Combined 3D analysis of lower-limb morphology and function in children with idiopathic equinovarus clubfoot: A preliminary study

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

Combined gait analysis and radiologic examination in children with X-linked hypophosphatemia

Autre financement : Kyowa Kirin PharmaBackground: X-linked hypophosphataemia causes bone deformities and gait abnormalities that tend to worsen with age in the absence of appropriate treatment. However, doctors do not currently use quantitative tools to characterize these symptoms and their possible interactions. Methods: Radiographs and 3D gait data from 43 non-surgical growing children with X-linked hypophosphataemia were acquired prospectively. Data from age-matched typically developing children were used to form the reference group. Subgroups based on radiological parameters were compared with each other and with the reference population. Linear correlations between radiographic parameters and gait variables were examined. Finding: X-linked hypophosphatemic patients differed from the control group in pelvic tilt, ankle plantarflexion, knee flexion moment and power. High correlations with tibiofemoral angle were found for trunk lean, knee and hip adduction, and knee abduction moment. The Gait Deviation Index was below 80 for 88% of the patients with a high tibiofemoral angle (varus). Compared to other subgroups, varus patients had augmented trunk lean (+3°) and knee adduction (+10°) and decreased hip adduction (-5°) and ankle plantarflexion (-6°). Femoral torsion was associated with alterations in rotation at the knee, and hip. Interpretation: Gait abnormalities induced in X-linked hypophosphataemia have been described in a large cohort of children. Links between gait alterations and lower limb deformities were found, with varus deformities standing out. Since bony deformities appear when X-linked hypophosphatemic children start walking and have been found to alter gait patterns, we suggest that combining radiology with gait analysis may improve the clinical management of X-linked hypophosphataemia

Analyse prospective et biomécanique de la marche et des déformations osseuses chez les patients atteints de rachitisme hypophosphatémique lié au chromosome X

X-linked hypophosphatemic rickets (XLH) is a rare disease affecting the musculoskeletal system and lower limb function. Most of the symptoms of XLH have a strong impact on the daily life of patients but can be minimized during growth with adapted treatment. To date, only a qualitative assessment of the physical symptoms of XLH is possible. This thesis aims to define a protocol for the quantitative evaluation of XLH and its evolution during growth for the lower limbs. The first part deals with the 3D study of the skeleton. It shows that the femoral shaft is particularly affected. In follow-up we see that the mechanical angles normalize first under the effect of the treatment, the femur and the tibia evolving together. A second part focusing on the quantitative gait analysis shows that the alterations mainly concern the frontal plane and that they are linked to bone deformities. A final part, dealing with muscles, highlights an alteration in composition and muscle atrophy in patients with XLH which may explain the muscle weakness observed. By combining these three examinations, the protocol proposed in this thesis makes it possible both to quantify the alterations of the musculoskeletal system and of gait in children with XLH and to improve our understanding of the existing interactions between these three elements.Le rachitisme hypophosphatémique lié au chromosome X (XLH) est une maladie rare touchant le système musculosquelettique et la fonction des membres inférieurs. La plupart des symptômes du XLH ont un impact fort sur le quotidien des patients mais peuvent être minimisés lors de la croissance sous l’effet d’un traitement adapté. A ce jour, seule une appréciation qualitative des symptômes physiques du XLH est possible. Cette thèse vise à définir un protocole d’évaluation quantitative du XLH et de son évolution durant la croissance pour les membres inférieurs. La première partie porte sur l’étude 3D du squelette. On y montre que la diaphyse fémorale est particulièrement touchée. En suivi on voit que les angles mécaniques se normalisent en premiers sous l’effet du traitement, le fémur et le tibia évoluant au même rythme. Une deuxième partie sur l’analyse quantifiée de la marche montre que les altérations concernent principalement le plan frontal et qu’elles sont liées aux déformations osseuses. Une dernière partie, consacrée aux muscles, met en avant une altération de la composition et une atrophie musculaire chez les patients avec XLH pouvant expliquer la faiblesse musculaire observée. En combinant ces trois examens, le protocole proposé dans cette thèse permet à la fois de quantifier les altérations du système musculosquelettique et de la marche chez des enfants avec XLH et d’améliorer notre compréhension des interactions existantes entre ces trois éléments

