Inferior Outcomes of Posterior Correction and Fusion Surgery for Adults With Residual Lenke Type 5 Adolescent Idiopathic Scoliosis: A Comparative Study With Adolescents

Study Design Retrospective cohort study. Objective This study aimed to determine whether the outcomes of posterior correction and fusion surgery (PSF) in patients with residual adolescent idiopathic scoliosis (AIS) during adulthood (Lenke type 5 AdIS) are inferior to those in patients with AIS treated during adolescence. Methods We retrospectively evaluated 48 patients with type 5 AdIS who underwent PSF after 20 years old. As controls, we selected 67 patients with type 5 AIS who underwent PSF before 18 years old. Both groups were matched based on the preoperative thoracic and thoracolumbar/lumbar Cobb angles, resulting in 33 patients in each group. We compared preoperative and postoperative radiographic parameters and SRS-22 scores between the 2 groups. Results Preoperatively, the AdIS group had significantly lower flexibility index (59.0% ± 13.0% vs 66.6% ± 16.7%; P = 0.01). The preoperative SRS-22 scores for pain and mental health domain were significantly worse in the AdIS group (pain, 3.9 ± 0.8 vs 4.3 ± 0.7, P < 0.01; mental health, 3.6 ± 0.8 vs 4.2 ± 0.6, P < 0.01). The AdIS group had significantly more fused vertebrae and longer intraoperative time than the AIS group. Postoperatively, lumber Cobb angle (16.1° ± 5.6° vs 8.6° ± 4.0°, P < 0.01) and correction rate were both less favorable in the AdIS group. Both pain and mental health scores remained significantly worse in the AdIS group (pain: AdIS, 4.3 ± 0.6 vs AIS, 4.7 ± 0.3; P < 0.01; mental health: AdIS, 4.1 ± 0.7 vs AIS, 4.5 ± 0.5; P = 0.02). Conclusion Patients with type 5 AdIS had a similar correction of the major curve as those with AIS; however, the surgery was more invasive, with inferior postoperative clinical outcomes, than those with AIS. These findings suggest that the surgical timing should be carefully considered in patients with type 5 AIS to optimize outcomes.