Congenital scoliosis caused by a unilateral failure of vertebral segmentation with contralateral hemivertebrae

Study Design. The medical records and serial spine radiographs of 59 consecutive patients with congenital scoliosis caused by unilateral unsegmented bar with contralateral hemivertebrae were reviewed. Objectives. To study the presentation, natural history, and treatment of these patients. Summary and Background Data. This is the least common type of congenital scoliosis. Methods. The mean age at diagnosis was 4 years 1 month. Forty-three patients were observed without treatment for a mean of 6 years and 1 month. Prophylactic arthrodesis was performed in 10 patients before they were 5 years old. Thirty-five patients had a corrective procedure and arthrodesis after they were 5 years old. Results. Thoracolumbar curves had the worst prognosis: without management all but two exceeded 50 degrees when the patients were 2 years old. All untreated curves exceeded 88 degrees. Midthoracic curves had only a less severe prognosis, and all but one exceeded 40 degrees by the time the patient was 2 years old. All untreated curves exceeded 70 degrees. In eight of the 14 patients whose congenital curves had their apexes at T5, T6, or T7, a long secondary structural curve developed on the opposite side in the thoracolumbar region, and this contributed significantly to the overall deformity. Occult intraspinal anomalies were present in 24 patients (41%). Surgical treatment after the patient was 5 years old was not successful in producing significant correction of these severe rigid deformities. Conclusion. These patients have the most rapidly progressive and severely deforming of all types of congenital scoliosis. All midthoracic, thoracolumbar, and lumbar curves require immediate prophylactic surgical treatment by anterior and posterior arthrodesis-preferably in the first year of life.