Increased Surgical Invasiveness but Favorable Scoliosis Research Society-22 Scores in Adult Idiopathic Scoliosis with Major Thoracic Curves: A Comparative Study with Adolescent Idiopathic Scoliosis.

Introduction: Surgical outcomes for adult patients with residual adolescent idiopathic scoliosis (AdIS) with a major thoracic curve are expected to be inferior to those of AIS but have not been well reported. This study aimed to evaluate surgical, radiographical, and clinical results in adult patients with AdIS and to characterize these patients by comparing their results with those of patients with adolescent idiopathic scoliosis (AIS).

Methods: Thirty-five patients with AdIS, who were diagnosed with AIS Lenke type 1 or 2 before the age of 19 years and underwent surgery after the age of 20 years, were included in the study. As a control group, 84 patients with AIS Lenke type 1 or 2 who underwent surgery before the age of 19 were included. Both groups were matched on the basis of the preoperative main thoracic (MT) and proximal thoracic (PT) Cobb angles, causing 30 patients to be selected in each group.

Results: The AdIS group exhibited a greater preoperative bending Cobb angle of the MT and PT curves (MT: 35.1° vs. 31.3°, PT: 17.8° vs. 13.8°) and a lower MT curve flexibility index than in the AIS group (36.6% vs. 42.2%). Postoperatively, the AdIS group had a higher number of fused intervertebral segments than did the AIS group (8.2 vs. 7.4), but the correction rate was comparable in the 2 groups. Moreover, the intraoperative time was longer and blood loss was larger in the AdIS group. In the Scoliosis Research Society (SRS)-22 score, self-image and mental health domains were significantly lower preoperatively in the AdIS group. Postoperative improvement of self-image domain was significantly greater in the AdIS group (Δ self-image: 1.6 vs. 0.9), and postoperative satisfaction was similar in the 2 groups.

Conclusions: Surgical invasiveness was increased in AdIS, and preoperative SRS-22 scores were lower in self-image and mental health domains than in AIS. However, postoperative SRS-22 scores were comparable, and postoperative self-image improvement was significantly greater in AdIS than in AIS.