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Aims This study addressed two questions: first, does surgical correction of an idiopathic scoliosis increase the volume of the rib cage, and second, is it possible to evaluate the change in lung function after corrective surgery for adolescent idiopathic scoliosis (AIS) using biplanar radiographs of the ribcage with 3D reconstruction? Methods A total of 45 patients with a thoracic AIS which needed surgical correction and fusion were included in a prospective study. All patients underwent pulmonary function testing (PFT) and low-dose biplanar radiographs both preoperatively and one year after surgery. The following measurements were recorded: forced vital capacity (FVC), slow vital capacity (SVC), and total lung capacity (TLC). Rib cage volume (RCV), maximum rib hump, main thoracic curve Cobb angle (MCCA), medial-lateral and anteroposterior diameter, and T4-T12 kyphosis were calculated from 3D reconstructions of the biplanar radiographs. Results All spinal and thoracic measurements improved significantly after surgery (p < 0.001). RCV increased from 4.9 l (SD 1) preoperatively to 5.3 l (SD 0.9) (p < 0.001) while TLC increased from 4.1 l (SD 0.9) preoperatively to 4.3 l (SD 0.8) (p < 0.001). RCV was correlated with all functional indexes before and after correction of the deformity. Improvement in RCV was weakly correlated with correction of the mean thoracic Cobb angle (p = 0.006). The difference in TLC was significantly correlated with changes in RCV (p = 0.041). It was possible to predict postoperative TLC from the postoperative RCV. Conclusion 3D rib cage assessment from biplanar radiographs could be a minimally invasive method of estimating pulmonary function before and after spinal fusion in patients with an AIS. The 3D RCV reflects virtual chest capacity and hence pulmonary function in this group of patients. Cite this article: Bone Joint J 2022;104-B(1):112–119.

Contexte Les troubles fonctionnels de la main sont généralement investigués, en premier lieu, à l’aide de l’imagerie radiographique conventionnelle. Cependant, les radiographies (deux dimensions (2D)) fournissent des renseignements limités, et l’information peut être réduite par le chevauchement des os et les biais de projection. Ce travail présente une méthode de reconstruction de la main en trois dimensions (3D) à partir de radiographies biplanes. Méthode Cette approche consiste en la déformation d’un modèle générique de main sur les radiographies biplanes par des processus manuels et automatiques. L’examen de référence étant la segmentation manuelle scanographique, la précision de la méthode a été évaluée par une comparaison entre les reconstructions à partir de radiographies biplanes et les reconstructions correspondantes à partir de scanner (0,3 mm d’épaisseur de coupe). Pour évaluer la reproductibilité de la méthode, 6 mains saines (6 sujets, 3 gauches, 3 hommes) ont été considérées. Deux opérateurs ont répété trois fois chaque reconstruction à partir de radiographies biplanes pour étudier la variabilité inter- et intra-opérateur. Trois paramètres anatomiques, qui pourraient être calculés automatiquement à partir des reconstructions, ont été considérés à partir des surfaces osseuses : la longueur du scaphoïde, la profondeur de l’extrémité distale du radius et la hauteur du trapèze. Résultats Le double de l’erreur quadratique moyenne (2 Root Mean Square, 2RMS), au niveau de la différence point/surface entre les radiographies biplanes et les reconstructions tomodensitométriques, variait de 0,46 mm pour les phalanges distales à 1,55 mm pour les os de la deuxième rangée. La variabilité inter-/intra-observateur a montré une précision à 95 % de l’intervalle de confiance inférieure à 1,32 mm, pour les paramètres anatomiques, et à 2,12 mm pour les barycentres osseux. Discussion La méthode actuelle permet d’obtenir une reconstruction 3D précise de la main et du poignet par rapport au scanner segmenté traditionnel. En améliorant l’automatisation de la méthode, cela nous permettrait d’obtenir rapidement des informations objectives sur la position des os dans l’espace. L’intérêt de cette méthode réside dans le diagnostic précoce de certaines pathologies ligamentaires (instabilité carpienne) et a également des implications dans la planification chirurgicale et la modélisation personnalisée par éléments finis.

Objective: To identify the different apex and transitional vertebra according to the shape of the pelvis of individuals despite their difference in sagittal alignment using our measurement system. Methods: Full spine X-rays using EOS in standard stand-position of 99 volunteers were selected (47 women, 52 men, mean age 31years old). Validated 3D reconstruction technique allowing extraction of spinopelvic parameters, and position and rotation of each vertebra and lumbar discs. Subjects were divided in three groups: low PI (low PI, n=37), moderate PI (mid PI, n=52), high PI (high PI, n=10), with respectively a PI below 45 °, between 45 °-60 ° and above 60 °. Occurrence of specific position and rotation values of apex and transitional vertebra were assessed in each groups. Results: Frequency curves tend to move cranially when the incidence increases except in cervicothoracic where T1 is a constant for all shape of spine with occurrence approaching 90%. Angulation value of relevant vertebra and lumbar lordosis are significantly positively correlated for the whole population. Conclusions: Our study allowed the assessment of the distribution of spine curvatures according to the pelvic incidence. It describes the occurrence of localization of the apex and transitional vertebrae according to pelvic incidence. These results should be taken into account during the analysis of the sagittal balance, especially when planning deformity surgery in adults.

International audience; Introduction: This study analyzes anatomical variations of the thoracic cage (TC) according to spinopelvic alignment, age and gender using stereoradiography in erect position.Methods: This retrospective multicentric study analyzed computed parameters collected from free-standing position bi-planar radiographs, among healthy subjects. Collected data were: age, gender, pelvic parameters (Pelvic Incidence, Pelvic Tilt (PT) and Sacral Slope), T1-T12 Kyphosis (TK), L1-S1 Lordosis (LL), curvilinear spinal length, global TC parameters (maximum thickness and width, rib cage volume, mean Spinal Penetration Index (SPI)), 1st–10th rib parameters (absolute and relative (to the corresponding vertebra) sagittal angles).Results: Totally, 256 subjects were included (140 females). Mean age was 34 (range: 8–83). Significant correlations were found between TK and TC thickness (0.3, p

X-linked hypophosphatemic (XLH) rickets causes significant bone deformities in the lower limbs resulting from a bone mineralization defect. According to Frost's Mechanostat theory, compensatory modeling of the bones takes place during increased mechanical loads. In addition, mechanical stimuli modulate the differentiation of mesenchymal stem cells; common precursors to bone marrow adipocytes and osteoblasts.Bone deformities of the lower limbs lead to increased femoral bone mass and decreased fatty infiltration of the bone marrow (FIBM) in children with XLH rickets compared to a control group.Eleven children (10.3y [6-17]) with XLH rickets and 22 healthy children (10.2y [5-15.5]) underwent lower limb Magnetic Resonance Imaging. A calculation of FIBM was performed at the mid-femur, as well as a calculation of the total bone cross-sectional area (CSA), the cortical CSA, the anteroposterior and mediolateral axes of the femur, bone marrow and the thickness of the femoral cortices.Total bone CSA, total cortical CSA and bone marrow CSA were higher in the XLH group than in the control group (p0.05). The mid-lateral diameters of the femur and bone marrow were more elongated than those of the control group (p0.001). Only the anterior cortex was thinned in the XLH group (p=0.001), while there was no difference with the control group for the posterior, medial and lateral cortices. The total percentage of FIBM was 72.81% [±3.95] and 77.4% [±5.52] for the XLH and control groups respectively (p0.001).The increase in bone mass in the XLH population reflects an adaptation of bone tissue to the bone deformities present in this pathology. The decrease in FIBM indicates a lower risk of osteoporosis in the XLH population and may constitute a new monitoring parameter in this pathology.III; Case-control study.

