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Toe walking in children with cerebral palsy: a possible functional role for the plantar flexors
Abstract
Equinus and toe walking are common locomotor disorders in children with cerebral palsy (CP) walking barefoot or with normal shoes. We hypothesized that, regardless of the type of footwear, the plantar flexors do not cause early equinus upon initial foot contact, but decelerate ankle dorsiflexion during weight acceptance (WA). This latter action promoted by early flat-foot contact is hypothesized to be functional. Hence, we performed an instrumented gait analysis of 12 children with CP (Gross Motor Function Classification System class: I or II; mean age: 7.2 years) and 11 age-matched typically developing children. The participants walked either barefoot, with unmodified footwear (4° positive-heel shoes) or with 10° negative-heel shoes (NHSs). In both groups, wearing NHSs was associated with greater ankle dorsiflexion upon initial foot contact, and greater tibialis anterior activity (but no difference in soleus activity) during the swing phase. However, the footwear condition did not influence the direction and amplitude of the first ankle movement during WA and the associated peak negative ankle power. Regardless of the footwear condition, the CP group displayed (i) early flattening of the foot and ample dorsiflexion (decelerated by the plantar flexors) during WA, and (ii) low tibialis anterior and soleus activities during the second half of the swing phase (contributing to passive equinus upon foot strike). In children with CP, the early action of plantar flexors (which typically decelerate the forward progression of the center of mass) may be a compensatory mechanism that contributes to the WA's role in controlling balance during gait.
... This may be attributed to the multisensory stimulation experienced during barefoot walking, which engages various sensory receptors in the feet and promotes heightened sensory awareness. Furthermore, the stimulation of the toes during barefoot walking [30] can dilate brain capillaries and increase brain blood flow, thus improving oxygen supply to the brain and promoting brain activation [31,32]. These mechanisms may explain the decrease in Gamma and Hbeta waves and increase in SMR and Alpha waves observed in our study. ...
... Taken together, barefoot walking can effectively improve cognitive performance in adolescents, as evidenced by significant changes in EEG activity. of aerobic exercise for improving cognitive function and brain health in adolescents. Barefoot walking can activate the enteric nervous system, increase brain blood flow, and stimulate the toes [32] to activate nerve cells in the sensory cortex, thalamus, and cerebellum, leading to improved overall cognitive ability [39]. Furthermore, barefoot walking stimulates the toes more than walking in sneakers, thereby enhancing lower skeletal muscle strength [32,40]. ...
... Barefoot walking can activate the enteric nervous system, increase brain blood flow, and stimulate the toes [32] to activate nerve cells in the sensory cortex, thalamus, and cerebellum, leading to improved overall cognitive ability [39]. Furthermore, barefoot walking stimulates the toes more than walking in sneakers, thereby enhancing lower skeletal muscle strength [32,40]. These mechanisms can facilitate increased blood flow to the brain [41]. ...
... 42 At IC, the ankle angle is often in plantar flexion, i.e., equinus. 48 The absence of the first rocker in children with CP is also associated with early-onset intense power absorption and negative work exerted at the ankle joint, 49,50 which in turn decelerates ankle dorsiflexion and the anterior tilt of the tibia during the weight acceptance (WA) phase of gait (defined as the period of combined initial power absorption activity around the lower limb joints). 51 This behavior involves early-onset activity of the triceps surae, which starts at the terminal swing and lasts throughout the WA phase. ...
... 52 Prolonged plantar flexor activity during gait in children with CP is generally considered to be due to spasticity (hyper-excitable stretch reflexes) and to induce equinus. 1 Nevertheless, the existence and/or functional significance of exaggerated stretch reflexes during gait in spastic patients has been subject to debate for decades. [53][54][55] In particular, spasticity is unlikely to contribute to toe-walking in children with CP; soleus activity during the swing phase is depressed, 49,54 and an exaggerated reflex activity is absent. 56 In contrast, toe walking in both children with CP and TD children is characterized by feed-forward control of the ankle muscles -suggesting that this gait pattern is part of an adaptive process. ...
... This hypothesis is supported by a study of children with CP walking with negative-heel shoes and barefoot. 49 Although a kinematic adaptation to the shoes occurred upon IC (consisting of ankle dorsiflexion when the children wore negativeheel shoes and equinus when the children walked barefoot), toe walking was maintained and an equivalent deceleration of ankle dorsiflexion by the plantar flexors was observed in the two footwear conditions. 49 It is noteworthy that during the WA phase, the plantar flexors' direct effect on deceleration of the anterior tilt of the tibia and their indirect effect on the forward and downward displacement of the trunk occur in children with CP but not in TD children. ...
Purpose:
In children with cerebral palsy (CP), with impaired trunk control and toe-walking, trunk-focused rehabilitation (TFR) based on postural activities was hypothesized to improve trunk postural control, early trunk deceleration, and ankle dorsiflexion braking during walking. Methods: Seventeen children with CP (5-12 years) walking autonomously were randomly assigned to TFR and then usual rehabilitation (TFR-UR) or vice versa (UR-TFR).
Results:
Only after TFR was significant improvements in (i) the Trunk Control Measurement Scale score, postural sway on an unstable sitting device and standing, and (ii) early sternal and sacral decelerations and coupled negative ankle power due to plantar flexors.
Conclusion:
TFR improves trunk dynamics and consequently improves coupled toe-walking.
... 42 At IC, the ankle angle is often in plantar flexion, i.e., equinus. 48 The absence of the first rocker in children with CP is also associated with early-onset intense power absorption and negative work exerted at the ankle joint, 49,50 which in turn decelerates ankle dorsiflexion and the anterior tilt of the tibia during the weight acceptance (WA) phase of gait (defined as the period of combined initial power absorption activity around the lower limb joints). 51 This behavior involves early-onset activity of the triceps surae, which starts at the terminal swing and lasts throughout the WA phase. ...
... 52 Prolonged plantar flexor activity during gait in children with CP is generally considered to be due to spasticity (hyper-excitable stretch reflexes) and to induce equinus. 1 Nevertheless, the existence and/or functional significance of exaggerated stretch reflexes during gait in spastic patients has been subject to debate for decades. [53][54][55] In particular, spasticity is unlikely to contribute to toe-walking in children with CP; soleus activity during the swing phase is depressed, 49,54 and an exaggerated reflex activity is absent. 56 In contrast, toe walking in both children with CP and TD children is characterized by feed-forward control of the ankle muscles -suggesting that this gait pattern is part of an adaptive process. ...
... This hypothesis is supported by a study of children with CP walking with negative-heel shoes and barefoot. 49 Although a kinematic adaptation to the shoes occurred upon IC (consisting of ankle dorsiflexion when the children wore negativeheel shoes and equinus when the children walked barefoot), toe walking was maintained and an equivalent deceleration of ankle dorsiflexion by the plantar flexors was observed in the two footwear conditions. 49 It is noteworthy that during the WA phase, the plantar flexors' direct effect on deceleration of the anterior tilt of the tibia and their indirect effect on the forward and downward displacement of the trunk occur in children with CP but not in TD children. ...
Introduction
Les enfants atteints de paralysie cérébrale (PC) présentent des difficultés de contrôle des segments axiaux qui pourraient expliquer certains déficits locomoteurs tels que le freinage excessif lors l’appui initial. Tandis que les interventions thérapeutiques classiques se centrent majoritairement sur les membres inférieurs, cette étude visait à déterminer si l’amélioration du contrôle du tronc des enfants PC, grâce à une rééducation axiale accentuée, pouvait entraîner des répercussions favorables sur le freinage initial lors de la marche.
Matériel et méthodes
Treize enfants PC (8 ans ± 2,4), ont suivi en cross-over deux phases de rééducation de 3 mois, l’une de rééducation habituelle et l’autre ciblant davantage les segments axiaux (rééducation axiale accentuée, RAA). Avant et après chaque phase de rééducation, ont été réalisées (1) une évaluation de la stabilisation des segments axiaux via un dispositif d’assise instable et via l’échelle Trunk Control Measurement Scale (TCMS) et (2) une analyse quantifiée de la marche. Les performances initiales des enfants PC étaient comparées à celles de 16 enfants contrôles (EC).
