PurposeTo characterize differences in patient demographics and outcomes by surgeon experience in a cohort of patients undergoing adult spinal deformity surgery.MethodsPatients undergoing degenerative spinal deformity were included. Patients whose surgeons graduated from fellowship <= 5 years prior to surgery versus>5 years were compared. Multivariable linear and logistic regression, controlling for age, sex, comorbidity burden, number of segments fused, blood loss and operative time were used to evaluate differences in outcomes. Characteristics of operative invasiveness were plotted against surgeons' level of experience, and trends in these measures were assessed with univariate linear regression.ResultsThree-hundred sixty-three patients were included. 147 patients' surgeons had <= 5 years of experience. Patient demographics were evenly matched. Patients with junior surgeons had more pre-existing medical complications, and senior surgeons were less likely to take care of patients with Medicare/Medicaid (p<0.001). Junior surgeons were more likely to operate on non-elective patients (p<0.001). Patients of junior surgeons received larger fusions (9.6 vs. 7.6 segments fused, p<0.001). There were no differences in complication rates or death. Patients of junior surgeons had longer overall length of stays (p=0.037) and higher rates of nonhome discharge (OR 2.0, p<0.001), 30- and 90-day (p<0.005) ED visits, and higher costs (+$8548, 95% CI: $1596 to $15,502; p=0.016).ConclusionJunior surgeons tend to perform more extensive deformity operations on more medically complex patients compared to senior surgeons, associated with higher costs and more resource utilization than senior surgeons.