Purpose: To assess dynamic postural alignment in ASD during walking using a subject-specific 3D approach. Methods: 69 ASD (51 ± 20 years, 77%F) and 62 controls (34 ± 13 years, 62%F) underwent gait analysis along with full-body biplanar Xrays and filled HRQoL questionnaires. Spinopelvic and postural parameters were computed from 3D skeletal reconstructions, including radiographic odontoid to hip axis angle (ODHA) that evaluates the head's position over the pelvis (rODHA), in addition to rSVA and rPT. The 3D bones were then registered on each gait frame to compute the dynamic ODHA (dODHA), dSVA, and dPT. Patients with high dODHA (> mean + 1SD in controls) were classified as ASD-DU (dynamically unbalanced), otherwise as ASD-DB (dynamically balanced). Between-group comparisons and relationship between parameters were investigated. Results: 26 patients were classified as ASD-DU having an average dODHA of 10.4° (ASD-DB: 1.2°, controls: 1.7°), dSVA of 112 mm (ASD-DB: 57 mm, controls: 43 mm), and dPT of 21° (ASD-DB: 18°, controls: 14°; all p < 0.001). On static radiographs, ASD-DU group showed more severe sagittal malalignment than ASD-DB, with more altered HRQoL outcomes. The ASD-DU group had an overall abnormal walking compared to ASD-DB & controls (gait deviation index: 81 versus 93 & 97 resp., p < 0.001) showing a reduced flexion/extension range of motion at the hips and knees with a slower gait speed and shorter step length. Dynamic ODHA was correlated to HRQoL scores. Conclusion: Dynamically unbalanced ASD had postural malalignment that persist during walking, associated with kinematic alterations in the trunk, pelvis, and lower limbs, making them more prone to falls. Dynamic-ODHA correlates better with HRQoL outcomes than dSVA and dPT.

Purpose: To evaluate the global alignment of non-operated subjects with adolescent idiopathic scoliosis. Method: A total of 254 subjects with AIS and 64 controls underwent low dose biplanar X-rays and had their spine, pelvis, and rib cage reconstructed in 3D. Global alignment was measured in the sagittal and frontal planes by calculating the OD-HA angle (between C2 dens to hip axis with the vertical). Subjects with AIS were classified as malaligned if the OD-HA was > 95th percentile relative to controls. Results: The sagittal OD-HA in AIS remained within the normal ranges. In the frontal plane, 182 AIS were normally aligned (Group 1, OD-HA = 0.9°) but 72 were malaligned (Group 2, OD-HA = 2.9°). Group 2 had a more severe spinal deformity in the frontal and horizontal planes compared to Group 1 (Cobb: 42 ± 16° vs. 30 ± 18°; apical vertebral rotation AVR: 19 ± 10° vs. 12 ± 7°, all p < 0.05). Group 2 subjects were mainly classified as Lenke 5 or 6. 19/72 malaligned subjects had a mild deformity (Cobb < 30°) but a progressive scoliosis (severity index ≥ 0.6). The frontal OD-HA angle was found to be mainly determined (adjusted-R2 = 0.22) by the apical vertebral rotation and secondarily by the Lenke type. Conclusions: This study showed that frontal malalignment is more common in distal major structural scoliosis and its main driver is the apical vertebral rotation. This highlights the importance of monitoring the axial plane deformity in order to avoid worsening of the frontal global alignment.

Introduction X-linked hypophosphatemia (XLH) rickets mainly causes leg deformities in children that can get worse as they grow. We hypothesized that quantifying the bone parameters will help to document and monitor these deformities in children with XLH. Methods Thirty-five growing children affected by XLH were included in this cross-sectional study. Biplanar radiographs were taken with an EOS system allowing 3D reconstructions of the pelvis and legs. Sixteen geometric parameters were calculated for the legs and pelvis. A control group of 40 age-matched patients was used to define the reference values for these geometric parameters. Results For the legs, significant differences (p < 0.05) appeared between the XLH patients and the control group in the neck-shaft angle, femur/tibia length ratio and HKS. Among the 70 legs in the XLH group, 23 were in genu varum, 25 were in genu valgum and 22 were straight. There were significant differences between the genu varum and genu valgum subgroups in the femoral mechanical angle and the HKS. A strong correlation was found between the femoral mechanical angle and tibiofemoral angle (r² = 0.73) and between the femoral mechanical angle and HKS (r²=0.69) The sacral slope and acetabular anteversion were significant different from the reference values. Discussion Quantitative radiological parameters derived from 3D reconstructions show that the deformities in XLH patients are 1) mainly in but not limited to the femoral shaft; 2) highly variable from one person to another. Some of these radiological parameters may be useful for the diagnosis and monitoring of XLH patients. Kyowa Kirin Pharma provided financial support for this study.

To evaluate 3D kinematic alterations during gait in Adult Spinal Deformity (ASD) subjects with different deformity presentations.One hundred nineteen primary ASD (51 ± 19y, 90F), age and sex-matched to 60 controls, underwent 3D gait analysis with subsequent calculation of 3D lower limb, trunk and segmental spine kinematics as well as the gait deviation index (GDI). ASD were classified into three groups: 51 with sagittal malalignment (ASD-Sag: SVA 50 mm, PT 25°, and/or PI-LL 10°), 28 with only frontal deformity (ASD-Front: Cobb 20°) and 40 with only hyperkyphosis (ASD-HyperTK: TK 60°). Kinematics were compared between groups.ASD-Sag had a decreased pelvic mobility compared to controls with a decreased ROM of hips (38 vs. 45°) and knees (51 vs. 61°). Furthermore, ASD-Sag exhibited a decreased walking speed (0.8 vs. 1.2 m/s) and GDI (80 vs. 95, all p 0.05) making them more prone to falls. ASD-HyperTK showed similar patterns but in a less pronounced way. ASD-Front had normal walking patterns. GDI, knee flex/extension and walking speed were significantly associated with SVA and PT (r = 0.30-0.65).Sagittal spinal malalignment seems to be the driver of gait alterations in ASD. Patients with higher GT, SVA, PT or PI-LL tended to walk slower, with shorter steps in order to maintain stability with a limited flexibility in the pelvis, hips and knees. These changes were found to a lesser extent in ASD with only hyperkyphosis but not in those with only frontal deformity. 3D gait analysis is an objective tool to evaluate functionality in ASD patients depending on their type of spinal deformity.Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

International audience; This study aims to describe the spinopelvic sagittal alignment in transfemoral amputees (TFAs) from a radiologic study of the spine with a postural approach to better understand the high prevalence of low back pain (LBP) in this population.METHODS:TFAs underwent X-rays with 3-D reconstructions of the full spine and pelvis. Sagittal parameters were analyzed and compared to the literature. Differences between TFAs with and without LBP were also observed.RESULTS:Twelve subjects have been prospectively included (TFA-LBP group (n = 5) and TFA-NoP group (n = 7)). Four of the five subjects of the TFA-LBP group and two of the seven in TFAs-NoP group had an imbalanced sagittal posture, especially regarding the T9-tilt, significantly higher in the TFA-LBP group than in the TFA-NoP (p = 0.046). Eight subjects (6 TFA-NoP and 2 TFA-LBP) had abnormal low value of thoracic kyphosis (TK). Moreover, the mean angle of TK in the TFA-NoP group was lower than in the TFA-LBP group (p = 0.0511).CONCLUSION:In the considered sample, TFAs often present a sagittal imbalance. A low TK angle seems to be associated with the absence of LBP. It can be hypothesized that this compensatory mechanism of the sagittal imbalance is the most accessible in this population. This study emphasizes the importance of considering the sagittal balance of the pelvis and the spine in patients with a TFA to better understand the high prevalence of LBP in this population. It should be completed by the analysis of the spinopelvic balance and the lower limbs in 3D. These slides can be retrieved under Electronic Supplementary Material.

To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS). 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 examination, 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 intra-class correlation coefficient). Eighty-five percentage 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 examination. The novel severity index assessment took less than 4 min of operator time. The fast and semiautomatic 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. These slides can be retrieved under Electronic Supplementary Material.

