Bilateral, Misalignment-Compensating, Full-DOF Hip Exoskeleton: Design and Kinematic Validation

A shared design goal for most robotic lower limb exoskeletons is to reduce the metabolic cost of locomotion for the user. Despite this, only a limited amount of devices was able to actually reduce user metabolic consumption. Preservation of the natural motion kinematics was defined as an important requirement for a device to be metabolically beneficial. This requires the inclusion of all human degrees of freedom (DOF) in a design, as well as perfect alignment of the rotation axes. As perfect alignment is impossible, compensation for misalignment effects should be provided. A misalignment compensation mechanism for a 3-DOF system is presented in this paper. It is validated by the implementation in a bilateral hip exoskeleton, resulting in a compact and lightweight device that can be donned fast and autonomously, with a minimum of required adaptations. Extensive testing of the prototype has shown that hip range of motion of the user is maintained while wearing the device and this for all three hip DOFs. This allowed the users to maintain their natural motion patterns when they are walking with the novel hip exoskeleton

Effect of supporting 3D-garment on gait postural stability in children with bilateral spastic cerebral palsy

BACKGROUND: Children with cerebral palsy show dysfunctional postural control which interferes with their functional performance and daily-life activities. OBJECTIVE: The aim of the study was to identify the effect of a 3D supporting garment on trunk postural control and interjoint coordination during gait in children with bilateral cerebral palsy. METHODS: We analyzed tridimensional trunk motion, trunk-thigh and interjoint coordination in 15 4-10 year-old children with bilateral spastic cerebral palsy (GMFCS I or II) and 16 4-10 year-old typically developing children while walking with or without a supporting garment. RESULTS: We found significantly changes in the coordination between trunk and lower limbs in children with cerebral palsy. Step velocity and cadence both increased significantly in children with cerebral palsy but in controls, the cadence remained unaltered. Interjoint coordination between hip-knee and knee-ankle was altered during the stance phase only in the subgroup of children with cerebral palsy without any limitations in ankle joint passive range of motion. CONCLUSION: 3D supporting garments improve trunk-thigh and lower limb interjoint coordination in walking in children with bilateral cerebral palsy.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Effect of ankle-foot orthoses on gait in typically developing children: Developmental trend in segmental coordination

Objective: As orthoses, and particularly ankle-foot orthoses, are widely used in the management of children with motor disorders, including cerebral palsy, we aimed to study their effect in normal children in order to add to normative gait data, which are essential for diagnosing, understanding and treating abnormal gait patterns. Design: We analyzed the effect of ankle-foot orthoses on classical gait parameters and lower limb segments coordination patterns in typically developing children in two age groups reflecting different neuromaturational/developmental situations. We recorded 3D kinematic gait patterns in 9 children (4-5 years) and 11 children (9-10 years) walking barefoot or wearing bilateral solid ankle-foot orthoses maintaining the ankle joint angle at a neutral position. Results: Ankle-foot orthoses induced little change in cadence, step length, step width or walking velocity in younger children, though they altered intralimb coordination through the gait cycle. In older children, walking velocity was reduced, shank elevation amplitude increased, while lower limb coordination changed less significantly. In this age group, ankle-foot orthoses significantly reduced the variability of coordinative strategies. Conclusion: Ankle-foot orthoses affect the gait pattern in children with a typical development at different levels in younger and older subjects, but the resulting changes are minimal. © 2010 IOS Press and the authors. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Examen clinique de l'enfant infirme moteur cérébral: existe-t-il un consensus entre les praticiens?