Résultats
Les enfants PC avaient davantage de difficultés pour stabiliser le tronc que les EC (score inférieur au TCMS et surface de déplacement du CoP supérieure sur assise instable). Après RAA, ces performances posturales étaient améliorées et le freinage initial lors de la marche était significativement moins important. La rééducation habituelle ne montrait pas d’effet significatif.
Discussion/Conclusion
Incorporer des activités challengeant les segments axiaux semble pertinent pour améliorer le contrôle postural mais aussi la locomotion des enfants atteints de PC.
... These compensatory strategies must be identified and considered in rehabilitation programs for CP children. These aspects may be improved with rehabilitative interventions focusing on postural control and trunk activity [18,19]. ...
... Intervention group: patients under Vojta Therapy intervention [17][18][19][20][21][22][23][24][25][26][27][28] • Control group: patients under regular physiotherapy intervention, such as environmental enrichment and task-specific training [25] This methodology will be useful to provide a service evaluation of the operation of the rehabilitation service itself. ...
Background: Infantile cerebral palsy is a neurological pathology that causes great morbidity, mortality, and disability in people who suffer from it, mainly affecting motor development. There are a multitude of non-pharmacological methods or therapies for its treatment. One of the main methods is Vojta therapy. This methodology acts on ontogenetic postural function and automatic postural control. Objective: This study aims to demonstrate that there are changes in the motor development of children with cerebral palsy with the application of Vojta therapy. Methods and analysis: This is a randomized controlled trial on the effectiveness of two neurorehabilitation techniques in patients with cerebral palsy conducted at the Physical Medicine and Rehabilitation Service of the Teresa Herrera Maternal and Child Hospital of the A Coruña and Cee Health Area. The study will be conducted from January 2023 to December 2024. There will be two groups: the Vojta therapy group (n = 30) and the conventional physiotherapy group (n = 30). The measurement variables will be gross motor function as measured by the Gross Motor Function Measure (GMFM) and Infant Motor Profile (IMP) scales. Ethics and dissemination: The study was approved by the Research Ethics Committee of the University of Murcia (1823/2018) and Comité de Ética de la Investigación de A Coruña-Ferrol (2022/099). Trial registration number: ClinicalTrials.gov; identifier: NCT06092619.
... 10 Children with CP have flat caused of the reduced plantar activity in the second part of the swing phase. 11 Muscular dystrophy is a genetic condition with several variants. Each has its unique genetic pattern, onset duration, and rate of muscle loss and weakness. ...
The purpose of this systematic review was to study all the randomized controlled trials on the effects of conservative treatment and physiotherapy programs on children with toe walking. A literature search was performed in the databases: PubMed, Scopus, PsychInfo, SportDiscus, and ResearchGate. Toe-walking and toe walking were the keywords searched. Furthermore, explicit inclusion and exclusion criteria were established, and the research selection procedure was carried out by two distinct reviewers. The physiotherapy evidence data-base (PEDro) scale was used to assess the quality of the final studies included in the systematic review. Out of the total of 2079 studies initially identified, 6 studies were finally included. The results showed that physiotherapy interventions and conservative therapy, such as botulinum toxin, ankle foot orthosis or foot orthosis and electric stimulation therapy can help reduce toe walking especially when these methods are combined with classic physiotherapeutic exercises and stretches. Conservative treatment and physiotherapy have positive effect on children who have toe walking symptoms. However, further research is needed in this area to determine the most effective treatment methods to reduce the symptoms of toe walking and find the best treatment to improve the daily lives of these patients, focusing on avoiding surgical procedures.
Automated Gait event identification of Foot Strike (FS) and Foot Off (FO) in pathological gait data, can be time saving in comparison to conventional manual annotations done currently. Identification of FS and FO allows breaking walking trials into gait cycles and hence aids in comparison of gait parameters like joint angles, forces and moments across gait cycles. Automated Gait Event Detection is also useful in development of wearable sensor devices and robotic systems that assist gait. Researchers have proposed several automatic gait event detection algorithms based on kinematic parameters and systematic study of the literature suggests specific parameters to have higher contribution in identification of FS event in all common pathological gait patterns. We used Random Forest Classifier Feature selection technique to identify high contributing features in FS event in toe walking pediatric pathological gait dataset and the results suggest high similarity in selected features by the machine learning technique with those suggested by popular event detection algorithms based on kinematic parameters for pathological gait. Hence we conclude that RFC feature selection is suitable for feature selection in toe walkers gait dataset for event detection purpose. Keyword : Feature selection, foot off, foot strike, pathological gait.
Automated Gait event identification of Foot Strike (FS) and Foot Off (FO) in pathological gait data, can be time saving in comparison to conventional manual annotations done currently. Identification of FS and FO allows breaking walking trials into gait cycles and hence aids in comparison of gait parameters like joint angles, forces and moments across gait cycles. Automated Gait Event Detection is also useful in development of wearable sensor devices and robotic systems that assist gait. Researchers have proposed several automatic gait event detection algorithms based on kinematic parameters and systematic study of the literature suggests specific parameters to have higher contribution in identification of FS event in all common pathological gait patterns. We used Random Forest Classifier Feature selection technique to identify high contributing features in FS event in toe walking pediatric pathological gait dataset and the results suggest high similarity in selected features by the machine learning technique with those suggested by popular event detection algorithms based on kinematic parameters for pathological gait. Hence we conclude that RFC feature selection is suitable for feature selection in toe walkers gait dataset for event detection purpose.
Background:
Patients with cerebral palsy, a group of movement disorders with motor, communication, and behavioral features that can mimic catatonic signs, could benefit from efforts to improve detection and treatment of comorbid catatonia. Given that cerebral palsy frequently co-occurs with conditions associated with catatonia such as autism spectrum disorder, epilepsy, intellectual disability, and mood and psychotic disorders, lifetime prevalence of catatonia in this population may be high.
Objective:
To systematically review the literature on catatonia and the related condition of neuroleptic malignant syndrome (NMS) in patients with cerebral palsy, while presenting two additional cases of catatonia.
Methods:
We used the terms "cerebral palsy" in combination with "catatoni*", related terms for catatonia, and "neuroleptic malignant syndrome" to query OVID Medline (1948 - November 28, 2022), PsycINFO, Cumulative Index to Nursing, and Allied Health Literature, and Embase for applicable case reports. The Neuroleptic Malignant Syndrome Information Service database was also manually searched.
Results:
In addition to our two catatonia reports, we identified ten reports of catatonia in patients with cerebral palsy, as well as eight reports of NMS. Patients with both conditions responded well and, sometimes rapidly, to treatment. Notably, of the five patients with catatonia and cerebral palsy who received electroconvulsive therapy (ECT), two developed recurrent self-limited hyperthermia post-treatment. We also identified several cases of baclofen withdrawal, which can be life threatening due to seizure risk, presenting with NMS-like features in patients with cerebral palsy who had malfunctioning intrathecal baclofen pumps for spasticity management.
Conclusions:
Given frequent comorbidity of conditions associated with catatonia in patients with cerebral palsy, as well as routine treatment with medications that can induce NMS, such as metoclopramide and anticholinergics, catatonia and NMS may be underreported in the cerebral palsy patient population, despite being highly treatable. Possible underdiagnosis of catatonia in patients with cerebral palsy may be due to misattribution of overlapping features between the two conditions to cerebral palsy. Clinicians should be aware of possible recurrent self-limited fever when employing ECT to treat patients with catatonia and cerebral palsy, while also being vigilant for intrathecal baclofen withdrawal when encountering NMS-like features in patients with cerebral palsy.
