Introduction
Lumbar spondylolisthesis can be asymptomatic, but many patients present with low back pain or radicular symptoms, often requiring surgical intervention. Degenerative spondylolisthesis typically occurs at the L4 level, while isthmic spondylolisthesis predominantly affects the L5 level, both exhibiting distinct lumbopelvic alignment characteristics. This study aimed to compare lumbopelvic alignment in patients with degenerative and isthmic spondylolisthesis requiring surgery to that in the general adult population.
Methods
We analyzed 37 patients with L4 degenerative spondylolisthesis and 16 patients with L5 isthmic spondylolisthesis who underwent spinal fusion surgery at our institution. For comparison, CT images from 708 patients who had abdominal or lumbar CT scans for non-back-pain-related reasons were reconstructed. We identified 28 patients with L4 degenerative spondylolisthesis and 15 with L5 isthmic spondylolisthesis as representative of the general adult population. Sagittal CT images were evaluated for lumbar lordosis (LL) and sacral slope (SS), and statistical analysis was conducted using Student’s t-test and Chi-square test to compare age, LL, SS, and male/female ratios between groups.
Results
The mean age for L4 degenerative spondylolisthesis surgery patients was 69.0 ± 9.7 years (male/female: 15/22), with an LL of 40.9 ± 9.9° and an SS of 35.2 ± 7.9°. L5 isthmic spondylolisthesis surgery patients had a mean age of 63.6 ± 10.2 years (male/female: 13/3), LL of 39.1 ± 9.8°, and SS of 36.6 ± 6.8°. L5 isthmic patients were significantly more likely to be male (p=0.0064) and showed a trend toward younger age (p=0.071), with no significant differences in LL or SS compared to L4 degenerative patients. In the general population, those with L4 degenerative spondylolisthesis had a mean age of 75.7 ± 9.6 years (male/female: 13/15), LL of 44.5 ± 11.0°, and SS of 39.2 ± 9.0°. Patients with L5 isthmic spondylolisthesis in the general population had a mean age of 73.9 ± 11.2 years (male/female: 12/3), LL of 48.5 ± 9.8°, and SS of 42.7 ± 6.5°. No significant differences in age, LL, or SS were found between the general population groups, except for the male/female ratio (p=0.033). While LL and SS in L4 degenerative spondylolisthesis surgery patients did not differ significantly from the general population, L5 isthmic spondylolisthesis surgery patients showed significantly lower LL (p=0.012) and SS (p=0.017) compared to the general population.
Discussion
Lumbopelvic alignment in L4 degenerative spondylolisthesis surgery patients was comparable to that of the general population. However, L5 isthmic spondylolisthesis surgery patients exhibited significantly decreased lumbar lordosis and sacral slope, indicating altered alignment compared to the general population.