A reference method for the evaluation of femoral head joint center location technique based on external markers

Accurate localization of joint centers is essential in movement analysis. However, joint centers cannot be directly palpated and alternative methods must be used. To assess the relative merits of these methods, a medical image based reference should be used. The EOS1 system, a new low dose bi-planar X-rays imaging technique may be considered. The aim of this study was to evaluate the accuracy of hip joint center (HJC) localization using the EOS1 system. Seventeen healthy young adults participated in the study. Femoral heads and pelvic external markers were localized using the EOS1 system and the HJCs were expressed in the movement analysis coordinate system. Results showed that external marker localization was reliable within 0.15 mm for trained assessors. Mean accuracy for HJC localization was 2.9 mm (SD: 1.3, max: 6.2). The EOS based method therefore appeared reliable and may be used for femoral head localization or as a reference to assess the accuracy of other methods for HJC localization.The authors are grateful to VICON (OMG-UK) for the loan of a motion capture system necessary for the overall study

Which method of hip joint centre localization should be used in gait analysis?

Accurate localisation of the hip joint centre is required to obtain accurate kinematics, kinetics and musculoskeletal modelling results. Literature data showed that conclusions drawn from synthetic data, adult normal subjects and cerebral palsy children may vary markedly. This study investigated the localisation accuracy of the hip joint centre against EOS. The EOS system allowed us to register the hip joint centres with respect to the skin markers on standing subjects. A comprehensive set of predictive and functional calibration techniques were tested. For the functional calibration techniques, our results showed that algorithm, range of motion and self-performance of the movement were factors significantly affecting the results. Best results were obtained for comfortable range and self-performance of the movement. The best method in this scenario was the functional geometrical sphere fitting method which localised the hips 1.1. cm from the EOS reference in average and 100% of the time within 3. cm. Worst results for functional calibration methods occurred when the movement was assisted with a reduced range of movement. The best method in this scenario was the Harrington et al. regression equations since it does not rely on a functional calibration movement. Harrington et al. equations put the hips 1.7. cm from the EOS reference in average and 97% of the time within 3. cm. We conclude that accurate localisation of the hip joint centre is possible in gait analysis providing that method to localise the hip joint centres are adapted to the population studied: functional geometrical sphere fitting when hip calibration movements are not a problem and Harrington et al. predictive equations otherwise.We are grateful to VICON® (Oxford, UK) for loaning us the full motion capture system used in this study

On the use of knee functional calibration to determine the medio-lateral axis of the femur in gait analysis: Comparison with EOS biplanar radiographs as reference

Accurate calibration of the medio-lateral axis of the femur is crucial for clinical decision making based on gait analysis. This study proposes a protocol utilizing biplanar radiographs to provide a reference medio-lateral axis based on the anatomy of the femur. The biplanar radiographs allowed 3D modelling of the bones of the lower limbs and the markers used for motion capture, in the standing posture. A comprehensive analysis was performed and results from biplanar radiographs were reliable for 3D marker localization (±0.35 mm) and for 3D localization of the anatomical landmarks (±1 mm), leading to a precision of 1° for the orientation of the condylar axis of the femur and a 95% confidence interval of ±3° after registration with motion capture data. The anatomical condylar axis was compared to a conventional, marker-based, axis and three functional calibration techniques (axis transformation, geometric axis fit and DynaKAD). Results for the conventional method show an average difference with the condylar axis of 15° (SD: 6°). Results indicate DynaKAD functional axis was the closest to the anatomical condylar axis, mean: 1° (SD: 5°) when applied to passive knee flexion movement. However, the range of the results exceeded 15° for all methods. Hence, the use of biplanar radiographs, or an alternative imaging technique, may be required to locate the medio-lateral axis of the femur reliably prior to clinical decision making for femur derotational osteotomies

Kinematic Deviations In Children With Cerebral Palsy

In gait analysis, a large portion of the work consists in finding the underlying causes of the abnormal movement observed during walking. The patient’s kinematics of walking is compared to that of typically developed children and the deviations are further analysed. Over the years, clinicians have observed multiple-joints kinematics deviations that were frequent in children with cerebral palsy and devised gait patterns in order to group patients and support management algorithms. However, the gait patterns are broad tools and cannot render the complexity and varying degrees of impairments seen in children with cerebral palsy. To devise individualised management plan, clinicians prefer to list single joint kinematic deviations and to link these with underlying impairments. This chapter will present the main clinical gait patterns for children with unilateral or bilateral spastic palsy in the first part and the principal single joint/plane kinematic deviations together with their associated impairments in the second part

Modélisation mécanique in vivo personnalisée du genou via l Imagerie par Résonance Magnétique