People with cerebral palsy (CP) suffer primarily from lower-limb impairments. These impairments contribute to the abnormal performance of functional activities and ambulation. Footprints, such as plantar pressure images, are usually used to assess functional performance in people with spastic CP. Detecting left and right feet based on footprints in people with CP is a challenge due to abnormal foot progression angle and abnormal footprint patterns. Identifying left and right foot profiles in people with CP is essential to provide information on the foot orthosis, walking problems, index gait patterns, and determination of the dominant limb. Deep learning with object detection can localize and classify the object more precisely on the abnormal foot progression angle and complex footprints associated with spastic CP. This study proposes a new object detection model to auto-determine left and right footprints. The footprint images successfully represented the left and right feet with high accuracy in object detection. YOLOv4 more successfully detected the left and right feet using footprint images compared to other object detection models. YOLOv4 reached over 99.00% in various metric performances. Furthermore, detection of the right foot (majority of people’s dominant leg) was more accurate than that of the left foot (majority of people’s non-dominant leg) in different object detection models.
Spastic movement disorder is characterized by reduced ability to selectively activate muscles with significant co-activation of antagonist muscles. It has traditionally been thought that hyperexcitable stretch reflexes have a central role in the pathophysiology and the clinical manifestations of the disorder. Here we argue that the main functional challenges for persons with spastic movement disorder are related to contractures, paresis, weak muscles and inappropriate central motor commands, whereas hyperexcitable reflexes play no or only an insignificant functional role. Co-activation of antagonist muscles and stiff posture and gait may rather be adaptations that aim to ensure joint and postural stability due to insufficient muscle strength. Aberrant (involuntary) muscle activity is likely related to an inadequate prediction of the sensory consequences of movement and a resulting impairment of muscle coordination. We argue that improvement of functional muscle strength and muscle coordination following central motor lesions may be achieved by optimizing integration of somatosensory information into central feedforward motor programs, whereas anti-spastic therapy that aims to reduce reflex activity may be less efficient. This opens for novel investigations into new treatment strategies that may improve functional control of movement and prevent reduced joint mobility in people with brain lesions.
Sensory dysfunction is prevalent in cerebral palsy (CP). Evidence suggests that sensory deficits can contribute to manual ability impairments in children with CP, yet it is still unclear how they contribute to balance and motor performance. Therefore, the objective of this study was to investigate the relationship between lower extremity (LE) somatosensation and functional performance in children with CP. Ten participants with spastic diplegia (Gross Motor Function Classification Scale: I-III) and who were able to stand independently completed the study. Threshold of light touch pressure, two-point discriminatory ability of the plantar side of the foot, duration of cutaneous vibration sensation, and error in the joint position sense of the ankle were assessed to quantify somatosensory function. The balance was tested by the Balance Evaluation System Test (BESTest) and postural sway measures during a standing task. Motor performance was evaluated by using a battery of clinical assessments: (1) Gross Motor Function Measure (GMFM-66-IS) to test gross motor ability; (2) spatiotemporal gait characteristics (velocity, step length) to evaluate walking ability; (3) Timed Up and Go (TUG) and 6 Min Walk (6MWT) tests to assess functional mobility; and (4) an isokinetic dynamometer was used to test the Maximum Volitional Isometric Contraction (MVIC) of the plantar flexor muscles. The results showed that the light touch pressure measure was strongly associated only with the 6MWT. Vibration and two-point discrimination were strongly related to balance performance. Further, the vibration sensation of the first metatarsal head demonstrated a significantly strong relationship with motor performance as measured by GMFM-66-IS, spatiotemporal gait parameters, TUG, and ankle plantar flexors strength test. The joint position sense of the ankle was only related to one subdomain of the BESTest (Postural Responses). This study provides preliminary evidence that LE sensory deficits can possibly contribute to the pronounced balance and motor impairments in CP. The findings emphasize the importance of developing a thorough LE sensory test battery that can guide traditional treatment protocols toward a more holistic therapeutic approach by combining both motor and sensory rehabilitative strategies to improve motor function in CP.
To compare medial gastrocnemius muscle-tendon structure, gait propulsive forces, and ankle joint gait kinetics between typically developing children and those with spastic cerebral palsy, and to describe significant associations between structure and function in children with spastic cerebral palsy.
A sample of typically developing children (n = 9 /16 limbs) and a sample of children with spastic cerebral palsy (n = 29 /43 limbs) were recruited. Ultrasound and 3-dimensional motion capture were used to assess muscle-tendon structure, and propulsive forces and ankle joint kinetics during gait, respectively.
Children with spastic cerebral palsy had shorter fascicles and muscles, and longer Achilles tendons than typically developing children. Furthermore, total negative power and peak negative power at the ankle were greater, while total positive power, peak positive power, net power, total vertical ground reaction force, and peak vertical and anterior ground reaction forces were smaller compared to typically developing children. Correlation analyses revealed that smaller resting ankle joint angles and greater maximum dorsiflexion in children with spastic cerebral palsy accounted for a significant decrease in peak negative power. Furthermore, short fascicles, small fascicle to belly ratios, and large tendon to fascicle ratios accounted for a decrease in propulsive force generation.
Alterations observed in the medial gastrocnemius muscle-tendon structure of children with spastic cerebral palsy may impair propulsive mechanisms during gait. Therefore, conventional treatments should be revised on the basis of muscle-tendon adaptations.
Understanding the relation between (sensory) stimuli and the activity of neurons (i.e. `the neural code') lies at heart of understanding the computational properties of the brain. However, quantifying the information between a stimulus and a spike train has proven to be challenging. We propose a new (in vitro) method to measure how much information a single neuron transfers from the input it receives to its output spike train. The input is generated by an artificial neural network that responds to a randomly appearing and disappearing `sensory stimulus': the hidden state. The sum of this network activity is injected as current input into the neuron under investigation. The mutual information between the hidden state on the one hand and spike trains of the artificial network or the recorded spike train on the other hand can easily be estimated due to the binary shape of the hidden state. The characteristics of the input current, such as the time constant as a result of the (dis)appearance rate of the hidden state or the amplitude of the input current (the firing frequency of the neurons in the artificial network), can independently be varied. As an example, we apply this method to pyramidal neurons in the CA1 of mouse hippocampi and compare the recorded spike trains to the optimal response of the 'Bayesian neuron' (BN). We conclude that like in the BN, information transfer in hippocampal pyramidal cells is non-linear and amplifying: the information loss between the artificial input and the output spike train is high if the input to the neuron (the firing of the artificial network) is not very informative about the hidden state. If the input to the neuron does contain a lot of information about the hidden state, the information loss is low. Moreover, neurons increase their firing rates in case the (dis)appearance rate is high, so that the (relative) amount of transferred information stays constant.
The Conventional Gait Model (CGM) is a generic name for a family of closely related and very widely used biomechanical models for gait analysis. After describing its history, the core attributes of the model are described followed by evaluation of its strengths and weaknesses. An analysis of the current and future requirements for practical biomechanical models for clinical and other gait analysis purposes which have been rigorously calibrated suggests that the CGM is better suited for this purpose than any other currently available model. Modifications are required, however, and a number are proposed.
Introduction:
This study was planned to compare the static and dynamic balance in children with Duchenne Muscular Dystrophy (DMD) at different functional levels with each other and with healthy peers.
Material and methods:
Sixty nine children between the ages of 6 and 11 were included in this study where 52 of them were diagnosed with DMD in Level I (18 patients), Level II (17 patients), and Level III (17 patients) according to Brooke Functional Classification Scale and 17 of them healthy peers were included. In order to assess static and dynamic balance pediatric functional reach test (PFRT) and timed up and go test (TUGT) were used.
Results:
When compared in terms of the TUGT, differences were found between all groups, i.e. Level 1 and 2, Level 2 and 3, Level 1 and 3, Healthy peers and Level 1, Healthy peers and Level 2, and Healthy peers and Level 3 (p < 0.0083). When compared in terms of the PFRT in the standing positions, there was difference between level 3 and healthy peers (p < 0.0083), but not between the other groups.
