Quantitative Analysis of Lumbar Disc Bulging in Patients with Lumbar Spinal Stenosis: Implication for Surgical Outcomes of Decompression Surgery

This study aimed to quantitatively assess disc bulging using computed tomography (CT) in patients with lumbar spinal stenosis (LSS) and to examine whether disc bulging affects the surgical outcomes of patients with LSS after posterior decompression surgery. Sixty-three patients who underwent posterior decompression surgery for LSS were included. The extent of disc bulging was evaluated as the percentage of the extended area of the disc against the endplate area (%EAD) on axial CT images. The participants completed the following clinical outcome assessments (COAs) preoperatively and 12 months postoperatively: the JOA Back Pain Evaluation Questionnaire (JOABPEQ), Oswestry Disability Index (ODI), and Roland–Morris Disability Questionnaire (RDQ). The mean %EAD of 315 intervertebral discs was 18.9 ± 8.0. The %EAD was highest at L4/L5, followed by L3/L4, L2/L3, L1/L2, and L5/S1. The %EAD of the surgical level showed no significant correlation with all the preoperative COAs, but it had significant correlation with lumbar function, walking ability, social function domains of the JOABPEQ, ODI score, and RDQ score 12 months postoperatively. %EAD was significantly associated with the postoperative score in the walking ability domain of the JOABPEQ. %EAD affects postoperative clinical outcomes, including low back pain-related quality of life after decompression surgery.