The dynamic balance of the children with cerebral palsy and typical developing during gait. Part I: Spatial relationship between COM and COP trajectories

Evaluation of postural stability in children with hemiplegic cerebral palsy

[Purpose] Postural stability is the ability of to maintain the position of the body within the support area. This function is affected in cerebral palsy. The aim of the present study was to compare static and dynamic postural stability between children with hemiplegic cerebral palsy and healthy controls. [Subjects and Methods] Thirty-seven children between the ages of 5 and 14 diagnosed with hemiplegic cerebral palsy (19 right, 18 left) and 23 healthy gender- and age-matched controls were included in the study. Postural stability was evaluated in both of the groups using a Neurocom Balance. Sway velocity was measured both with the eyes open and closed. Sit to stand and turning abilities were also assessed. [Results] The sway velocities with the eyes open and closed were significantly different between the groups. The weight transfer time in the Sit to Stand test was also significantly slower in children with cerebral palsy. Children with cerebral palsy also showed slower turning times and greater sway velocities during the Step and Quick Turn test on a force plate compared with their healthy counterparts. [Conclusion] Both static and dynamic postural stability parameters are affected in hemiplegic cerebral palsy. Further research is needed to define rehabilitation interventions to improve these parameters in patients.

External Mechanical Work and Pendular Energy Transduction of Overground and Treadmill Walking in Adolescents with Unilateral Cerebral Palsy

PURPOSE

Motor impairments affect functional abilities and gait in children and adolescents with cerebral palsy (CP). Improving their walking is an essential objective of treatment, and the use of a treadmill for gait analysis and training could offer several advantages in adolescents with CP. However, there is a controversy regarding the similarity between treadmill and overground walking both for gait analysis and training in children and adolescents. The aim of this study was to compare the external mechanical work and pendular energy transduction of these two types of gait modalities at standard and preferred walking speeds in adolescents with unilateral cerebral palsy (UCP) and typically developing (TD) adolescents matched on age, height and body mass.

METHODS

Spatiotemporal parameters, external mechanical work and pendular energy transduction of walking were computed using two inertial sensors equipped with a triaxial accelerometer and gyroscope and compared in 10 UCP (14.2 ± 1.7 year) and 10 TD (14.1 ± 1.9 year) adolescents during treadmill and overground walking at standard and preferred speeds.

RESULTS

The treadmill induced almost identical mechanical changes to overground walking in TD adolescents and those with UCP, with the exception of potential and kinetic vertical and lateral mechanical works, which are both significantly increased in the overground-treadmill transition only in UCP (P < 0.05).

CONCLUSIONS

Adolescents with UCP have a reduced adaptive capacity in absorbing and decelerating the speed created by a treadmill (i.e., dynamic stability) compared to TD adolescents. This may have an important implication in rehabilitation programs that assess and train gait by using a treadmill in adolescents with UCP.

The Effects of Selective Dorsal Rhizotomy on Balance and Symmetry of Gait in Children with Cerebral Palsy

Aim

Cerebral palsy (CP) is associated with dysfunction of the upper motor neuron and results in balance problems and asymmetry during locomotion. Selective dorsal rhizotomy (SDR) is a surgical procedure that results in reduced afferent neuromotor signals from the lower extremities with the aim of improving gait. Its influence on balance and symmetry has not been assessed. The aim of this prospective cohort study was to evaluate the impact of SDR on balance and symmetry during walking.

Methods

18 children (10 girls, 8 boys; age 6 years (y) 3 months (m), SD 1y 8m) with bilateral spastic CP and Gross Motor Function Classification System levels I to II underwent gait analysis before and 6 to 12 months after SDR. Results were compared to 11 typically developing children (TDC; 6 girls, 5 boys; age 6y 6m, SD 1y 11m). To analyse balance, sway velocity, radial displacement and frequency were calculated. Symmetry ratios were calculated for balance measures and spatio-temporal parameters during walking.

Results

Most spatio-temporal parameters of gait, as well as all parameters of balance, improved significantly after SDR. Preoperative values of symmetry did not vary considerably between CP and TDC group and significant postoperative improvement did not occur.

Interpretation

The reduction of afferent signalling through SDR improves gait by reducing balance problems rather than enhancing movement symmetry.

Multilevel Upper Body Movement Control during Gait in Children with Cerebral Palsy