Conclusions:
We found poor functional level in DMD to affect the dynamic and static balance parameters in this study. The dynamic balance of a child with DMD at Level 3 is decreased to a third of a healthy peer.
Introduction: Individuals with cerebral palsy (CP) demonstrate high response variability to motor training insufficiently accounted for by age or severity. We propose here that differences in the inherent ability to learn new motor tasks may explain some of this variability. Damage to motor pathways involving the cerebellum, which may be a direct or indirect effect of the brain injury for many with CP, has been shown to adversely affect the ability to learn new motor tasks and may be a potential explanation. Classic adaptation paradigms that evaluate cerebellar integrity have been utilized to assess adaptation to gait perturbations in adults with stroke, traumatic brain injury and other neurological injuries but not in children with CP.
Materials and Methods: A case-control study of 10 participants with and 10 without hemiplegic CP within the age range of 5–20 years was conducted. Mean age of participants in the CP group was slightly but not significantly higher than controls. Step length and swing time adaptation, defined as gradual accommodation to a perturbation, and aftereffects, or maintenance of the accommodation upon removal of the perturbation, to unilateral leg weighing during treadmill gait were quantified to assess group differences in learning.
Results: Adaptation and aftereffects were demonstrated in step length across groups with no main effect for group. In CP, the dominant leg had a greater response when either leg was weighted. Swing time accommodated immediately (no adaptation) in the weighted leg only, with the non-dominant leg instead showing a more pronounced response in CP.
Discussion: This group of participants with unilateral CP did not demonstrate poorer learning or retention similar to reported results in adult stroke. Deficits, while not found here, may become evident in those with other etiologies or greater severity of CP. Our data further corroborate an observation from the stroke literature that repeated practice of exaggerating the asymmetry (error augmentation), in this case by weighting the more involved or shorter step leg, vs. minimizing it by weighting the less involved or longer step leg (error reduction) may be a useful training strategy to improve step symmetry in unilateral CP.
Sagittal plane alignment of the foot presents challenges when the subject wears shoes during gait analysis. Typically, visual alignment is performed by positioning two markers, the heel and toe markers, aligned with the foot within the shoe. Alternatively, software alignment is possible when the sole of the shoe lies parallel to the ground, and the change in the shoe’s sole thickness is measured and entered as a parameter. The aim of this technical note was to evaluate the accuracy of visual and software foot alignment during shod gait analysis. We calculated the static standing ankle angles of 8 participants (mean age: 8.7 years, SD: 2.9 years) wearing bilateral solid ankle foot orthoses (BSAFOs) with and without shoes using the visual and software alignment methods. All participants were able to stand with flat feet in both static trials and the ankle angles obtained in BSAFOs without shoes was considered the reference. We showed that the current implementation of software alignment introduces a bias towards more ankle dorsiflexion, mean = 3°, SD = 3.4°, p = 0.006, and proposed an adjusted software alignment method. We found no statistical differences using visual alignment and adjusted software alignment between the shoe and shoeless conditions, p = 0.19 for both. Visual alignment or adjusted software alignment are advised to represent foot alignment accurately.
Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging.
We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait.
This study examines the process of learning to walk from a functional perspective. To move forward, one must generate and control propulsive forces. To achieve this, it is necessary to create and tune a distance between the centre of mass (CoM) and the centre of pressure (CoP) along the antero-posterior axis. We hypothesize that learning to walk consists of learning how to calibrate these self-generated propulsive forces to control such distance. We investigated this question with six infants (three girls and three boys) who we followed up weekly for the first 8 weeks after the onset of walking and then biweekly until they reached 14-16 weeks of walking experience. The infants' walking patterns (kinematics and propelling forces) were captured via synched motion analysis and force plate. The results show that the distance between the CoM and the CoP along the antero-posterior axis increased rapidly during the first months of learning to walk and that this increase was correlated with an increase in velocity. The initial small values of (CoM-CoP) observed at walking onset, coupled with small velocity are interpreted as the solution infants adopted to satisfy a compromise between the need to generate propulsive forces to move forward while simultaneously controlling the disequilibrium resulting from creating a with distance between the CoM and CoP.
The aim of the current study was to explore the role of dorsal foot skin on the joint kinematics of gait during level walking. Twelve volunteers experienced sensory perturbations with either reduced dorsal skin feedback using topical anesthetic, reduced visual feedback of the lower visual field, or a combination of both cutaneous and visual reductions (paired). The visual condition was introduced to impose a greater reliance on skin input (goggles occluded lower visual field input). Our results showed that a reduction in skin input, alone, resulted in significant angular position changes at both the ankle and knee joints through swing (increased flexion, p < 0.010), despite preservation of minimal toe clearance (MTC; p = 0.908). Conversely, a reduction in lower visual field input resulted in a greater minimal toe clearance affect (MTC; p < 0.001), a slight increase in dorsiflexion at the ankle (p = 0.046), yet no effect on angular position changes for the knee (p = 0.110). The locomotor changes observed following a reduction in cutaneous feedback from the foot dorsum suggest an important role of the skin over this region for the regulation of level ground walking. Interestingly, it appears that these healthy young adults were able to compensate for the reduced skin information while preserving locomotor efficiency via a maintained ground clearance (MTC). Our data also demonstrated an interaction between skin and visual inputs; vision appears to have a less dominant role compared to skin in controlling the joint positions through swing phase of gait. This work is the first to highlight the influence of reduced cutaneous input from the dorsum of the foot on locomotor strategies.
Neuromechanical principles define the properties and problems that shape neural solutions for movement. Although the theoretical and experimental evidence is debated, we present arguments for consistent structures in motor patterns, i.e., motor modules, that are neuromechanical solutions for movement particular to an individual and shaped by evolutionary, developmental, and learning processes. As a consequence, motor modules may be useful in assessing sensorimotor deficits specific to an individual and define targets for the rational development of novel rehabilitation therapies that enhance neural plasticity and sculpt motor recovery. We propose that motor module organization is disrupted and may be improved by therapy in spinal cord injury, stroke, and Parkinson's disease. Recent studies provide insights into the yet-unknown underlying neural mechanisms of motor modules, motor impairment, and motor learning and may lead to better understanding of the causal nature of modularity and its underlying neural substrates.
Copyright © 2015 Elsevier Inc. All rights reserved.
Previous reports of the mechanics and energetics of post-stroke hemiparetic walking have either not combined estimates of mechanical and metabolic energy or computed external mechanical work based on the limited combined limbs method. Here we present a comparison of the mechanics and energetics of hemiparetic and unimpaired walking at a matched speed.
Mechanical work done on the body centre of mass (COM) was computed by the individual limbs method and work done at individual leg joints was computed with an inverse dynamics analysis. Both estimates were converted to average powers and related to simultaneous estimates of net metabolic power, determined via indirect calorimetry. Efficiency of positive work was calculated as the ratio of average positive mechanical power P ¯ + to net metabolic power.
Total P ¯ + was 20% greater for the hemiparetic group (H) than for the unimpaired control group (C) (0.49 vs. 0.41 W · kg-1). The greater P ¯ + was partly attributed to the paretic limb of hemiparetic walkers not providing appropriately timed push-off P ¯ + in the step-to-step transition. This led to compensatory non-paretic limb hip and knee P ¯ + which resulted in greater total mechanical work. Efficiency of positive work was not different between H and C.
Increased work, not decreased efficiency, explains the greater metabolic cost of hemiparetic walking post-stroke. Our results highlighted the need to target improving paretic ankle push-off via therapy or assistive technology in order to reduce the metabolic cost of hemiparetic walking.
