The establishment of the first nonsurgical experimental model of progressive scoliosis -The biomechanical mechanism involved in the etiology of the thoracic scoliosis-

Objective Idiopathic scoliosis is a structural, lateral, rotated curvature of the spine. Scoliosis may worsen progressively, in some cases leading to back pain, body image concerns, and cardiopulmonary compromise. To date, a variety of pathogenic factors have been proposed as a cause of idiopathic scoliosis. However, the pathogenesis of idiopathic scoliosis remains unclear, and a consistent and relevant animal model has not yet been established. We recently reported that the anteroposterior chest dimension in patients with thoracic scoliosis was significantly smaller than that in normal subjects and that there was a correlation between the anteroposterior chest dimension and the severity of the thoracic curvature. These findings led us to hypothesize that rib cage deformities were associated with the etiology of the thoracic scoliosis. The goal of this study was to clarify whether a shallow chest depth is a causative factor or a consequence of structural scoliosis, and also to establish a nonsurgical mouse model of progressive scoliosis.