Upper body movements during walking provide information about balance control and gait stability. Typically developing (TD) children normally present a progressive decrease of accelerations from the pelvis to the head, whereas children with cerebral palsy (CP) exhibit a general increase of upper body accelerations. However, the literature describing how they are transmitted from the pelvis to the head is lacking. This study proposes a multilevel motion sensor approach to characterize upper body accelerations and how they propagate from pelvis to head in children with CP, comparing with their TD peers. Two age- and gender-matched groups of 20 children performed a 10m walking test at self-selected speed while wearing three magneto-inertial sensors located at pelvis, sternum, and head levels. The root mean square value of the accelerations at each level was computed in a local anatomical frame and its variation from lower to upper levels was described using attenuation coefficients. Between-group differences were assessed performing an ANCOVA, while the mutual dependence between acceleration components and the relationship between biomechanical parameters and typical clinical scores were investigated using Regression Analysis and Spearman’s Correlation, respectively (α = 0.05). New insights were obtained on how the CP group managed the transmission of accelerations through the upper body. Despite a significant reduction of the acceleration from pelvis to sternum, children with CP do not compensate for large accelerations, which are greater than in TD children. Furthermore, those with CP showed negative sternum-to-head attenuations, in agreement with the documented rigidity of the head-trunk system observed in this population. In addition, the estimated parameters proved to correlate with the scores used in daily clinical practice. The proposed multilevel approach was fruitful in highlighting CP-TD gait differences, supported the in-field quantitative gait assessment in children with CP and might prove beneficial to designing innovative intervention protocols based on pelvis stabilization.

The use of turning tasks in clinical gait analysis for children with cerebral palsy

BACKGROUND

Turning while walking is a crucial component of locomotion that is performed using an outside (step) or inside (spin) limb strategy. The aims of this paper were to determine how children with cerebral palsy perform turning maneuvers and if specific kinematic and kinetic adaptations occur compared to their typically developing peers.

METHODS

Motion capture data from twenty-two children with cerebral palsy and fifty-four typically developing children were collected during straight and 90° turning gait trials. Experimental data were used to compute spatio-temporal parameters, margin of stability, ground reaction force impulse, as well as joint kinematics and kinetics.

FINDINGS

Both child groups preferred turning using the spin strategy. The group of children with cerebral palsy exhibited the following adaptations during turning gait compared to the typically developing group: stride length was decreased across all phases of the turn with largest effect size for the depart phase (2.02), stride width was reduced during the turn phase, but with a smaller effect size (0.71), and the average margin of stability during the approach phase of turning was reduced (effect size of 0.98). Few overall group differences were found for joint kinematic and kinetic measures; however, in many cases, the intra-subject differences between straight walking and turning gait were larger for the majority of children with cerebral palsy than for the typically developing children.

INTERPRETATION

In children with cerebral palsy, turning gait may be a better discriminant of pathology than straight walking and could be used to improve the management of gait abnormalities.

Effects of modified constraint-induced movement therapy on the lower extremities in patients with stroke: a pilot study

PURPOSE

This study aimed to qualify the improvements of modified constraint-induced movement therapy (m-CIMT) on the lower limb of stroke patients via assessing the centre of mass (COM) displacement and the basic gait parameters.

METHODS

A total of 22 hemiplegic patients after stroke with first-time clinical cerebral infarction or haemorrhagic cerebrovascular accident were included in this study from May to December, 2014. The patients were randomly divided into m-CIMT group and the conventional therapy group (control group), and received corresponding training for five days/week for four weeks. The COM displacement and gait parameters were assessed by three-dimensional segmental kinematics method in pre-intervention and post- intervention therapy.

RESULTS

After four weeks of m-CIMT, the COM displacement on sagittal plane of paretic leg during stance phase was increased (pre: 91.04 ± 4.39 cm, post: 92.38 ± 4.58 cm, p < 0.05) and swing range of frontal plane was remarkably decreased (pre: 10.15 ± 3.05 cm, post: 7.83 ± 1.90 cm, p < 0.001). Meantime, the normalised swing range of COM in m-CIMT was superior to that in control group. Moreover, the gait parameters, including velocity (0.27 m/s), step width (0.10 m), step length (0.22 m) and swing time percentage (29.80%), were significantly improved by post-interventions of m-CIMT (p < 0.05).

CONCLUSION

The m-CIMT intervention improves the COM displacement in sagittal and frontal plane, as well as gait parameters. These suggest that m-CIMT intervention may be feasible and effective for the rehabilitation of hemiplegic gait. Implications for Rehabilitation Segmental kinematics method was used to estimate the displacement of the COM. m-CIMT interventions improved the COM displacement of patients after stroke. m-CIMT interventions improved the hemiplegic gait parameters.

Improved determination of dynamic balance using the centre of mass and centre of pressure inclination variables in a complete golf swing cycle

Golf requires proper dynamic balance to accurately control the club head through a harmonious coordination of each human segment and joint. In this study, we evaluated the ability for dynamic balance during a golf swing by using the centre of mass (COM)-centre of pressure (COP) inclination variables. Twelve professional, 13 amateur and 10 novice golfers participated in this study. Six infrared cameras, two force platforms and SB-Clinic software were used to measure the net COM and COP trajectories. In order to evaluate dynamic balance ability, the COM-COP inclination angle, COM-COP inclination angular velocity and normalised COM-COP inclination angular jerk were used. Professional golfer group revealed a smaller COM-COP inclination angle and angular velocity than novice golfer group in the lead/trail direction (P < 0.01). In the normalised COM-COP inclination angular jerk, the professional golfer group showed a lower value than the other two groups in all directions. Professional golfers tend to exhibit improved dynamic balance, and this can be attributed to the neuromusculoskeletal system that maintains balance with proper postural control. This study has the potential to allow for an evaluation of the dynamic balance mechanism and will provide useful basic information for swing training and prevention of golf injuries.

