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

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: 1) postoperative alignment, 2) complications, and 3) patient-reported outcome measures (PROMs). A retrospective analysis (2010-23, 2-year-follow-up) was conducted of patients undergoing ASD surgery. Metabolic syndrome was defined as concurrent hypertension, diabetes, and body mass index (BMI)≥30 kg/m2. The primary outcomes were 1) alignment, evaluated as sagittal vertical axis (SVA) cm > 5cm and L1-pelvic angle (L1PA) within 5° of target, or coronal vertical axis (CVA) >3 cm, and 2) medical and mechanical complications. Secondary outcomes were 2-year Oswestry Disability Index (ODI) 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). Postoperative Alignment:Metabolic syndrome was independently associated with higher rates ofpostoperativeSVA>5 cm(OR:5.2, 95%CI:1.4-19.0). Medical Complications:Metabolic syndrome was not associated with medical complications (all p >0.05). Mechanical Complications: Metabolic syndrome was independently associated with rod fractures/pseudarthrosis (OR:4.0, 95%CI: 1.6-10.1, p=0.003). 2-Year PROMs: 2-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.