Shear wave elastography of lumbar annulus fibrosus in adolescent idiopathic scoliosis before and after surgical intervention

Abstract Objectives To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic (AIS) patients before and after surgery, and compare them with asymptomatic controls. Methods Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle ranging between 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed (SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurements took place before surgery, and 3 months (N = 13) or 1 year after (N = 12). Results No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher in preop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop (3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended to decrease with the Cobb angle (Spearman’s rho = − 0.4, p = 0.05). Conclusion Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomatic ones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing of mild scoliosis has an effect on disc properties. Key Points • Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis. • Disc elastography tends to normalize 1 year after surgery

Prediction of clinical height gain from surgical posterior correction of idiopathic scoliosis

OBJECTIVE: The best predictors of height gain due to surgical correction are the number of fused vertebrae and the degrees of the corrected Cobb angle. Existing studies of predictive models measured the radiographic spinal height and did not report the clinical height gain. The aims of this study were to determine the best predictive factors of clinical height gain before surgical correction, construct a predictive model using patient population data for machine learning, and test the performance of this model on a validation population.METHODS: The authors reviewed 145 medical records of consecutive patients who underwent surgery that included placement of posterior spinal instrumentation and fusion for idiopathic scoliosis between 2012 and 2016. Standing and sitting clinical heights were measured before and after surgery in patients who had been surgically treated under similar conditions. Multivariate analysis was then performed and the results were used to develop a predictive model for height gain after surgery. The data from the included patients were randomly assigned to a learning set or a test set. RESULTS : In total, 116 patients were included in the analysis, for whom the average postoperative clinical height gain in a standing position was 4.2 ± 1.8 cm (range 0–11 cm). The best prediction model was calculated as follows: standing clinical height gain (cm) = 1 − 0.023 × sitting clinical height (cm) − 0.19 × Risser stage + 0.058 × Cobb preoperative angle (°) + 0.021 × T5–12 kyphosis (°) + 0.14 × number of levels fused. In the validation cohort, 91% of the predicted values had an error of less than one-half of the actual height gain.CONCLUSIONS: This predictive model formula for calculating the potential postoperative height gain after surgical treatment can be used preoperatively to inform idiopathic scoliosis patients of what outcomes they may expect from posterior spinal instrumentation and fusion (taking into account the model’s uncertainty)

Biomechanical Evaluation of Intercostal Muscles in Healthy Children and Adolescent Idiopathic Scoliosis: A Preliminary Study

Spine deformity during adolescent idiopathic scoliosis can induce a rib-cage deformity. This bone deformity can have direct consequences on the chest-wall muscles, including intercostal muscles, leading to respiratory impairments in individuals with severe cases. The aim of this study was to determine whether shear-wave elastography can be used to measure intercostal-muscle shear-wave speed (SWS) in healthy children and those with adolescent idiopathic scoliosis (AIS). Nineteen healthy participants and 16 with AIS took part. SWS measurements were taken by three operators, twice each. Average SWS was 2.3 ± 0.4 m/s, and inter-operator reproducibility was 0.2 m/s. SWS was significantly higher during apnea than in normal breathing (p < 0.01) in both groups. No significant difference was observed between groups in apnea or in normal breathing. Characterization of the intercostal muscles by ultrasound elastography is therefore feasible and reliable for children and adolescents with and without scoliosis

Sagittal plane assessment of manual concave rod bending for posterior correction in adolescents with idiopathic thoracic scoliosis (Lenke 1 and 3)

Objectives The objectives of this study were to evaluate the repeatability and reproducibility of a method for measuring freehand rod bending and to analyze the relationship between the rod's bend and the resulting sagittal correction. Materials and methods All the children who underwent correction by posterior translation using pedicle screws at all levels were included prospectively in 2018 and 2019. The rod's sagittal parameters were measured retrospectively by three independent surgeons on two separate occasions using the same protocol. After the rods were bent but before they were inserted, the surgeon traced the contours of the rods on a sheet of paper that was later scanned and analyzed semiautomatically. The spinal parameters were calculated based on biplanar radiographs taken preoperatively, postoperatively and at the final follow-up visit. Patients who had less than 10° thoracic kyphosis (T5–T12) made up the “Lenke N−” subgroup. Results Thirty patients were included (14 of whom were Lenke N−) who had a Cobb angle of 59.2 ± 11.3° preoperatively and 13.3 ± 8.4° postoperatively (p 0.9 (excellent). The mean kyphosis of the concave rod was 48.4 ± 5.7° (38.3–60.9°). The mean change in T5–T12 kyphosis was 9.7 ± 10.8° (−14.3–30.8°) (p < 0.0001) in the entire population, while it was 17.7 ± 7.1° (5.5–30.8°) (p < 0.0001) in the Lenke N− subgroup. The change in thoracic kyphosis was positively correlated with the kyphosis of the concave rod (rho = 0.52; p = 0.003). Conclusion This study found excellent reproducibility and repeatability of measuring freehand rod bending. The kyphosis applied to the concave rod is positively correlated to the change in the resulting kyphosis and made it possible to restore satisfactory thoracic kyphosis