Analyse prospective et biomécanique de la marche et des déformations osseuses chez les patients atteints de rachitisme hypophosphatémique lié au chromosome X

X-linked hypophosphatemic rickets (XLH) is a rare disease affecting the musculoskeletal system and lower limb function. Most of the symptoms of XLH have a strong impact on the daily life of patients but can be minimized during growth with adapted treatment. To date, only a qualitative assessment of the physical symptoms of XLH is possible. This thesis aims to define a protocol for the quantitative evaluation of XLH and its evolution during growth for the lower limbs. The first part deals with the 3D study of the skeleton. It shows that the femoral shaft is particularly affected. In follow-up we see that the mechanical angles normalize first under the effect of the treatment, the femur and the tibia evolving together. A second part focusing on the quantitative gait analysis shows that the alterations mainly concern the frontal plane and that they are linked to bone deformities. A final part, dealing with muscles, highlights an alteration in composition and muscle atrophy in patients with XLH which may explain the muscle weakness observed. By combining these three examinations, the protocol proposed in this thesis makes it possible both to quantify the alterations of the musculoskeletal system and of gait in children with XLH and to improve our understanding of the existing interactions between these three elements.Le rachitisme hypophosphatémique lié au chromosome X (XLH) est une maladie rare touchant le système musculosquelettique et la fonction des membres inférieurs. La plupart des symptômes du XLH ont un impact fort sur le quotidien des patients mais peuvent être minimisés lors de la croissance sous l’effet d’un traitement adapté. A ce jour, seule une appréciation qualitative des symptômes physiques du XLH est possible. Cette thèse vise à définir un protocole d’évaluation quantitative du XLH et de son évolution durant la croissance pour les membres inférieurs. La première partie porte sur l’étude 3D du squelette. On y montre que la diaphyse fémorale est particulièrement touchée. En suivi on voit que les angles mécaniques se normalisent en premiers sous l’effet du traitement, le fémur et le tibia évoluant au même rythme. Une deuxième partie sur l’analyse quantifiée de la marche montre que les altérations concernent principalement le plan frontal et qu’elles sont liées aux déformations osseuses. Une dernière partie, consacrée aux muscles, met en avant une altération de la composition et une atrophie musculaire chez les patients avec XLH pouvant expliquer la faiblesse musculaire observée. En combinant ces trois examens, le protocole proposé dans cette thèse permet à la fois de quantifier les altérations du système musculosquelettique et de la marche chez des enfants avec XLH et d’améliorer notre compréhension des interactions existantes entre ces trois éléments

Analyse prospective et biomécanique de la marche et des déformations osseuses chez les patients atteints de rachitisme hypophosphatémique lié au chromosome X

X-linked hypophosphatemic rickets (XLH) is a rare disease affecting the musculoskeletal system and lower limb function. Most of the symptoms of XLH have a strong impact on the daily life of patients but can be minimized during growth with adapted treatment. To date, only a qualitative assessment of the physical symptoms of XLH is possible. This thesis aims to define a protocol for the quantitative evaluation of XLH and its evolution during growth for the lower limbs. The first part deals with the 3D study of the skeleton. It shows that the femoral shaft is particularly affected. In follow-up we see that the mechanical angles normalize first under the effect of the treatment, the femur and the tibia evolving together. A second part focusing on the quantitative gait analysis shows that the alterations mainly concern the frontal plane and that they are linked to bone deformities. A final part, dealing with muscles, highlights an alteration in composition and muscle atrophy in patients with XLH which may explain the muscle weakness observed. By combining these three examinations, the protocol proposed in this thesis makes it possible both to quantify the alterations of the musculoskeletal system and of gait in children with XLH and to improve our understanding of the existing interactions between these three elements.Le rachitisme hypophosphatémique lié au chromosome X (XLH) est une maladie rare touchant le système musculosquelettique et la fonction des membres inférieurs. La plupart des symptômes du XLH ont un impact fort sur le quotidien des patients mais peuvent être minimisés lors de la croissance sous l’effet d’un traitement adapté. A ce jour, seule une appréciation qualitative des symptômes physiques du XLH est possible. Cette thèse vise à définir un protocole d’évaluation quantitative du XLH et de son évolution durant la croissance pour les membres inférieurs. La première partie porte sur l’étude 3D du squelette. On y montre que la diaphyse fémorale est particulièrement touchée. En suivi on voit que les angles mécaniques se normalisent en premiers sous l’effet du traitement, le fémur et le tibia évoluant au même rythme. Une deuxième partie sur l’analyse quantifiée de la marche montre que les altérations concernent principalement le plan frontal et qu’elles sont liées aux déformations osseuses. Une dernière partie, consacrée aux muscles, met en avant une altération de la composition et une atrophie musculaire chez les patients avec XLH pouvant expliquer la faiblesse musculaire observée. En combinant ces trois examens, le protocole proposé dans cette thèse permet à la fois de quantifier les altérations du système musculosquelettique et de la marche chez des enfants avec XLH et d’améliorer notre compréhension des interactions existantes entre ces trois éléments