The State of the Art on Sensors and Sensor Placement Procedures for Surface ElectroMyoGraphy: A proposal for sensor placement procedures, Deliverable of the SENIAM project, is a publication of the SENIAM project, published by Roessingh Research and Development b.v. ISBN 90-75452-09-8. PREFACE SENIAM, Surface EMG for the Non-Invasive Assessment of Muscles, is a concerted action, funded by the European Commission as part of the Biomed 2 Research Program. The aim of concerted actions is to facilitate and enhance international co-operation in promising fields of specific interest. The SENIAM project has two objectives: In the first place SENIAM will enable scientists and clinicians working with Surface EMG (SEMG) to exchange knowledge and experience on both basic and applied aspects of SEMG. With respect to this, it is important to notice that the 16 partners originate from many different disciplines, like rehabilitation, orthopaedics, neurology, ergonomy, sports, psychology, all with largely different specific knowledge and experience on SEMG. SENIAM brings together for the first time this variety of knowledge and experience, enabling exchange and discussion and the creation of a European common body of knowledge on SEMG. The second objective of SENIAM is to develop recommendations for key items in the use of SEMG that presently prevent a useful exchange of data and knowledge and a further maturation of the field. The key items concern: sensors, sensor placement, signal processing and modelling. The development of recommendations is essential to bring SEMG a major step forward as a general tool to be used in many applications focused on the assessment of the functioning and status of the neuromuscular system. The creation of consensus on the key items will enable exchange of information and experience and as such a rapid increase of the common body of knowledge. The present report is a major achievement in the SENIAM project. It comprises the state of the art on sensors and sensor placement, the obtained consensus about recommendations in order to optimise the sensor configuration as well as a first proposal for the standardisation of the electrode placement on more then 20 muscles. As it is well known, the choice of the sensor configuration as well as the placement on the muscle has a major effect on the SEMG characteristics, so it is felt extremely important that consensus on these items has been obtained. Nevertheless one has to realise that such recommendations will never be finished. The scientific and clinical progress being made in this field will cause that these recommendations have to be updated from time to time. The present results provide a firm basis to start from and in that sense it is something a lot of application focused EMG-users have been waiting for a long time. Finally I would like to express my sincere thanks to all the experts in the field that have contributed to this report. In addition to this, I would like to thank especially Bart Freriks, Cathy Disselhorst-Klug and Roberto Merletti, who have made a major contribution especially with respect to the inventory on the actual use of the sensors and the guidelines for reporting as well as Bart Freriks for his assistance in compiling all the knowledge into this report.
Several studies demonstrated how cerebellar ataxia (CA) affects gait, resulting in deficits in multi-joint coordination and stability. Nevertheless, how lesions of cerebellum influence the locomotor muscle pattern generation is still unclear. To better understand the effects of CA on locomotor output, here we investigated the idiosyncratic features of the spatiotemporal structure of leg muscle activity and impairments in the biomechanics of CA gait. To this end, we recorded the electromyographic (EMG) activity of 12 unilateral lower limb muscles and analyzed kinematic and kinetic parameters of 19 ataxic patients and 20 age-matched healthy subjects during overground walking. Neuromuscular control of gait in CA was characterized by a considerable widening of EMG bursts and significant temporal shifts in the center of activity due to overall enhanced muscle activation between late swing and mid-stance. Patients also demonstrated significant changes in the intersegmental coordination, an abnormal transient in the vertical ground reaction force and instability of limb loading at heel strike. The observed abnormalities in EMG patterns and foot loading correlated with the severity of pathology (clinical ataxia scale, ICARS) and the changes in the biomechanical output. The findings provide new insights into the physiological role of cerebellum in optimizing the duration of muscle activity bursts and the control of appropriate foot loading during locomotion.
Understanding postural control requires considering various mechanisms underlying a person's ability to stand, to walk, and to interact with the environment safely and efficiently. The purpose of this paper is to summarize the functional relation between biomechanical and neurophysiological perspectives related to postural control in both standing and walking based on movement efficiency. Evidence related to the biomechanical and neurophysiological mechanisms is explored as well as the role of proprioceptive input on postural and movement control.
Because of the availability of new knowledge about the neurobiology of developmental brain injury, information that epidemiology and modern brain imaging is providing, the availability of more precise measuring instruments of patient performance, and the increase in studies evaluating the efficacy of therapy for the consequences of injury, the need for reconsideration of the definition and classification of cerebral palsy (CP) has become evident. Pertinent material was reviewed at an international symposium participated in by selected leaders in the preclinical and clinical sciences. Suggestions were made about the content of a revised definition and classification of CP that would meet the needs of clinicians, investigators, and health officials, and provide a common language for improved communication. With leadership and direction from an Executive Committee, panels utilized this information and have generated a revised Definition and Classification of Cerebral Palsy. The Executive Committee presents this revision and welcomes substantive comments about it.
To address the need for a standardized system to classify the gross motor function of children with cerebral palsy, the authors developed a five-level classification system analogous to the staging and grading systems used in medicine. Nominal group process and Delphi survey consensus methods were used to examine content validity and revise the classification system until consensus among 48 experts (physical therapists, occupational therapists, and developmental pediatricians with expertise in cerebral palsy) was achieved. Interrater reliability (k) was 0.55 for children less than 2 years of age and 0.75 for children 2 to 12 years of age. The classification system has application for clinical practice, research, teaching, and administration.
Gait disorders in cerebral palsy can be accurately analyzed using the CODA-3 system presenting quantitative data representing movement of the hip, knee, and ankle in the sagittal plane. We describe a technique that classifies abnormal gait automatically on the basis of sagittal kinematic data. Fifty-five hemiplegic and 91 diplegic patients were analyzed using an opto-electronic scanner (CODA-3). The sagittal kinematics of the affected limb in hemiplegics correlated with those of both affected limbs in diplegics. We introduce the concept of the "plegic limb." Sagittal kinematics of 237 affected limbs were studied using cluster statistical analysis. Eight clear groups emerged. The predominant clinical features, typical of each group, were identified and described (eg, stiff leg gait, genu recurvatum, or crouch gait). We propose this classification system as a new technique to use gait analysis data to automatically classify abnormal movements of the lower limb in cerebral palsy.
To quantify dynamic spasticity, i.e. the coupling between muscle-tendon stretch velocity and muscle activity during gait, of the gastrocnemius and soleus muscles in children with spastic cerebral palsy.
Prospective, cross-sectional study.
Seventeen ambulatory children with cerebral palsy with spastic calf muscles, and 11 matched typically developing children.
The children walked at 3 different speeds. Three-dimensional kinematic and electromyographic data were collected. Muscle-tendon velocities of the gastrocnemius medialis and soleus were calculated using musculoskeletal modelling.
In typically developing children, muscles were stretched fast in swing without subsequent muscle activity, while spastic muscles were stretched more slowly for the same walking speed, followed by an increase in muscle activity. The mean ratio between peak activity and peak stretch velocity in swing was approximately 4 times higher in spastic muscles, and increased with walking speed. In stance, the stretch of muscles in typically developing children was followed by an increase in muscle activity. Spastic muscles were stretched fast in loading response, but since muscle activity was already built up in swing, no clear dynamic spasticity effect was present.
Spastic calf muscles showed increased coupling between muscle-tendon stretch velocity and muscle activity, especially during the swing phase of gait.
In gait analysis, calculation of the ankle joint centre is a difficult task. The conventional way to calculate the ankle joint centre is using the Vicon Plug-in-Gait model. The present study proposes a new model, which calculates the joint centre from two markers positioned over the medial and lateral malleoli (i.e. Two-marker-model).
In order to compare the proposed model with Plug-in-Gait model, gait data from healthy and patient subjects were captured using a motion capture system. The ankle joint centres were calculated by the two models. A test-retest experiment was carried out to check reliability and repeatability for Two-marker-model.
Two ankle joint centres produced by two models were significantly different. The distances between two ankle joint centres were approximately 16.8 (mm), and the differences in the posterior-anterior, medial-lateral and inferior-superior directions were approximately 6.3, 7.7 and 8.2 (mm). Further error analysis highlighted that the probability of producing errors in Two-marker-model is lower than that in Plug-in-Gait model due to the Two-marker-model's simple and reliable marker positioning. The reliability and repeatability coefficients for the new model were greater than 0.9.
