Shoulder balance in adolescent idiopathic scoliosis: Current concepts and technical challenges

Abstract

Cosmesis and self-image perception are important aspects of adolescent idiopathic scoliosis (AIS). Shoulder balance plays an important role in this aspect. In this article, we provide a broad narrative review of the clinical and radiological assessment of shoulder balance along with various factors affecting the postoperative shoulder imbalance (PSI). Systematic literature search was done using specific keywords, and studies were screened using PRISMA flowchart. Concept of medial and lateral shoulder balance, which are two distinct and independent entities, has been discussed. The trapezial angle and area are medial shoulder parameters, and are of more concern as they directly affect the cosmesis. Choice of the upper instrumented vertebra (UIV), behavior of the proximal thoracic curve, and preoperative levels of shoulder are important determinants of PSI. The relative correction of middle and distal curves also plays an important role to prevent imbalance and adding-on, especially in type 5 and 6 curves. Hooks at the UIV may provide a soft landing and help in the adjustment of any PSI.