Le travail de thèse concerne l'étude du comportement mécanique du genou. Un modèle numérique 3D in vivo personnalisé du genou obtenu par la méthode des éléments finis a été développé à partir de l'Imagerie par Résonance Magnétique. La première partie du travail a concerné la mise en place et l'exploitation sur Il sujets sains d'un protocole d'analyse du mouvement. Cette partie a permis l'évaluation d'un système de marqueurs externes. La deuxième partie concerne l'étude des pressions de contact dans le cartilage et les ménisques au cours du mouvement. Cette partie a débouchée sur une méthode de cartographie de l'épaisseur du cartilage ainsi que la création d'un modèle éléments finis. La troisième partie concerne la détermination in vivo des propriétés du ligament croisé antérieur à partir du test clinique de Lachman réalisé au sein de l'IRM. Les résultats trouvent leur application dans l'évaluation quantitative des pathologies du genou ainsi que dans le développement des prothèses.This work concerned the mechanical behavior of the knee. A numerical 3D model in vivo has been developed derived from MRI images. The first part of the work was the development and the use on 11 normal subjects of a movement analysis protocol based on MRI data. The results allowed to provide a quantitative evaluation of an external marker set system. ln the second part, the computation of the contact pressure areas on the cartilage and the meniscus during the personalized knee movement was performed. A method to determine the cartilage thickness map and the building of a personalized finite element model of the knee has been developed. The last part of the work concerned the in vivo determination of the mechanical properties of the Anterior Cruciate Ligament derived from the Lachman test reproduced in the MRI environment. The results of the work are of interest for the quantitative evaluation of pathological knee and in the development of numerical models for testing knee implants.COMPIEGNE-BU (601592101) / SudocSudocFranceF

Modélisation mécanique in vivo personnalisée du genou via l Imagerie par Résonance Magnétique

Le travail de thèse concerne l'étude du comportement mécanique du genou. Un modèle numérique 3D in vivo personnalisé du genou obtenu par la méthode des éléments finis a été développé à partir de l'Imagerie par Résonance Magnétique. La première partie du travail a concerné la mise en place et l'exploitation sur Il sujets sains d'un protocole d'analyse du mouvement. Cette partie a permis l'évaluation d'un système de marqueurs externes. La deuxième partie concerne l'étude des pressions de contact dans le cartilage et les ménisques au cours du mouvement. Cette partie a débouchée sur une méthode de cartographie de l'épaisseur du cartilage ainsi que la création d'un modèle éléments finis. La troisième partie concerne la détermination in vivo des propriétés du ligament croisé antérieur à partir du test clinique de Lachman réalisé au sein de l'IRM. Les résultats trouvent leur application dans l'évaluation quantitative des pathologies du genou ainsi que dans le développement des prothèses.This work concerned the mechanical behavior of the knee. A numerical 3D model in vivo has been developed derived from MRI images. The first part of the work was the development and the use on 11 normal subjects of a movement analysis protocol based on MRI data. The results allowed to provide a quantitative evaluation of an external marker set system. ln the second part, the computation of the contact pressure areas on the cartilage and the meniscus during the personalized knee movement was performed. A method to determine the cartilage thickness map and the building of a personalized finite element model of the knee has been developed. The last part of the work concerned the in vivo determination of the mechanical properties of the Anterior Cruciate Ligament derived from the Lachman test reproduced in the MRI environment. The results of the work are of interest for the quantitative evaluation of pathological knee and in the development of numerical models for testing knee implants.COMPIEGNE-BU (601592101) / SudocSudocFranceF

The Functional Gait Deviation Index

A typical gait analysis requires the examination of the motion of nine joint angles on the left-hand side and six joint angles on the right-hand side across multiple subjects. Due to the quantity and complexity of the data, it is useful to calculate the amount by which a subject's gait deviates from an average normal profile and to represent this deviation as a single number. Such a measure can quantify the overall severity of a condition affecting walking, monitor progress, or evaluate the outcome of an intervention prescribed to improve the gait pattern. The gait deviation index, gait profile score, and the overall abnormality measure are standard benchmarks for quantifying gait abnormality. However, these indices do not account for the intrinsic smoothness of the gait movement at each joint/plane and the potential co-variation between the joints/planes. Utilizing a multivariate functional principal components analysis we propose the functional gait deviation index (FGDI). FGDI accounts for the intrinsic smoothness of the gait movement at each joint/plane and the potential co-variation between the joints. We show that FGDI scales with overall gait function, provides a consistent measure of gait abnormality, and is implemented easily using an interactive web app.Comment: arXiv admin comment: This version has been removed by arXiv administrators as the submitter did not have the rights to agree to the license at the time of submissio

Détermination des pressions de contact dans le cartilage au cours d'une flexion de genou via l'IRM

International audienceThis paper adresses the methodology used to model the knee joint in vivo from MRI images. The knee joint model obtain is subject specific. The paper presents all the process: Geometrical acquisitions, Joint movement analysis, Meshing technics and non-linear finite element modeling with contact between the bones, the cartilage and the menisci. The model is able to determine the stress applied on the various components of the joint for normal subject during a knee flexion movement.Une méthodologie de modélisation personnalisée in vivo de l'articulation du genou est proposée à partir d'images IRM. Les étapes de traitement présentées sont : l'acquisition de la géométrie des structures, le calcul du mouvement de l'articulation, la construction du maillage des structures et les calculs éléments finis non-linéaire incluant le contact entre les os, le cartilage et les ménisques. Le modèle ainsi obtenu permet de déterminer les efforts appliqués aux structures de l'articulation du genou sain au cours d'un mouvement de flexion

Frameworks and methods for estimating causal effect of clinical treatment in orthopaedics: A scoping review protocol

<p>The gold standard for establishing the causal effect of a clinical treatment is a randomized controlled trial (RCT), which is challenging to apply in orthopaedics, mainly due to ethical reasons. Therefore, retrospective observational studies were conducted to elucidate potential treatment effects. Unfortunately, causal inference has remained largely underutilized in neuro-orthopaedics and gait analysis. Many causal inference methodologies worthy of consideration may have been utilized in orthopaedics, where RCTs are difficult to implement. The objective of the scoping review is to facilitate a better understanding of the use of causal inference methods in orthopaedics. </p&gt