Towards a predictive simulation of brace action in adolescent idiopathic scoliosis

The data collection was approved of by the ethical commit-tee (CPP 6001 Ile de France V), and patients and their parents signed an informed consent.Bracing is the most common treatment to stop the progression of adolescent idiopathic scoliosis. Finite element modeling could help improve brace design, but model validation is still a challenge. In this work, the clinical relevance of a predictive and subject-specific model for bracing was evaluated in forty-six AIS patients. The model reproduces brace action and the patient’s spinopelvic adjustments to keep balance. The model simulated 70% or more patients with geometrical parameters within a preselected tolerance level. Although the model simulation of the sagittal plane could be improved, the approach is promising for a realistic and predictive simulation of brace action.The authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Proteor, Société Génerale and Covea). We are also thankful to David Barrie Colridge for his support

Evidence of spinal stiffening following fusionless bipolar fixation for neuromuscular scoliosis: a shear wave elastography assessment of lumbar annulus fibrosus

Objectives There are no established criteria for stiffness after fusionless surgery for neuromuscular scoliosis (NMS). As a result, there is no consensus regarding the surgical strategy to propose at long-term follow-up. This study reports the first use of shear wave elastography for assessing the mechanical response of lumbar intervertebral discs (IVDs) after fusionless bipolar fixation (FBF) for NMS and compares them with healthy controls. The aim was to acquire evidence from the stiffness of the spine following FBF. Patients and methods Nineteen NMS operated on with FBF (18 ± 2y at last follow-up, 6 ± 1 y after surgery) were included prospectively. Preoperative Cobb was 89 ± 20° and 35 ± 1° at latest follow-up. All patients had reached skeletal maturity. Eighteen healthy patients (20 ± 4 y) were also included. Shear wave speed (SWS) was measured in the annulus fibrosus of L3L4, L4L5 and L5S1 IVDs and compared between the two groups. A measurement reliability was performed. Results In healthy subjects, average SWS (all disc levels pooled) was 7.5 ± 2.6 m/s. In NMS patients, SWS was significantly higher at 9.9 ± 1.4 m/s (p < 0.05). Differences were significant between L3L4 (9.3 ± 1.8 m/s vs. 7.0 ± 2.5 m/s, p = 0.004) and L4L5 (10.3 ± 2.3 m/s vs. 7.1 ± 1.1 m/s, p = 0.0006). No difference was observed for L5S1 (p = 0.2). No correlation was found with age at surgery, Cobb angle correction and age at the SWE measurement. Conclusions This study shows a significant increase in disc stiffness at the end of growth for NMS patients treated by FBF. These findings are a useful adjunct to CT-scan in assessing stiffness of the spine allowing the avoidance of surgical final fusion at skeletal maturity

Quasi-automatic early detection of progressive idiopathic scoliosis from biplanar radiography: a preliminary validation

Purpose To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS). Methods Fifty-five AIS patients were prospectively included (Age: 10-15, Cobb: 16° ± 4°). Patients underwent low-dose biplanar x-rays and a novel fast method for 3D reconstruction of the spine was performed. They were followed until skeletal maturity (stable patients) or brace prescription (progressive patients). The severity index was calculated at the first exam, based on 3D parameters of the scoliotic curve, and it was compared with the patient’s final outcome (progressive or stable). Three operators have repeated the 3D reconstruction twice for a subset of 30 patients to assess reproducibility (through Cohen’s kappa and intraclass correlation coefficient). Results 85% of the patients were correctly classified as stable or progressive by the severity index, with a sensitivity of 92% and specificity of 74%. Substantial intra-operator agreement and good inter-operator agreement were observed, with 80% of the progressive patients correctly detected at the first exam. The novel severity index assessment took less than 4 minutes of operator time. Conclusions The fast and semi-automatic method for 3D reconstruction developed in this work allowed for a fast and reliable calculation of the severity index. The method is fast and user friendly. Once extensively validated, this severity index could allow very early initiation of conservative treatment for progressive patients, thus increasing treatment efficacy and therefore reducing the need for corrective surgery.BiomecA