Learning to tune the antero-posterior propulsive forces during walking: a necessary skill for mastering upright locomotion in toddlers

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.

Balance improvement after physical therapy training using specially developed serious games for cerebral palsy children: preliminary results

PURPOSE

Cerebral palsy (CP) leads to various clinical signs mainly induced by muscle spasticity and muscle weakness. Among these ones impaired balance and posture are very common. Traditional physical therapy exercise programs are focusing on this aspect, but it is difficult to motivate patients to regularly perform these exercises, especially at home without therapist supervision. Specially developed serious games (SG) could therefore be an interesting option to motivate children to perform specific exercise for balance improvement.

METHOD

Ten CP children participated in this study. Patients received four sessions of SG included into conventional therapy (1 session of 30 min a week during 4 weeks). Trunk control and balance were assessed using Trunk Control Motor Scale (TCMS) before and after interventions.

RESULTS

Children presented a significant improvement in TCMS global score after interventions [37.6 (8.7) and 39.6 (9.5) before and after interventions, respectively, p = 0.04].

CONCLUSION

SG could therefore be an interesting option to integrate in the conventional treatment of CP children. Implication for Rehabilitation Cerebral palsy (CP) leads to balance issues. Rehabilitation exercises are not performed (enough) at home. Serious games (SG) could increase patients' motivation. SG increase balance control of CP children.

Effect of postural balance training on gait parameters in children with cerebral palsy

OBJECTIVE

The aim of this study was to evaluate the effect of dynamic bilateral postural stability on balance control and gait parameters in children with cerebral palsy.

DESIGN

Thirty children with spastic diplegia (8-10 yrs) were included in this study. The children were randomly assigned into two groups: control group A and study group B. The children in both groups received traditional physical therapy program, 2 hrs per day for group A and 1.5 hrs followed by 30 mins of dynamic postural stability training program using the Biodex Stability System for group B. The treatment frequency was three sessions per week for 8 consecutive weeks on two stability levels (7 and 8). The participating children received pretreatment and posttreatment assessments using the Biodex Stability System to evaluate the stability indices (anteroposterior, mediolateral, and overall) at the two stability levels (7 and 8) and three-dimensional motion analysis system (pro-reflex system) to evaluate the spatiotemporal parameters including step length, velocity, cycle time, stance, and swing phase percentage.

RESULTS

The children in both groups showed significant improvements in the mean values of all measured variables after treatment indexed by a significant reduction in stability indices and improvement in gait parameters. The results also showed significant differences in all measured parameters in favor of group B, when compared with those in group A (P < 0.01).

CONCLUSIONS

Balance training on the Biodex Stability System could be a useful tool in conjunction with traditional physical therapy program for improving balance control and gait functions in children with spastic diplegic cerebral palsy.

Development and validity of the early clinical assessment of balance for young children with cerebral palsy

OBJECTIVES

Validity of the Early Clinical Assessment of Balance (ECAB), to monitor postural stability in children with cerebral palsy (CP), was evaluated.

METHODS

410 children with CP, 1.5 to 5 years old, participated. Physical therapists scored children on the Movement Assessment of Infants Automatic Reactions section and Pediatric Balance Scale. Through consensus, researchers selected items from both measures to create the ECAB. Content and construct validity were examined through item correlations, comparison of ECAB scores among motor ability, age and gender groups and correlations with the Gross Motor Function Measure 66 basal and ceiling (GMFM-66-B&C).

RESULTS

Internal consistency was high (Cronbach's alpha = 0.92). ECAB differed significantly among motor ability, children <31 months old scored lower than older children, but there was no difference between boys and girls. ECAB and GMFM-66-B&C scores correlated strongly (r = 0.97).

CONCLUSION

Validity of the ECAB was supported. Reliability and responsiveness need study.

An fNIRS exploratory investigation of the cortical activity during gait in children with spastic diplegic cerebral palsy

OBJECTIVE

The primary aim of this exploratory investigation was to determine if there are differences in cortical activation of children with spastic diplegic cerebral palsy (CP) and typically developing children during gait.

METHODS

Functional near-infrared spectroscopy was used to measure the concentration of oxygenated hemoglobin that was present in the supplementary motor area, pre-central gyrus, post-central gyrus and superior parietal lobule as the children walked on a treadmill. A sagittal plane video was concurrently collected and later digitized to quantify the temporal gait variations.

RESULTS

(1) The children with CP had an increased amount of activation in the sensorimotor cortices and superior parietal lobule during gait, (2) the children with CP had a greater amount of variability or error in their stride time intervals, and (3) an increased amount of error in the temporal gait kinematics was associated with an increased amount of activity across the cortical network.

CONCLUSION

Our results suggest that the perinatal damage and subsequent neural reorganization that occurs with spastic diplegic CP may impact the functional cortical activity for controlling gait. Furthermore, our results imply the increased cortical activity of the somatosensory cortices and superior parietal cortices may underlie the greater amount of error in the temporal gait kinematics.

