Short-Term Functional Recovery Trajectories After Adult Spinal Deformity Surgery Differ by Upper Instrumented Vertebra Level

STUDY DESIGN: A retrospective study utilizing a prospectively collected database. OBJECTIVE: To compare postoperative recovery trajectories of disability following adult spinal deformity (ASD) surgery among patients with different upper instrumented vertebra (UIV) selections. SUMMARY OF BACKGROUND DATA: Choosing the UIV is crucial decision making in ASD surgery. The added morbidity by fusing to the upper versus lower thoracic spine remains unknown. MATERIAL AND METHODS: This study involved patients who had primary ASD surgery from UIV at L2 or above to pelvis. The primary outcome measured was the Oswestry Disability Index (ODI), collected longitudinally. Multivariable mixed-effects regression model with restricted cubic splines were used to evaluate recovery trajectories across three UIV locations: upper thoracic (UT=T2-T5), lower thoracic (LT=T9-T12), and upper lumbar (UL=L1-L2). RESULTS: Of 222 patients (UT, 58; LT, 135; UL, 29), preoperative demographics and clinical characteristics differed significantly in age (UT, 62.6 vs. LT, 65.7 vs. UL, 70.3 y, P=0.001), body mass index (UT, 26.2 vs. LT, 26.5 vs. UL, 29.5, P=0.039), length of stay (8.4 vs. 5.4 vs. 5.3 d, P