Shoulder Imbalance in Adolescent Idiopathic Scoliosis: A Systematic Review of the Current State of the Art

Background: Shoulder imbalance (SI) is among the most rated manifestations of adolescent idiopathic scoliosis (AIS)pointed to by patients and spine surgeons. It serves as a criterion to assess the outcome of scoliosis surgery and isalso a cause of dissatisfaction for the patients postoperatively. Despite the availability of multiple studies on this issue,a comprehensive survey of the risk factors and preventive measures has yet to be elucidated. The present study aimedto highlight the most recent approach to the evaluation and management of SI, as well as medical counseling about theexpectations and limitations of the surgery.Methods: A systematic literature review using electric databases was conducted, including PubMed, Embase, theCochrane Library, and Google Scholar, with a well-defined search strategy on SI definition, risk factors, and preventiveand surgical recommendations.Results: A total of 69 articles were identified; SI 2 cm was the most used cut-off, and its risk factors included the mainthoracic Cobb angle 80˚, preoperative level shoulder, high left shoulder, and higher Risser grade. The most statedstrategies to preclude SI were the sufficient correction of the proximal thoracic curve, and moderate correction of themain thoracic and lumbar curve (LC).Conclusion: Shoulder imbalance should be prevented not only for appearance or satisfaction but also for possiblecomplications such as distal adding-on, new LC progression, or trunk shift postoperatively in AIS patients.Level of evidence: V