Validity of an activity monitor in young people with cerebral palsy gross motor function classification system level I

The activPAL™ activity monitor has potential for use in youth with Cerebral Palsy (CP) as it has demonstrated acceptable validity for the assessment of sedentary and physical activity in other populations. This study determined the validity of the activPAL™ activity monitor for the measurement of sitting, standing, walking time, transitions and step count for both legs in young people with hemiplegic and asymmetric diplegic CP. Seventeen participants with CP Gross Motor Function Classification System level I completed two video recorded test protocols that involved wearing an activPAL™ activity monitor on alternate legs. Agreement between observed video recorded data and activPAL™ activity monitor data was assessed using the Bland and Altman (BA) method and intraclass correlation coefficients (ICC 3,1). There was perfect agreement for transitions and high agreement for sitting (BA mean differences (MD): -1.8 and -1.8 s; ICCs: 0.49 and 0.95) standing (MD: 0.8 and 0.1 s; ICCs: 0.59 and 0.98) walking (MD: 1 and 1.1 s; ICCs: 0.99 and 0.94) timings and low agreement for step count (MD: 4.1 and 2.8 steps; ICCs: 0.96 and 0.95) for both legs. This study found clinically acceptable agreement with direct observation for all activPAL™ activity monitor functions, except for step count measurement with respect to the range of measurement values obtained for both legs in this study population.

Evaluation of two approaches for aligning data obtained from a motion capture system and an in-shoe pressure measurement system

An in-shoe pressure measurement (IPM) system can be used to measure center of pressure (COP) locations, and has fewer restrictions compared to the more conventional approach using a force platform. The insole of an IPM system, however, has its own coordinate system. To use an IPM system along with a motion capture system, there is thus a need to align the coordinate systems of the two measurement systems. To address this need, the current study examined two different approaches—rigid body transformation and nonlinear mapping (i.e., multilayer feed-forward neural network (MFNN))—to express COP measurements from an IPM system in the coordinate system of a motion capture system. Ten participants (five male and five female) completed several simulated manual material handling (MMH) activities, and during these activities the performance of the two approaches was assessed. Results indicated that: (1) performance varied between MMH activity types; and (2) a MFNN performed better than or comparable to the rigid body transformation, depending on the specific input variable sets used. Further, based on the results obtained, it was argued that a nonlinear mapping vs. rigid body transformation approach may be more effective to account for shoe deformation during MMH or potentially other types of physical activity.

Do traditionally recommended cane lengths equally influence walking in patients after stroke?

BACKGROUND

A cane has been used to improve hemiplegic gait by assisting affected limb to smoothly shift body mass toward the sound limb.

OBJECTIVE

The purpose of this study was to compare the walking parameters of patients after stroke while walking using traditionally recommended cane lengths that is fitted to the height of the greater trochanter (GT) or to the wrist crease (WC).

METHODS

Sixteen patients with stroke participated in this study and were randomly assigned to walking with a GT or WC cane length. The two traditionally recommended cane lengths were from the ground to the top of the GT or to the distal WC. Measured walking parameters were foot contact area of the affected side, stride length, center of pressure trajectory, foot axis, foot pressures, and walking velocity when walking with a cane.

RESULTS

Significant differences in foot contact area, foot pressure, and center of pressure trajectory were observed between the two cane lengths (p < 0.05). The GT cane length had a wider mid-foot contact area (by 19.7%), a longer anterior/posterior center of pressure trajectory (by 9.7%), a greater toe pressure (by 26.7%), and a greater mid-foot pressure (by 14.3%) than the WC cane length (p < 0.05). No significant differences were observed for other walking parameters.

CONCLUSION

Hemiplegic walking with cane fitted at the GT might results in more normal walking of the affected limb in patients after stroke.

Relationship between static postural control and the level of functional abilities in children with cerebral palsy

Background:

Postural control deficits can impair functional performance in children with cerebral palsy (CP) in daily living activities.

Objective:

To verify the relationship between standing static postural control and the functional ability level in children with CP.

Method:

The postural control of 10 children with CP (gross motor function levels I and II) was evaluated during static standing on a force platform for 30 seconds. The analyzed variables were the anteroposterior (AP) and mediolateral (ML) displacement of the center of pressure (CoP) and the area and velocity of the CoP oscillation. The functional abilities were evaluated using the mean Pediatric Evaluation of Disability Inventory (PEDI) scores, which evaluated self-care, mobility and social function in the domains of functional abilities and caregiver assistance.

Results:

Spearman's correlation test found a relationship between postural control and functional abilities. The results showed a strong negative correlation between the variables of ML displacement of CoP, the area and velocity of the CoP oscillation and the PEDI scores in the self-care and caregiver assistance domains. Additionally, a moderate negative correlation was found between the area of the CoP oscillation and the mobility scores in the caregiver assistance domain. We used a significance level of 5% (p <0.05).

Conclusions:

We observed that children with cerebral palsy with high CoP oscillation values had lower caregiver assistance scores for activities of daily living (ADL) and consequently higher levels of caregiver dependence. These results demonstrate the repercussions of impairments to the body structure and function in terms of the activity levels of children with CP such that postural control impairments in these children lead to higher requirements for caregiver assistance.

