Preoperative left shoulder elevation > 1cm is predictive of severe postoperative shoulder imbalance in early onset idiopathic scoliosis patients treated with growth-friendly instrumentation.

Abstract

Prior research has demonstrated the influence of preoperative shoulder elevation (SE), proximal thoracic curve magnitude, and upper instrumented vertebra (UIV) on shoulder balance after PSF for AIS. Our purpose was to evaluate the impact of these factors on shoulder balance in early onset idiopathic scoliosis (EOIS) patients treated with growth-friendly instrumentation. This was a multicenter retrospective review. Children with EOIS treated with dual TGR, MCGR, or VEPTR and minimum 2-year follow-up were identified. Demographics and radiographic/surgical data were collected. 145 patients met inclusion criteria: 74 had right SE (RSE), 49 left SE (LSE), and 22 even shoulders (EVEN) preoperatively. Mean follow-up was 5.3years (range, 2.0-13.1years). The LSE group had a larger pre-index mean main thoracic curve (p = 0.021) but no difference was observed between groups at the post-index or most recent timepoints. RSE patients with UIV of T2 were more likely to have balanced shoulders post-index than patients with UIV of T3 or T4 (p = 0.011). Pre-index radiographic shoulder height (RSH) was predictive of post-index shoulder imbalance ≥ 2cm in the LSE group (p = 0.007). A ROC curve showed a cut-off of 1.0cm for RSH. 0/16 LSE patients with pre-index RSH < 1.0cm had post-index shoulder imbalance ≥ 2cm compared to 8/28 (29%) patients with pre-index RSH > 1.0cm (p = 0.006). Preoperative LSE > 1.0cm is predictive of shoulder imbalance ≥ 2cm after insertion of TGR, MCGR, or VEPTR in children with EOIS. In patients with preoperative RSE, UIV of T2 resulted in a higher likelihood of balanced shoulders postoperatively.