In principle, the Plug-in-Gait model is more likely to produce errors than the Two-marker-model, because the former employs multiple markers from the pelvis to calf to define the ankle joint centre with marker positions being very user-dependent. The results suggest that the Two-marker-model can be considered an alternative to Plug-in-Gait model for calculating ankle joint centre.
Evidence suggests that the nervous system controls motor tasks using a low-dimensional modular organization of muscle activation. However, it is not clear if such an organization applies to coordination of human walking, nor how nervous system injury may alter the organization of motor modules and their biomechanical outputs. We first tested the hypothesis that muscle activation patterns during walking are produced through the variable activation of a small set of motor modules. In 20 healthy control subjects, EMG signals from eight leg muscles were measured across a range of walking speeds. Four motor modules identified through nonnegative matrix factorization were sufficient to account for variability of muscle activation from step to step and across speeds. Next, consistent with the clinical notion of abnormal limb flexion-extension synergies post-stroke, we tested the hypothesis that subjects with post-stroke hemiparesis would have altered motor modules, leading to impaired walking performance. In post-stroke subjects (n = 55), a less complex coordination pattern was shown. Fewer modules were needed to account for muscle activation during walking at preferred speed compared with controls. Fewer modules resulted from merging of the modules observed in healthy controls, suggesting reduced independence of neural control signals. The number of modules was correlated to preferred walking speed, speed modulation, step length asymmetry, and propulsive asymmetry. Our results suggest a common modular organization of muscle coordination underlying walking in both healthy and post-stroke subjects. Identification of motor modules may lead to new insight into impaired locomotor coordination and the underlying neural systems.
Children with spastic hemiplegia secondary to cerebral palsy show disrupted patterns of work and power in gait. A computer-assisted feedback system was used to deliver EMG feedback from the triceps surae muscle group to walking subjects in conjunction with amplitude and timing targets for muscle relaxation and activation. Biofeedback of triceps surae muscle activity during gait was compared with physical therapy (PT) in a twoperiod crossover design, with intervening biomechanical gait analyses to assess the effects of each type of treatment. Kinematic and kinetic gait variables were affected differently by each type of treatment. Stride length and velocity were positively affected by the biofeedback protocol. Positive work done by the affected ankle increased through PT, but gait symmetry was negatively affected, such that the stance phase was prolonged, and peak ankle power at push-off was not improved. In contrast, the biofeedback treatment improved gait symmetry, and was associated with greater ankle power for push-off, as well as increases in total positive work at the hip and ankle. It is concluded that the feedback protocol might be an effective adjunct to physical therapy in hemiplegic children.
Background:
The Center of mass (CoM) analysis reveals important aspects of gait dynamic stability of stroke patients, but the variety of methods and measures represents a challenge for planning new studies.
Research question:
How have the CoM measures been calculated and employed to investigate gait stability after a stroke? Three issues were addressed: (i) the methodological aspects of the calculation of CoM measures; (ii) the purposes and (iii) the conclusions of the studies on gait stability that employed those measures.
Methods:
PubMed and Science Direct databases have been searched to collect original articles produced until July 2017. A set of 26 studies were selected according to criteria involving their methodological quality.
Results:
A compromise between accuracy and feasibility in CoM calculation could be reached using the segmental method with 7-9 segments. Regarding their purposes, two types of studies were identified: clinical and research oriented. From the first ones, we highlighted: the margin of stability (MoS) in the mediolateral (ML) direction, and the angular momentum in the frontal plane could be indicators of dynamical stability; the MoS in the anteroposterior (AP) direction might be able to detect the risk of falls and the symmetry of vertical CoM displacement could be used to analyze energy expenditure during gait. These and other CoM measures are potentially useful in clinical settings, but their psychometric properties are still to be determined. The research oriented studies allowed to clarify that stability is not improved by widening the step in stroke patients and that the impaired control of the non-paretic limb might be the main source of instability.
Significance:
This review provides recommendations on the methods for estimating CoM and its measures, identifies the potential usefulness of CoM parameters and indicates issues that could be addressed in future studies.
Background
Equinus is a common deformity in children with bilateral spastic cerebral palsy (BSCP). While dynamic equinus usually is treated by conservative therapy, fixed contractures need surgical correction. To choose the appropriate surgical method, it is important to discriminate between isolated gastrocnemius shortening and combined gastrosoleus complex contracture.
Methods
In a retrospective study 938 patients with BSCP were studied. Patients underwent gait analysis and clinical examination. 248 patients (496 limbs) met the inclusion criteria. Data from motion analysis and clinical examination were used to calculate the prevalence and to further classify fixed equinus foot.
Results
The prevalence of equinus was 83.3%. During clinical exam 246 (59.6%) limbs showed combined gastrosoleus complex contracture and 167 (40.4%) isolated gastrocnemius contracture. Max. DF at stance and mean DF at initial contact were significantly reduced in combined contracture, while max. ROM was increased (P < 0.05).
Conclusions
Corroborating the results of previous studies, in this study there was a high prevalence of fixed equinus in patients with BSCP. The prevalence of equinus correlated with increasing age. As half of the patients with fixed equinus show a different involvement of gastrocnemius and soleus muscle, we recommend to apply Silfverskiöld’s test to discriminate between those two types to choose the appropriate surgical therapy.
Voluntary toe walking in adults is characterized by feedforward control of ankle muscles in order to ensure optimal stability of the ankle joint at ground impact. Toe walking is frequently observed in children with cerebral palsy, but the mechanisms involved have not been clarified. Here, we investigated maturation of voluntary toe walking in typically-developing children and typically-developed adults and compared it to involuntary toe walking in children with cerebral palsy. Twenty-eight children with cerebral palsy (age 3-14 years), 24 typically-developing children (age 2-14 years) and 15 adults (mean age 30.7 years) participated in the study. EMG activity was measured from the tibialis anterior and soleus muscles together with knee and ankle joint position during treadmill walking. In typically-developed adults, low step-to-step variability of the drop of the heel after ground impact was correlated with low tibialis anterior and high soleus EMG with no significant coupling between the antagonist muscle EMGs. Typically-developing children showed a significant age-related decline in EMG amplitude reaching an adult level at 10-12 years of age. The youngest typically-developing children showed a broad peak EMG-EMG synchronization (4100 ms) associated with large 5-15 Hz coherence between antagonist muscle activities. EMG coherence declined with age and at the age of 10-12 years no correlation was observed similar to adults. This reduction in coherence was closely related to improved step-to-step stability of the ankle joint position. Children with cerebral palsy generally showed lower EMG levels than typically-developing children and larger step-to-step variability in ankle joint position. In contrast to typically-developing children, children with cerebral palsy showed no age-related decline in tibialis anterior EMG amplitude. Motor unit synchronization and 5-15 Hz coherence between antagonist EMGs was observed more frequently in children with cerebral palsy when compared to typically-developing children and in contrast to typically-developing participants there was no age-related decline. We conclude that typically-developing children develop mature feedforward control of ankle muscle activity as they age, such that at age 10-12 years there is little agonist-antagonist muscle co-contraction around the time of foot-ground contact during toe walking. Children with cerebral palsy, in contrast, continue to co-contract agonist and antagonist ankle muscles when toe walking. We speculate that children with cerebral palsy maintain a co-contraction activation pattern when toe walking due to weak muscles and insufficient motor and sensory signalling necessary for optimization of feedforward motor programs. These findings are important for understanding of the pathophysiology and treatment of toe walking.
The goal of this study is to determine whether the size and the variability of error have an impact on the retention of locomotor adaptation in children with cerebral palsy (CP). Eleven children with CP, aged 7-16 years old, were recruited to participate in this study. Three types of force perturbations (i.e., abrupt, gradual and noisy loads) were applied to the right leg above the ankle starting from late stance to mid-swing in three test sessions while the subject walked on a treadmill. Spatial-temporal gait parameters were recorded using a custom designed 3D position sensor during treadmill walking. We observed that children with CP adapted to the resistance force perturbation and showed an aftereffect consisting of increased step length after load release. Further, we observed a longer retention of the aftereffect for the condition with a gradual load than that with an abrupt load. Results from this study suggested that the size of error might have an impact on the retention of motor adaptation in children with CP with a longer retention of motor adaptation for the condition with a small size of error than that with a large error. In addition, enhanced variability of error seems facilitate motor learning during treadmill training. Results from this study may be used for the development of force perturbation based training paradigms for improving walking function in children with CP.
