[Comparison of clinical outcomes between type B and type C coronal pattern patients with degenerative scoliosis]

Objective: To investigate the differences of the radiographic and clinical outcomes after posterior correction surgeries between degenerative scoliosis (DS) patients with type B and type C coronal pattern. Methods: From March 2010 to August 2017, the clinical data of 38 patients (type B: 24; type C: 14) who were treated with posterior correction surgeries for DS were retrospectively reviewed. Radiographic parameters including Cobb angle of main curve, coronal imbalance (CI), lumbar lordosis (LL), global kyphosis (GK) and sagittal vertical axis (SVA) were measured on standing anteroposterior and lateral radiographs of the whole spine before and after surgery. Patient-reported outcomes were evaluated by using the visual analogue scale (VAS), the Oswestry disability index (ODI) and SF-36 questionnaire. The independent t-test was applied to compare the difference for statistical analysis. Results: There was no significant differences between the two groups in terms of age, gender, follow-up duration, preoperative curve magnitude, severity of CI, sagittal malalignment and surgical strategies (all P>0.05). In patients with type B coronal pattern, the main curve was corrected from 44°±19° before surgery to 19°±7° immediately after surgery (t=8.496, P<0.001) and to 19°±6° at the last follow-up (t=-0.657, P=0.518). In patients with type C coronal pattern, the main curve was corrected from 43°±9° before surgery to 21°±4° immediately after surgery (t=13.537, P<0.001) and to 21°±5° at the last follow-up (t=-0.186, P=0.856). No significant difference of Cobb angle of main curve was found between the two groups either before the operation or immediately post operation (all P>0.05). In addition, significant improvement of CI was observed after surgery in both groups and the correction was maintained well at the last follow-up. However, patients with type C coronal pattern had greater CI than that in those with type B coronal pattern immediately post operation (t=-2.401, P=0.022) and at the last follow-up (t=-2.659, P=0.012). At the last follow-up the scores of SF-36 questionnaire, ODI and VAS showed significant improvement in both groups (all P<0.05). Conclusion: Posterior correction surgery could provide remarkable radiographic and clinical outcomes in DS patients with type B and type C coronal pattern, and DS patients with type B coronal pattern could achieve a more satisfied coronal balance after surgery.