Vaulting quantification during level walking of transfemoral amputees

Background: Vaulting is a gait compensatory mechanism used by transfemoral amputees to assist toe clearance during the prosthetic swing phase. It is defined by a plantar flexion of the contralateral ankle during the single-limb support phase. The aim of the study is to propose a method to quantify vaulting of transfemoral amputees. Methods: 17 transfemoral amputees and 28 asymptomatic subjects participated in the data collection. Kinematics and kinetics of thewhole bodywere recordedwhile subjectswerewalking on a level surface. Biomechanical gait analysis was focused on a reduced set of parameters linked to the contralateral ankle, the contralateral knee and the trajectory of the center of pressure. The patients were classified in two groups: with orwithout vaulting using video recordings. Differences between both groups and the control group were analyzed. Findings: A higher generated ankle powerwas found during the single support phase of the contralateral limb of transfemoralamputees presenting vaulting. These subjects presented also a higher dissipated knee flexion power before the peak in ankle flexion power. The trajectory of the center of pressurewas also modified by the vaulting. Interpretation: Vaulting for transfemoral amputees is characterized by a propulsive plantar flexion at the contralateral ankle. Quantifying the ankle flexion power during the contralateral single support phase will help in understanding vaulting.This study was supported by the French National Research Agency, under reference ANR-2010-TECS-020. The authors are deeply grateful to F. Lavaste, N. Martinet, J. Paysant, and N. Rapin for their contribution to the study

INFLUENCE OF PLAYING SURFACE ON KNEE LOADS DURING RUNNING, SIDESTEP CUTTING AND DROP JUMPING

The purpose of this study was to analyse the influence of 3 different playing surfaces on knee load during sport tasks. 15 young skilled rugby players (17-19 year old) performed running, sidestep cutting and drop jumping tasks on 3 different tracks; i.e. a natural turf, an artificial turf and an hybrid turf (natural grass rooted in artificial rootzone). Kinematic analysis and inverse dynamic methods were applied to assess the knee loads during these exercises. A special attention was paid to knee valgus and internal rotation moments related to ACL injury risk. Results showed that moment of knee valgus during running and sidestep cutting were significantly higher on artificial turf compared with natural ones (3.73 ± 1.13 vs. 1.98 ±. 0.83 N.m.kg-1). In the same way, internal rotation moments in sidestep cutting displayed higher values on artificial track than natural grass (2.97 ± 1.21 vs. 2.51 ±. 1.15 N.m.kg-1). Furthermore, hybrid turf exhibited the lowest knee moments except for the running task. In conclusion, the type of the playing surface play an important role in knee loads related to ACL injury risk

Early Detection of Progressive Adolescent Idiopathic Scoliosis: A Severity Index

Study Design. Early detection of progressive adolescent idiopathic scoliosis (AIS) was assessed based on 3D quantification of the deformity. Objective. Based on 3D quantitative description of scoliosis curves, the aim is to assess a specific deformation pattern that could be an early detectable severity index for progressive AIS. Summary of Background Data. Early detection of progressive scoliosis is important for adapted treatment to limit progression. However, progression risk assessment is mainly based on the follow up, waiting for signs of rapid progression that generally occur during the growth peak. Methods. 65 mild scoliosis (16 boys, 49 girls, Cobb Angle between 10 and 20°) with a Risser between 0 and 2 were followed from their first exam until a decision was made by the clinician, either considering the spine as stable at the end of growth (26 patients) or planning to brace because of progression (39 patients). Calibrated bi-planar X-rays were performed and 3D reconstructions of the spine allowed to calculate six local parameters related to main curve deformity. For progressive curve 3D phenotype assessment, data were compared to those previously assessed for 30 severe scoliosis (Cobb Angle > 35°), 17 scoliosis before brace (Cobb Angle > 29°) and 53 spines of non-scoliosis subjects. A predictive discriminant analysis was performed to assess similarity of mild scoliosis curves either to those of scoliosis or non-scoliosis spines, yielding a severity index (S-index). S index value at first exam was compared to clinical outcome. Results. At the first exam, 53 out of 65 predictions (82%) were in agreement with actual clinical outcome. 89 % of the curves that were predicted as progressive proved accurate Conclusion. Although still requiring large scale validation, results are promising for early detection of progressive curves.The “Fondation Yves Cotrel pour la recherche en pathologie rachidienne” and the other partners of the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling (ParisTech Foundation, Société Générale, Proteor and Covea) funds were received in support of this work

Evolution of vaulting strategy during locomotion of individuals with transfemoral amputation on slopes and cross-slopes compared to level walking