Gait characteristics in children and adolescents with cerebral palsy assessed with a trunk-worn accelerometer

This study aimed to investigate gait characteristics reflecting balance and progression in children and adolescents with cerebral palsy (CP) compared with typically developing (TD) children. Gait characteristics variables representing aspects of balance were trunk acceleration, interstride regularity and asymmetry of accelerations while gait characteristics representing progression were gait speed, cadence, step time and step length. Children in the age range 5-18 years (mean age 11.1 years) with spastic CP (n=41) and a gross motor function corresponding to GMFCS I-III and children with TD (n=29) were included. The children walked back and forth along a 5m pathway with a tri-axial accelerometer worn on the lower back to allow assessment of their gait characteristics. Data were recorded along the anterioposterior (AP), mediolateral (ML), and vertical (V) axes. To assess the magnitude of potential differences in gait characteristics, standard deviation scores were calculated, using TD children as reference. Gait parameters related to balance, such as AP, ML, and V accelerations, were higher in the children with CP (z-scores between 0.4 and 0.7) and increased with increasing GMFCS levels. The differences in accelerations in the AP and V directions increased between children with CP and TD children with increasing speed. Also asymmetry in trunk accelerations differed significantly between the two groups in all three directions (z-scores between 0.8 and 1.8 higher in the CP group), while interstride regularity differed only slightly between children with CP and TD children, and only in the AP direction. Gait characteristics also differed between children with the spastic subtypes unilateral and bilateral CP, for accelerations and asymmetry in the AP and ML directions. Our results showed significant differences in gait characteristics between children with CP and TD children. The differences may be more related to balance than progression, and these problems seem to rise with increasing gross motor impairment and speed.

Variability of centre of pressure movement during gait in young and middle-aged women

The variability of the centre of pressure (COP) movement is a tool that is often used for stability assessments during standing; however, this variable can provide relevant findings during dynamic conditions, which are more related to fall risks. The aim of this study was to investigate age-related differences in the variability of COP movement. Healthy young (younger group - 25 subjects, age 22.2 ± 1.8 years) and middle-aged (elder group - 25 subjects, age 56.6 ± 4.9 years) females participated in this study. The ground reaction forces and COP movement during walking at a self-selected speed were recorded using two force platforms. Each stance phase was divided into four subphases: loading response (LR), mid-stance (MSt), terminal stance (TSt) and preswing (PS). Standard deviations of the medial-lateral, anterior-posterior and total COP displacements were assessed. For statistical comparisons, one-way ANOVA and the Bonferroni post-hoc test were used. These results showed significantly higher COP movement variability in selected variables in the PS, LR and MSt subphases in the elder group (p < 0.05) compared with the younger group; no differences were found in the TSt subphase. A comparison of the subphases within the groups revealed significant differences (p < 0.001 for all cases and both groups) between the parameters in the LR × MSt, LR × TSt, MSt × PS and TSt×PS subphases. The LR and PS subphases showed significantly higher values for the variability parameters.

Upper body movements in children with hemiplegic cerebral palsy walking with and without an ankle-foot orthosis

BACKGROUND

It has previously been discussed that treatment of the hemiplegic arm in patients with cerebral palsy can improve gait parameters in the lower body. Our question was whether improving the ankle rocker with an orthosis has an effect on the upper body during walking. The main aim was to investigate, which trunk and arm kinematics of toe walking children with hemiplegic cerebral palsy are changed by wearing a hinged ankle-foot orthosis, restoring an initial heel contact.

METHODS

Specific parameters of the pelvis, thorax, and arm kinematics were investigated. Differences in the hemiplegic side between the barefoot and the orthotic condition were calculated by Students t-tests. Additionally, the 95% confidence intervals were used to explore clinically relevant differences between the controls and the patients and asymmetries within the patients' affected and unaffected sides.

FINDINGS

Pelvic tilt range of motion (barefoot: 7.5° (6.1-9.0°), orthosis: 6.6° (5.1-8.1) P=0.040) and mean shoulder abduction (barefoot: 14.3° (10.2-18.4°), orthosis: 12.1° (8.4-15.8) P=0.027) were the only two parameters with statistically significant differences, although not clinically relevant, between the barefoot and orthotic conditions. Abnormalities in all three planes were explored between the patients and controls. The entire trunk was more externally rotated, the pelvis stood lower, and the elbow was more flexed on the hemiplegic side compared to the unaffected side.

INTERPRETATION

A hinged ankle-foot orthosis, restoring the first ankle rocker, had no clinically relevant effects on trunk kinematics. None of the observed upper body gait deviations seemed to be secondary to or caused by toe walking.