International audience; Purpose: To explore 3D hip orientation in standing position in subjects with adult spinal deformity (ASD) presenting with different levels of compensatory mechanisms.Methods: Subjects with ASD (n = 159) and controls (n = 68) underwent full-body biplanar X-rays with the calculation of 3D spinopelvic, postural and hip parameters. ASD subjects were grouped as ASD with knee flexion (ASD-KF) if they compensated by flexing their knees (knee flexion ≥ 5°), and ASD with knee extension (ASD-KE) otherwise (knee flexion

Introduction: Global alignment analysis is of upmost importance in adult spinal deformity patients (ASD). Numerous parameters exist in the literature to measure global alignment based upon C7 or T1. One common limitation of these parameters is that they neglect the cervical segment which is essential in spinal compensatory mechanisms and in horizontal gaze preservation. A recent stereoradiography analysis of asymptomatic subjects introduced a new 3D parameter (ODHA), defined as the angle between the vertical reference line and the line joining the odontoid tip (OD) to hip axis center (HA). Thus, the goal of this study was to analyze 3D global alignment of ASD patients using the new parameter odontoid hip axis angle and its relationship to other spinal parameters. Methods: In this prospective study, 90 adult patients with lumbar scoliosis (Cobb > 20°) were included. All subjects underwent low dose biplanar X-rays with 3D spinal reconstructions. Based on published normative values of ODHA, we defined abnormally high value as mean ODHA of asymptomatic subject + 2SD (i.e., ODHA > 6.1°). Values of 3D radiographic parameters and ODI were compared between patients with ODHA > 6.1° and

STUDY DESIGN A prospective study. OBJECTIVE The aim of this study was to report the results of an alternative technique to growing rods (GR) for neuromuscular scoliosis using a minimally invasive fusionless surgery with a minimum of 5 years' follow-up. SUMMARY OF BACKGROUND DATA Conservative treatment is not effective in progressive neuromuscular scoliosis. Early surgery using GR is increasingly advocated to control the deformity while preserving spinal and thoracic growth before arthrodesis. These techniques still provide a high rate of complications. METHODS The technique relies on a bilateral double rod sliding instrumentation anchored proximally by four hooks claws and distally to the pelvis by iliosacral screws through a minimally invasive approach. The clinical and radiological outcomes of 100 consecutive patients with neuromuscular scoliosis who underwent this fusionless surgery with a minimum follow-up of 5 years were reviewed. RESULTS 6.5 ± 0.7 years after initial surgery, six patients were lost of follow-up and 11 died of unrelated raison. Of the 83 remaining patients at latest follow-up, mean Cobb angle was stable to 35.0° which correspond to 61% correction of the initial deformation. Mean pelvic obliquity was 29.6° (0.3°-80.0°) preoperatively and 7.2 (0.2°-23.5°) at latest follow-up. Correction of the hyper kyphosis remained stable. Skeletal maturitywas reached in 42 of 83 patients (50.6%). None of these patients has required spinal fusion. The global complication rate was 31.3%. CONCLUSION The outcomes of this minimally invasive fusionless technique at 5 years follow-up showed a stable correction of spinal deformities and pelvic obliquity over time, with a reduced rate of complication. The arthrodesis was not required for all patients at skeletal maturity. This technique could be a good alternative to arthrodesis for neuromuscular scoliosis.Level of Evidence: 3.

International audience; Study Design: This was a multicentric cross-sectional descriptive study.Objective: To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity.Summary of Background Data: Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated.Methods: A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16).Results: Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb.Conclusions: This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery.

Resume Introduction Chez l’enfant ayant ete traite pour un pied bot varus equin idiopathique (PBVE), le lien entre defauts morphologiques constates cliniquement ou par radiographie standard et anomalies fonctionnelles est difficile a etablir objectivement. Le but de ce travail est de demontrer la faisabilite d’une etude combinee par reconstructions en 3-dimensions du pied et du membre inferieur a partir de radiographies biplanaires EOS, et par analyse de marche. L’hypothese est que cela permette une meilleure comprehension des anomalies de forme et de fonction. Methodes Dix enfants avec un antecedent de PBVE unilateral et un resultat « tres bon » ont ete inclus. Ils ont beneficie d’une analyse de la marche a l’aide du modele multisegmentaire de l’Institut Rizzoli, decrivant specifiquement le pied. Les donnees cinematiques de la hanche, du genou, de la cheville, et du pied (arriere-medio, medio-avant et arriere-avant) ont ete recueillies. Des radiographies biplanaires EOS ont ete realisees afin de preciser les reperes anatomiques et les parametres radiologiques. Resultats Le temps complet d’acquisition etait d’environ 2 heures par patient. Aucune difference significative n’a ete mise en evidence entre les PBVE et les pieds sains hormis pour l’incidence calcaneenne, l’angle tibio-calcaneen et l’inversion arriere/medio pied et arriere/avant pied. Discussion La faisabilite de l’analyse combinee est confirmee. Il n’y a pas de difference de mobilite, moment ou puissance entre les PBVE et les pieds sains dans cette serie de patients aux tres bons resultats. Ces resultats fonctionnels sont lies aux resultats radiologiques situes dans les corridors de normalite. Ce protocole permet d’obtenir des donnees anatomiques et cinematiques de reference. Une etude plus large permettra d’apprecier de maniere plus objective l’interet des radiographies EOS avec marqueurs optoelectroniques en place. Niveau de preuve II, prospective, de faible puissance.

Resume Introduction L’examen clinique et l’etude radiologique en charge sont les 2 principaux moyens d’analyse des pieds et des membres inferieurs. L’anatomie et la fonction de ces 2 structures ont des consequences reciproques. Ces 2 moyens sont sujets a la subjectivite et aux biais de projection. La radiographie biplane est devenue une alternative prometteuse pour l’etude des membres inferieurs de l’enfant. Cependant, l’analyse du pied n’est pour l’instant pas possible par ce systeme. Afin de permettre une analyse en 3D, la premiere question est d’etudier la reproductibilite de reperes definis a l’aide de radiographies biplanes, la seconde, de donner la valeur des parametres radiologiques calcules. Hypothese L’hypothese du travail etait de proposer une nouvelle methode de mesure radiologique du pied, en 3D, a partir de radiographies biplanes. Patients et methodes Deux radiographies biplanes simultanees et orthogonales (EOS® Imaging, Paris, France) des pieds ont ete acquises en position standardisee chez 10 enfants sains. Pour evaluer l’incertitude de mesure, 2 operateurs ont realise les reconstructions des 10 pieds, 3 fois (60 reconstructions). L’ecart-type de reproductibilite des points anatomiques et des parametres cliniques a ete calculee. L’incertitude de mesure a ensuite ete evaluee a partir de l’intervalle de confiance a 95 %. Pour les valeurs de reference, la normalite des donnees a ete verifiee et, la valeur moyenne et l’ecart-type de chaque parametre ont ete rapportes. Resultats Les reperes anatomiques d’interet, ainsi que l’angle d’incidence calcaneenne, l’angle tibio-calcaneen de profil, l’angle tibio-talien de face et l’angle d’incidence du 1er metatarsien (IC95 % Discussion/Conclusion Cela ouvre la voie a l’elaboration de nouveaux parametres de description des pieds en 3D, ainsi qu’a l’etude simultanee du membre inferieur et du pied en position debout. Niveau de preuve I.

The initial assessment and postoperative monitoring of patients with various abnormalities of the foot in clinical routine practice is primarily based on the analysis of radiographs taken in the weightbearing position. Conventional x-ray imaging, however, only provides a 2-dimensional projection of 3-dimensional (3D) bony structures, and the clinical parameters assessed from these images can be affected by projection biases. In the present work, we addressed this issue by proposing an accurate 3D reconstruction method of the foot in the weightbearing position from low-dose biplanar radiographs with clinical index measurement assessment for clinical routine practice. The accuracy of the proposed reconstruction method was evaluated for both shape and clinical indexes by comparing 3D reconstructions of 6 cadaveric adult feet from computed tomographic images and from biplanar radiographs. For the reproducibility study, 3D reconstructions from the biplanar radiographs of the foot of 6 able-bodied subjects were considered, with 2 observers repeating each measurement of anatomic landmarks 3 times. Baseline assessment of important 3D clinical parameters was performed on 17 subjects (34 feet; mean age 27.7, range 20 to 52 years). The average point to surface distance between the 3D stereoradiographic reconstruction and the computed tomographic scan-based reconstruction was 1 mm (range 0mm to 6mm). The selected radiographic landmarks were highly reproducible (95% confidence interval

Resume Introduction La prise en charge de la scoliose idiopathique de l’adolescent (SIA) peut necessiter des traitements chirurgicaux aux consequences lourdes. L’existence d’un desequilibre frontal, authentifie par l’examen clinique a l’aide d’un fil a plomb (DFFP) est un element important qui pousse a un traitement chirurgical. La technique de reference pour l’appreciation de l’equilibre postural du tronc reste neanmoins la materialisation de la ligne de gravite (LG) et sa projection dans un referentiel determine et connu. De recentes etudes ont montre la possibilite de materialiser la LG d’un patient a partir de stereoradiographies apres reconstruction de l’enveloppe corporelle (technique de barycentremetrie). L’hypothese que nous nous proposons de verifier est qu’il existe une concordance entre le DFFP et la LG. Materiels et methodes Dans un premier temps la determination de la LG par la methode de barycentremetrie a ete validee chez 14 SIA en la comparant aux donnees recueillies sur une plate-forme de force. Les valeurs normales de DFFP et LG ont ensuite ete determinees chez 27 adolescents asymptomatiques au moyen d’une technique stereoradiographique. Une comparaison de ces memes valeurs a ete ensuite realisee sur une population de 53 patients porteurs d’une SIA. Resultats La fiabilite des mesures de la LG dans le plan frontal avec la technique de barycentremetrie etait de 2,4 mm (intervalle de confiance a 95 %). Il existait une concordance statistiquement forte entre la distance de la LG par rapport au milieu de la ligne joignant les centres des 2 tetes femorales (LG/HA) et le DFFP calcule comme la distance entre la verticale au milieu de T1 et le centre du plateau sacre (T1 V/S) : r = 0,71 p Conclusion Cette etude valide la determination de la LG a partir de stereoradiographies dans une population de SIA. Le DFFP etait statistiquement correle a la LG, mais moins precis pour decider d’une indication chirurgicale. Niveau de preuve IV, Etude retrospective.

