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).