Prospective Evaluation of Spino-Pelvic Parameters with Clinical Correlation in Patients Operated with an Anterior Lumbar Interbody Fusion

STUDY DESIGN: Prospective study. PURPOSE: The goal of this study was to evaluate the impact of anterior lumbar interbody fusion (ALIF) on L5–S1 level for restitution of distal segmental lordosis and to investigate its consequences on spino-pelvic parameters and the global sagittal balance. OVERVIEW OF LITERATURE: Lumbar surgery must be adapted to the spinal morphology in order to restore an adequate relation between pelvic and spinal parameters and especially to the pelvic incidence. METHODS: An observational, prospective study was conducted between January 2013 and May 2017. Eighty-six patients were treated by L5–S1 ALIF procedure regardless of disc replacement above L5–S1 level. Thirty-seven patients were included and subset analyses were performed on 25 patients operated on an isolated ALIF L5–S1 (group 1), and 12 patients with hybrid surgery consisting of an L5– S1 ALIF procedure and a L4–L5 lumbar disc replacement (group 2). Clinical parameters were analyzed using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) at M0 (preoperative) and M12 (12 months). Lumbo-pelvic parameters were assessed on a standingfull-spine X-ray, preoperatively and at M12 after surgery. RESULTS: We observed a significant evolution of L1–S1 lumbar lordosis (p <0.001) with a significant increase of the distal arch L4–S1 lordosis (p <0.001) and decrease of the proximal arch lordosis (p =0.03). Preoperatively, 27% of the patients were unbalanced. Significant variation in sagittal balance parameters was observed, with a decrease of the sagittal vertebral axis (p <0.001). VAS and ODI improved significantly but no correlation was found. An evolution in the same direction was found in the two subgroup analyses. CONCLUSIONS: ALIF procedure on L5–S1 level allowed a reconstruction of lumbosacral segmental lordosis, modification of global lordosis, without variation of spino-pelvic parameters except an improvement in sagittal balance.