Alignment schematic impact on complications and outcomes in adult spinal deformity corrective surgery

BACKGROUND CONTEXT: Multiple alignment schematics have been proposed and utilized in adult spinal deformity (ASD). The utility of SRS-Schwab, GAP, SAAS, and Roussouly targets on reducing complications and improving outcomes in a cohort remains to be evaluated. PURPOSE: To evaluate meeting SRS-Schwab, GAP, SAAS, and Roussouly targets in ASD impact on complications and outcomes. STUDY DESIGN/SETTING: Retrospective cohort study of a prospectively collected single-center ASD database. PATIENT SAMPLE: Adult spinal deformity. OUTCOME MEASURES: Complications, Health-Related Quality of Life Outcomes. METHODS: We included ASD patients fused from at least L1 to Sacrum with 2-year follow-up. Patients were grouped by postoperative SRS-Schwab, GAP, SAAS, and Roussouly target categories. Patients were considered matched in SRS-Schwab if all criteria were ‘0’, GAP proportioned, SAAS matched, and Roussouly target matched. Complications and patient-reported outcomes (ODI, SRS22r, SF-36) were assessed via ANOVA and multivariable logistic regression. The combination of two schematics that provided the greatest improvement in complications and outcomes was evaluated. RESULTS: A total of 334 patients met inclusion. (Age 63±10, 77% F, BMI 27.6±5.1 kg/m2, frailty 3.5±1.5, CCI 1.9±1.7). Postoperatively, 35.5% met SRS-Schwab, 33% were GAP proportioned, 48.2% met Roussouly target, and 25.3% were SAAS matched. Those who met SRS-Schwab had lower rates of reoperation (28% vs 39%, p=0.049), with no difference in clinical outcomes at 2Y. GAP proportioned had lower rates of reoperation for mechanical complication and PJK (5% vs 17% vs 18%, p=0.003), but had no difference in clinical outcomes at 2Y. Roussouly matched had no difference in complications, but had significantly better appearance (SRS22r appearance 3.64 vs 3.42, p=.047) and improvement in physical function (dif SF36 PF 10.4 vs 7.1, p=0.006). SAAS matched patients had higher rates of minor mechanical complications (76% M vs 48% U vs 74% O, p<0.001) with no difference in major or reoperation for mechanical complications or clinical outcomes. In those with major mechanical complications, only matching in GAP had improved activity, appearance, and overall disability at 2Y (SRS activity 3.6 P, 3.1 MD, 3.1 SD, p=0.019) (SRS appearance 3.8 P, 3.4 MD, 3.1 SD, p= 0.014), (SRS total 3.8 P, 3.4 MD, 2.3 SD, p= 0.022), (ODI 26 P vs 33 MD vs 39 SD, p =0.029). In those SAAS matched, BMI was predictive of major mechanical complications (p<0.05), while for Roussouly, higher PT and lower PI-LL at baseline (PT 1.072 [1.018-1.129], p=0.008) (PI-LL 0.959 [0.932-0.988], p=0.006). For SRS-Schwab, greater correction of PI-LL and inadequate correction TPA were predictive of major mechanical complications (PI-LL dif 1.073 [1.022-1.126], p=0.005) (TPA dif 0.906 [0.846-0.971], p=0.005). CONCLUSIONS: Predictive factors for mechanical complications varied across different alignment criteria. Being GAP proportioned in the setting of major mechanical complications was associated with better clinical outcomes at two years postoperatively. FDA Device/Drug Status: This abstract does not discuss or include any applicable devices or drugs.

Duke Scholars

Author Peter Passias Orthopaedic Surgery