Biomechanical marker research improving diagnosis and therapeutic evaluation of adolescent idiopathic scoliosis

L’avènement de l’analyse personnalisée tridimensionnelle non invasif de la colonne vertébrale a permis de développer de nombreux paramètres biomécaniques mais certains restent à évaluer. L’objectif de cette thèse était d’évaluer le rôle possible de ces paramètres dans la prédiction d’une scoliose progressive et d’étudier leurs variations après une correction chirurgicale.Un trouble de l’alignement global précoce semble être un potentiel paramètre de progression et plus particulièrement la mesure coronale dans les scolioses thoraciques. La barycentrométrie est perturbée à un stade précoce et les propriétés liées à la vertèbre sommet (le centre de masse ou son moment intersegmentaire) semblent être prédicteur d’une progression d’une courbure thoracique. Ces perturbations biomécaniques liées à l’asymétrie du pli de taille et du barycentre sont réversibles après traitement chirurgical et sont corrélées à la correction du plan axial. Enfin, les perturbations biomécaniques de l’annulus fibrosus lombaire sont détectables par l’élastographie ultrasonore et sont réversibles après une correction chirurgicale.Les résultats sont prometteurs et démontrent l’intérêt de l’analyse tridimensionnelle de l’alignement, de l’asymétrie du pli du taille, du barycentre et de l’utilisation de l’élastographie dans la prise en charge de la scoliose idiopathique. Ces travaux ouvrent des perspectives de recherche et une application clinique importante avec comme exemple la validation à grande échelle de l’ajout de paramètres spécifiques dans l’indice de sévérité ou une meilleure planification de la correction chirurgicale.The advent of custom three-dimensional and non-invasive spinal analysis has led to the development of many biomechanical parameters, but some remain to be assessed. The purpose of this thesis was to assess the potential role of these parameters in predicting progressive scoliosis and to study their variations after surgical correction.Early global alignment disorders appear to be a potential parameter of progression and especially coronal measurement in thoracic scoliosis. Barycentremetry is disrupted at an early stage and the properties related to the apical vertebra (the center of mass or its intersegmental moment) appear to predict a progression of a thoracic curvature. The coronal trunk balance and the barycenter-related biomechanical disturbances are reversible after surgical treatment and correlate with axial plane correction. Finally, biomechanical disturbances of the annulus fibrosus lumbar are detectable by ultrasonic elastography and are reversible after surgical correction.The findings are promising and demonstrate the value of three-dimensional analysis of alignment, coronal trunk balance, barycenter and the use of elastography in the management of idiopathic scoliosis. This work provides prospects for research and important clinical application, such as large-scale validation of the inclusion of selected parameters in the severity index or better planning of surgical correction

Recherche de marqueurs biomécaniques améliorant le diagnostic et l’évaluation thérapeutique d’une scoliose idiopathique de l’adolescent

