Validation of A New Classification System For Surgical Planning of Vertebral Body Tethering (VBT)

BACKGROUND: Vertebral body tethering (VBT) may represent a paradigm shift in the management of adolescent idiopathic scoliosis (AIS). However, the ideal candidates, who may profit the most from this technique, have not yet been identified. We evaluated patients based on their curve type and on the potential benefits of VBT over fusion and developed a new classification to guide decision making for VBT, evaluating 5 different curve types (lumbar, double, long thoracic, short thoracic, presence of high thoracic curve). This study analyzed the inter- and intrarater variability of this new classification. METHODS: 11 spinal deformity surgeons contributed to the validation. Four radiographs (p. a., lateral, right and left p. a. side bending) were prepared for 27 patients. Two sets of the patients’ images were sent to each participant, with identical radiographs but in different order. Each participant was given instructions on how to employ the classification and was asked to apply it to the radiographs. The inter- and intra-observer reliability was assessed evaluating the kappa coefficient ( k ). RESULTS: The overall inter-observer reliability was k = 0.84 (confidence interval: 0.76 to 0.91). The overall intra-observer reliability was k = 0.88 (confidence interval 95%: 0.68 to 1.00). All k values were statistically significant and indicated an excellent inter- and intra-observer reliability of the classification. CONCLUSION: The newly developed classification for VBT planning showed an excellent reliability.