• Rob C Brink, Schlösser Tom P C TPC Department of Orthopaedic Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands., Marijn van Stralen, Koen L Vincken, Moyo C Kruyt, Hui Steve C N SCN Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, 4/F Main Clinical Block and Trauma Ce, Max A Viergever, Chu Winnie C W WCW Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, 4/F Main Clinical Block and Trauma C, Cheng Jack C Y JCY Department of Orthopaedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, 4/F Main Clinical Block and Trauma Centre, , and René M Castelein.
• Department of Orthopaedic Surgery, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
• Spine J. 2018 Dec 1; 18 (12): 2259-2265.

Background ContextOne of the characteristics of reported observations in adolescent idiopathic scoliosis (AIS) is that the thoracic spine is longer anteriorly than posteriorly, more pronounced around the apex than the transitional zones. This reversal of the normal kyphotic anatomy of the thoracic spine is related to questions of etiopathogenesis of AIS. The changes in the anatomy of the anterior column have been described rather in detail; however, the role of the posterior spinal column and the laminae has so far not been elucidated. If the posterior column exhibits a longitudinal growth disturbance, it could act as a tether, leading to a more or less normal anterior column with a deformed and shorter posterior aspect of the spine. So far, it has remained unclear whether this anterior-posterior length discrepancy is the result of relative anterior lengthening or relative posterior shortening, and which tissues (bone, disc, intervertebral soft tissue) are involved.PurposeThe present study aimed to compare the discrepancy of the anterior-posterior length of the spinal column in the "true" midsagittal plane of each vertebra in patients with idiopathic scoliosis versus controls, using three-dimensional computed tomography (CT) scans.Study Design/SettingThis is a cross-sectional study.Patient SampleThe sample consisted of computed tomography scans of 80 patients with moderate to severe AIS (Cobb angle: 46°-109°) before scoliosis navigation surgery and 30 non-scoliotic age-matched controls.Outcome MeasuresThe height of the osseous and non-osseous structures from anterior to posterior in the "true" midsagittal plane has been determined: the anterior side of the vertebral body and disc, the posterior side of the vertebral body and disc, the lamina and interlaminar space and the spinous process and interspinous space, as well as the height ratios between the anterior column and posterior structures of the primary thoracic and lumbar AIS curves and corresponding levels in non-scoliotic controls.MethodsSemiautomatic software was used to reconstruct and measure the parameters in the true midsagittal plane of each vertebra and intervertebral structure that are rotated and tilted in a different way.ResultsIn AIS, the anterior height of the thoracic curve was 3.6±2.8% longer than the posterior height, 2.0±6.1% longer than the length along the laminae, and 8.7±7.1% longer than the length along the spinous processes, and this differed significantly from controls (-2.7±2.4%, -7.4±5.2%, and +0.7±7.8%; p<.001). The absolute height of the osseous parts did not differ significantly between AIS and controls in the midsagittal plane. In contrast, the intervertebral structures contributed significantly to the observed length discrepancies. In absolute lengths, the anterior side of the disc of the thoracic curve was higher in AIS (5.4±0.8 mm) than controls (4.8±1.0 mm; p<.001), whereas the interspinous space was smaller in AIS (12.3±1.4 mm vs. 14.0±1.6 mm; p<.001).ConclusionsBased on this in vivo analysis, the true three-dimensional anterior-posterior length discrepancy of AIS curves was found to occur through both anterior column lengthening and posterior column shortening, with the facet joints functioning as the fulcrum. The vertebrae contribute partly to the anterior-posterior length discrepancy accompanied by more significant and possibly secondary increased anterior intervertebral discs height.Copyright © 2018 Elsevier Inc. All rights reserved.

31 keywords...

hide…