Progression of congenital scoliosis due to hemivertebrae and hemivertebrae with bars.

From 315 cases of congenital scoliosis seen from 1925 to 1970, sixty cases of scoliosis or kyphoscoliosis due only to a hemivertebra, hemivertebrae, or a unilateral bar associated with the hemivertebrae were selected, classified into six types, and analyzed. Progression occurred in all but the balanced hemivertebrae group in two patients with cervical-high thoracic curves due to multiple hemivertebrae. Location of the hemivertebra or hemivertebrae and the presence of unilateral bars are the major determinants of deformity. The rate of progression of the scoliosis was variable, ranging from 1 to 33 degrees per year (average, 4 degrees per year).