Radiographic Restoration of Sagittal Spinopelvic Alignment After Posterior Lumbar Interbody Fusion in Degenerative Spondylolisthesis

A retrospective study. This study was aimed to analyze the changes in spinopelvic parameters after surgical correction of degenerative spondylolisthesis and to determine which deformity is most responsible for changes in sagittal spinopelvic alignment. The basic deformities of degenerative spondylolisthesis are forward slippage of the vertebral body, segmental kyphotic angle, and loss of disk height. Correction of those deformities during surgery will subsequently affect the spinopelvic parameters. A few studies have reported the changes of sagittal spinopelvic alignment after surgical treatment of isthmic spondylolisthesis. However, there appears to be relatively little information regarding degenerative spondylolisthesis. Fifty-three patients with L4-L5 degenerative spondylolisthesis were included. All patients underwent posterior lumbar interbody fusion and posterior instrumentation. Back pain, as the clinical outcome, was evaluated by visual analogue scale (VAS). The preoperative and postoperative spinopelvic parameters, including sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), and L1 axis S1 distance were measured, and then the correlations between spinopelvic parameters and local deformity parameters such as slip degree, slip angle (SA), and height of the intervertebral disk were evaluated. After surgical correction of local deformity, all spinopelvic parameters changed subsequently: PT and L1 axis S1 distance had a decrease, SS and LL had an increase. VAS score decreased from 6.1±2.3 before surgery to 2.4±1.7 at the final follow-up assessment. Patients with VAS score changes ≥3 showed significantly higher SS and LL, and lower PT compared with those with VAS score changes