Search

Background Sensorimotor control of axial segments, which develops during childhood and is not mature until adolescence, is essential for the development of balance control during motor activities. Children with cerebral palsy (CP) have deficits in postural control when standing or walking, including less stabilization of the head and trunk which could affect postural control. Research question Is dynamic stabilization of axial segments during an unstable sitting task deficient in children with CP compared to typically developing children? Is this deficit correlated with the deficit of postural control during standing? Method Seventeen children with CP (GMFCS I-II) and 17 typically-developing children from 6 to 12 years old were rated on the Trunk Control Measurement Scale (TCMS). In addition, posturography was evaluated in participants while they maintained their balance in stable sitting, unstable sitting, and quiet standing, under “eyes open” and “eyes closed” conditions. In sitting tasks, the participants had to remain stable while being prevented from using the lower and upper limbs (i.e. to ensure the involvement of axial segments alone). Results Children with CP compared to TD children had significantly larger surface area, mean velocity and RMS values of CoP displacements measured during the unstable sitting task and the standing task, under both “eyes open” and “eyes closed” conditions. No significant group effects were observed during the stable sitting task. The TCMS total score was significantly lower, indicating trunk postural deficit, in the CP group than in the TD group and was significantly correlated with postural variables in the sitting and standing tasks. Significance Children with CP indeed have a specific impairment in the postural control of axial segments. Since the postural control of axial segments is important for standing and walking, its impairment should be taken into account in rehabilitation programs for children with CP.

The functionalities of myoelectric hooks, such as whether they allow wrist movements, as well as the volume and design of the devices, may impact how fitted transradial amputees use their upper limbs. The aim of the current study was to compare two prosthetic myoelectric hooks in terms of compensatory shoulder movements, functionality and user satisfaction. This monocentric, randomized, controlled, cross-over trial evaluated eight transradial amputees fitted with two prosthetic myoelectric hooks, the Greifer and the Axon-Hook, during two consecutive periods. At the end of each period, shoulder abduction (mean and percentage of time with shoulder abduction > 60°) and manual dexterity were assessed using the Box and Blocks Test (BBT) on both sides, and satisfaction was assessed with the Evaluation of Satisfaction with Assistive Technology questionnaire. For each patient, data obtained with the BBT on the amputated side were compared with those obtained on the non-amputated side. Shoulder abduction was significantly higher with the Greifer (60.9°± 20.3°, p = 0.03) than with the Axon-Hook (39.8°± 16.9°) and also than with the NA side (37.6 ± 19.4°, p = 0.02). Shoulder abduction on the NA side (37.6 ± 19.4°) was close to that of the Axon-Hook (39.8°± 16.9°). The percentage of time spent with shoulder abduction > 60° during the BBT was higher with the Greifer than with the Axon-Hook or with the NA side (53.3 ± 34.4%, 17.6 ± 27.0% and 18.4 ± 34.9%, respectively), but the differences were not significant (p = 0.15). A significant strong negative correlation was found between shoulder abduction and wrist position with the Axon-Hook (r = -0.86; p < 0.01), but not with the Greifer. Manual dexterity and satisfaction did not differ significantly between the two devices. These results revealed compensatory movements, such as shoulder abduction in transradial amputees equipped with hooks, themselves influenced by the prosthetic device settings.

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 yr) 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 1) early flattening of the foot and ample dorsiflexion (decelerated by the plantar flexors) during WA and 2) 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.NEW & NOTEWORTHY Adaptation to walking in negative-heel shoes was similar in typically developing children and children with cerebral palsy: it featured ankle dorsiflexion upon initial contact, even though (in the latter group) the soleus was always spastic in a clinical examination. Hence, in children with cerebral palsy, the early deceleration of ankle dorsiflexion by the plantar flexors (promoted by early flattening of the foot, and regardless of the type of footwear) may have a functional role.

