Abdominal aortic calcification and functional recovery in patients undergoing posterior lumbar interbody fusion: a retrospective cohort study

Lumbar degenerative diseases (LDDs) are a major cause of disability globally, and posterior lumbar interbody fusion (PLIF) is a common treatment. Abdominal aortic calcification (AAC), a vascular lesion linked to metabolic disorders, may impair postoperative functional recovery, though its impact remains unclear. This retrospective study analyzed 124 patients (70 females [56.5%], 54 males [43.5%]) who underwent PLIF for LDDs between December 2022 and June 2023. AAC was evaluated on lateral lumbar radiographs using the Kauppila score (AAC-24). AAC was defined as AAC-24 ≥ 1; AAC-24 severity was further categorized (0, 1–4, 5–8, ≥ 9) and modeled continuously to examine dose–response relationships. Fusion status at 1 year was assessed using the Brantigan interbody fusion grading. Functional outcomes included the Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) score, back and leg pain visual analog scales (VAS), and Modified MacNab criteria. Minimal clinically important difference (MCID) in ODI was defined as an absolute improvement ≥ 10 points (primary) and ≥ 30% improvement (sensitivity). Baseline-adjusted analysis of covariance (ANCOVA) models and penalized logistic regression were used to evaluate the association between AAC-24 and 1-year outcomes, with both full and minimal models to address potential over-adjustment and model stability. Among the 124 patients, 55 had AAC. The AAC group showed significantly higher ODI scores (p < 0.001) and lower JOA scores (p < 0.001) at 1 year postoperatively compared to the non-AAC group. After adjusting for confounding factors, these differences remained significant. There were no significant differences in VAS scores between the two groups. The distribution of Modified MacNab grades did not differ significantly between groups (p = 0.223). The AAC group had a fusion rate of 89.1%, compared to 81.2% in the non-AAC group (p = 0.308). A dose-dependent association between AAC severity and poorer ODI/JOA scores was observed. Higher AAC-24 scores were also associated with lower odds of achieving the predefined ODI MCID thresholds. Preoperative abdominal aortic calcification, quantified by the AAC-24 Kauppila score, was independently associated with poorer 1-year functional recovery after PLIF, without affecting fusion rates or pain relief, and showed a dose–response relationship with disability and functional limitation. AAC-24 may serve as a pragmatic preoperative prognostic marker to identify patients at risk of suboptimal functional improvement, although these findings are associative and require confirmation in larger prospective cohorts.