Introduction: Multiple alignment schematics have been proposed and utilized in ASD. The utility of SRS-Schwab, GAP, SAAS, and Roussouly targets on reducing complications and improving outcomes in a cohort remains to be evaluated.
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 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: 334 patients met inclusion(Age:63±10, 77%F,BMI:27.6±5.1kg/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%vs17%vs18%,p=0.003). 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). 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).
Conclusion : 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.
.jpg)