Postural control continues to develop during middle childhood as shown by the decrease in body sway in stance between the ages of 5 and 11. Although head and trunk control is crucial for balance control during both static and dynamic activities, evaluating its specific development and its contribution to overall postural control is methodologically challenging. Here, we used an unstable sitting device adapted to ensure that only the axial segments could control the balance of the device and thus the balance of the upper body. This study aimed to assess the development of the postural stabilization of axial body segments during middle childhood. Thirty-six children (in three age groups: 6-7yo, 8-9yo, and 10-11yo) and 11 adults sat on the unstable sitting device and had to stabilize their axial segments under several conditions: a moderate vs. high level of balance challenge, and eyes open vs. eyes closed. Upper-body postural sway (area, mean velocity and root mean square (RMS) of the center of pressure (CoP) displacement) decreased progressively with age (6-7yo > 8-9yo > 10-11yo > adults), and this effect was accentuated when the balance challenge was high (for CoP area) or in the “eyes closed” condition (for CoP area and RMS). The stabilization strategies were assessed by anchoring indexes computed from three-dimensional kinematics. A progressive shift was showed, from an “en bloc” pattern at 6–7 years of age toward a more articulated (i.e. adult-like) pattern at 10–11. A head-on-space stabilization strategy first emerged at the age of 8–9. Middle childhood is an important period for the development of axial segment stabilization, which continues to mature until adulthood. This development might be related to the introduction and progressive mastery of feedforward sensorimotor processes and might contribute strongly to the development of overall postural control.

In the literature, several studies on Trans-tibial amputee (TTA) gait focused on kinematics of lower limbs variables. Former studies confirm the essential role of shoulder movement in the human gait. In the horizontal plane, a counter-rotation of pelvis and scapulae girdles occurred characterizing certain gait pathologies’. The purpose of this study is to enhance the compensation strategies of TTA individuals during walking, by analysing the kinematics of pelvis and scapulae girdle’s movements in the sagittal and the horizontal planes. Twenty healthy human subjects (HS) and nineteen TTA participated in this study. A three-dimensional gait analysis with an optoelectronic VICON device were used. In the sagittal plane, the shoulder’s movements are significantly higher during TTA gait. Two counter-rotations of the scapulae and pelvis girdles intervene in the early and in the middle of gait cycle. The kinematic analysis of the scapulae and pelvis girdles during walking showed that TTA have a specific character of gait.

It has been suggested that vestibular cues are inhibited for the benefit of spinal locomotor centres in parallel with the increase in locomotion speed. This study aimed at quantifying the influence of a transient vestibular tone imbalance (TVTI) on gait kinematics, muscle activity and muscle synergies during walking and running. Twelve participants walk or run at a self-selected speed with or without TVTI, which was generated by 10 body rotations just prior the locomotion task. Three-dimensional lower-limb kinematic was recorded simultaneously with the surface electromyographic (EMG) activity of 8 muscles to extract muscle synergies via non-negative matrix factorization. Under TVTI, there was an increased gait deviation in walking compared to running (22.8 ± 8.4° and 8.5 ± 3.6°, respectively; p 0.01), while the number (n = 4) and the composition of the muscle synergies did not differ across conditions (p = 0.78). A higher increase (p 0.05) in EMG activity due to TVTI was found during walking compared to running, especially during stance. These findings confirmed that the central nervous system inhibited misleading vestibular signals according to the increase in locomotion speed for the benefit of spinal mechanisms, expressed by the muscle synergies.

