportion of PI-LL mismatch correction, 85% in obese versus 78% in nonobese patients (p=.526).
Conclusion: Obese patients have similar surgical outcomes to nonobese patients with respect to functional outcome scores, reoperation rates, graft subsidence and correction of PI-LL mismatch after long-term follow-up. With similar outcome and reoperation profiles, minimally-invasive approaches to the spine, such as XLIF, may be an acceptable alternative to traditional open procedures in obese patients.
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