Three-dimensional effect of the Boston brace on the thoracic spine and rib cage.

Abstract

Three-dimensional reconstructions of the spine and rib cage were done and compared just before and 1 month after initiation of treatment with a Boston brace in a group of adolescents with idiopathic scoliosis. To document the immediate changes in shape of the thoracic spine and rib cage induced by the original Boston brace design. The effect of the Boston brace has been well documented in the frontal plane but is poorly understood in the other planes of deformity. Three-dimensional reconstructions were obtained with and without the brace using a stereoradiographic technique in a group of 40 adolescents with idiopathic scoliosis. Several geometric indices of the spine and rib cage were compared using Student t tests. The brace produced significant curve correction of the spinal deformity in the frontal plane at the expense of a significant reduction of thoracic kyphosis in the sagittal plane, as well as in the plane of minimum deformity. No significant effect on rotation of the thoracic apical vertebra, on the rib hump, or on frontal balance could be documented, but changes were noted in the sagittal orientation of the rib cage and in the sagittal balance of the spine. The original Boston brace does not completely correct the three-dimensional deformities associated with thoracic idiopathic scoliosis, although it reduces Cobb angles in the frontal plane.