Advantages of vertebral coplanar alignment technique for restoring physiological thoracic kyphosis in hypokyphotic adolescent idiopathic scoliosis with < 10° of kyphosis.

OBJECTIVE

Conventional segmental pedicle screw fixation for thoracic adolescent idiopathic scoliosis (AIS) often compromises the ability to restore physiological thoracic kyphosis (TK). The vertebral coplanar alignment (VCA) technique addresses 3D deformity correction on the convex side in thoracic scoliosis. In particular, it enhances sagittal plane correction by adding kyphotic contouring via the concave-side rod while preserving the ideal thoracic curvature, including the physiological TK apex location on the convex side. This multicenter cohort study aimed to analyze the surgical outcomes of the VCA technique and demonstrate its effectiveness in restoring physiological TK in hypokyphotic AIS patients with < 10° of kyphosis.

METHODS

Data from 127 consecutive patients who underwent corrective surgery using the VCA technique for hypokyphotic (TK < 10°) thoracic AIS at 13 institutions, with a minimum follow-up of 2 years, were retrospectively analyzed. Outcome measures included patient demographics, radiographic parameters, TK apex location, and Scoliosis Research Society (SRS)-22 scores assessed preoperatively and at 2 years postoperatively.

RESULTS

The mean main thoracic Cobb angle improved significantly from 55.0° to 14.1° at 2 years postoperatively, with a mean correction rate of 74%. The mean TK (T5-12) increased significantly from 4.4° to 19.5°. The proportion of patients with the TK apex located at T6-8 significantly increased from 22% to 73%. The mean SRS-22 total score improved from 3.6 to 4.5 at 2 years postoperatively.

CONCLUSIONS

This multicenter study highlights the advantages of VCA, particularly in restoring physiological TK in hypokyphotic (TK < 10°) thoracic AIS. The VCA procedure contributed to maintaining an ideal thoracic shape with the physiological TK apex on the convex side prior to rod placement and before performing various manipulations via the rod on the concave side.