Background:
Plantarflexor tightness due to muscle degenerations has been frequently documented in children with spastic cerebral palsy but the contractile behavior of muscles during ambulation is largely unclear. Especially the adaptability of gastrocnemius muscle contraction on sloped surface could be relevant during therapy.
Methods:
Medial gastrocnemius contractions were measured during flat-forward, uphill (+12% incline) and backward-downhill (-12% decline) treadmill gait in 15 children with bilateral cerebral palsy, walking in crouch, and 17 typically developing controls (age: 7-16years) by means of ultrasound and motion analysis. Tracked fascicle and calculated series elastic element length during gait were normalized on seated rest length. Additionally electromyography of the medial gastrocnemius, soleus and tibialis anterior was collected.
Findings:
During forward gait spastic gastrocnemii reached 10% shorter relative fascicle length, 5% shorter series elastic element length and showed 37% less concentric fascicle excursion than controls. No difference in eccentric fascicle excursion existed. Uphill gait increased concentric fascicle excursion in children with cerebral palsy and controls (by 23% and 41%) and tibialis anterior activity during swing (by 33% and 48%). Backward downhill gait more than doubled (+112%) eccentric fascicle excursion in cerebral palsy patients.
Interpretation:
Apart from having innately shorter fascicles at rest, flat-forward walking showed that spastic gastrocnemius fascicles work at shorter relative length than those of controls. Uphill gait may be useful to concentrically train push-off skills and foot lift. During backward-downhill gait the gastrocnemius functions as a brake and displays more eccentric excursion which could potentially stimulate sarcomere-genesis in series with repeated training.
In this study, we simplified the analysis of kinetic gait data using pattern recognition. Gait patterns were studied in 42 spastic children with cerebral palsy (age range: 3 to 17 years old), and 24 age- and sex-matched children. Gait analysis was performed using the DynoGraphy (CDG) system (Infortronic, Holland). The foot enrollment and the role of the heel or forefoot were assessed to form the gaitline. The bipedal phase was examined using a cyclogram, which is a cyclic characteristic formed by the changing position of the application point of the resultant normal force on a vertical supporting horizontal plane during motion. Based on the pattern recognition, the gait patterns of the subjects could be classified into 4 different patterns in both the gaitline and the cyclogram. The classification of the gait was parallel to the clinical evaluation of cerebral palsy obtained based on Minear's classification of daily activity (p < 0.05). The correlation between the gaitline and cyclogram was also highly significant (p < 0.05). The results of this study suggest that an automated pattern recognition program might provide an additional method for comprehensive gait evaluation in children with cerebral palsy.
Altered trunk movements during gait in children with CP are considered compensatory due to lower limb impairments, although scientific evidence for this assumption has not yet been provided. This study aimed to study the functional relation between trunk and lower limb movement deficits during gait in children with spastic diplegia. Therefore, the relationship between trunk control in sitting, and trunk and lower limb movements during gait was explored in 20 children with spastic diplegia (age 9.2 ± 3 yrs; GMFCS level I n = 10, level II n = 10). Trunk control in sitting was assessed with the Trunk Control Measurement Scale (TCMS), a clinical measure that reflects the presence of an underlying trunk control deficit. Trunk movements during gait were measured with a recently developed trunk model including the pelvis, thorax, head, shoulder line and spine. Lower limb movements were assessed with the Plug-in-Gait model (Vicon®). Range of motion (ROM) of the different trunk segments was calculated, as well as the Trunk Profile Score (TPS) and Trunk Variable Scores (TVSs). Similarly, the Gait Profile Score (GPS) and Gait Variable Scores (GVSs) were calculated to describe altered lower limb movements during gait. Correlation analyses were performed between the presence of impaired trunk control in sitting (TCMS) and altered trunk movements during gait (ROM, TPS/TVSs) and between these altered trunk movements and lower limb movements (GPS/GVSs) during gait. A poorer performance on the TCMS correlated with increased ROM and TPS/TVSs, particularly for the thorax, indicating the presence of an underlying trunk control deficit. No significant correlation was found between the TPS and GPS, suggesting that overall trunk and lower limb movement deficits were not strongly associated. Only few correlations between specific lower limb deficits (GVSs for hip ab/adduction, knee flexion/extension and ankle flexion/extension) and TVSs for thorax lateral bending and rotation were found. This study provided first evidence that the altered trunk movements observed during gait should not be solely considered compensatory due to lower limb impairments, but that these may also partially reflect an underlying trunk control deficit. A better understanding of underlying trunk control deficits in children with CP may facilitate targeted therapy planning and ultimately can optimize a child's functionality.
It is commonly assumed that exaggerated stretch reflex activity and the resulting increased muscle tone in ankle plantar flexors contribute to reduced ankle joint movement during gait in children with cerebral palsy (CP). We investigated the contribution of sensory feedback mechanisms to ankle plantar flexor muscle activity during treadmill walking in 20 children with CP and 41 control children. Stretch responses in plantar flexor muscles evoked in stance by dorsiflexion perturbations showed an age-related decline in control children but not in children with CP. In swing responses were abolished in control children, but not in children with CP. Removal of sensory feedback to the soleus muscle in stance by shortening the plantar flexors produced a drop in soleus EMG activity of a similar size and latency in control children and children with CP. Soleus EMG activity was observed in swing in a similar proportion in both groups. Shortening of the plantar flexors in swing caused a larger drop in Soleus EMG in control children than in children with CP. The lack of age related decline in stretch reflexes in the stance phase and the inability to suppress the reflex in the swing phase is likely related to lack of maturation of corticospinal control in children with CP. However, since they did not show soleus EMG activity to a larger extent than control children in swing and since sensory afferent feedback did not contribute more to their muscle activity, spasticity is unlikely to contribute to foot drop and toe walking.
This study describes and contrasts the kinematics and kinetics of stair ambulation in people with chronic stroke and healthy control subjects. Three dimensional motion data were collected from 10 persons with stroke (7 males) and 10 sex and age-matched older adults as they ascended and descended an instrumented staircase at self-selected speed with and without a handrail. Ankle, knee and hip joint angle and moment profiles were generated during stance and range of motion and peak moments were contrasted between groups, sides (stroke only) and condition. Cadence was lower in stroke than controls, although the kinematic profiles appeared similar during ascent and decent. Notable differences in joint kinetics were evident as the peak extensor moments were typically lower on the affected side in stroke compared to controls and the less affected side. These differences accounted for the lower magnitude net extensor support moment. The lower affected side hip abductor moments likely limited lateral stability. Handrail use tended to reduce the peak moments on the affected side only leading to more side-to-side differences than occurred without the handrail. The findings reveal differences in task performance between stroke and healthy groups that help inform rehabilitation practice.
Although weakness has been identified in cerebral palsy (CP) in isolated muscle groups, the magnitude of weakness in multiple muscles and the patterns of weakness across joints have not been documented. The maximum voluntary contraction of eight muscle groups in the lower extremities of 15 children with spastic diplegia, 15 with spastic hemiplegia, and 16 age-matched peers was determined using a hand-held dynamometer. Children with spastic diplegia were shown to be weaker than age-matched peers in all muscles tested, as were the children with hemiplegia on the involved side, with strength differences also noted on the uninvolved side. Weakness was more pronounced distally in the groups with CP, and the hip flexors and ankle plantarflexors in spastic CP tended to be relatively stronger than their antagonists as compared with the strength ratios of the comparison group. In conclusion, children with spastic CP demonstrate quantifiable lower-extremity weakness and muscle imbalance across joints.