Purpose The aim of this work is to propose a classification algorithm to automatically detect treatment for scoliosis (brace, implant or no treatment) in postero-anterior radiographs. Such automatic labelling of radiographs could represent a step towards global automatic radiological analysis. Methods Seven hundred and ninety-six frontal radiographies of adolescents were collected (84 patients wearing a brace, 325 with a spinal implant and 387 reference images with no treatment). The dataset was augmented to a total of 2096 images. A classification model was built, composed by a forward convolutional neural network (CNN) followed by a discriminant analysis; the output was a probability for a given image to contain a brace, a spinal implant or none. The model was validated with a stratified tenfold cross-validation procedure. Performance was estimated by calculating the average accuracy. Results 98.3% of the radiographs were correctly classified as either reference, brace or implant, excluding 2.0% unclassified images. 99.7% of brace radiographs were correctly detected, while most of the errors occurred in the reference group (i.e. 2.1% of reference images were wrongly classified). Conclusion The proposed classification model, the originality of which is the coupling of a CNN with discriminant analysis, can be used to automatically label radiographs for the presence of scoliosis treatment. This information is usually missing from DICOM metadata, so such method could facilitate the use of large databases. Furthermore, the same model architecture could potentially be applied for other radiograph classifications, such as sex and presence of scoliotic deformity. Acknowledgements The authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Proteor and Covea).

Purpose: To evaluate the 3D deformity of the acetabula and lower limbs in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with spino-pelvic alignment. Methods: Two hundred and seventy-four subjects with AIS (frontal Cobb: 33.5° ± 18° [10°-110°]) and 84 controls were enrolled. All subjects underwent full-body biplanar X-rays with subsequent 3D reconstructions. Classic spino-pelvic and lower limb parameters were collected as well as acetabular parameters: acetabular orientation in the 3 planes (tilt, anteversion and abduction), center-edge angle (CEA) and anterior and posterior sector angles. Subjects with AIS were represented by both lower limb sides and classified by elevated (ES) or lowered (LS), depending on the frontal pelvic obliquity. Parameters were then compared between groups. Determinants of acetabular and lower limb alterations were investigated among spino-pelvic parameters. Results: Acetabular abduction was higher on the ES in AIS (59.2° ± 6°) when compared to both LS (55.6° ± 6°) and controls (57.5° ± 3.9°, p < 0.001). CEA and acetabular anteversion were higher on the LS in AIS (32° ± 6.1°, 20.5° ± 5.7°) when compared to both ES (28.7° ± 5.1°, 19.8° ± 5.1°) and controls (29.8° ± 4.8°, 19.1° ± 4°, respectively, p < 0.001). Anterior sector angle was lower on both ES and LS in AIS when compared to controls. CEA, acetabular abduction and acetabular anteversion were found to be mostly determined (adjusted R2: 0.08-0.32) by pelvic tilt and less by frontal pelvic obliquity, frontal Cobb and T1T12. Conclusions: Subjects with AIS had a more abducted acetabulum at the lowered side, more anteverted acetabulum and a lack of anterior coverage of both acetabula. These alterations were strongly related to pelvic tilt. This study was funded by the University of Saint-Joseph (Grant No. FM300).

Purpose This in vitro biomechanical study compares residual lumbar range of motion (ROM) and rod strain after lumbopelvic instrumentation using 2 rods, 4 rods and interbody cages. Methods Seven human cadaveric specimens were instrumented from L1 to sacrum, and pelvic screws were implanted. The pelvis was constrained and moments up to 7.5 Nm were applied to T12. Segmental L1–S1 ROM was analyzed by tracking radiopaque balls implanted in each vertebra using biplanar radiographs. Deformation within principal rods was measured by strain gauges. Four configurations were compared: 2 rods (2R), 4 rods (4R), 4 rods + ALIF at L4–L5 and L5–S1 (4R + ALIF), 2 rods + ALIF (2R + ALIF). Results Intact average global L1–S1 ROM was 42.9° (27.9°–66.0°) in flexion–extension (FE), 35.2° (26.8°–51.8°) in lateral bending (LB), 18.6° (6.7°–47.8°) in axial rotation (AR). In FE, average ROM was 1.9° with both 4-rod configurations versus 2.5° with 2R and 2.8° with 2R + ALIF (p < 0.05). In LB, ROM ranged between 1.2° and 1.5° without significant differences. In AR, ROM was 2.5° with both 4-rod configurations versus 2.9° with 2R (p = 0.07) and 3.1° with 2R ALIF (p = 0.01). In FE, strain decreased by 64% and 65% in principal rods at L3–L4 with 4-rod. When comparing 2-rod configurations, strain decreased by 1% in flexion and increased by 22% in extension at L3–L4 when adding an ALIF at L4–L5 and L5–S1. Conclusions Double rods and interbody cages decrease residual ROM in FE and AT. Double rods seem efficient in limiting strain in principal rods. The use of single rods with cages at the lumbosacral junction increases strain at the first adjacent level without cage. A research grant was obtained from the Société Française de Chirurgie Rachidienne (SFCR). Technical and financial support was provided by Clariance.

International audience; Background: The magnetic resonance imaging (MRI) parameters used to diagnose rotator cuff tears are weakly correlated to shoulder function. Our hypothesis was that adding 3-dimensional morphologic parameters resulting from biplanar radiographs (3DXR parameters) to the MRI parameters would improve this correlation.Methods: We assessed 52 patients with rotator cuff tears with an EOS Imaging radiographic examination, MRI study, and clinical evaluation of the shoulder, as well as the Constant score. The bones of the 52 shoulders were reconstructed 3-dimensionally, and eleven 3DXR parameters were automatically extracted. First, the trueness and reliability of these parameters were evaluated. Then, bivariate correlations between each parameter and the Constant score were made. A linear regression model was subsequently built to correlate the 11 parameters and 5 MRI findings with shoulder function at diagnosis, as assessed by the Constant score.Results: The parameters showed good trueness and reliability of most 3DXR parameters. Supraspinatus tear extension, muscle atrophy, and the distance between the greater and deltoid tuberosities were the only parameters with a statistically significant correlation to a lower Constant score (P < .05) in the bivariate study. These correlations were either weak or negligible. A regression model was successfully built with one MRI parameter and four 3DXR parameters. Correlation to function increased from 16.7% to 43.3% with this model.Conclusion: For patients with rotator cuff tears, the combination of MRI and 3DXR parameters of the shoulder in a linear regression model improves the correlation with the Constant score (shoulder function) at diagnosis.

Objective To quantify muscle characteristics (volumes and fat infiltration) and identify their relationship to sagittal malalignment and compensatory mechanism recruitment. Methods Female adult spinal deformity patients underwent T1-weighted MRI with a 2-point Dixon protocol from the proximal tibia up to the T12 vertebra. 3D reconstructions of 17 muscles, including extensors and flexors of spine, hip and knee, were obtained. Muscle volume standardized by bone volume and percentage of fat infiltration (Pfat) were calculated. Correlations and regressions were performed. Results A total of 22 patients were included. Significant correlations were observed between sagittal alignment and muscle parameters. Fat infiltration of the hip and knee flexors and extensors correlated with larger C7-S1 SVA. Smaller spinal flexor/extensor volumes correlated with greater PI-LL mismatch (r = − 0.45 and − 0.51). Linear regression identified volume of biceps femoris as only predictor for PT (R2 = 0.34, p = 0.005) and Pfat of gluteus minimus as only predictor for SVA (R2 = 0.45, p = 0.001). Sagittally malaligned patients with larger PT (26.8° vs. 17.2°) had significantly smaller volume and larger Pfat of gluteus medius, gluteus minimus and biceps femoris, but similar values for gluteus maximus, the hip extensor. Conclusion This study is the first to quantify the relationship between degeneration of spino-femoral muscles and sagittal malalignment. This pathoanatomical study identifies the close relationship between gluteal, hamstring muscles and PT, SVA, which deepens our understanding of the underlying etiology that contributes to adult spinal deformity. The manuscript submitted does not contain information about medical device(s)/drug(s). This work received funding from Youth Fund of Natural Science Foundation of Jiangsu Province (BK20180122). This work received funding from Key Project supported by Medical Science and Technology Development Foundation, Nanjing Department of Health (YKK18092).

