Lateral hemivertebrae represent a developmental defect resulting from the failure of the contralateral chondral center to develop. Dorsal hemivertebrae result from a developmental defect in which the anterior chondral centers fail to develop, and ventral hemivertebrae result from failure of the posterior centers to ossify. The affected half of the vertebral body may by hypoplastic or absent, as is the pedicle, and (for thoracic vetebrae) the corresponding rib. The affected half of the vertebral body may also show a fusion or segmentation defect.