Détermination d’un patron représentatif de la cinématique 3D du genou à l’aide d’une analyse fonctionnelle des données

Le but de cette étude est de déterminer un patron représentatif des signaux cinématiques tridimensionnels (3D) du genou. Ces signaux correspondent à des courbes continues décrivant la variation en fonction du temps des angles de rotation du genou dans les plans sagittal, frontal et transverse durant un cycle de marche. La détermination d’un patron représentatif à partir de ces courbes est confrontée à une grande complexité qui est due principalement à la présence des courbes aberrantes et à la variabilité en phase entre les différentes courbes. Nous proposons une approche basée sur l’analyse fonctionnelle des données cinématiques qui consiste à (1) éliminer les courbes aberrantes à l’aide de l’indice MBD (Modified Band Depth Index) et (2) à minimiser la variabilité à l’aide de la technique curve registration. Finalement le patron retenu est défini par une moyenne des courbes traitées

Analyse de complexité des données cinématiques tridimensionnelles du genou

L'analyse de la marche à partir des données cinématiques du genou offre des informations importantes sur la fonction de la locomotion humaine. Ces données ont été récemment promues pour le diagnostic des pathologies de genou à travers leur classification. Le but de cette étude est d'analyser la complexité intrinsèque des données cinématiques en vue de leur classification. Nous proposons d'évaluer deux mesures : le chevauchement entre les attributs et la séparabilité des classes. Les résultats obtenues prouvent que l'ordre de complexité des données cinématiques est assez élevé comparé à celui d'autres ensembles de données utilisées dans la littérature comme données de référence

Investigation of 3D glenohumeral displacements from 3D reconstruction using biplane X-ray images: Accuracy and reproducibility of the technique and preliminary analysis in rotator cuff tear patients

Rotator cuff (RC) tears may be associated with increased glenohumeral instability; however, this instability is difficult to quantify using currently available diagnostic tools. Recently, the three-dimensional (3D) reconstruction and registration method of the scapula and humeral head, based on sequences of low-dose biplane X-ray images, has been proposed for glenohumeral displacement assessment. This research aimed to evaluate the accuracy and reproducibility of this technique and to investigate its potential with a preliminary application comparing RC tear patients and asymptomatic volunteers. Accuracy was assessed using CT scan model registration on biplane X-ray images for five cadaveric shoulder specimens and showed differences ranging from 0.6 to 1.4 mm depending on the direction of interest. Intra- and interobserver reproducibility was assessed through two operators who repeated the reconstruction of five subjects three times, allowing defining 95% confidence interval ranging from ±1.8 to ±3.6 mm. Intraclass correlation coefficient varied between 0.84 and 0.98. Comparison between RC tear patients and asymptomatic volunteers showed differences of glenohumeral displacements, especially in the superoinferior direction when shoulder was abducted at 20 and 45 . This study thus assessed the accuracy of the low-dose 3D biplane X-ray reconstruction technique for glenohumeral displacement assessment and showed potential in biomechanical and clinical research.Fondation Paris-Tech Programme BIOMECAM Chaire ParisTech Institut de Recherche Robert-Sauvé en Santé et Sécurité du Travail du Québec Natural Science and Engineering Research Council of Canada Fonds de Recherche sur la Nature et les Technologies du Québec Fonds de Recherche en Santé du Québec, EOS Imaging, and French pôle de compétitivité MEDICEN (STEREOS + program)

The Haploinsufficient Hematopoietic Microenvironment Is Critical to the Pathological Fracture Repair in Murine Models of Neurofibromatosis Type 1

Germline mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a complex genetic disorder with a high predisposition of numerous skeletal dysplasias including short stature, osteoporosis, kyphoscoliosis, and fracture non-union (pseudoarthrosis). We have developed murine models that phenocopy many of the skeletal dysplasias observed in NF1 patients, including reduced bone mass and fracture non-union. We also show that the development of these skeletal manifestations requires an Nf1 haploinsufficient background in addition to nullizygous loss of Nf1 in mesenchymal stem/progenitor cells (MSCs) and/or their progenies. This is replicated in two animal models of NF1, PeriCre+;Nf1flox/− and Col2.3Cre+;Nf1flox/−mice. Adoptive transfer experiments demonstrate a critical role of the Nf1+/− marrow microenvironment in the impaired fracture healing in both models and adoptive transfer of WT bone marrow cells improves fracture healing in these mice. To our knowledge, this is the first demonstration of a non-cell autonomous mechanism in non-malignant NF1 manifestations. Collectively, these data provide evidence of a combinatory effect between nullizygous loss of Nf1 in osteoblast progenitors and haploinsufficiency in hematopoietic cells in the development of non-malignant NF1 manifestations

3D knee kinematics variability pre-operation versus post-operation in adolescence with Anterior Cruciate Ligament injury using functional principle component analysis

Background: Anterior cruciate ligament (ACL) injuries in adolescents have increased in the past decade. The goal of ACL reconstructive surgery is to restore knee stability, however apart from subjective manual testing, there is no objective method to assess the impact of the treatment on knee stability. In clinical biomechanics, decreased variability in three dimensional (3D) kinematic angles can be associated with increased stability of the joint in performing a movement. Typically, the study of variability of 3D knee kinematics proceeds by reducing what are intrinsically functional responses to a single discrete measurement (e.g. peak flexion angle). As a result, many potentially informative data is ignored. Aim: Prospective gait variability analysis pre- and 6 months post- ACL reconstructive surgery in adolescence patients using Principle Component Analysis (FPCA). Method: FPCA is a multivariate statistical data analysis technique that focuses on treating an entire dataset as functions. Twenty eight ACL adolescent patients pre- and post-operation walked on a treadmill and the 3D knee kinematics were collected (flexion/extension, abduction/adduction and internal/external rotation angles). Functional Principle Component (FPCs) scores of the angle data were extracted to compare variability in gait. Repeated measures of ANOVA and box plots on FPC scores provided evidence of significant difference with decreased variability post-operation for both within-group and within-patients studies. Conclusion: Variability in the 3D knee kinematics have been significantly reduced six months post- versus pre-operation. The proposed functional objective assessment method suggests that ACL reconstructive surgery increases joint stability during walking in adolescents

Biomechanical analysis to characterize the impact of knee osteoarthritis on hip, knee, and ankle kinematics

Background: Numerous studies use a biomechanical assessment to evaluate joint function in knee pathologies such as osteoarthritis. However, most of them focus only on the knee and the consequences of the pathology on other lower limb joints are poorly documented. The objective of this study is to analyze the impact of knee osteoarthritis on ipsilateral hip and ankle joint during gait.Methods: Three-dimension (3D) angular kinematic patterns of the three joints were analyzed on 32 patients diagnosed with knee osteoarthritis (OA) and a control group of 15 asymptomatic subjects (AS). Kinematic data was captured during treadmill gait trials at a self-selected comfortable speed. Analysis of covariance (ANCOVA) was performed on selected points of interest from 3D kinematic patterns of the hip, knee and ankle joints to compare both groups. The significance level was set at p = .05.Results: Gait 3D kinematic gait patterns of OA patients revealed significant differences with those of AS subjects at the three joints.Conclusions: Results suggest that patients with knee osteoarthritis also present alterations in hip and ankle kinematic during gait that should be considered when tailoring conservative treatments.  </jats:p