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 standing full-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.