Defining Factors with Shoulder Balance during Scoliosis Correction in Lenke Type 1 Using the Vertebral Coplanar Alignment (VCA) Technique

Abstract

Introduction: Postoperative shoulder imbalance (PSI) significantly affects the quality of life of patients with scoliosis. Several studies report the risk factors for PSI; however, the imaging factors that define T1 tilt and RSH motion are unknown, and there are no reports on the magnitude of change in these factors. Herein, we investigated the factors influencing radiographic shoulder height (RSH) and T1 tilt in patients who underwent scoliosis correction using the vertebral coplanar alignment (VCA) technique.

Methods: In total, 76 patients with Lenke type 1, who underwent posterior spinal fusion using the VCA technique at 11 centers, were included. Correlation coefficients between pre- and post-operative changes in RSH and T1 tilt (ΔRSH and ΔT1 tilt) and changes in other parameters were analyzed.

Results: Flexibility of the proximal thoracic curve (PTC) showed a weak negative correlation with ΔRSH. PTC correction rate revealed a weak negative correlation with ΔT1 tilt from preoperative to 2 years postoperative. Change in the main thoracic apical vertebral translation (ΔMT-AVT) indicated a positive weak correlation with ΔRSH from preoperative to immediate postoperative and ΔT1 tilt immediate postoperative and 2 years postoperative.

Conclusions: PTC flexibility and correction rate are important for achieving good shoulder balance in Lenke type 1 scoliosis. ΔMT-AVT is the defining factor for ΔRSH and ΔT1 tilt and the marker for intraoperative evaluation to adjust shoulder balance.