Introduction In children treated for idiopathic equinovarus clubfoot (EVCF), the relation between morphologic defects on clinical examination and standard X-ray on the one hand and functional abnormalities on the other is difficult to objectify. The aim of the present study was to demonstrate the feasibility of combined 3D analysis of the foot and lower limb based on biplanar EOS radiographs and gait analysis. The study hypothesis was that this provides better understanding of abnormalities in form and function. Methods Ten children with unilateral EVCF and “very good” clinical results were included. They underwent gait analysis on the Rizzoli Institute multisegment foot model. Kinematic data were collected for the hip, knee, ankle and foot (hindfoot/midfoot, midfoot/forefoot and hindfoot/forefoot). Biplanar EOS radiographs were taken to determine anatomic landmarks and radiological parameters. Results Complete acquisition time was around 2 hours per patient. No significant differences were found between EVCF and healthy feet except for calcaneal incidence, tibiocalcaneal angle and hindfoot/midfoot and hindfoot/forefoot inversion. Discussion The feasibility of the combined analysis was confirmed. There were no differences in range of motion, moment or power between EVCF and healthy feet in this series of patients with very good results. The functional results are related to radiological results within the normal range. The protocol provided anatomic and kinematic reference data. A larger-scale study could more objectively assess the contribution of EOS radiography using optoelectronic markers. Level of evidence II, low-power prospective study. The authors thank Chaire ParisTech BiomecAM (personalized musculoskeletal modeling) for financial help.

International audience; Introduction While the clinical impact of coronal and sagittal alignment in adult spinal deformity (ASD) patients (pts) is established, there is a paucity of data in terms of axial plane deformity and potential association between muscle degenera- tion and 3D deformity. The purpose of this study was to analyze spinopelvic muscles characteristics in association with the 3D deformity of ASD patients. Methods This is a prospective cohort study; primary lumbar scoliosis patients (Cobb > 20°) were enrolled and sustained a low-dose X-rays with 3D spinal reconstructions and a fat/water separation MRI (from C7 to the knee). Volumetric 3D reconstructions and fat infiltration (FI) of 6 muscles groups were performed. Relationships between muscular data, radio- graphic parameters and health-related quality of life were investigated. Patients were stratified and compared based on the SRS classification, the odontoid-hip axis (ODHA) angle (> or < 6.1°) and occurrence of rotatory subluxation. Results and discussion Twenty-eight patients were enrolled with a mean age of 60 ± 16yo and mean body mass index of 26 ± 4 kg/m2 without differences between groups. There were a moderate sagittal malalignment and a Cobb angle of 45 ± 11° (table). Muscular volume was smaller in patients with more severe deformity (p > 0.05). Pts with ODHA > 6.1° or pelvic incidence minus lumbar lordosis > 10° had significantly higher FI for the 6 muscular groups, patients with pelvic tilt > 20° had significantly higher FI for erector spinae, hip flexors and extensors (p < 0.05). SF36-PCS significantly correlated with the muscular volume; SRS and Oswestry disability index correlated with the erectors spinae volume (p < 0.05). Conclusion This study analyzed for the first time the relationship between 3D radiographic parameters and muscular charac- teristics in ASD. Sagittal malalignment is associated with increased FI and decreased muscle volumes with poor outcomes.

Purpose The origin of the deformity due to adolescent idiopathic scoliosis (AIS) is not known, but mechanical instability of the spine could be involved in its progression. Spine slenderness (the ratio of vertebral height to transversal size) could facilitate this instability, thus playing a role in scoliosis progression. The purpose of this work was to investigate slenderness and wedging of vertebrae and intervertebral discs in AIS patients, relative to their curve topology and to the morphology of control subjects. Methods A total of 321 AIS patients (272 girls, 14 ± 2 years old, median Risser sign 3, Cobb angle 35° ± 18°) and 83 controls were retrospectively included (56 girls, median Risser 2, 14 ± 3 years). Standing biplanar radiography and 3D reconstruction of the spine were performed. Geometrical features were computed: spinal length, vertebral and disc sizes, slenderness ratio, frontal and sagittal wedging angles. Measurement reproducibility was evaluated. Results AIS girls before 11 years of age had slightly longer spines than controls (p = 0.04, Mann–Whitney test). AIS verte- brae were significantly more slender than controls at almost all levels, almost independently of topology. Frontal wedging of apical vertebrae was higher in AIS, as expected, but also lower junctional discs showed higher wedging than controls. Conclusion AIS patients showed more slender spines than the asymptomatic population. Analysis of wedging suggests that lower junctional discs and apex vertebra could be locations of mechanical instability. Numerical simulation and longitudinal clinical follow-up of patients could clarify the impact of wedging, slenderness and growth on the biomechanics of scoliosis progression. The authors are grateful to the BiomecAM chair programme on subject-specific musculoskeletal modelling (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Covea and Proteor) and to the DHU MAMUTH for funding.

International audience; Purpose: To determine the short-term effect of bracing of adolescent idiopathic scoliotic (AIS) patients on the relationships between spinopelvic parameters related to balance, by comparing their in and out-of-brace geometry and versus healthy subjects. Methods: Forty-two AIS patients (Cobb angle 29° ± 12°, ranging from 16° to 61°) with a prescription of orthotic treatment were included retrospectively and prospectively. They all underwent biplanar radiography and 3D reconstruction of the spine and pelvis before bracing as well as less than 9 months after bracing. Eighty-three age-matched healthy adolescents were also included as control group and underwent biplanar radiography and 3D reconstruction. Results: Sacral slope was higher in AIS than healthy patients (p = 0.005). Bracing induced large changes of pelvic tilt (between - 9° and 9°), although patients' sagittal spinopelvic alignment tended to remain within the normality corridors defined by the healthy patients. Patients had flatter backs compared to healthy subjects and bracing further reduced their spinal curves. The head tended to remain above the pelvis in-brace. Conclusion: Analysis of sagittal alignment from head to pelvis showed that bracing further flattened the patients' backs and induced large compensating reorientations of the pelvis. Sagittal balance should be included in the planning and evaluation of brace treatment, since it could play a role in its outcome. These slides can be retrieved under Electronic Supplementary Material.

Background Existing imaging techniques and single-parameter analyses, in nonfunctional positions, fail to detect the differences between patients with good vs poor results after total hip arthroplasty. Methods The present study developed an analysis method using the EOS full-body, low-dose, biplanar, weightbearing imaging system to compare good vs poor patients after total hip arthroplasty and to report on our preliminary experiences (17 good, 18 poor). Results All revision cases were found to have at least 4 high or low implant or anatomic parameters relative to the good group. These included acetabular cup orientation, sagittal pelvic tilt, sacral slope, femoral offset, and neck–shaft angle. Acetabular cup orientation differed significantly between groups. Conclusion With the EOS system, a large cohort can be studied relatively quickly and at low dose, which could lead to patient-specific guidelines.