Background: Vaulting is a walking strategy qualitatively characterized in clinics by the sound ankle plantiflexion in midstance to assist prosthetic foot clearance. Even though potentially harmful, this strategy is often observed among people with transfemoral amputation to secure clearance of the prosthetic limb during swing phase. The aim of the study is to provide a quantitative analysis of the evolution of the vaulting strategy in challenging situations of daily living. Methods: 17 persons with transfemoral amputation and 17 able-bodied people participated in the study. Kinematic and kinetic gait analyses were performed for level walking, 10% inclined cross-slope walking, 5% and 12% inclined slope ascending. To study vaulting strategy, peak of generated power at the sound ankle at midstance was identified and quantified in the different walking situations. In particular, values were compared to a vaulting threshold corresponding to a peak of generated power superior to 0.15 W/kg. Findings: The vaulting threshold was exceeded for a larger proportion of people with amputation during crossslope locomotion and slope ascent than during level walking. In addition, magnitude of the peak of generated power increased significantly compared to level walking in these situations. Interpretation: Vaulting seems to be widely used by patients with transfemoral amputation in daily living situations. The number of patients using vaulting increased with the difficulty of the walking situation. Results also suggested that patients could dose the amount of vaulting according to gait environment to secure prosthetic toe clearance. During rehabilitation, vaulting should also be corrected or prevented in daily living tasks

Early detection of progressive adolescent idiopathic scoliosis : a severity index

Study Design. Early detection of progressive adolescent idiopathic scoliosis (AIS) was assessed based on 3D quantification of the deformity. Objective. Based on 3D quantitative description of scoliosis curves, the aim is to assess a specific deformation pattern that could be an early detectable severity index for progressive AIS. Summary of Background Data. Early detection of progressive scoliosis is important for adapted treatment to limit progression. However, progression risk assessment is mainly based on the follow up, waiting for signs of rapid progression that generally occur during the growth peak. Methods. 65 mild scoliosis (16 boys, 49 girls, Cobb Angle between 10 and 20°) with a Risser between 0 and 2 were followed from their first exam until a decision was made by the clinician, either considering the spine as stable at the end of growth (26 patients) or planning to brace because of progression (39 patients). Calibrated biplanar X-rays were performed and 3D reconstructions of the spine allowed to calculate six local parameters related to main curve deformity. For progressive curve 3D phenotype assessment, data were compared to those previously assessed for 30 severe scoliosis (Cobb Angle > 35°), 17 scoliosis before brace (Cobb Angle > 29°) and 53 spines of non-scoliosis subjects. A predictive discriminant analysis was performed to assess similarity of mild scoliosis curves either to those of scoliosis or non-scoliosis spines, yielding a severity index (S-index). S-index value at first exam was compared to clinical outcome. Results. At the first exam, 53 out of 65 predictions (82%) were in agreement with actual clinical outcome. 89 % of the curves that were predicted as progressive proved accurate Conclusion. Although still requiring large scale validation, results are promising for early detection of progressive curves

APSIC: Training and fitting amputees during situations of daily living

Today, the prevalence of major amputation in France can be estimated between 90,000 and 100,000 and the incidence is about 8300 new amputations per year (according to French National Authority for Health estimation). This prevalence is expected to increase in the next decade due to the ageing of the population. Even if prosthetic fitting allows amputee people recovering the walking ability, their autonomy remains limited when crossing obstacles such as slopes, stairs or cross-slopes frequently encountered during outdoors displacements. The aim of the project APSIC was to complete scientific knowledge about adaptation strategies to situations of daily living compared to level walking through an extensive motion analysis study of transtibial and transfemoral amputee compared to non-amputee people. APSIC succeeded in identifying physiologic joint functions and current prosthetic joint limitations in the studied situations, which notably resulted in the design of a prototype of ankle-knee prosthesis adapted to multimodal locomotion of transfemoral amputee. Perspectives of the clinical use of motion analysis within the rehabilitation process were explored and proved to be relevant for personalized approach of motor learning

Analyse biomécanique des mécanismes d'aggravation de la scoliose idiopathique de l'adolescent à l'aide de la modélisation géométrique et mécanique personnalisée

Adolescent idiopathic scoliosis is a three dimensional deformity of the spine. Young girls are mainly affected during their growth. Early detection of sudden progression of the deformities is essential for a better management. Progression mechanisms analysis will help in prognosis tool development. The aim of the study is to analyse scoliosis progression mechanisms using geometrical and mechanical patient-specific modelling. First, combine effect of abnormal growth and intervertebral disc's hyperlaxity was investigated using a patient-specific finite element model. Then, a specific geometrical pattern of progressive scoliosis was used to assess the progression risk at first exam of the follow-up. The proposed method was validated on 49 subjects. Differences in scoliosis mechanical behaviour were investigated to characterize progressive scoliosis using numerical simulation of progression. It seems that a specific initial geometrical defect and an abnormal growth are necessary to scoliosis progression. Discs' hyperlaxity seems to be a progression catalyst. Progression simulation results were used to evaluate preliminary an early and local correction of the deformities.La scoliose idiopathique de l'adolescent est une déformation tridimensionnelle de la colonne vertébrale. Elle touche principalement des jeunes filles en pleine croissance. La détection au plus tôt d'une soudaine aggravation des déformations est indispensable pour améliorer la prise en charge thérapeutique du patient. Le développement d'outil d'aide au pronostic nécessite au préalable une analyse des mécanismes de progression. L'objectif de cette étude est d'analyser les mécanismes de progression de la scoliose à l'aide de la modélisation géométrique et mécanique personnalisée. L'effet combiné d'un trouble de croissance et de l'hyperlaxité des disques intervertébraux sur le développement des déformations a été analysé à l'aide d'un modèle en éléments finis personnalisé. Un schéma géométrique descriptif des scolioses évolutives a été utilisé pour évaluer le risque de progression dès le premier examen du suivi à l'aide d'une méthode statistique. La méthode utilisée a été validée sur 49 sujets et par comparaison à des méthodes de classification supervisée. Les différences de comportement mécanique pouvant caractériser l'évolutivité de la scoliose ont été analysées à l'aide de la simulation numérique de progression. Il apparaît qu'un défaut géométrique initial spécifique ainsi qu'un trouble de croissance sont nécessaire à la progression des déformations. L'hyperlaxité des disques joue le rôle de catalyseur de progression. Les résultats de simulation de progression ont été exploités pour évaluer préliminairement une correction locale précoce des déformations