The advent of custom three-dimensional and non-invasive spinal analysis has led to the development of many biomechanical parameters, but some remain to be assessed. The purpose of this thesis was to assess the potential role of these parameters in predicting progressive scoliosis and to study their variations after surgical correction.Early global alignment disorders appear to be a potential parameter of progression and especially coronal measurement in thoracic scoliosis. Barycentremetry is disrupted at an early stage and the properties related to the apical vertebra (the center of mass or its intersegmental moment) appear to predict a progression of a thoracic curvature. The coronal trunk balance and the barycenter-related biomechanical disturbances are reversible after surgical treatment and correlate with axial plane correction. Finally, biomechanical disturbances of the annulus fibrosus lumbar are detectable by ultrasonic elastography and are reversible after surgical correction.The findings are promising and demonstrate the value of three-dimensional analysis of alignment, coronal trunk balance, barycenter and the use of elastography in the management of idiopathic scoliosis. This work provides prospects for research and important clinical application, such as large-scale validation of the inclusion of selected parameters in the severity index or better planning of surgical correction.L’avènement de l’analyse personnalisée tridimensionnelle non invasif de la colonne vertébrale a permis de développer de nombreux paramètres biomécaniques mais certains restent à évaluer. L’objectif de cette thèse était d’évaluer le rôle possible de ces paramètres dans la prédiction d’une scoliose progressive et d’étudier leurs variations après une correction chirurgicale.Un trouble de l’alignement global précoce semble être un potentiel paramètre de progression et plus particulièrement la mesure coronale dans les scolioses thoraciques. La barycentrométrie est perturbée à un stade précoce et les propriétés liées à la vertèbre sommet (le centre de masse ou son moment intersegmentaire) semblent être prédicteur d’une progression d’une courbure thoracique. Ces perturbations biomécaniques liées à l’asymétrie du pli de taille et du barycentre sont réversibles après traitement chirurgical et sont corrélées à la correction du plan axial. Enfin, les perturbations biomécaniques de l’annulus fibrosus lombaire sont détectables par l’élastographie ultrasonore et sont réversibles après une correction chirurgicale.Les résultats sont prometteurs et démontrent l’intérêt de l’analyse tridimensionnelle de l’alignement, de l’asymétrie du pli du taille, du barycentre et de l’utilisation de l’élastographie dans la prise en charge de la scoliose idiopathique. Ces travaux ouvrent des perspectives de recherche et une application clinique importante avec comme exemple la validation à grande échelle de l’ajout de paramètres spécifiques dans l’indice de sévérité ou une meilleure planification de la correction chirurgicale

Recherche de marqueurs biomécaniques améliorant le diagnostic et l’évaluation thérapeutique d’une scoliose idiopathique de l’adolescent

The advent of custom three-dimensional and non-invasive spinal analysis has led to the development of many biomechanical parameters, but some remain to be assessed. The purpose of this thesis was to assess the potential role of these parameters in predicting progressive scoliosis and to study their variations after surgical correction.Early global alignment disorders appear to be a potential parameter of progression and especially coronal measurement in thoracic scoliosis. Barycentremetry is disrupted at an early stage and the properties related to the apical vertebra (the center of mass or its intersegmental moment) appear to predict a progression of a thoracic curvature. The coronal trunk balance and the barycenter-related biomechanical disturbances are reversible after surgical treatment and correlate with axial plane correction. Finally, biomechanical disturbances of the annulus fibrosus lumbar are detectable by ultrasonic elastography and are reversible after surgical correction.The findings are promising and demonstrate the value of three-dimensional analysis of alignment, coronal trunk balance, barycenter and the use of elastography in the management of idiopathic scoliosis. This work provides prospects for research and important clinical application, such as large-scale validation of the inclusion of selected parameters in the severity index or better planning of surgical correction.L’avènement de l’analyse personnalisée tridimensionnelle non invasif de la colonne vertébrale a permis de développer de nombreux paramètres biomécaniques mais certains restent à évaluer. L’objectif de cette thèse était d’évaluer le rôle possible de ces paramètres dans la prédiction d’une scoliose progressive et d’étudier leurs variations après une correction chirurgicale.Un trouble de l’alignement global précoce semble être un potentiel paramètre de progression et plus particulièrement la mesure coronale dans les scolioses thoraciques. La barycentrométrie est perturbée à un stade précoce et les propriétés liées à la vertèbre sommet (le centre de masse ou son moment intersegmentaire) semblent être prédicteur d’une progression d’une courbure thoracique. Ces perturbations biomécaniques liées à l’asymétrie du pli de taille et du barycentre sont réversibles après traitement chirurgical et sont corrélées à la correction du plan axial. Enfin, les perturbations biomécaniques de l’annulus fibrosus lombaire sont détectables par l’élastographie ultrasonore et sont réversibles après une correction chirurgicale.Les résultats sont prometteurs et démontrent l’intérêt de l’analyse tridimensionnelle de l’alignement, de l’asymétrie du pli du taille, du barycentre et de l’utilisation de l’élastographie dans la prise en charge de la scoliose idiopathique. Ces travaux ouvrent des perspectives de recherche et une application clinique importante avec comme exemple la validation à grande échelle de l’ajout de paramètres spécifiques dans l’indice de sévérité ou une meilleure planification de la correction chirurgicale