Halo-gravity traction followed by definitive fusion in severe early onset scoliosis: results of a trunk analysis based on biplanar 3D reconstructions.

Abstract

Definitive fusion can be considered in early onset scoliosis (EOS) around triradiate cartilage closure. Halo-gravity traction (HGT) is an old strategy that can help lengthen and balance the spine before fusion. The postoperative changes of the trunk have never been investigated to date with modern imaging. The goal of this study was to analyze the 3D radiological outcomes, and the associated pulmonary function, of a cohort of severe EOS patients treated by definitive posterior fusion prepared by HGT. All consecutive EOS patients with severe (> 85°) and stiff (flexibility < 25%) curves, treated by HGT followed by posterior fusion, were followed. 3D radiological measurements and pulmonary function were assessed. Forty-nine EOS patients underwent fusion, with a mean follow-up of 4years (± 1). Age at surgery averaged 13.5years old. HGT protocol reached on average 41% of body weight. Mean preoperative 3D Cobb angle was 95° (± 10) and final correction averaged 68.4% after surgery. 3D T4T12 kyphosis was reduced after surgery (11°, p < 0.01), while the apical vertebral rotation was improved by 27.8% (p = 0.06). 3D thoracic volume increased after surgery (p = 0.02), with a 3D T1T12 height gain averaging 3.7cm (± 2). Both parameters were significantly correlated with total lung capacity improvement. Seven complications (14.2%) were reported, and 5 patients (10.6%) underwent unplanned revision. HGT is a safe and efficient strategy to prepare posterior fusion in severe EOS patients. The 3D trunk analysis demonstrated significant postoperative gains in thoracic and spinal lengths, as well as in thoracic volume. IV.