Diagnosis and most of all classification of children with cerebral palsy (CP) remain a challenge for clinicians. To help them in this process, clinicians can rely on several clinical testing procedures as well as complementary investigations. The goal of this study was to determine which clinical tests found in the literature are the most frequently used in common practice in Belgium. Forty tests have been found in the literature. They have been sorted into five different categories: quantitative evaluation of motor function, spasticity evaluation, orthopaedic testing, upper limb evaluation and complementary investigations. Seven clinicians (five medical doctors and two physiotherapists) with a mean experience of sixteen years with CP children answered the questionnaire. Concerning the quantitative evaluation of motor function the most used tests are: Gross Motor Function Classification System, Manual Ability Classification System and the Pediatric Evaluation of Disability Inventory (PEDI). As regards spasticity, Ashworth scale is more frequently used than Tardieu test. No trend currently exist for the upper limb evaluation, but it was noted that these tests are rarely used in clinical practice. We observed a significant use of gait analysis at diagnosis and follow-up of CP children. We conclude that there are large differences between clinicians for clinical examination of CP children. This lack of consensus makes patient data comparison difficult between clinical centers. This seems to indicate that a homogenization effort should be organized if one wishes to better stimulate collaborations between centers.English AbstractJournal ArticleMulticenter StudyResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Data mining toolbox for gait analysis in children with cerebral palsy

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Influence of Botulinum Toxin Therapy on Postural Control and Lower Limb Intersegmental Coordination in Children with Spastic Cerebral Palsy

Botulinum toxin injections may significantly improve lower limb kinematics in gait of children with spastic forms of cerebral palsy. Here we aimed to analyze the effect of lower limb botulinum toxin injections on trunk postural control and lower limb intralimb (intersegmental) coordination in children with spastic diplegia or spastic hemiplegia (GMFCS I or II). We recorded tridimensional trunk kinematics and thigh, shank and foot elevation angles in fourteen 3–12 year-old children with spastic diplegia and 14 with spastic hemiplegia while walking either barefoot or with ankle-foot orthoses (AFO) before and after botulinum toxin infiltration according to a management protocol. We found significantly greater trunk excursions in the transverse plane (barefoot condition) and in the frontal plane (AFO condition). Intralimb coordination showed significant differences only in the barefoot condition, suggesting that reducing the degrees of freedom may limit the emergence of selective coordination. Minimal relative phase analysis showed differences between the groups (diplegia and hemiplegia) but there were no significant alterations unless the children wore AFO. We conclude that botulinum toxin injection in lower limb spastic muscles leads to changes in motor planning, including through interference with trunk stability, but a combination of therapies (orthoses and physical therapy) is needed in order to learn new motor strategies

The contribution of decreased muscle size to muscle weakness in children with spastic cerebral palsy

Muscle weakness is a common clinical symptom in children with spastic cerebral palsy (SCP). It is caused by impaired neural ability and altered intrinsic capacity of the muscles. To define the contribution of decreased muscle size to muscle weakness, two cohorts were recruited in this cross-sectional investigation: 53 children with SCP [median age, 8.2 (IQR, 4.1) years, 19/34 uni/bilateral] and 31 children with a typical development (TD) [median age, 9.7 (IQR, 2.9) years]. Muscle volume (MV) and muscle belly length for m. rectus femoris, semitendinosus, gastrocnemius medialis, and tibialis anterior were defined from three-dimensional freehand ultrasound acquisitions. A fixed dynamometer was used to assess maximal voluntary isometric contractions for knee extension, knee flexion, plantar flexion, and dorsiflexion from which maximal joint torque (MJT) was calculated. Selective motor control (SMC) was assessed on a 5-point scale for the children with SCP. First, the anthropometrics, strength, and muscle size parameters were compared between the cohorts. Significant differences for all muscle size and strength parameters were found (p <= 0.003), except for joint torque per MV for the plantar flexors. Secondly, the associations of anthropometrics, muscle size, gross motor function classification system (GMFCS) level, and SMC with MJT were investigated using univariate and stepwise multiple linear regressions. The associations of MJT with growth-related parameters like age, weight, and height appeared strongest in the TD cohort, whereas for the SCP cohort, these associations were accompanied by associations with SMC and GMFCS. The stepwise regression models resulted in ranges of explained variance in MJT from 29.3 to 66.3% in the TD cohort and from 16.8 to 60.1% in the SCP cohort. Finally, the MJT deficit observed in the SCP cohort was further investigated using the TD regression equations to estimate norm MJT based on height and potential MJT based on MV. From the total MJT deficit, 22.6-57.3% could be explained by deficits in MV. This investigation confirmed the disproportional decrease in muscle size and muscle strength around the knee and ankle joint in children with SCP, but also highlighted the large variability in the contribution of muscle size to muscle weakness