Feasibility of Minimally Invasive Scoliosis Surgery in Adolescent Idiopathic Scoliosis Exceeding 80° of Curve Magnitude

Objective: To investigate feasibility and effectiveness of minimally invasive scoliosis surgery (MISS) via posterior approach in patients with adolescent idiopathic scoliosis (AIS) presenting with very severe curve exceeding 80°.Methods: A total of 257 flexible AIS patients who underwent deformity correction using posterior MISS were retrospectively categorized into 3 groups based on the curve magnitude: moderate (M group, main Cobb angle <60°, n=142), severe (S group, 60°–80°, n=91), and very severe (VS group, ≥80°, n=24). Radiological parameters, perioperative outcomes, and complication rates were compared among the 3 groups.Results: The VS group required significantly longer operative times (p<0.001), more fused segments (p<0.001), and a greater number of rib resections during thoracoplasty (p=0.032) compared to the other groups. Despite these surgical demands, there were no statistical differences in the correction rate (p=0.954) and last follow-up thoracic kyphosis (p=0.830) among the 3 groups. Regarding complications, while the overall complication rate showed no statistical difference, the VS group required significantly more invasive management for pleural effusions (p=0.012).Conclusion: Posterior MISS demonstrated acceptable radiological and perioperative outcomes even in flexible AIS with Cobb angles ≥80°. These findings suggest the posterior MISS can be a feasible surgical option for selected very severe AIS patients with sufficient flexibility.