Mechanical work performed by individual limbs of transfemoral amputees during step-to-step transitions: Effect of walking velocity

The greater metabolic demand during the gait of people with a transfemoral amputation limits their autonomy and walking velocity. Major modifications of the kinematic and kinetic patterns of transfemoral amputee gait quantified using gait analysis may explain their greater energy cost. Donelan et al. proposed a method called the individual limb method to explore the relationships between the gait biomechanics and metabolic cost. In the present study, we applied this method to quantify mechanical work performed by the affected and intact limbs of transfemoral amputees. We compared a cohort of six active unilateral transfemoral amputees to a control group of six asymptomatic subjects. Compared to the control group, we found that there was significantly less mechanical work produced by the affected leg and significantly more work performed by the unaffected leg during the step-to-step transition. We also found that this mechanical work increased with walking velocity; the increase was less pronounced for the affected leg and substantial for the unaffected leg. Finally, we observed that the lesser work produced by the affected leg was linked to the increase in the hip flexion moment during the late stance phase, which is necessary for initiating knee flexion in the affected leg. It is possible to quantify the mechanical work performed during gait by people with a transfemoral amputation, using the individual limb method and conventional gait laboratory equipment. The method provides information that is useful for prosthetic fitting and rehabilitation

Influence of physical capacities of males with transtibial amputation on gait adjustments on sloped surfaces

The aim of the study was to investigate how kinematic and kinetic adjustments between level and slope locomotion of persons with transtibial amputation are related to their individual muscular and functional capacities. A quantified gait analysis was conducted on flat and slope surfaces for seven patients with transtibial amputation and a control group of eight subjects to obtain biomechanical parameters. In addition, maximal isometric muscular strength (knee and hip extensors) and functional scores were measured. The results of this study showed that most of the persons with transtibial amputation could adapt to ramp ascent either by increasing ankle, knee, and hip flexion angles of the residual limb and/or by recruiting their hip extensors to guarantee enough hip extension power during early stance. Besides, 6-minute walk test score was shown to be a good predictor of adaptation capacities to slope ascent. In ramp descent, the increase of knee flexion moment was correlated with knee extensor strength and residual-limb length. However, no correlation was observed with functional parameters. Results show that the walking strategy adopted by persons with transtibial amputation to negotiate ramp locomotion mainly depends on their muscular capacities. Therefore, muscular strengthening should be a priority during rehabilitation.This material was based on work supported by the French National Research Agency (grant ANR-2010-TECS-020)

Finite element and automatic remeshing methods for the simulation of complex blow molded polymer components

International audienceThis paper presents a three dimensional finite element model of the extrusion blow molding process. The code Tform3 has the following characteristics: membrane formulation, linear triangle elements, updated Lagrangian implicit formulation, viscoelastic differential constitutive equations. The paper presents a brief recall of the formulation and then addresses three key issues of the simulation: automatic identification of constitutive equation parameters, automatic remeshing, coupling between gas pressure and inflation. An example of application to the extrusion blow molding of a bottle is presented

Foot-flat Period Estimation During Daily Living Situations of Asymptomatic and Lower Limb Amputee Subjects

Walking in various situations is a challenging task for people with a lower limb amputation. Walking upslope and downslope requires a larger ankle range of motion than waking on a level ground. Most of prosthetic feet do not include an ankle joint. The ankle mobility is obtained via the deformation of a composite structure or via rub- bers. The range of motion of the “ankle-foot” component is directly linked to the stiffness of the structure and to the load applied on the prosthesis. In ramps, prosthetic “ankle-feet” present a lack of dorsiflexion when going up and a lack of plantar flexion when going down (Williams et al. 2009). A decreased “ankle-foot” range of motion results in a reduced foot-flat period (FFP) which can induce insta- bility. New systems were proposed to allow ankle-foot prostheses to adapt to slopes (Sup et al. 2009; Williams et al. 2009; Fradet et al. 2010). Foot flat evaluation during different situations within the asymptomatic population could help to define a tar- get for prosthetic design. This parameter could also be a very interesting tool for orthoprosthesist to give a feed- back of the fitting of the prosthesis to the patient (Agrawal et al. 2009). A good adaptation of the prosthetic foot to the ground should result in a longer FFP and traduce the security of the subject on its prosthesis during stance phase. In the same way, a correct toe clearance during the swing phase will correspond to a contralateral side FFP close to normal. Actually, amputee people often demon- strate vaulting during swing phase showing their fear to stumble and fall. The evaluation of this parameter is all the more interesting for comparison purpose as it is not well taken into account during nowadays prosthesis design (Williams et al. 2009). Besides, FFP can be determined from on board measurements (Mariani et al. 2013) in real life conditions. However, for the moment, there are no reference data of FFP available in the literature.his work was supported by the French National Research Agency [grant number ANR-292 2010-TECS-020]

Spinopelvic sagittal alignment of patients with transfemoral amputation

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

Evaluating the SEE sensitivity of a 45nm SOI Multi-core Processor due to 14 MeV Neutrons

The aim of this work is to evaluate the SEE sensitivity of a multi-core processor having implemented ECC and parity in their cache memories. Two different application scenarios are studied. The first one configures the multi-core in Asymmetric Multi-Processing mode running a memory-bound application, whereas the second one uses the Symmetric Multi-Processsing mode running a CPU-bound application. The experiments were validated through radiation ground testing performed with 14 MeV neutrons on the Freescale P2041 multi-core manufactured in 45nm SOI technology. A deep analysis of the observed errors in cache memories was carried-out in order to reveal vulnerabilities in the cache protection mechanisms. Critical zones like tag addresses were affected during the experiments. In addition, the results show that the sensitivity strongly depends on the application and the multi-processsing mode used

Measurement of wheelchair adjustment effects on turning deceleration

No abstract availabl

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

Reliability quantification and gait loading asymmetry assessment with wearable insoles in transfemoral amputee people at different speeds

Introduction Amputee people have gait defaults, as for example loading asymmetry, which increase with daily living situations. Replication of realistic daily living environment in a motion analysis laboratory (MAL) is difficult. Wearable pressure insoles, by providing normal ground reaction force (NGrF), can be used to quantify loading gait asymmetry in real life conditions. This asymmetry, considered as an indicator of the quality of the gait, is useful for physicians to monitor the rehabilitation progress or the prosthetic fitting suitability. The study aimed at quantifying the reliability of NGrF measurement and assessing the gait asymmetry of transfemoral amputee people with Pedoped® insoles against force plates. Walking speed effect was also evaluated on gait asymmetry for transfemoral amputee people (TFP). Material and methods In a MAL, five active TFP walked at three self-selected speeds on level ground wearing Pedoped® insoles. Reliability was assessed by comparing NGrF obtained from both systems with Bland-Altman plots, normalized RMSE (NRMSE) and correlation coefficient. Gait loading asymmetry was computed by Absolute Symmetry Index in loading at the three self-selected speeds with insoles. Results The mean NRMSE of NGrF was 7.2% (± 2.8%) and 9.8% (± 3.5%); and coefficient correlation was 0.91 and 0.95 for the prosthetic side and the intact side respectively. Loading asymmetry increased significantly with walking speed for each specific variable of NGrF. Discussion–conclusion After overcoming the calibration problem in amputee population, Pedoped® insoles could be easily used for gait asymmetry follow-up during rehabilitation