Is Convex Derotation Equally Effective as Concave Derotation for Achieving Adequate Correction of Selective Lenke's Type- 1 Scoliosis?

Background: Correcting the scoliosis and stabilizing the spine in the corrected position is the basis of treatment for adolescent idiopathic scoliosis (AIS). Spinal instrumentation and derotation are the principle steps of surgery for any type of AIS. A perspicuous understanding needs to be attained regarding derotation maneuvers in practice; therefore, we intend to compare radiological outcomes following concave and convex rod derotation maneuvers to analyze their efficacy to correct selective Lenke's Type-1 scoliosis.

Materials and Methods: Retrospectively, 88 patients with Lenke's Type-1 scoliosis who were operated with selective thoracic instrumentation were divided into two groups depending on the derotation side. Preoperative radiographs were analyzed for curve angles, thoracic apical vertebral translation, apical vertebral rotation, and coronal/sagittal balance. Postoperative and followup assessment was focused on curve correction. Correction rate of main thoracic (MT) curve and its corresponding loss of correction at final followup are calculated.

Results: Concave group ( n = 40; age 13.8 ± 1.9) and the convex group ( n = 48; Age 14.3 ± 2.4) showed similar demographic characteristics. Postoperative and followup parameters showed no significant difference. Correction rate of MT curve between both groups (concave group = 69.2 ± 10.5%; convex group = 66 ± 12.8%; P = 0.20) was similar. There was minimal loss of correction at final followup among both groups (concave group = 2.2° ±5.4°; Convex group = 1.5° ± 4.8°; P = 0.52).

Conclusion: The study results showed similar sustained satisfactory correction of flexible Lenke's type 1 scoliotic curves irrespective of the derotation maneuver used. Adequate correction, thereby restoring balance was predominantly perceived among the entire sample. Hence, convex derotation can be considered equally effective as that of concave derotation for achieving adequate correction of selective Lenke's Type-1 scoliosis.