Are We Missing the Bigger Comorbidity Picture? Metabolic Syndrome Worsens Alignment and Increases Mechanical Complications After Adult Spinal Deformity Surgery.

Abstract

Metabolic syndrome may influence recovery after complex spine surgery. In patients undergoing adult spinal deformity (ASD) surgery, we evaluated the relationship between metabolic syndrome and postoperative alignment, complications, and patient-reported outcome measures (PROMs). A retrospective analysis (2010-2023, 2-year-follow-up) was conducted of patients undergoing ASD surgery. Metabolic syndrome was defined as concurrent hypertension, diabetes, and body mass index ≥30 kg/m². The primary outcomes were the following: alignment, evaluated as sagittal vertical axis >5 cm or L1-pelvic angle not within 5° of target, or coronal vertical axis >3 cm; and medical and mechanical complications. Secondary outcomes were 2-year Oswestry Disability Index scores. Multivariable regression controlled for age, sex, prior fusion, operative time, and preoperative alignment/PROMs. Of 288 patients undergoing ASD surgery, 31 (11%) had metabolic syndrome. Patients with metabolic syndrome were significantly older (71 ± 8 vs. 62 ± 18 years; P < 0.001) and had a higher preoperative muscle-to-vertebral body ratio, indicating sarcopenic obesity (β = 0.6; 95% CI, 0.3-0.9; P < 0.001). Metabolic syndrome was independently associated with higher rates of postoperative sagittal vertical axis (>5 cm) (OR, 5.2; 95% CI, 1.4-19.0). Metabolic syndrome was not associated with medical complications (all P > 0.05). Metabolic syndrome was independently associated with rod fractures/pseudarthrosis (OR, 4.0; 95% CI, 1.6-10.1; P = 0.003).Two-year PROMs were similar between the cohorts (all P > 0.05). Preoperative metabolic syndrome was independently associated with postoperative sagittal malalignment and rod fractures/pseudarthrosis. Continued awareness of metabolic syndrome may enable surgeons to holistically address the syndrome preoperatively.