Emerging S-shaped curves in congenital scoliosis after hemivertebra resection and short segmental fusion

Background Context Posterior hemivertebra resection with short fusion has gradually become the mainstream treatment for the congenital scoliosis due to single fully segmented hemivertebra. A kind of unexpected emerging S-shaped scoliosis was found secondary to this surgery, and that has not been reported yet. Purpose The aim of the present study was to analyze the possible pathogenesis, clinical feature, and treatment of the emerging S-shaped scoliosis after posterior hemivertebra resection and short fusion. Study Design This study is a retrospective case series. Patient Sample A total of 128 patients participated. Outcome Measures Preoperative and postoperative whole spine radiographs were used to measure the Cobb angle of main curve, compensatory curve, and emerging curves. And the hemivertebra location, the fused segment, the apical and ending vertebrae of postoperative-emerging curve (and preoperative compensatory curves) were assessed. Methods Both the demographics and radiographic data were reviewed. Postoperative-emerging scoliosis was defined as the curve with an increasing angle of 20° and an apical vertebra locating at least two levels away from fusion region. Results Of the 128 patients, 9 (7%) showed postoperative-emerging S-shaped scoliosis. The mean age was 11.4 years old. The mean main curve was 36.1±14.4° preoperatively and been significantly corrected to 6.9±6.1° (p<.001). No significant difference was found in the main curve, kyphosis, coronal balance, or sagittal balance during follow-up. The emerging scoliosis occurred at 3 months (in four patients) or 6 months (in five patients) after initial surgery with an average angle of 42.6±12.9° at last follow-up. All patients underwent bracing or observation when the S-shaped scoliosis was arising, and four patients underwent a revision surgery because of deformity developing. Conclusions The emerging S-shaped scoliosis was an extraordinary complication that may be developing from the preoperative compensatory scoliosis and usually occurred at 3–6 months after hemivertebra resection. The feature of these curves was similar to the adolescent idiopathic scoliosis (AIS) and brace or revision surgeries were suitable for therapy.