Ten-year follow-up study of lower thoracic hemivertebrae treated by convex fusion and concave distraction

Study Design. A retrospective review of patient records with recent clinical and radiologic assessment was conducted. Objective. To evaluate the long-term results of fully segmented hemivertebrae treated by convex fusion combined with instrumented concave subcutaneous distraction. Summary of Background Data. Convex fusion has been described for the treatment of hemivertebrae in children, whereas distraction without fusion has been shown to enhance spinal growth. No long-term follow-up studies have combined these two methods. Methods. Between 1986 and 1994, six consecutive patients (5 males and 1 female) with hemivertebrae located at T11 or T12 underwent convex anterior and posterior fusion as well as concave subcutaneous distraction without fusion. Results. The mean age at surgery was 3.4 years. The mean follow-up period was 10.8 years (range, 8-14 years). There was a mean improvement of 41% in the coronal deformity, from a mean angle of 49 before surgery to 29 at the latest follow-up assessment. In four of the cases, this correction was achieved immediately after surgery and did not significantly change despite repeated distraction. The kyphosis improved in three cases, remained unchanged in one case, and deteriorated in two cases. In these two cases, an adjacent wedge vertebra contributed to the kyphotic deformity. Conclusions. Although growth-mediated correction was seen in only two cases, this procedure could be recommended for children with severe deformities and decompensation in the lower thoracic spine. It is safer than hemivertebra excision, with less risk of spinal cord injury. The concave distraction produces immediate improvement in the coronal balance, such that there is no need to wait for uncertain growth-mediated correction in patients who undergo convex fusion only.