BACKGROUND CONTEXT Adults with spinal deformity (ASD) are known to have postural malalignment affecting their quality of life. Classical evaluation and follow-up are usually based on full-body static radiographs and health related quality of life questionnaires. Despite being an essential daily life activity, a formal gait assessment is lacking in clinical practice. Moreover, gait alterations and their relationships with static deformities in ASD still remain to be elucidated PURPOSE To investigate gait alterations in subjects with ASD and their static radiographic determinants. STUDY DESIGN/SETTING Prospective Single Center. PATIENT SAMPLE A total of 52 Adult Spinal Deformity patients, and 63 control subjects. OUTCOME MEASURES Full body image, 3D gait analysis. METHODS A total of 52 Adult Spinal Deformity (ASD) patients age and weight-matched to 63 controls underwent full-body 3D gait analysis with extraction of 3D lower limb and trunk kinematics. All subjects underwent full-body biplanar X-rays with subsequent calculation of classical 3D postural parameters. Kinematics and postural parameters were compared between ASD and controls. Determinants of gait alterations among postural radiographic parameters were explored in ASD. RESULTS ASD subjects had significantly increased SVA (33.6±59 vs -4.6±20mm), CAM-HA (12±62 vs -21±26mm), PT (19±13 vs 11±6°), frontal Cobb (25±21 vs 4±6°) compared to controls (all p CONCLUSIONS Subjects with ASD are known to have spinal malalignment causing postural alterations such as forward bending of the trunk; they also recruit compensatory mechanisms in the pelvis and lower limbs by increasing radiographic pelvic tilt and knee flexion. This study showed that static compensations in the lower limbs persist during gait where ASD patient exhibit a flexed attitude at the trunk, hips and knees, a reduced hip mobility and loss of lordosis. ASD walked at a slower pace with an elevation of their single support time that might contribute to their stability while walking. These dynamic discrepancies were shown to be strongly related to skeletal radiological alterations, specifically the increased forward shift of the head and trunk, the pelvic retroversion and the lack of lumbar lordosis. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Various spinal and rib cage parameters measured from complex examinations were found to be correlated with preoperative pulmonary function tests (PFT). The aim was to investigate the relationship between preoperative rib cage parameters and PFT using biplanar stereoradiography in patients with severe adolescent idiopathic scoliosis. Fifty-four patients, 45 girls and nine boys, aged 13.8 ± 1.2 years, with Lenke 1 or 2 thoracic scoliosis (> 50°) requiring surgical correction were prospectively included. All patients underwent preoperative PFT and low-dose biplanar X-rays. The following data were collected: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, residual volume, slow vital capacity (SVC), total lung capacity (TLC), rib cage volume (RCV), maximum rib hump, maximum width, mean thoracic index, spinal penetration index, apical vertebral rotation, main curve Cobb angle (MCCA), T4–T12 kyphosis. The primary outcome was the relationship between rib cage parameters and PFT. The secondary outcome was the relationship between rib cage parameters and spine parameters. Data were analyzed using Spearman’s rank test. A multivariable regression analysis was performed to compare PFTs and structural parameters. Significance was set at α = 0.05. The mean MCCA was 68.7° ± 16.7°. RCV was highly correlated with all pulmonary capacities: TLC (r = 0.76, p

Purpose Measurement of vertebral axial rotation (VAR) is relevant for the assessment of scoliosis. Stokes method allows estimating VAR in frontal X-rays from the relative position of the pedicles and the vertebral body. This method requires identifying these landmarks for each vertebral level, which is time-consuming. In this work, a quasi-automated method for pedicle detection and VAR estimation was proposed. Method A total of 149 healthy and adolescent idiopathic scoliotic (AIS) subjects were included in this retrospective study. Their frontal X-rays were collected from multiple sites and manually annotated to identify the spinal midline and pedicle positions. Then, an automated pedicle detector was developed based on image analysis, machine learning and fast manual identification of a few landmarks. VARs were calculated using the Stokes method in a validation dataset of 11 healthy (age 6–33 years) and 46 AIS subjects (age 6–16 years, Cobb 10°–46°), both from detected pedicles and those manually annotated to compare them. Sensitivity of pedicle location to the manual inputs was quantified on 20 scoliotic subjects, using 10 perturbed versions of the manual inputs. Results Pedicles centers were localized with a precision of 84% and mean difference of 1.2 ± 1.2 mm, when comparing with manual identification. Comparison of VAR values between automated and manual pedicle localization yielded a signed difference of − 0.2 ± 3.4°. The uncertainty on pedicle location was smaller than 2 mm along each image axis. Conclusion The proposed method allowed calculating VAR values in frontal radiographs with minimal user intervention and robust quasi-automated pedicle localization. The authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modeling for funding (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Proteor and Covea).

Study Design Cross-sectional and longitudinal retrospective study. Objectives To measure thoracic dimensions and volume during growth in early-onset idiopathic scoliosis (EOIS) patients and to compare them to a population of asymptomatic adults and to the previous literature. Summary of Background Data Data on trunk growth for scoliotic children between 6 and 14 years of age is sparse in the literature. Methods Thirty-six patients (29 girls and 7 boys, between 3 and 14 years old, average Cobb angle 33°±15°) were included, all with a minimum two-year follow-up. Sixty-one asymptomatic girls and 54 asymptomatic adults were included as control groups. All subjects underwent biplanar radiography and 3D reconstruction of the spine, pelvis, and rib cage. EOIS patients repeated their radiologic examination every six months. Cobb angle, rib cage volume, anteroposterior and transverse diameters, thoracic index, thoracic perimeter, pelvic incidence, and T1–T12 and T1–S1 distance were calculated. Reproducibility of measurement was assessed. Results Measurement reliability in such young patients was comparable to previous studies in adolescents and adults. Geometrical parameters of EOIS patients increased linearly with age. For instance, rib cage volume in girls with EOIS increased from 2200 cm3 at six to seven years of age to 4100 cm3 at 13–14 years (65% of adult values, 294 cm3/y). Comparison with asymptomatic girls showed that EOIS could affect growth spurt. Longitudinal analysis on a cohort of six girls who had a follow-up of six years confirmed the cross-sectional data. Conclusions In this longitudinal and cross-sectional study, trunk growth between 3 and 14 years of age was characterized, for the first time, with biplanar radiography and 3D reconstruction. The results can be useful to estimate patient growth and thus have potential application in the surgical planning of EOIS patients. Level of Evidence Level II, retrospective study.

Background The physical examination and weight-bearing radiography are the two main available methods for assessing the feet and lower limbs. The anatomy and function of these two structures interact with each other. These two assessment methods are affected by subjectivity and projection bias. Low-dose biplanar radiography (LDBR) is now a promising alternative for evaluating the lower limbs in children. At present, however, the foot cannot be assessed using LDBR. The objective of this study was to work towards developing a new method for 3D radiographic analysis of the paediatric foot during weight-bearing, first by determining the reproducibility of landmarks defined by LDBR then by reporting the values of the calculated radiographic parameters. Hypothesis A new radiographic method based on LDBR can be used to obtain a 3D evaluation of the foot in paediatric patients. Patients and methods Two biplanar radiographs in perpendicular planes were obtained simultaneously in a standardised position using the EOS system (EOS® Imaging, Paris, France) in each of 10 healthy children. To assess measurement uncertainty, two observers performed 3D reconstructions of each of the 10 feet three times (60 reconstructions). The standard error of reproducibility of the anatomic landmarks and clinical parameters was computed. Measurement uncertainty was then estimated based on the 95% confidence interval (95%CI). To obtain reference values, the mean ± SD of each variable was computed after checking that the data were normally distributed. Results Reproducibility was high for the anatomical landmarks of interest, calcaneal pitch angle, tibio-calcaneal angle on the lateral view, and first metatarsal pitch angle (95%CI Discussion and conclusion The data reported here pave the way towards developing new parameters for describing 3D foot morphology and for simultaneously assessing the lower limb and foot in the standing position. Level of evidence I.

Resume Introduction Caracteriser la fonction femoropatellaire a l’aide de criteres cinematiques est essentiel a sa comprehension, a son evaluation et a son suivi. Le but etait d’evaluer une methode d’analyse 3D sequentielle par radiographies biplanaires a partir d’un protocole in vitro. Hypothese L’utilisation d’un systeme d’imagerie biplanaire associe a de nouvelles methodes de reconstruction 3D permet une analyse femoropatellaire fiable, sans imagerie prealable. Materiel et methodes Huit pieces anatomiques ont ete etudiees au cours de cycles de flexion de genou de 0 a 60° par un simulateur in vitro. La validation du protocole comprenait une evaluation du mouvement sequentiel et continu a l’aide d’un systeme optoelectronique, une analyse de la precision et de la reproductibilite des mesures a partir de billes metalliques inserees dans la patella, ainsi qu’une verification de la geometrie patellaire 3D comparativement a des acquisitions tomodensitometriques. Resultats Les differences de position entre cinematique sequentielle et continue etaient inferieures a 1 mm et 1°. Certaines composantes de mouvement pouvaient etre suivies de maniere fiable : les translations, la flexion et la bascule patellaires. Cette analyse rapportait une incertitude inferieure a 2 mm pour les translations et a 3° pour les rotations, a l’exception de la rotation frontale. L’incertitude autour de la bascule patellaire etait de 5°. La difference moyenne de geometrie etait de 0,49 mm. Discussion L’analyse sequentielle est coherente avec la cinematique continue. Cette methode d’analyse fournit au clinicien des parametres positionnels de la patella sans imagerie scanner ou IRM prealable. Une etude clinique reste a envisager pour l’identification de profils cinematiques femoropatellaires et de criteres positionnels in vivo. Niveau de preuve IV (etude experimentale).