Prospective and biomechanical analysis of gait and bone deformities in patients with X-linked hypophosphatemic rickets

Le rachitisme hypophosphatémique lié au chromosome X (XLH) est une maladie rare touchant le système musculosquelettique et la fonction des membres inférieurs. La plupart des symptômes du XLH ont un impact fort sur le quotidien des patients mais peuvent être minimisés lors de la croissance sous l’effet d’un traitement adapté. A ce jour, seule une appréciation qualitative des symptômes physiques du XLH est possible. Cette thèse vise à définir un protocole d’évaluation quantitative du XLH et de son évolution durant la croissance pour les membres inférieurs. La première partie porte sur l’étude 3D du squelette. On y montre que la diaphyse fémorale est particulièrement touchée. En suivi on voit que les angles mécaniques se normalisent en premiers sous l’effet du traitement, le fémur et le tibia évoluant au même rythme. Une deuxième partie sur l’analyse quantifiée de la marche montre que les altérations concernent principalement le plan frontal et qu’elles sont liées aux déformations osseuses. Une dernière partie, consacrée aux muscles, met en avant une altération de la composition et une atrophie musculaire chez les patients avec XLH pouvant expliquer la faiblesse musculaire observée. En combinant ces trois examens, le protocole proposé dans cette thèse permet à la fois de quantifier les altérations du système musculosquelettique et de la marche chez des enfants avec XLH et d’améliorer notre compréhension des interactions existantes entre ces trois éléments.X-linked hypophosphatemic rickets (XLH) is a rare disease affecting the musculoskeletal system and lower limb function. Most of the symptoms of XLH have a strong impact on the daily life of patients but can be minimized during growth with adapted treatment. To date, only a qualitative assessment of the physical symptoms of XLH is possible. This thesis aims to define a protocol for the quantitative evaluation of XLH and its evolution during growth for the lower limbs. The first part deals with the 3D study of the skeleton. It shows that the femoral shaft is particularly affected. In follow-up we see that the mechanical angles normalize first under the effect of the treatment, the femur and the tibia evolving together. A second part focusing on the quantitative gait analysis shows that the alterations mainly concern the frontal plane and that they are linked to bone deformities. A final part, dealing with muscles, highlights an alteration in composition and muscle atrophy in patients with XLH which may explain the muscle weakness observed. By combining these three examinations, the protocol proposed in this thesis makes it possible both to quantify the alterations of the musculoskeletal system and of gait in children with XLH and to improve our understanding of the existing interactions between these three elements

Assessment of a novel deep learning-based marker-less motion capture system for gait study

