[Hemivertebra. -- classification, natural history and prognosis (author's transl)].

The authors have studied a series of seventy patients with hemivertebra. Classification should be based on two criteria--firstly, that the hemivertebra can be fused or separate and secondly, vertebrae above and below the hemivertebra may or may not show transitional abnormality. The natural history may take one of three courses: 1--Deformity may be severe from the beginning in cases of separate hemivertebra associated with transitional abnormalites. 2--The deformity may be stable until the age of nine or ten years, after which a severe scoliosis or kypho-scoliosis may develop. 3--The deformity may be stable throughout the whole of the growing period. The prognosis should be based on the existence of transitional abnormalities, the characteristics of the hemisvertebra (separate or fused), the sex of the patient, assoicated congenital defects, the rotation of the hemivertebra, and the level of the deformity. Treatment should be surgical in cases with early progression during the first few years of life by excision of the hemisvertebra associated with correction using Harrington rods. At the thoracic level, this surgical procedure is dangerous and spine fusion is more appropriate. The second period for surgical treatment is at puberty, either by spine fusion or correction and fusion. At this age, excision of the hemivertebra may still be indicated in the lumbar spine.