The Impact of Relative Curve Correction on Postoperative Shoulder Balance in Adolescent Idiopathic Scoliosis

Abstract

Background: Postoperative shoulder asymmetry frequently emerges as a prevalent adverse outcome following the surgical rectification of adolescent idiopathic scoliosis (AIS).

Objective: This study aimed to evaluate the influence exerted by the degree of rectification of the primary thoracic (MT) and proximal  thoracic (PT) curvatures in correlation with one another on the equilibrium of the shoulders following surgical intervention.

Patients and methods: Fifteen patients harbouring AIS curvatures underwent correction via pedicle screw/rod constructs. The  determinants of postoperative shoulder disparity were pinpointed through univariate examination. Furthermore, to ascertain the  autonomous predictors of shoulder asymmetry, a multivariate assessment was conducted employing the classification and regression  tree technique.

Results: Post-surgical observation revealed that a third of the patients (33.3%) experienced shoulder imbalance. In instances where the correction of the PT Cobb angle surpassed 52%, the majority (57%) exhibited shoulder equilibrium. In a similar vein,  when the correction of the PT curve was inferior to 52% and the correction of MT curve did not exceed 67%, a significant 86% of the  subjects achieved shoulder balance. Conversely, with the PT curve correction falling below 52% and the MT curve correction exceeding  67%, only half of the patients attained balanced shoulders.

Conclusions: Within the context of AIS deformities, a pronounced rectification  of the main thoracic curve (67%) accompanied by a concurrent 'under-correction' (<52%) of the upper thoracic curve  precipitated a disparity in shoulder height in half of the patients, irrespective of UIV placement.