Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Congenital Spinal Deformity*†

Abstract

Congenital spinal deformities, which are caused by congenitally anomalous vertebral development, usually are seen on conventional radiographs but may be detected on tomograms, on magnetic resonance images, or at the time of an operation. Although patients who have myelomeningocele have congenitally anomalous vertebrae, most of the spinal deformity in such patients is paralytic in nature; therefore, they will not be included in the present discussion. The three major patterns of congenital spinal deformity are lordosis, kyphosis, and scoliosis. Although combinations such as lordoscoliosis and kyphoscoliosis are common, the natural history and methods of treatment of spinal deformity correspond to the three major subdivisions. It is important to distinguish between scoliosis with marked rotation (which should not be labeled kyphoscoliosis) and true kyphoscoliosis (in which rotation is not a major component of the deformity). Congenital spinal anomalies are divided into two basic groups: defects of formation and defects of segmentation. A classic example of a defect of formation is a hemivertebra that has a mobile disc both caudad and cephalad to it (a so-called free hemivertebra). A classic example of a defect of segmentation is a unilateral unsegmented bar, in which one side of the spine has failed to segment over the length of several vertebrae while the other side has segmented normally. The cause of congenital spinal deformities usually is unknown. Embryologically, spinal anomalies must develop between the fifth and eighth weeks of gestation; however, even a detailed maternal history seldom reveals that any untoward events occurred during that time. Most patients have mixed anomalies in which both types of defects are present. The most important step in the evaluation of these patients is to estimate whether the spine is balanced and will remain balanced during growth; the greater the potential growth discrepancy between the two sides, the greater the …