Accurate 3D-measurements demonstrate that vertebral bodies increase in height up to adulthood, bu... more Accurate 3D-measurements demonstrate that vertebral bodies increase in height up to adulthood, but discs only in the first years. The discs transverse surface area increases continuously; thus, disc slenderness decreases overall. Relatively, adolescent female discs remain slenderer. These measurements may assist future studies on disc morphology in spinal deformities. Study Design. Cross-sectional. Objective. The aim of this study was to describe the morphology of intervertebral discs and vertebral bodies during growth in asymptomatic children and adolescents. Summary of Background Data. Earlier studies demonstrated that spinal growth occurs predominantly in vertebral bodies. This axiom introduced a vertebral-body-focus for unravelling etiological questions and achieve growth-modulation in young spinal deformity patients. Recent studies show the importance of the intervertebral discs in the early phases and possible etiology of pediatric spinal deformities. There is presently a paucity of 3D morphometric data of spinal elements during growth. Methods. A database of 298 patients aged 0 to 21 that have received a computed tomography scan for indications not related to the spine was analyzed. Custom made software was used to semi-automatically measure intervertebral disc and vertebral body morphology, corrected for orientation in all 3 planes. Results. Vertebral body height increased from birth up to adulthood, from 4-to-14 mm in the cervical, 6 to 20 mm in the thoracic, and 9 to 28 mm in the lumbar spine. This increase was 0.70 mm/year in males, more pronounced than females with 0.62 mm/year (P = 0.001). Lumbar discs increased throughout growth from 4.4 to 9.0 mm, whereas thoracic discs only increased from 3.5 to 4.9 mm at age 4 and remained stable afterwards, similarly for cervical discs. The disc transverse surface area increased greatly and consistently throughout growth. Disc slenderness was stable in the lumbar spine during growth, but decreased in the thoracic and cervical spine. Overall, discs were more slender in females, especially around early adolescence. Conclusion. The spine grows predominantly in the vertebral bodies. Thoracic discs increase in height only during the first years, whereas the transverse surface area continues to increase throughout growth, thus discs slenderness decreases. Relatively, female discs remained slenderer around growth-spurt. These measurements may assist future studies on the role of disc morphology in the etiology and treatment of spinal deformity. Level of Evidence: 4
Current surgical treatment options for Early Onset Scoliosis (EOS), with distraction- or growth-g... more Current surgical treatment options for Early Onset Scoliosis (EOS), with distraction- or growth-guidance systems, show limited growth and high complication rates. We developed the Spring Distraction System (SDS), which does not have to be periodically lengthened and which provides continuous corrective force to stimulate spinal growth. This study aimed to assess curve correction and maintenance, spinal growth, and complication rate following SDS treatment. All primary- and revision patients (conversion from failed other systems) with SDS and ≥2 years follow-up were included. Outcome measures were coronal Cobb angle, sagittal parameters, spinal length measurements and complications and re-operations. Radiographic parameters were compared pre-operatively, post-operatively and at latest follow-up. Spinal length increase was expressed as mm/year. Twenty-four skeletally immature EOS patients (18 primary and 6 revision cases) were included. There were 5 idiopathic, 7 congenital, 3 syndromic and 9 neuromuscular EOS patients. Mean age at implantation was 9.1 years (primary: 8.4; conversion: 11.2). Major curve improved from 60.3° to 35.3°, and was maintained at 40.6° at latest follow-up. Mean spring length increase during follow-up was 10.4mm/year. T1-S1 length increased 13.6mm/year and the instrumented segment length showed a mean increase of 0.8mm/segment/year. In total, 17 re-operations were performed. Ten re-operations were performed to treat 9 implant-related complications. In addition, 7 patients showed spinal growth that exceeded expected growth velocity; their springs were re-tensioned during a small re-operation. Spring distraction may be feasible as an alternative to current growing spine solutions. Curve correction and growth could be maintained satisfactory without the need for repetitive lengthening procedures. Complications and re-operations could not be prevented, which emphasizes the need for further improvement.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Ultrasound shear wave elastography is a radiation-free and low-cost technique for evaluating the ... more Ultrasound shear wave elastography is a radiation-free and low-cost technique for evaluating the mechanical properties of different tissues. This study systematically reviewed all relevant literature on shear wave elastography of the intervertebral disc. The purpose was twofold: first, to determine the validity of the elastography method, that is, the correlation between elastographically measured shear wave speed and disc mechanical properties, and inter-/intra-operator reliability; and second, to explore if disc elastography is potentially useful in identifying children at risk for idiopathic scoliosis. This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. A comprehensive search was performed in PubMed and Embase, and study quality was assessed using the AXIS (Appraisal Tool for Cross-sectional Studies) critical appraisal instrument. Seven articles were included. Three animal ex vivo studies reported moderate-to-good correlations between shear wave speed and disc mechanical properties (r = 0.45-0.81). Three studies reported high intra-operator repeatability (intra-class correlation coefficient [ICC] 0.94-0.99) and inter-operator reproducibility (ICC 0.97-0.98). Four clinical studies measured shear wave speed in asymptomatic children. Two studies reported significantly higher shear wave speeds in scoliosis patients compared with healthy controls, measured in discs both inside and outside the scoliotic curve. In conclusion, shear wave elastography appears reliable in assessing intervertebral disc mechanical characteristics. Despite its promising capabilities to distinguish patients with asymptomatic from those with pathological discs, the exact correlation between disc mechanical properties and shear wave speed remains unclear.
