Current Knowledge of Respiratory Function in Early Onset Scoliosis and the Effect of Its Contemporary Surgical Treatment.

Early Onset Scoliosis (EOS), defined as presenting before 10 years of age, often has a significant adverse impact on pulmonary function, due to a complex interrelationship between the spine, chest, pulmonary structures and their development. Left untreated, EOS leads to premature death, with early fusion surgery to arrest curve progression making little impact on this. To date, the natural history has not been clearly established as compounded by the heterogeneity of pathologies, causing EOS and challenges in objective measurements of pulmonary function in this young age group. A desire to address this poor natural history has motivated interest in pursuing 'growth friendly' surgical strategies. The implants used have evolved with time, often to address compromises and poor results, with multiple options now available based on treatment principles (distraction, compression, or guided growth systems). The aims of such strategies are to control the structural spinal deformity, whilst allowing spinal and thoracic growth, with the seemingly reasonable expectation that this will result in improved pulmonary function and avoidance of premature death. Most studies have focused on radiological outcome measures such as Cobb angle and thoracic height to gauge the success of surgery, with these measures acting as surrogate markers of improved pulmonary outcome. This assumption, however, is not supported by more recent clinical data which has attempted to assess directly the pulmonary outcomes associated with growth-friendly surgical strategies. This literature review therefore sets out to characterise the effect of EOS on pulmonary function and to critically analyse the impact surgical treatment options will have while addressing this.