A review of the literature on the mechanical aspects of the etiology for id
iopathic scoliosis reveals that the buckling hypothesis has been presented
as a purely mechanical phenomenon, In an attempt to confirm the buckling hy
pothesis, a numerical simulation of growth and the resulting buckling pheno
mena was done by means of finite element analysis. It previously was observ
ed that growth was induced in the T4 to T10 vertebrae, Only the sacrum was
assumed to be stationary. From the growth analysis, a deformation process t
hat mitigated thoracic kyphosis was obtained as observed in healthy childre
n during early adolescence, From the buckling analysis, the first to the fo
urth buckling modes that correspond to the first side bending, first forwar
d bending, first rotation, and second side bending modes were obtained. The
shape of the fourth buckling mode (second side bending mode) was in good a
greement with the clinical shape. Considering the potential for controlling
these modes by posture change, it is concluded that the second bending mod
e in the coronal plane is one of the most likely etiologic candidates in th
e mechanics of thoracic idiopathic scoliosis.