The surface electromyogram (EMG) of leg muscles was recorded together with the changes of the angle at the ankle joint during slow gait in 10 normal children and 10 with cerebral palsy. The characteristic pattern of muscle activity recorded from the spastic legs mainly consisted of a co-activation of antagonistic leg muscles during the stance phase of a gait cycle and a general reduction in amplitude of EMG activity. The tension of the Achilles tendon, measured in 2 hemiparetic children during gait, increased much more steeply in the spastic leg than in the normal one at the beginning of the stance phase, when the electrically almost silent triceps surae was stretched. It is suggested that muscle hypertonia during gait in spastic children is mainly due to changed muscle fibre mechanical properties, as recently discussed also for spastic adults. While in the latter the reciprocal EMG activity of antagonistic leg muscles was preserved it is proposed that muscle co-activation recorded in spastic children is due to an impaired maturation of the locomotor pattern with an early neuronal adaptation to altered muscle fibre mechanical characteristics.
This study investigated the energetics of the human ankle during the stance phase of downhill walking with the goal of modeling ankle behavior with a passive spring and damper mechanism. Kinematic and kinetic data were collected on eight male participants while walking down a ramp with inclination varying from 0° to 8°. The ankle joint moment in the sagittal plane was calculated using inverse dynamics. Mechanical energy injected or dissipated at the ankle joint was computed by integrating the power across the duration of the stance phase. The net mechanical energy of the ankle was approximately zero for level walking and monotonically decreased (i.e., became increasingly negative) during downhill walking as the slope decreased. The indication is that the behavior of the ankle is energetically passive during downhill walking, playing a key role in dissipating energy from one step to the next. A passive mechanical model consisting of a pin joint coupled with a revolute spring and damper was fit to the ankle torque and its parameters were estimated for each downhill slope using linear regression. The passive model demonstrated good agreement with actual ankle dynamics as indicated by low root-mean-square error values. These results indicate the stance phase behavior of the human ankle during downhill walking may be effectively duplicated by a passive mechanism with appropriately selected spring and damping characteristics.
Gait analysis is widely used in clinics to study walking abnormalities for surgery planning, definition of rehabilitation protocols, and objective evaluation of clinical outcomes. Surface electromyography allows the study of muscle activity non-invasively and the evaluation of the timing of muscle activation during movement. The aim of this study was to present a normative dataset of muscle activation patterns obtained from a large number of strides in a population of 100 healthy children aged 6-11 years. The activity of Tibialis Anterior, Lateral head of Gastrocnemius, Vastus Medialis, Rectus Femoris and Lateral Hamstrings on both lower limbs was analyzed during a 2.5-min walk at free speed. More than 120 consecutive strides were analyzed for each child, resulting in approximately 28,000 strides. Onset and offset instants were reported for each observed muscle. The analysis of a high number of strides for each participant allowed us to obtain the most recurrent patterns of activation during gait, demonstrating that a subject uses a specific muscle with different activation modalities even in the same walk. The knowledge of the various activation patterns and of their statistics will be of help in clinical gait analysis and will serve as reference in the design of future gait studies.
3D analysis of the gait of children with Duchenne muscular dystrophy (DMD) was the topic of only a few studies and none of these considered the effect of gait velocity on the gait parameters of children with DMD. Gait parameters of 11 children with DMD were compared to those of 14 control children while considering the effect of gait velocity using 3D biomechanical analysis. Kinematic and kinetic gait parameters were measured using an Optotrak motion analysis system and AMTI force plates embedded in the floor. The data profiles of children with DMD walking at natural gait velocity were compared to those of the control children who walked at both natural and slow gait velocities. When both groups walked at similar velocity, children with DMD had higher cadence and shorter step length. They demonstrated a lower hip extension moment as well as a minimal or absent knee extension moment. At the ankle, a dorsiflexion moment was absent at heel strike due to the anterior location of the center of pressure. The magnitude of the medio-lateral ground reaction force was higher in children with DMD. Despite this increase, the hip abductor moment was lower. Hip power generation was also observed at the mid-stance in DMD children. These results suggest that most of the modifications observed are strategies used by children with DMD to cope with possible muscle weakness in order to provide support, propulsion and balance of the body during gait.
To measure the Tardieu Scale's reliability in children with cerebral palsy (CP) when used by raters with and without experience in using the scale, before and after training.
Single-center, intrarater and interrater reliability study.
Institutional ambulatory care.
Referred children with CP in the pretraining phase (n=5), during training (n=3), and in the posttraining phase (n=15).
The Tardieu Scale involves performing passive muscle stretch at 2 velocities, slow and fast. The rater derives 2 parameters; the Spasticity Angle X is the difference between the angles of arrest at slow speed and of catch-and-release or clonus at fast speed; the Spasticity Grade Y is an ordinal variable that grades the intensity (gain) of the muscle reaction to fast stretch. In phase 1, experienced raters without formalized training in the scale graded elbow, knee, and ankle plantar flexors bilaterally, without and with a goniometer. In phase 2, after training, the experienced and nonexperienced raters graded the same muscles unilaterally.
Intrarater and interrater reliability of the Tardieu Scale.
After training, nonexperienced raters had mean +/- SD intrarater and interrater agreement rates across all joints and parameters of 80%+/-14% and 74%+/-16%, respectively. For experienced raters, intrarater and interrater agreement rates before training were 77%+/-13% and 66%+/-15%, respectively, versus 90%+/-8% and 81%+/-13%, respectively, after training (P<.001 for both). Specific angle measurements at the knee were less reliable for the angles of catch measured at fast speed. Across all joints, agreement rates were similar using visual or goniometric measurements.
Both parameters of the Tardieu Scale have excellent intrarater and interrater reliability when assessed at the elbow and ankle joints of children with CP, with no difference noted between visual and goniometric measurements. Angle measurements were less reliable at the knee joints. Training was associated with a highly significant improvement in reliability.
The purpose of this investigation was to evaluate the work performed on the center of mass by the legs of children with cerebral palsy. 10 children that were diagnosed as having cerebral palsy with spastic diplegia (Age=9.1+/-2 years), and 10 healthy children with no walking disabilities participated (Age=9.4+/-2 years). We collected individual leg ground reaction forces from four force platforms, and calculated the mechanical work performed on the center of mass by the lead and trail legs. The normalized walking speeds were not significantly (p=0.33) different between the children with cerebral palsy (0.26+/-0.07) and the controls (0.28+/-0.06). The children with cerebral palsy performed significantly more negative work by the lead leg during double support (p=0.0004), and significantly less positive work by the trail leg (p<0.00001). During single support, the children with cerebral palsy performed significantly more positive work on the center of mass (p<0.00001). No significant differences were found for the amount of negative work performed by the leg in single support (p=0.84). Children with spastic diplegic cerebral palsy show a diminished ability to appropriately perform mechanical work by the legs to lift and redirect the center of mass. The altered mechanical work performed by the legs on the center of mass may play a role in the higher metabolic cost for walking noted in children with cerebral palsy.
A healthy gait pattern depends on an array of biomechanical features, orchestrated by the central nervous system for economy and stability. Injuries and other pathologies can alter these features and result in substantial gait deficits, often with detrimental consequences for energy expenditure and balance. An understanding of the role of biomechanics in the generation of healthy gait, therefore, can provide insight into these deficits. This article examines the basic principles of gait from the standpoint of dynamic walking, an approach that combines an inverted pendulum model of the stance leg with a pendulum model of the swing leg and its impact with the ground. The heel-strike at the end of each step has dynamic effects that can contribute to a periodic gait and its passive stability. Biomechanics, therefore, can account for much of the gait pattern, with additional motor inputs that are important for improving economy and stability. The dynamic walking approach can predict the consequences of disruptions to normal biomechanics, and the associated observations can help explain some aspects of impaired gait. This article reviews the basic principles of dynamic walking and the associated experimental evidence for healthy gait and then considers how the principles may be applied to clinical gait pathologies.