Development and decline of upright gait stability

Upright gait is a peculiar characteristic of humans that requires the ability to manage upper body dynamic balance while walking, despite the perturbations that are generated by movements of the lower limbs. Most of the studies on upright gait stability have compared young adults and the elderly to determine the effects of aging. In other studies, the comparison was between healthy subjects and patients to examine specific pathologies. Fewer researches have also investigated the development of upright gait stability in children. This review discusses these studies in order to provide an overview of this relevant aspect of human locomotion. A clear trend from development to decline of upright gait stability has been depicted across the entire lifespan, from toddlers at first steps to elderly. In old individuals, even if healthy, the deterioration of skeletal muscle, combined with sensorial and cognitive performance, reduces the ability to maintain an upright trunk during walking, increasing the instability and the risk of falls. Further, the pathological causes of altered development or of a sudden loss of gait stability, as well as the environmental influence are investigated. The last part of this review is focused on the control of upper body accelerations during walking, a particularly interesting topic for the recent development of low-cost wearable accelerometers.

Functionality level and its relation to postural control during sitting-to-stand movement in children with cerebral palsy

In this study we studied functional performance and functional balance in children with cerebral palsy (CP) and typically developing (TD) children. The relationship between these components and postural control during sit-to-stand movement (STS) was also investigated. Ten children with CP (GMFCS I and II) and 27 TD children, ages 5-12 years, were included in the study. The Pediatric Evaluation of Disability Inventory (PEDI) and the Pediatric Balance Scale (PBS) were used to measure functional performance and functional balance, respectively. Postural control during STS was assessed by means of a force plate. Participants were asked to stand from a chair with feet over a force plate. Children with CP exhibited lower scores than TD children in the PBS and in the mobility Functional Skills and Caregiver Assistance domains of the PEDI (p≤0.05). In both groups postural control during STS movement was correlated with mobility Caregiver Assistance scores of the PEDI. The results demonstrate that although the participants had mild to moderate motor impairment, they exhibit deficits in their level of functional performance and functional balance compared to typical children. Moreover, it was observed that impairments in postural control during the STS movement are related to functional performance in both groups. This result demonstrates the importance of the structure and function components to the level of activity in children.

Differences in standing balance between patients with diplegic and hemiplegic cerebral palsy

Maintaining standing postural balance is important for walking and handling abilities in patients with cerebral palsy. This study included 23 patients with cerebral palsy (seven with spastic diplegia and 16 with spastic hemiplegia), aged from 7 to 16 years of age. Standing posture balance measurements were performed using an AMTI model OR6-7 force platform with the eyes open and closed. Patients with diplegic cerebral palsy exhibited greater center of pressure displacement areas with the eyes open and greater center of pressure sway in the medial-lateral direction with the eyes open and closed compared with hemiplegic patients. Thus, diplegic patients exhibited weaker postural balance control ability and less standing stability compared with hemiplegic cerebral palsy patients.

Effect of balance training on postural balance control and risk of fall in children with diplegic cerebral palsy

PURPOSE

The purpose of this study was to evaluate the effects of balance training on postural control and fall risk in children with diplegic cerebral palsy.

METHODS

Thirty spastic diplegic cerebral palsied children (10-12 years) were included in this study. Children were randomly assigned into two equal-sized groups: control and study groups. Participants in both groups received a traditional physical therapy exercise program. The study group additionally received balance training on the Biodex balance system. Treatment was provided 30 min/d, 3 d/week for 3 successive months. To evaluate the limit of stability and fall risk, participated children received baseline and post-treatment assessments using the Biodex balance system. Overall directional control, total time to complete the test, overall stability index of the fall risk test and total score of the pediatric balance scale were measured.

RESULTS

Children in both groups showed significant improvements in the mean values of all measured variables post-treatment (p < 0.05). The results also showed significantly better improvement in the measured parameters for the study group, as compared to the control group (p < 0.05).

CONCLUSION

Balance training on Biodex system is a useful tool that can be used in improving postural balance control in children with diplegic cerebral palsy.

Postural responses of adults with cerebral palsy to combined base of support and visual field rotation

We employed a virtual environment to examine the postural behaviors of adults with cerebral palsy (CP). Four adults with CP (22-32 years) and nine healthy adults (21-27 years) were tested with a Rod and Frame protocol. They then stood quietly on a platform within a three-wall virtual environment. The platform was either kept stationary or tilted 3(°) into dorsiflexion in the dark or with pitch up and down visual field rotations at 30(°)/s and 45(°)/s. While the visual field rotated, the platform was held tilted for 30 s and then slowly returned to a neutral position over 30 s. Center of pressure (CoP) was recorded and center of mass (CoM) as well as trunk and ankle angles were calculated. Electromyography (EMG) responses of the ankle and the hip muscles were recorded and analyzed using wavelets. Larger angular deviations from vertical and horizontal in the Rod and Frame test indicated that adults with CP were more visually dependent than healthy adults. Adults with CP had difficulty maintaining balance when standing on a stationary platform during pitch upward rotation of the visual scene. When the platform was tilted during visual field rotations, adults with CP took longer to stabilize their posture and had larger CoM oscillations than when in the dark. The inability to compensate for busy visual environments could impede maintenance of functional locomotion in adults with CP. Employing a visual field stimulus for assessment and training of postural behaviors would be more meaningful than testing in the dark.