International audienceBackground. Marker-less systems based on digital video cameras and deep learning for gait analysis could have a deep impact in clinical routine. A recently developed system has shown promising results in terms of joint center position but has not been yet evaluated in terms of gait outcomes.Research question. How does this novel marker-less system compare to a marker-based reference system in terms of clinically relevant gait parameters?Methods. The deep learning method behind the developed marker-less system was trained on a dedicated dataset consisting of forty-one asymptomatic and pathological subjects each performing ten walking trials. The system could estimate the three-dimensional position of seventeen joint centers or keypoints (e.g., neck, shoulders, hip, knee, and ankles). We evaluated the marker-less system against a marker-based system in terms of differences in joint position (Euclidean distance), detection of gait events (e.g., heel strike and toe-off), spatiotemporal parameters (e.g., step length, time), kinematic parameters (e.g., hip and knee extension-flexion), and inter-trial reliability for kinematic parameters.Results. The marker-less system was able to estimate the three-dimensional position of joint centers with a mean difference of 13.1 mm (SD = 10.2 mm). 99% of the estimated gait events were estimated within 10 milliseconds of the corresponding reference values. Estimated spatiotemporal parameters showed zero bias. The mean and standard deviation of the differences of the estimated kinematic parameters varied by parameter (for example, the mean and standard deviation for knee extension flexion angle were -3.0° and 2.7°). Inter-trial reliability of the measured parameters was similar to that of the marker-based references.Significance. The developed marker-less system can measure the spatiotemporal parameters within the range of the minimum detectable changes obtained using the marker-based reference system. Moreover, except for hip extension flexion, the system showed promising results in terms of several kinematic parameters

A novel dataset and deep learning-based approach for marker-less motion capture during gait

International audienceBackground: The deep learning-based human pose estimation methods, which can estimate joint centers position, have achieved promising results on the publicly available human pose datasets (e.g., Human3.6 M). However, these datasets may be less efficient for gait study, particularly for clinical applications, because of the limited number of subjects, their homogeneity (all asymptomatic adults), and the errors introduced by marker placement on subjects’ regular clothing. Research question: How a new human pose dataset, adapted for gait study, could contribute to the advancement and evaluation of marker-less motion capture systems? Methods: A marker-less system, based on deep learning-based pose estimation methods, was proposed. A new dataset (ENSAM dataset) was collected. Twenty-two asymptomatic adults, one adult with scoliosis, one adult with spondylolisthesis, and seven children with bone disease performed ten walking trials, while being recorded both by the proposed marker-less system and a reference system – combining a marker-based motion capture system and a medical imaging system (EOS). The dataset was split into training and test sets. The pose estimation method, already trained on the Human3.6 M dataset, was evaluated on the ENSAM test set, then reevaluated after further training on the ENSAM training set. The joints coordinates were evaluated, using Bland-Altman bias and 95 % confidence interval, and joint position error (the Euclidean distance between the estimated joint centers and the corresponding reference values). Results: The Bland-Altman 95 % confidence intervals were substantially improved after finetuning the pose estimation method on the ENSAM training set (e.g., from 106.9 mm to 17.4 mm for the hip joint). With the new dataset and approach, the mean joint position error varied from 6.2 mm for ankles to 21.1 mm for shoulders. Significance: The proposed marker-less system achieved promising results in terms of joint position errors. Future studies are necessary to assess the system in terms of gait parameters

Quantitative analysis of lower limb and pelvic deformities in children with X-linked hypophosphatemic rickets

International audienceIntroductionX-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.MethodsThirty-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. DiscussionQuantitative 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

Fast quasi-automated 3D reconstruction of lower limbs from low dose biplanar radiographs using statistical shape models and contour matching

International audienceThree-dimensional bone reconstructions from medical imaging are essential for biomechanical modelling and aregrowing tools in clinics. Several methods of lower limbs reconstruction from biplanar radiographs have beenproposed in the literature but with significant operator dependence. A novel reconstruction method based onreduced manual annotation, statistical shape models and fully automatic adjustments was proposed in this study.While significantly reducing operator intervention, the proposed method demonstrated similar or better precisionthan previous approaches on clinical parameters. Meanwhile, shape accuracy was improved to around 1mm.By quasi-automating the 3D reconstruction without loss of accuracy and precision, the proposed approach is aconsiderable step towards extensive use of 3D personalized models in clinical routine and large cohort biomechanicalstudies