Objective It is known from animal experiments that the vestibulospinal pathway is an effector control of the vestibular nucleus, whose stimulation generates an increase in the muscular tone during the stance phase of walk without affecting the muscular coordination. Increasing movement speed (walk to run) inhibits peripheral vestibular afferents in favour of central automatic motor programs. The aim of this study was to quantify the impact of a transient vestibular tone imbalance (TVTI) on the level of muscular activity and muscular synergies during walking and running, in human. Material/Patients and methods Eleven asymptomatic participants aged between 20 and 28 years took part in the study. Participants were instructed to walk or run for a distance of 10 m with the eyes closed (control conditions). They also were instructed to perform the same tasks after 10 rotations on an armchair at 360°/s, before being abruptly stopped (experimental conditions). For each condition, muscular synergies were extracted by using the non-negative matrix factorization on the surface electromyographic (EMG) signal of 8 lower limb muscles. Additionally, the change in muscle activation (ΔEMG) due to the TVTI in each mode of locomotion (walk or run) was determined by the mean EMG amplitude during the TVTI condition with the one during the control condition. The lateral deviation of locomotion was quantified by a Vicon 3D analysis system. Results Muscle synergies were similar across conditions (in number, composition and activation), while ΔEMG of the stance phase during walking was significantly (P = 0.038) higher than during running. The TVTI increased the lateral deviation in both modes of locomotion (P Discussion/Conclusion This study corroborated previous findings that vestibular inputs were differentially regulated depending on the locomotion speed but had no effect on the underlying muscle coordination of locomotion. This result could open a new paradigm of rehabilitation of vestibulopathic subjects, by training them to flexibly regulated the weightings among sensory inputs to produce the motor response.

Introduction Les enfants atteints de paralysie cerebrale (PC) presentent des difficultes de controle des segments axiaux qui pourraient expliquer certains deficits locomoteurs tels que le freinage excessif lors l’appui initial. Tandis que les interventions therapeutiques classiques se centrent majoritairement sur les membres inferieurs, cette etude visait a determiner si l’amelioration du controle du tronc des enfants PC, grâce a une reeducation axiale accentuee, pouvait entrainer des repercussions favorables sur le freinage initial lors de la marche. Materiel et methodes Treize enfants PC (8 ans ± 2,4), ont suivi en cross-over deux phases de reeducation de 3 mois, l’une de reeducation habituelle et l’autre ciblant davantage les segments axiaux (reeducation axiale accentuee, RAA). Avant et apres chaque phase de reeducation, ont ete realisees (1) une evaluation de la stabilisation des segments axiaux via un dispositif d’assise instable et via l’echelle Trunk Control Measurement Scale (TCMS) et (2) une analyse quantifiee de la marche. Les performances initiales des enfants PC etaient comparees a celles de 16 enfants controles (EC). Resultats Les enfants PC avaient davantage de difficultes pour stabiliser le tronc que les EC (score inferieur au TCMS et surface de deplacement du CoP superieure sur assise instable). Apres RAA, ces performances posturales etaient ameliorees et le freinage initial lors de la marche etait significativement moins important. La reeducation habituelle ne montrait pas d’effet significatif. Discussion/Conclusion Incorporer des activites challengeant les segments axiaux semble pertinent pour ameliorer le controle postural mais aussi la locomotion des enfants atteints de PC.

Introduction L’indice d’ancrage (IA), proposee par Assaiante et Amblard (1993), permet d’identifier les differentes strategies de stabilisation segmentaire adoptee par l’enfant pendant la marche selon son developpement moteur. A notre connaissance, aucune etude n’a analyse les IA pendant la marche d’enfants atteints de paralysie cerebrale (PC) qui presentent pourtant des retards de developpement au niveau des synergies durant la posture debout statique (Woollacott et al., 1998). Materiel et methodes Les IA de la tete et du tronc ont ete calcules sur 9 cycles de marche a vitesse spontanee pour 59 enfants PC separes en 3 groupes : atteinte bilaterale symetrique (ABS) ( n = 25 ; 11,6 ± 3,2 ans), atteinte bilaterale asymetrique (ABA) ( n = 18 ; 11,5 ± 2,8 ans) ou atteinte unilaterale (AU) ( n = 16 ; 11,1 ± 2,9 ans). Resultats Le resultat le plus remarquable etait l’IA negatif de la tete dans le plan frontal pour les enfants du groupe ABS, differant significativement des indices positifs releves pour les deux autres groupes. La tete se comporte donc en bloc avec le thorax dans le plan frontal lors d’une ABS. En revanche, pour tous les groupes, le thorax n’etait pas ancre sur le bassin. Discussion–conclusion La strategie en bloc de la tete avec le thorax dans le plan frontal observee chez l’enfant PC seulement lors d’une ABS pose la question de son origine (retard developpemental, compensation) alors que l’enfant de developpement typique de plus de 7 ans, stabilise la tete par rapport a l’espace, dans les 3 plans de l’espace, meme lors d’une marche d’equilibre difficile. L’absence d’ancrage du thorax sur le bassin chez les enfants PC pourrait en partie etre imputee a la marche en Trendelenburg frequemment observee chez ces patients.