Ground reaction forces during stair locomotion in pregnancy

Pregnant women experience numerous physical alterations during pregnancy which may place them at an increased risk of falls. The purpose of this study was to examine ground reaction forces (GRFs) during staircase locomotion in pregnant and non-pregnant women.

METHODS

Data were collected on 29 pregnant women in their second and third trimesters, and on 40 control women. Subjects walked at their freely chosen speeds during stair ascent and descent. A force plate imbedded in the second stair, but structurally independent of the staircase, was used to collect GRF data (1080 Hz). A marker placed on the L3/L4 spinal segment was used to determine ascent and descent velocity from a motion-capture system. In the statistical analyses, trimester (control, second trimester, third trimester) and subject were the independent variables. Stance time and ascent/descent velocity were analyzed with an ANOVA. Mediolateral excursion of the COP during the step was analyzed with an ANCOVA. The GRFs were categorized into anterioposterior, mediolateral, and vertical forces. A two factor MANCOVA (subject, trimester) was performed on each GRF category. Mass and velocity served as covariates in each analysis (α=0.05).

RESULTS

The mediolateral excursion of the COP during ascent was greater in the third trimester (p=0.04). The anterioposterior braking impulse was greater in both ascent (p=0.01) and descent (p=0.01) during pregnancy. The vertical GRF loading rate during descent was greater in pregnant women than in controls (p=0.04).

CONCLUSION

These alterations are likely related to increased instability during stairway walking and could contribute to increased fall risk during pregnancy.

Contribution of hip joint proprioception to static and dynamic balance in cerebral palsy: a case control study

BACKGROUND

Balance problems are common in cerebral palsy (CP) but etiology is often uncertain. The classic Romberg test compares ability to maintain standing with eyes open versus closed. Marked instability without vision is a positive test and generally indicates proprioceptive loss. From previous work showing diminished hip joint proprioception in CP, we hypothesized that static and dynamic balance without vision (positive Romberg) would be compromised in CP.

METHODS

Force plate sway and gait velocity data were collected using 3D motion capture on 52 participants, 19 with diplegic CP, 13 with hemiplegic CP, and 20 without disability. Center of mass (COM) and center or pressure (COP) velocity, excursion, and differences between COM and COP in AP and ML directions were computed from static standing trials with eyes open and closed. Mean gait velocity with and without dribble glasses was compared. Hip joint proprioception was quantified as the root mean square of magnitude of limb positioning errors during a hip rotation task with and without view of the limb. Mixed model repeated measures analysis of variance (ANOVA) was performed with condition as within-subject (EO, EC) and group as between-subject factors (hemiplegia, diplegia, controls). Sway characteristics and gait speed were correlated with proprioception values.

RESULTS

Groups with CP had greater sway in standing with eyes open indicating that they had poorer balance than controls, with the deficit relatively greater in the ML compared to AP direction. Contrary to our hypothesis, the decrement with eyes closed did not differ from controls (negative Romberg); however, proprioception error was related to sway parameters particularly for the non-dominant leg. Gait speed was related to proprioception values such that those with worse proprioception tended to walk more slowly.

CONCLUSIONS

Postural instability is present even in those with mild CP and is yet another manifestation of their motor control disorder, the specific etiology of which may vary across individuals in this heterogeneous diagnostic category.

Gait stability in children with Cerebral Palsy

Children with unilateral Cerebral Palsy (CP) have several gait impairments, amongst which impaired gait stability may be one. We tested whether a newly developed stability measure (the foot placement estimator, FPE) which does not require long data series, can be used to asses gait stability in typically developing (TD) children as well as children with CP. In doing so, we tested the FPE's sensitivity to the assumptions needed to calculate this measure, as well as the ability of the FPE to detect differences in stability between children with CP and TD children, and differences in walking speed. Participants were asked to walk at two different speeds, while gait kinematics were recorded. From these data, the FPE, as well as the error that violations of assumptions of the FPE could have caused were calculated. The results showed that children with CP walked with marked instabilities in anterior-posterior and mediolateral directions. Furthermore, errors caused by violations of assumptions in calculation of FPE were only small (≈ 1.5 cm), while effects of walking speed (≈ 20 cm per m/s increase in walking speed) and group (≈ 5 cm) were much larger. These results suggest that the FPE may be used to quantify gait stability in TD children and children with CP.

Assessment of postural control in children with cerebral palsy: a review

This paper aimed to review studies that assessed postural control (PC) in children with cerebral palsy (CP) and describe the methods used to investigate postural control in this population. It also intended to describe the performance of children with CP in postural control. An extensive database search was performed using the keywords: postural control, cerebral palsy, children, balance and functionality. A total of 1065 papers were identified and 25 met the inclusion criteria. The survey showed that PC is widely studied in children with CP, with reliable methods. The link between postural control and functionality was also evident. However, a lack of studies was observed assessing postural control in these children by means of scales and functional tests, as well as exploring postural control during daily functional activities. Thus research addressing these issues can be a promising field for further research on postural control.