Analyse biomécanique des mécanismes d'aggravation de la scoliose idiopathique de l'adolescent à l'aide de la modélisation géométrique et mécanique personnalisée

La scoliose idiopathique de l'adolescent est une déformation tridimensionnelle de la colonne vertébrale. Elle touche principalement des jeunes filles en pleine croissance. La détection au plus tôt d'une soudaine aggravation des déformations est indispensable pour améliorer la prise en charge thérapeutique du patient. Le développement d'outil d'aide au pronostic nécessite au préalable une analyse des mécanismes de progression. L'objectif de cette étude est d'analyser les mécanismes de progression de la scoliose à l'aide de la modélisation géométrique et mécanique personnalisée. L'effet combiné d'un trouble de croissance et de l'hyperlaxité des disques intervertébraux sur le développement des déformations a été analysé à l'aide d'un modèle en éléments finis personnalisé. Un schéma géométrique descriptif des scolioses évolutives a été utilisé pour évaluer le risque de progression dès le premier examen du suivi à l'aide d'une méthode statistique. La méthode utilisée a été validée sur 49 sujets et par comparaison à des méthodes de classification supervisée. Les différences de comportement mécanique pouvant caractériser l'évolutivité de la scoliose ont été analysées à l'aide de la simulation numérique de progression. Il apparaît qu'un défaut géométrique initial spécifique ainsi qu'un trouble de croissance sont nécessaire à la progression des déformations. L'hyperlaxité des disques joue le rôle de catalyseur de progression. Les résultats de simulation de progression ont été exploités pour évaluer préliminairement une correction locale précoce des déformations.Adolescent idiopathic scoliosis is a three dimensional deformity of the spine. Young girls are mainly affected during their growth. Early detection of sudden progression of the deformities is essential for a better management. Progression mechanisms analysis will help in prognosis tool development. The aim of the study is to analyse scoliosis progression mechanisms using geometrical and mechanical patient-specific modelling. First, combine effect of abnormal growth and intervertebral disc's hyperlaxity was investigated using a patient-specific finite element model. Then, a specific geometrical pattern of progressive scoliosis was used to assess the progression risk at first exam of the follow-up. The proposed method was validated on 49 subjects. Differences in scoliosis mechanical behaviour were investigated to characterize progressive scoliosis using numerical simulation of progression. It seems that a specific initial geometrical defect and an abnormal growth are necessary to scoliosis progression. Discs' hyperlaxity seems to be a progression catalyst. Progression simulation results were used to evaluate preliminary an early and local correction of the deformities.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

Contribution of the supplementary motor area and the cerebellum to the anticipatory postural adjustments and execution phases of human gait initiation

International audienceSeveral brain structures including the brainstem, the cerebellum and the frontal cortico-basal ganglia network, with the primary and premotor areas have been shown to participate in the functional organization of gait initiation and postural control in humans, but their respective roles remain poorly understood. The aim of this study was to better understand the role of the supplementary motor area (SMA) and posterior cerebellum in the gait initiation process. Gait initiation parameters were recorded in 22 controls both before and after continuous theta burst transcranial stimulation (cTBS) of the SMA and cerebellum, and were compared to sham stimulation, using a randomized double-blind design study. The two phases of gait initiation process were analyzed: anticipatory postural adjustments (APAs) and execution, with recordings of soleus and tibialis anterior muscles. Functional inhibition of the SMA led to a shortened APA phase duration with advanced and increased muscle activity; during execution, it also advanced muscle co-activation and decreased the duration of stance soleus activity. Cerebellar functional inhibition did not influence the APA phase duration and amplitude but increased muscle co-activation, it decreased execution duration and showed a trend to increase velocity, with increased swing soleus muscle duration and activity. The results suggest that the SMA contributes to both the timing and amplitude of the APAs with no influence on step execution and the posterior cerebellum in the coupling between the APAs and execution phases and leg muscle activity pattern during gait initiation