Introduction Lors de la marche spontanee, la retraction des ischio-jambiers est un facteur de flexion excessive du genou lors du contact initial (CI) chez l’enfant ayant une paralysie cerebrale (PC). En effet, la longueur des ischio-jambiers est maximale au CI quand la difference entre la flexion de hanche et la flexion de genou (DFH-FG) est maximale. Nous avons teste si la marche a grands pas peut augmenter la DFH-FG chez l’enfant PC et l’enfant sain. Materiel et methodes Chez 47 enfants PC (GMFCS I et II, diplegiques (n = 34) et hemiplegiques (n = 13), 12 ± 3 ans) et 10 enfants sains (9 ± 1 ans), l’angle poplite a vitesses lente et rapide etait mesure pour estimer la retraction et la spasticite des ischio-jambiers. Une analyse 3D de la marche spontanee et a grands pas etait realisee pour evaluer entre les 2 conditions la variation de longueur des pas et la variation de DFH-FG (ΔDFH-FG). Resultats Deux sous-groupes d’enfants PC etaient clairement observes, ceux avec ΔDFH-FG Discussion–conclusion Alors que les angles poplites etaient comparables entre les 2 sous-groupes d’enfants PC, la marche a grands pas a permis de distinguer les enfants PC capables d’allonger les ischio-jambiers. Cette condition de marche apparait utile pour orienter une decision therapeutique pour les ischio-jambiers.

Objective Numerous studies have explored various kinematics, kinetics and spatiotemporal data in gait analysis of able-bodied subjects and amputees on slope and cross-slope. None have evaluated amputees’ shoulders-pelvis dissociation in these situations. It is important for health professionals to understand how these patients’ shoulder and pelvic girdles move and interact in theses situations to optimize their rehabilitation. The aim of this study is to compare shoulder girdle and pelvis forward progression and their dissociation in transtibial amputees as well as able-bodied subjects during slope and cross-slope conditions. Material/patients and methods Twenty transtibial amputees and 30 able-bodied subjects walked at self-selected paces uphill and downhill on a 12% slope incline and on a 10% cross-slope incline, in an eight-camera optoelectronic motion analysis system. Measurements included: distance between acromions; distance between anteriosuperior iliac spines according to the x-plane; and angle between the right acromion, left acromion, right anteriosuperior iliac spine and left anteriosuperior iliac spine according to the z-plane. These values were correlated with the gait cycle and compared between groups. Results Shoulder anterior displacements were significantly greater in the amputee population in every situation, except for downhill left shoulder maximal forward progression. In ascent, their timing of shoulder and pelvis forward progression was significantly altered when compared to able-bodied subjects. Amputees tended to delay their pelvis forward progression, which was quickly followed by their shoulder progression. Their shoulders-pelvis coordination was in-phase instead of being out-of-phase in this condition. During unstable situations, such as downhill and cross-slope, they tended to brake the movement by moving the shoulder after the pelvis, similar to able-bodied subjects. During downhill, amputees’ shoulder girdle and pelvis dissociation angles were significantly less than the control group. Discussion, conclusion Transtibial amputees, like able-bodied subjects, react differently depending on the surface they walk on. Due to the lack of adaptability of the prosthetic foot and the lesser muscular strength of the residual limb, transtibial amputees’ balance on difficult surfaces depends greatly on their shoulder girdle and its coordination with the pelvis. Therefore, sidewalks with slopes or cross-slopes may impede gait and increase risk of fall. As such, these conditions are important to address in rehabilitation.

