Imaging analysis of adjacent segment disease combined with retrolisthesis after posterior lumbar interbody fusion: a...

Adjacent segment disease (ASD) combined with retrolisthesis of the adjacent vertebrae is a common radiological phenomenon. However, its characteristics remain unclarified. This study aimed to investigate the epidemiology of ASD with retrolisthesis, preliminarily analyze its radiological features, and identify its risk factors.

The diagnostic criteria for symptomatic ASD were defined as the recurrence of radiating lower limb pain after the initial surgery and radiological evidence of degeneration at the adjacent fused segment indicating revision surgery. Retrolisthesis in ASD was defined as a ≥3 mm posterior slip of the superior vertebra of the affected segment on a lateral X-ray, no-slip status as the absence of anterior or posterior slippage of the superior vertebra in the affected segments, and anterolisthesis as a ≥3 mm anterior slip of the superior vertebral body. All patients who underwent surgical treatment for symptomatic ASD between November 2020 and July 2024 at the Third Hospital of Hebei Medical University with an initial operation of posterior lumbar interbody fusion (PLIF) were analyzed. Patients were divided into a retrolisthesis group (group A), a no-slip group (group B), and a anterolisthesis group (group C). The demographic information and imaging data were compared between the groups. In addition, we collected preoperative imaging data from the initial surgery for patients in each group and performed a comparative analysis.

A total of 165 patients were included in this study, with 102 (61.8%) being included in group A (retrolisthesis group), 20 (12.1%) in group B (no-slip group), and 43 (26%) in group C (anterolisthesis group). Group A, as compared to group B, had significantly lower disc height (0.76±0.25 vs. 0.96±0.23; P<0.001), more severe degeneration of discs (3.58±0.72 vs. 2.98±0.64; P<0.001) and facet joints (3.58±0.72 vs. 2.98±0.64, P<0.001), and a smaller multifidus (MF) relative muscle cross-sectional area (RCSA) (0.17±0.70 vs. 0.21±0.67; P=0.004). The risk factors for ASD with retrolisthesis were identified to be reduced disc height [odds ratio (OR) =11.185; 95% confidence interval (CI): 1.276-98.045; P=0.029], more severe disc degeneration (OR =0.400; 95% CI: 0.194-0.823; P=0.013), and greater MF atrophy (OR =4.087; 95% CI: 1.378-12.122; P=0.011).

ASD combined with retrolisthesis was the most common of the three patterns of ASD, and patients with this condition had severe degeneration of discs and facet joints and significant atrophy of the MF. Reduced disc height, severe disc degeneration, and atrophy of the MF were the risk factors for ASD combined with retrolisthesis. In summary, we hypothesize that early lumbar muscle-strengthening exercises may reduce ASD risk in patients with adjacent vertebral retrolisthesis detected on postoperative follow-up radiographs after lumbar fusion. This should be validated in controlled, prospective studies.