The effect of surgical level on self-reported clinical outcomes after minimally invasive transforaminal lumbar interbody fusion: L4-L5 versus L5-S1.

Objective: The anatomic and biomechanical aspects of the L5-S1 level present unique operative challenges compared with the L4-L5 level. However, it has not been determined if self-reported outcomes and complications are different between patients treated with a minimally invasive transforaminal lumbar interbody fusion at these specific levels.

Methods: There were 36 consecutive patients identified who were treated with a minimally invasive transforaminal lumbar interbody fusion procedure. Surgical indications included spondylolisthesis (grade 1 or 2) and degenerative disk disease with associated clinical symptoms. Patients completed a visual analog scale (VAS) for their back and leg and Oswestry Disability Index preoperatively and postoperatively. Outcomes were compared between patients with L4-L5 involvement and patients with L5-S1 involvement. In all patients, fusion was evaluated by dynamic view flexion and extension views at 1 year. In all patients with indeterminate results or incomplete imaging, computed tomography was performed to evaluate for bridging bone and stable hardware positioning.

Results: The surgical indications between the 2 groups were similar (χ(2) = 0.089, df = 2, P = 0.956). There was no significant difference in mean operating time, intraoperative blood loss, and hospital stay (P = 0.937, 0.627, and 0.587). There was no significant difference in the long-term postoperative questionnaire results (P = 0.819 for VAS [back], 0.626 for VAS [leg], and 0.962 for Oswestry Disability Index) or the mean preoperative to postoperative change in Cobb angle (P = 0.626) between the 2 groups. Two complications, one in each group, were a rash from an antibiotic and postoperative nausea.

Conclusions: Despite differences in biomechanics and unique anatomic challenges at the L5-S1 interspace, there is no difference in self-reported outcomes for patients treated with minimally invasive transforaminal lumbar interbody fusion at the L4-L5 level compared with the L5-S1 level.