Introduction: In degenerative adult spinal deformity (ASD), sagittal malalignment and rotatory sublux-ation (RS) correlate with clinical symptomatology. RS is defined as axial rotation with lateral listhesis.Stereoradiography, recently developed for medical applications, provides full-body standing radiographsand 3D reconstruction of the spine, with low radiation dose.Hypothesis: 3D stereoradiography improves analysis of RS and of its relations with transverse plane andspinopelvic parameters and clinical impact.Material and methods: One hundred and thirty adults with lumbar ASD and full-spine EOS®radiographs(EOS Imaging, Paris, France) were included. Spinopelvic sagittal parameters and lateral listhesis in thecoronal plane were measured. The transverse plane study parameters were: apical axial vertebral rotation(apex AVR), axial intervertebral rotation (AIR) and torsion index (TI). Two groups were compared: with RS(lateral listhesis > 5 mm) and without RS (without lateral listhesis exceeding 5 mm: non-RS). Correlationsbetween radiologic and clinical data were assessed.Results: RS patients were significantly older, with larger Cobb angle (37.4◦vs. 26.6◦, P = 0.0001), moresevere sagittal deformity, and greater apex AVR and TI (respectively: 22.9◦vs. 11.3◦, P < 0.001; and 41.0◦vs. 19.9◦, P < 0.001). Ten percent of patients had AIR > 10◦without visible RS on 2D radiographs. RS patientsreported significantly more frequent low back pain and radiculalgia.Discussion: In this EOS®study, ASD patients with RS had greater coronal curvature and sagittal and trans-verse deformity, as well as greater pain. Further transverse plane analysis could allow earlier diagnosisand prognosis to guide management.Level of evidence: 4, retrospective study. Master’s grant from the French Orthopedic and Traumatologic Surgery Society (SOFCOT), without which this research would not have been possible.

Resume Introduction Dans la scoliose degenerative de l’adulte (SDA), le defaut d’alignement sagittal et la dislocation rotatoire sont correles aux symptomes cliniques. La dislocation rotatoire est definie comme une rotation axiale avec listhesis lateral. La stereoradiographie, recemment developpee pour l’utilisation medicale, permet l’obtention d’image du corps entier, en position erigee avec la modelisation tridimensionnelle du rachis, a faible dose de radiation. Hypothese Notre hypothese etait de pouvoir mieux analyser la dislocation rotatoire et les relations entre listhesis lateral, parametres du plan transverse, parametres spinopelviens et le retentissement clinique, grâce a la stereoradiographie 3D. Materiel et methodes Cent trente adultes avec scolioses lombaires et radiographies EOS® (EOS Imaging, Paris, France) du rachis entier etaient inclus. Les parametres sagittaux spinopelviens et le listhesis lateral dans le plan coronal etaient mesures. Les parametres du plan transverse etudies etaient : rotation vertebrale apicale (AVR apex), rotation axiale intervertebrale (AIR) et index de torsion. Deux groupes de patients etaient compares : avec au moins un listhesis de plus de 5 mm (listhesis) ou sans aucun listhesis de plus de 5 mm (sans listhesis). Les correlations radiocliniques etaient etudiees. Resultats Les patients avec listhesis etaient significativement plus âges avec un angle de Cobb plus important (37,4° vs. 26,6°, p = 0,0001) et une plus grande deformation sagittale. Les patients avec listhesis avaient une AVR apex et un index de torsion significativement plus eleves que les patients sans listhesis (respectivement : 22,9° vs. 11,3°, p 10° sans listhesis visible sur la radiographie 2D. Les patients avec listhesis avaient significativement plus de lombalgies et de radiculalgies. Discussion Dans cette etude avec EOS®, les patients avec SDA et listhesis lateral ont une courbure coronale ainsi qu’une deformation sagittale et du plan transverse plus importantes. Ils presentent egalement plus de symptomatologie douloureuse. La poursuite de l’etude du plan transverse chez ces patients pourrait permettre un diagnostic et un pronostic plus precoces de la deformation afin d’adapter la therapeutique. Niveau de preuve 4, etude retrospective.

To design a quasi-automated three-dimensional reconstruction method of the spine from biplanar X-rays as the daily used method in clinical routine is based on manual adjustments of a trained operator and the reconstruction time is more than 10 min per patient. The proposed method of 3D reconstruction of the spine (C3–L5) relies first on a new manual input strategy designed to fit clinicians’ skills. Then, a parametric model of the spine is computed using statistical inferences, image analysis techniques and fast manual rigid registration. An agreement study with the clinically used method on a cohort of 57 adolescent scoliotic subjects has shown that both methods have similar performance on vertebral body position and axial rotation (null bias in both cases and standard deviation of signed differences of 1 mm and 3.5° around, respectively). In average, the solution could be computed in less than 5 min of operator time, even for severe scoliosis. The proposed method allows fast and accurate 3D reconstruction of the spine for wide clinical applications and represents a significant step towards full automatization of 3D reconstruction of the spine. Moreover, it is to the best of our knowledge the first method including also the cervical spine. These slides can be retrieved under electronic supplementary material.

International audience; Study design: A reproducibility study of preoperative rib cage 3D measurements was conducted for patients with Adolescent Idiopathic Scoliosis (AIS).Objective: to assess the reliability of rib cage 3D reconstructions using biplanar stereoradiography in patients with AIS before surgery.Summary: no prior reliability study has been performed for preoperative 3D reconstructions of the rib cage by using stereoradiography in patients with preoperative AIS. Materials: this series includes 21 patients with Lenke 1 or 2 scoliosis (74°+ - 20). All patients underwent low-dose standing biplanar radiographs. Two operators performed reconstructions twice each. Intraoperator repeatability, interoperator reproducibility and Intraclass coefficients (ICC) were calculated and compared between groups. Results: The average rib cage volume was 4.7l L (SD ± 0.75 L). SDr was 0.19 L with a coefficient of variation of 4.1% ; ICC was 0.968. The thoracic index was 0.6 (SD ± 0.1). SDr was 0.03 with a coefficient of variation of 4.7 % and a ICC of 0.820. As for the Spinal Penetration Index (6.4% ; SD ± 2.4), SDr was 0.9 % with a coefficient of variation of 14.3 % and a ICC of 0.901. The 3D rib hump SDr (average 27° ± 8°) was 1.4°. The coefficient of variation and ICC were respectively 5.1% and 0.991.Conclusion: 3D reconstruction of the rib cage using biplanar stereoradiography is a reliable method to estimate preoperative thoracic parameters in patients with AIS.

Background: Adolescent idiopathic scoliosis (AIS) can require surgical procedures that have major con-sequences. Coronal imbalance as assessed clinically using a plumb line is a key criterion for selecting patients to surgery. Nevertheless, the reference standard for assessing postural balance of the trunk is gravity line localisation within a validated frame of reference. Recent studies have established that the gravity line can be localised after body contour reconstruction from biplanar radiographs. The objec-tive of this study was to validate a gravity line localisation method based on biplanar radiographs in a population with AIS then to validate gravity line position versus plumb line position. Hypothesis: Plumb line and gravity line assessments of coronal balance correlate with each other. Material and methods: A gravity line localisation method based on biplanar radiography was validated in 14 patients with AIS versus force platform as the method of reference. Normal plumb line and gravity line positions were determined in 27 asymptomatic adolescents using biplanar radiography. The results of the two methods were then compared in 53 patients with AIS. Results: The reliability of gravity line localisation in the coronal plane based on biplanar radiography was 2.4 mm (95% confidence interval). The distance between the gravity line and the middle of the line connecting the centres of the two femoral heads (HA) showed a strongly significant association with plumb line position computed as the distance from the vertical line through the middle of T1 and the centre of the S1 endplate (T1V/S): r = 0.71, p < 0.0001. Of the 20 patients with plumb line results indicating coronal imbalance, 11 (55%) had a normal gravity line-to-HA distance. Of the 33 patients with normal plumb line results, 7 (21%) had an abnormal gravity line-to-HA distance. Conclusion: The results of this study validate gravity line determination from biplanar radiographs in a population with AIS. Plumb line position correlated significantly with gravity line position but was less accurate for guiding surgical decisions. Level of evidence: IV, retrospective study. Funding source SoFCOT grant to remunerate T. Hernandez during the year of research required for the project.

