The effects of vertebral body tethering on sagittal parameters: evaluations from a 2-years follow-up

Alice Baroncini,Filippo Migliorini,Philipp Kobbe,Per David Trobisch,Frank Hildebrand,Jörg Eschweiler,Pedro Berjano,Aurelien Courvoisier

doi:10.1007/s00586-021-07076-9

Abstract

IntroductionWhile the effects of VBT on coronal parameters have been investigated in various studies, this has not yet been the case for sagittal parameters. This is of particular relevance considering that VBT does not allow direct correction of the sagittal profile. Thus, we investigated the effects of VBT on sagittal parameters in patients with adolescent idiopathic scoliosis.Materials and methodsRetrospective, 2-Center study. Patients who underwent VBT and presented a 2-years follow-up were included. The differences in sagittal parameters were evaluated, along with modifications of sagittal profile following Abelin-Genevois’ classification.ResultsData from 86 patients were obtained. Mean Cobb angle was 52.4 ± 13.9° at thoracic level and 47.6 ± 14.3° at lumbar level before surgery, and 28.5 ± 13.6 and 26.6 ± 12.7° at the 2-year follow-up, respectively. Mean thoracic kyphosis increased from 28.3 ± 13.8 to 33 ± 13°, the lumbar lordosis (LL) was unvaried (from 47.5 ± 13.1 to 48.4 ± 13.5°), PT decreased from 9.4 ± 8.5 to 7.4 ± 6.1°, the sagittal vertical axis SVA decreased from 4.5 ± 31.4 to − 3.6 ± 27.9 mm. No kyphotic effect on LL in patients who underwent lumbar instrumentation was observed. Before surgery, 39 patients had a type 1 sagittal profile, 18 were type 2a, 14 type 2b and 15 type 3. Postoperatively, 54 were type 1, 8 were 2a, 13 were 2b and 11 were type 3.ConclusionsVBT positively influences sagittal parameters and does not have a kyphotic effect on LL.

Highlights

While the effects of Vertebral Body Tethering (VBT) on coronal parameters have been investigated in various studies, this has not yet been the case for sagittal parameters
Vertebral Body Tethering (VBT) is currently being investigated as a new option for the treatment of Adolescent Idiopathic Scoliosis (AIS): while published results are promising, the research aiming to identify the ideal candidate for this technique is still ongoing [1,2,3,4,5,6,7,8,9,10,11,12]
The data from 86 patients were available for this analysis

Summary

Introduction

While the effects of VBT on coronal parameters have been investigated in various studies, this has not yet been the case for sagittal parameters. We investigated the effects of VBT on sagittal parameters in patients with adolescent idiopathic scoliosis. The deformity induced by scoliosis in the coronal plane has been widely studied and classified, with the Lenke classification representing the gold standard for both classification and surgical planning in patients with AIS [15, 16]. As showed by Abelin-Genevois and colleagues, only 44% of patients with AIS present a physiological sagittal profile with three alternating curves (cervical lordosis, thoracic kyphosis and lumbar lordosis) and are defined as type 1 in their classification [18].

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