Accurate 3D-measurements demonstrate that vertebral bodies increase in height up to adulthood, bu... more Accurate 3D-measurements demonstrate that vertebral bodies increase in height up to adulthood, but discs only in the first years. The discs transverse surface area increases continuously; thus, disc slenderness decreases overall. Relatively, adolescent female discs remain slenderer. These measurements may assist future studies on disc morphology in spinal deformities. Study Design. Cross-sectional. Objective. The aim of this study was to describe the morphology of intervertebral discs and vertebral bodies during growth in asymptomatic children and adolescents. Summary of Background Data. Earlier studies demonstrated that spinal growth occurs predominantly in vertebral bodies. This axiom introduced a vertebral-body-focus for unravelling etiological questions and achieve growth-modulation in young spinal deformity patients. Recent studies show the importance of the intervertebral discs in the early phases and possible etiology of pediatric spinal deformities. There is presently a paucity of 3D morphometric data of spinal elements during growth. Methods. A database of 298 patients aged 0 to 21 that have received a computed tomography scan for indications not related to the spine was analyzed. Custom made software was used to semi-automatically measure intervertebral disc and vertebral body morphology, corrected for orientation in all 3 planes. Results. Vertebral body height increased from birth up to adulthood, from 4-to-14 mm in the cervical, 6 to 20 mm in the thoracic, and 9 to 28 mm in the lumbar spine. This increase was 0.70 mm/year in males, more pronounced than females with 0.62 mm/year (P = 0.001). Lumbar discs increased throughout growth from 4.4 to 9.0 mm, whereas thoracic discs only increased from 3.5 to 4.9 mm at age 4 and remained stable afterwards, similarly for cervical discs. The disc transverse surface area increased greatly and consistently throughout growth. Disc slenderness was stable in the lumbar spine during growth, but decreased in the thoracic and cervical spine. Overall, discs were more slender in females, especially around early adolescence. Conclusion. The spine grows predominantly in the vertebral bodies. Thoracic discs increase in height only during the first years, whereas the transverse surface area continues to increase throughout growth, thus discs slenderness decreases. Relatively, female discs remained slenderer around growth-spurt. These measurements may assist future studies on the role of disc morphology in the etiology and treatment of spinal deformity. Level of Evidence: 4
Current surgical treatment options for Early Onset Scoliosis (EOS), with distraction- or growth-g... more Current surgical treatment options for Early Onset Scoliosis (EOS), with distraction- or growth-guidance systems, show limited growth and high complication rates. We developed the Spring Distraction System (SDS), which does not have to be periodically lengthened and which provides continuous corrective force to stimulate spinal growth. This study aimed to assess curve correction and maintenance, spinal growth, and complication rate following SDS treatment. All primary- and revision patients (conversion from failed other systems) with SDS and ≥2 years follow-up were included. Outcome measures were coronal Cobb angle, sagittal parameters, spinal length measurements and complications and re-operations. Radiographic parameters were compared pre-operatively, post-operatively and at latest follow-up. Spinal length increase was expressed as mm/year. Twenty-four skeletally immature EOS patients (18 primary and 6 revision cases) were included. There were 5 idiopathic, 7 congenital, 3 syndromic and 9 neuromuscular EOS patients. Mean age at implantation was 9.1 years (primary: 8.4; conversion: 11.2). Major curve improved from 60.3° to 35.3°, and was maintained at 40.6° at latest follow-up. Mean spring length increase during follow-up was 10.4mm/year. T1-S1 length increased 13.6mm/year and the instrumented segment length showed a mean increase of 0.8mm/segment/year. In total, 17 re-operations were performed. Ten re-operations were performed to treat 9 implant-related complications. In addition, 7 patients showed spinal growth that exceeded expected growth velocity; their springs were re-tensioned during a small re-operation. Spring distraction may be feasible as an alternative to current growing spine solutions. Curve correction and growth could be maintained satisfactory without the need for repetitive lengthening procedures. Complications and re-operations could not be prevented, which emphasizes the need for further improvement.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Ultrasound shear wave elastography is a radiation-free and low-cost technique for evaluating the ... more Ultrasound shear wave elastography is a radiation-free and low-cost technique for evaluating the mechanical properties of different tissues. This study systematically reviewed all relevant literature on shear wave elastography of the intervertebral disc. The purpose was twofold: first, to determine the validity of the elastography method, that is, the correlation between elastographically measured shear wave speed and disc mechanical properties, and inter-/intra-operator reliability; and second, to explore if disc elastography is potentially useful in identifying children at risk for idiopathic scoliosis. This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. A comprehensive search was performed in PubMed and Embase, and study quality was assessed using the AXIS (Appraisal Tool for Cross-sectional Studies) critical appraisal instrument. Seven articles were included. Three animal ex vivo studies reported moderate-to-good correlations between shear wave speed and disc mechanical properties (r = 0.45-0.81). Three studies reported high intra-operator repeatability (intra-class correlation coefficient [ICC] 0.94-0.99) and inter-operator reproducibility (ICC 0.97-0.98). Four clinical studies measured shear wave speed in asymptomatic children. Two studies reported significantly higher shear wave speeds in scoliosis patients compared with healthy controls, measured in discs both inside and outside the scoliotic curve. In conclusion, shear wave elastography appears reliable in assessing intervertebral disc mechanical characteristics. Despite its promising capabilities to distinguish patients with asymptomatic from those with pathological discs, the exact correlation between disc mechanical properties and shear wave speed remains unclear.
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