Double-curve synchronous derotation with convex correction: a new corrective technique for adolescent idiopathic scoliosis with double curves

Report of a new technique.

We describe a new technique of double-curve synchronous derotation with convex correction for double-major adolescent idiopathic scoliosis (AIS) and is highlighted through illustrative cases.

Rotational deformity is a significant component of scoliosis, which causes a secondary rib hump, and adversely affects patients' psychological and social well-being, and long-term functional results. For AIS, direct vertebral rotation is confirmed as a better and effective method for apical rotational correction and rib hump improvement than rod rotation technique, avoiding the need for an adjuvant thoracoplasty. However, this technique is mainly applied to Lenke I type thoracic curves with derotation of the main curve. There are no reports applying this technique in double-major scoliosis.

With the patient lying prone, a standard posterior incision exposure and segmental screws placement was performed, 2 vertebral column manipulator devices were installed on the apical region of both curves, then both curves were synchronously derotated and following convex correction at both the curves, the concave rods were secured in situ.

There were 11 double-curve cases divided into 3 groups: double-curve derotation group (A group, 3 cases), single-curve derotation group (B group, 4 cases), and rod derotation group (C group, 4 cases); all cases had minimum 2-year follow-up. Three illustrative cases corrected by double-curve synchronous derotation with convex correction are presented with better apical rotational and correction in thoracic and lumbar curves than single-curve derotation and rod derotation cases. The mean apical derotational corrective rates were 95.3%, 46.7%, and 38.8% in the lumbar curve, 66%, -35.1%, and -38.9% in thoracic curve. The 3-dimensional correction was maintained at a minimum 2-year follow-up.

Double-curve synchronous derotation with convex correction is a safe and effective technique for rotational and coronal correction in AIS with double curves, which can avoid apical rotation aggravation in minor curve induced by major curve derotaion.