International audience; Aim: To estimate the effect of patients' axial rotation (AR) during pelvic radiograph acquisition, on the reliability and validity of sagittal pelvic parameters.Materials and methods: Lateral digitally reconstructed radiographs (LDRRs) were obtained from the pelvic computed tomography (CT) scans of eight children and nine adults. Then, the AR of the pelvis was simulated and the corresponding LDRRs were reconstructed at 5°, 10°, 15°, and 20° of the AR. Pelvic parameters were measured digitally on each radiograph. Intra- and interobserver variability were evaluated at each AR position (three operators repeated the measurements three times each). The bias on each clinical parameter, in each AR position, was calculated relatively to the 0° position.Results: Interobserver variability increased similarly in children and adults with AR. It reached 4.4° for pelvic incidence and 4.7° for the sacral slope at 20° of AR. Biases on radiological parameters increased with AR and exceeded the acceptable threshold of errors when AR reached 10°. A linear regression was established (R2=0.834, p

BACKGROUND CONTEXT Early-onset idiopathic scoliosis (EOIS) management needs a long follow-up during the entire patient growth. The very young patient's age at the diagnosis can expose them to high cumulated radiation doses. Low-dose radiographs allow high-quality view of the spine in standing position. Accuracy and reproducibility of digital measurements of Cobb angle have already been assessed in adults and adolescents. Nevertheless, reliability of Cobb angle measurement has not been evaluated in EOIS follow-up PURPOSE Low dose stereoradiography could be a minimally invasive way to evaluate early-onset scoliosis before six years of age. STUDY DESIGN/SETTING Prospective data collection. PATIENT SAMPLE Forty-one patients younger than 6 years with thoracic or thoracolumbar scoliosis were evaluated. Patients with spine congenital abnormalities were excluded. OUTCOME MEASURES Intra- and interoperator reliability of 2D Cobb angle measurement in EOIS low-dose radiographs. METHODS Patients underwent low-dose standing radiographs. Three operators independently measured Cobb angles on two separate occasions. A fourth trained operator had previously labeled the superior and inferior limits vertebrae to avoid a potential source of uncertainty unrelated to low-dose radiography. Interoperator reproducibility, intraoperator repeatability and intraclass correlation coefficients (ICC) were calculated. Bland-Altmann plot was used to present the limits of agreement. RESULTS The mean age was 4.4 years (SD 0.8 years, range 2.2-5.8). Average Cobb angle was 22° (SD 9°, range 11-80°). ICCs were higher than 0.98 for all three operators, showing an excellent agreement. Reproducibility and repeatability were respectively of 1.2° (coefficient of variation: 4.5 %) and 0.8° (coefficient of variation 3.2%). Measurements were easily feasible in all cases. There was no effect of age or curve severity on uncertainty. CONCLUSIONS EOIS management includes bracing or surgical growth-friendly techniques. These require multiple radiological assessments responsible for a significant cumulative radiation exposure. Cobb angle measurements on low-dose radiographs showed an excellent reproducibility despite bone immaturity. Clinical follow-up could be done with this low-dose technique. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Background context Facet supplementation stabilizes after facetectomy and undercutting laminectomy. It is indicated in degenerative spondylolisthesis with moderate disc degeneration and dynamic stenosis. Purpose To determine the influence of an auxiliary facet system (AFS) on the instrumented disc, adjacent levels' discs, and facet joints and to compare it with fusion. Study design Finite element study. Methods L3–L4, L4–L5, and L5–S1 were studied using a validated finite element model with prescribed displacements for an intact spine, lesion by facetectomy and undercutting laminectomy, AFS, and fusion at L4–L5. The distribution of segmental range of motion (ROM) and applied moments, von Mises stress at the annulus, and facet joint contact forces were calculated with rotations in all planes. Institutional support for implant evaluation and modeling was received by Clariance. Results In flexion-extension and lateral bending, fusion decreased L4–L5 ROM and increased adjacent levels' ROM. Range of motion was similarly distributed with intact lesion and AFS. In axial rotation, L4–L5 ROM represented 33% with intact, 55% after lesion, 25% with AFS, and 21% with fusion. Fusion increased annulus stress at adjacent levels in flexion-extension and lateral bending, but decreased stress at L4–L5 compared with AFS. In axial rotation, von Mises stress was similar with fusion and AFS. Facet loading increased in extension and lateral bending with fusion. It was comparable for fusion and AFS in axial rotation. Conclusions This study suggests that the AFS stabilizes L4–L5 in axial rotation after facetectomy and undercutting laminectomy as fusion does. This is because of the cross-link that generates an increased annulus stress in axial rotation at adjacent levels. With imposed displacements, without in vivo compensation of the hips, the solicitation at adjacent levels' discs and facet joints is higher with fusion compared with AFS. Fusion decreases intradiscal stress at the instrumented level.

The spinal penetration index (SPI) quantifies the portion of the rib cage occupied by vertebrae. When measured by computed tomography (CT) or magnetic resonance imaging, SPI can only be determined in the reclining position, which modifies spinal and thoracic morphology. CT results in high radiation exposure. The authors studied rib cage and spinal morphology using low-dose biplanar stereoradiography and their impact on respiratory function in adolescent idiopathic scoliosis (AIS).In eighty thoracic AIS patients, a slot-scanning radiologic device allowing simultaneous acquisition of orthogonal images and 3D reconstructions with low exposure to radiation (EOS) was used to determine thoracic volume, mean spinal penetration index (SPIm), apical spinal penetration index (SPIa), main thoracic (MT) curve Cobb angle, T4-T12 kyphosis, and apical vertebral rotation (AVR).Thoracic volume was correlated with thoracic kyphosis (r = 0.31, p = 0.006), but not with SPI, MT Cobb angle, or AVR. SPIm and SPIa were negatively correlated with thoracic kyphosis. Forced vital capacity and forced expiratory volume in 1 s were significantly lower in the hypokyphotic patients (p = 0.04, p = 0.03, respectively) and correlated with thoracic volume and T4-T12 kyphosis. No correlation was found between spinal penetration indices and pulmonary function tests, but SPIm was significantly greater in patients with obstructive syndrome (p = 0.01).With little radiation exposure, EOS biplanar stereoradiography permits routine imaging is a functional standing position. Hypokyphotic patients had significantly decreased FEV1 and FVC. SPIm was significantly higher in patients with obstructive syndrome.

We have evaluated the effect of bracing in scoliosis on coronal alignment in a cohort of patients. Current literature has not described the specific effect of bracing on the 3D shape of the scoliotic curves. The purpose of this study was to analyze the variability of the 3D effect of bracing on idiopathic scoliosis.The spines of 30 patients with adolescent idiopathic scoliosis were reconstructed using biplanar stereoradiography with and without the brace. The Cobb angle, sagittal and pelvic parameters and transverse plane parameters were calculated. The variability and the mean values of each parameter, with and without a brace, were analyzed and compared using a student t test.The Cobb angle improved in 50% of patients but remained unchanged in 50% cases. In 90% of the cases lordosis was decreased. The thoracic kyphosis was decreased in 26% cases, unchanged in 57% of cases and increased in 17% cases. The AVR was improved (5°) in 26% cases, worsened in 23% and unchanged in 50%. Only the differences of Cobb angle and the lordosis were statistically significant.Global statistics of this study concur with the literature. The Cobb angle was significantly improved. It also showed a significant hypolordotic effect. However, the results showed a high variability of the brace treatment effect in almost every parameter. Analysis of this variability by means of 3D reconstructions instead of global statistics should help characterize the mechanisms of correction of brace treatment.

Purpose To establish a new imaging technique using dynamic MRI three-dimensional (3D) volumetric acquisition in real-time, on six normal shoulders for the analysis of the 3D shoulder kinematics during continuous motion. Materials and Methods At first, a standard static acquisition was performed. Then, fast images were obtained with a multi-slice 3D balanced gradient echo sequence to get a real time series during the initial phase of shoulder abduction. Subsequently, the images were reconstructed; registered and the translational patterns of the humeral head relative to the glenoid and the size of the subacromial space were calculated. Additionally, the intraobserver reproducibility was tested. Results The maximal abduction was on average 43° (30° to 60°) and the mean width of the subacromial space was 7.7 mm (SD: ± 1.2 mm). Difference between extreme values and average values was low, respectively 2.5 mm on X-axis, 2 mm on Y-axis, 1.4 mm for the width of the subacromial space and 1.2° for the measure of the glenohumeral abduction. Conclusion This study reported a dynamic MRI protocol for the monitoring of shoulder 3D kinematics during continuous movement. The results suggest that there is no superior shift of the humeral head during the first phase of abduction. J. Magn. Reson. Imaging 2014;39:729–734. © 2013 Wiley Periodicals, Inc.