Association Between Spinopelvic Alignment, Sarcopenia, and Postoperative Functional Outcomes Among Adults with Lumbar Spine Disorders: A Cross-Sectional Study

Abstract

Background: Spinopelvic malalignment and paraspinal muscle degeneration are increasingly recognized as potential contributors to persistent disability after lumbar surgery, but their postoperative relationship is not routinely quantified within the same analytic framework. This study quantified differences in long-term spinopelvic alignment and functional outcomes according to sarcopenia status.
Methods: A secondary cross-sectional analysis was performed using published aggregate data from 213 adults after multilevel posterior lumbar interbody fusion, comprising 69 sarcopenic and 144 nonsarcopenic patients. The final postoperative assessment, obtained at approximately 40 months, was treated as the cross-sectional index visit. Mean differences, Hedges’ g with 95% confidence intervals (CIs), and odds ratios for fatty-infiltration categories were reconstructed from reported group summaries. Earlier assessments were used only to describe temporal patterns.
Results: At final follow-up, sarcopenic patients had higher Oswestry Disability Index scores (mean difference [MD], 7.68; 95% CI, 4.96–10.40; g=0.79), greater back-pain VAS scores (MD, 0.70; 95% CI, 0.41–0.99; g=0.71), greater sagittal vertical axis (MD, 14.26 mm; 95% CI, 9.35–19.17; g=0.86), and larger PI–LL mismatch (MD, 6.96°; 95% CI, 3.60–10.32; g=0.64). Lumbar lordosis was 5.60° lower in the sarcopenic group (95% CI, 3.02–8.18°; |g|=0.63). Moderate-to-severe multifidus fatty infiltration was more frequent with sarcopenia (OR, 3.14; 95% CI, 1.60–6.16). Between-group differences were small at baseline and early follow-up and were larger at the final assessment.
Conclusion: Sarcopenia was accompanied by a distinct long-term phenotype of poorer sagittal alignment, greater pain, and greater disability. Because only aggregate data were available, these findings establish group-level association rather than causality or independent patient-level effects; confirmation with individual-level multivariable data is required.