Adult versus adolescent idiopathic scoliosis surgery: a meta-analysis of clinical and radiographic outcomes

Introduction While the natural history of adolescent idiopathic scoliosis (AIS) and adult idiopathic scoliosis (AdIS) is well documented in the literature, the impact of age on postoperative outcomes remains an active area of research. We performed a systematic review and meta-analysis to compare patients undergoing surgery for AIS and AdIS with respect to: (1) postoperative Cobb correction, (2) perioperative variables, and (3) postoperative complications. Methods A systematic literature search was performed in accordance with preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Inclusion criteria: studies published between 2002 and 2022, retrospective, and comparing AIS vs. AdIS patients undergoing deformity surgery. The primary outcome was postoperative Cobb correction. Secondary outcomes included estimated blood loss (EBL), operative time, total instrumented levels, length of stay (LOS), and postoperative complications. Random-effects models were performed according to the method of DerSimonian and Laird. Results Of 190 identified articles, 14 fit the inclusion criteria. A total of 1788 patients were included, 1275(71.3%) with AIS, and 513(28.7%) with AdIS. There was a significant age difference between AIS and AdIS (15.3 vs. 36.7 years, mean difference (MD)=21.3 years, 95%CI=14.3-28.4,p<0.001). Mean postoperative Cobb percentage correction was reported in 5 articles and was significantly higher in AIS (68.4%) vs. AdIS (61.4%) (MD=-7.2, 95%CI=-11.6,-2.7,p=0.001). EBL was not significantly different between AIS and AdIS (695.6 mL vs 817.7 mL,p=0.204). Furthermore, no difference was found in operative time (MD=37.9 min,95%CI=-10.7;86.6,p=0.127), total instrumented level (MD=0.88,95%CI=-0.7,2.4,p=0.273), and LOS (MD=0.5, 95%CI=-0.2;1.2, p=0.188). Four articles reported postoperative complications in AIS vs AdIS, with no difference in neurological deficit, instrumentation-related complications, and medical complications. Conclusion AIS patients had better radiographic correction compared to AdIS. Though no difference was found in perioperative outcomes and complications, these findings emphasize the importance of counseling patients regarding the optimal timing of surgical correction.