Objective Modification of the musculoskeletal system of lower limb amputees, as well as the inability of the prosthesis to compensate the loss of the elements necessary for “normal” walking, could disrupt postural control and thus specifically characterize the gait of amputees. Most studies focused on kinematics lower limbs parameters to assess transtibial amputees (TTA) gait. However, other studies have shown the essential role of shoulder movement in the human gait. The modification of this counter-rotation movement in the horizontal plane is characteristic of specific pathologies. The aim was to enhance the compensation strategies of TTA during walking on level ground, by assessing the kinematic of pelvic and scapular girdles’ movements in the sagittal and horizontal planes. Material/patients and methods Twenty able-bodies individuals (AB) and 19 TTA walked, with their own prosthetic devices and shoes, at their self-selected speed on level ground in a motion capture laboratory. Distance between the right and the left acromions and distance between the right and the left anteriosuperior iliac spines in the sagittal plane and the angle of counter-rotation between the pelvic and the scapular girdles in the horizontal plane were measured manually. These values were assessed considering gait cycle, and compared between groups. Results In the sagittal plane, the shoulder movements were significantly greater in TTA compared to AB (P = 0.03). Moreover, an anticipation of the maximum forward shoulder displacement in TTA was observed at 40% of gait cycle, contrary to AB, in whom it was observed at 53% of gait cycle. However, the amplitude of counter-rotation between shoulder and pelvis and the moment when counter-rotation occurred in gait cycle were not significantly different between groups in the horizontal plane. Two counter-rotations of scapular and pelvic girdles occurred at the beginning and in the middle of the gait cycle. Discussion, conclusion The kinematic analysis of the scapular and pelvic girdles movements during level walking showed a specific characterization of the gait of TTA related to their disability due to the loss of residual limb muscles. The displacement of scapular girdle in the sagittal plane is an important compensatory factor for transtibial amputees.

Introduction Brandt et al. (1999) ont montre qu’un desequilibre transitoire du tonus vestibulaire (DTTV) engendrait une deviation laterale plus importante a la marche qu’a la course. Avec l’augmentation de la vitesse de deplacement, les centres locomoteurs spinaux et supra-spinaux supprimeraient les afferences vestibulaires destabilisantes au profit de programmes moteurs automatiques (Jahn et al., 2004, La Fougere et al., 2010). Cependant, aucune etude n’a a ce jour evalue l’effet d’un DTTV sur les synergies musculaires (d’origine spinale) a la marche et a la course. Ainsi, nous avons pose l’hypothese d’une alteration des synergies musculaires a la marche par rapport a la course lors d’un DTTV. Materiel et methodes Sept participants asymptomatiques (20–28 ans) ont participe a cette etude. Chaque participant effectuait 4 conditions de locomotion les yeux fermes : (i et ii) marche et course sans DTTV et (iii et iv) marche et course avec DTTV. L’ordre des essais etait randomise. Avant la tâche locomotrice, le DTTV etait provoque par 10 rotations sur fauteuil a une vitesse d’un tour par seconde avant d’etre brusquement stoppe. Pour chaque essai, les synergies musculaires ont ete extraites a partir des enveloppes electromyographiques (filtre passe-bas a 8 Hz) provenant de 8 muscles du membre inferieur droit. La similarite des synergies musculaires fut objectivee par une procedure de validation croisee. Resultats Quatre synergies musculaires ont ete systematiquement extraites pour l’ensemble des conditions de locomotion. Aucun effet significatif ( p = 0,70) du DTTV n’a ete detecte sur la composition des synergies musculaires que ce soit a la marche ou a la course. Discussion–conclusion Bien que le mode de locomotion (marche vs. course) entraine des differences d’activation de reseaux supra-spinaux locomoteurs (Jahn et al., 2008), il apparait ici que les informations vestibulaires n’ont pas d’influence sur l’organisation automatique des coordinations musculaires locomotrices.