Contributions of muscles to mediolateral ground reaction force over a range of walking speeds

Impaired control of mediolateral body motion during walking is an important health concern. Developing treatments to improve mediolateral control is challenging, partly because the mechanisms by which muscles modulate mediolateral ground reaction force (and thereby modulate mediolateral acceleration of the body mass center) during unimpaired walking are poorly understood. To investigate this, we examined mediolateral ground reaction forces in eight unimpaired subjects walking at four speeds and determined the contributions of muscles, gravity, and velocity-related forces to the mediolateral ground reaction force by analyzing muscle-driven simulations of these subjects. During early stance (0-6% gait cycle), peak ground reaction force on the leading foot was directed laterally and increased significantly (p<0.05) with walking speed. During early single support (14-30% gait cycle), peak ground reaction force on the stance foot was directed medially and increased significantly (p<0.01) with speed. Muscles accounted for more than 92% of the mediolateral ground reaction force over all walking speeds, whereas gravity and velocity-related forces made relatively small contributions. Muscles coordinate mediolateral acceleration via an interplay between the medial ground reaction force contributed by the abductors and the lateral ground reaction forces contributed by the knee extensors, plantarflexors, and adductors. Our findings show how muscles that contribute to forward progression and body-weight support also modulate mediolateral acceleration of the body mass center while weight is transferred from one leg to another during double support.

Differences in the dynamic gait stability of children with cerebral palsy and typically developing children

The aim of this investigation was to evaluate the differences in the dynamic gait stability of children with cerebral palsy (CP) and typically developing (TD) children. The participants walked on a treadmill for 2 min as a motion capture system assessed the walking kinematics. Floquet analysis was used to quantify the rate of dissipation of disturbances that were present in the walking kinematics, and the variability measures were used to assess the magnitude of the disturbances present in the step length and width. The Floquet multipliers, step width and length values were correlated with Sections D and E of the Gross Motor Function Measure (GMFM). The children with CP had a larger Floquet multiplier and used a wider step width than the TD children. The magnitude of the maximum Floquet multiplier was positively correlated with the step width. Furthermore, the magnitude of the maximum Floquet multiplier and the step width were negatively correlated with the score on Section E of the GMFM. Lastly, the children with CP used a more variable step length than the TD children. These results suggest that children with CP have poor dynamic gait stability because they require more strides to dissipate the disturbances that are present in their walking pattern. In effort to stabilize these disturbances, the children with CP appear to utilize a wider step width and modulate their step length. Overall the inability to effectively dissipate the gait disturbances may be correlated with the child's ability to perform a wide range of gross motor skills (e.g., step over obstacles, jump, walk up stairs).

BALANCE CONTROL DURING LEVEL WALKING IN CHILDREN WITH SPASTIC DIPLEGIC CEREBRAL PALSY

Children with cerebral palsy (CP) have been reported to have various levels of deficits in balance control, which can be described using the relationship between the body's centre of mass (COM) and the centre of pressure (COP). This study aimed to investigate the balance control of children with spastic diplegic CP during level walking. The COM-COP inclination angles and angular velocities, as well as temporal-spatial variables from 12 children with spastic diplegic CP (seven girls and five boys, aged 12.4 ± 4.4 years) and 12 normal controls (eight girls and four boys, aged 11.2 ± 4.4 years) were obtained using a motion analysis system and two forceplates. With compromised balance control as a result of neuromusculoskeletal pathologies, the CP group walked with reduced walking speed and stride length (p < 0.05), but increased stride time and step width (p < 0.05), indicating reduced gait efficiency. They also showed significantly reduced anterioposterior COM-COP inclination angles and angular velocities (p < 0.05), but increased mediolateral COM-COP inclination angles and angular velocities (p < 0.05) when compared to the normal controls. The latter phenomenon may be related to an increased risk of falling in these patients. Therefore, it appears that programs and/or devices for preventing falls are needed for children with spastic diplegic CP.

Anticipatory postural adjustments in children with hemiplegia and diplegia

Anticipatory postural adjustments (APAs) play an important role in the performance of many activities requiring the maintenance of standing posture. However, little is known about if and how children with cerebral palsy (CP) generate APAs. Two groups of children with CP (hemiplegia and diplegia) and a group of children with typical motor development performed arm flexion and extension movements while standing on a force platform. Electromyographic activity of six trunk and leg muscles and displacement of center of pressure (COP) were recorded. Children with CP were able to generate anticipatory postural adjustments and produce directionally specific APAs and COP displacements similar to those described in adults and typically developing children. However, children with diplegia were unable to generate APAs of the same magnitude as children with typical development and hemiplegia and had higher baseline muscle activity prior to movement. In children with diplegia, COP was posteriorly displaced and peak acceleration was smaller during bilateral extension compared to children with hemiplegia. The outcomes of the study highlight the role of APAs in the control of posture of children with CP and point out the similarities and differences in anticipatory control in children with diplegia and hemiplegia. These differences may foster ideas for treatment strategies to enhance APAs in children with CP.

Evaluation of lower body positive pressure supported treadmill training for children with cerebral palsy

PURPOSE

To examine the feasibility of using lower body positive pressure supported (LBPPS) treadmill training to improve the walking abilities, balance and lower extremity strength of children with cerebral palsy (CP).

METHODS

Nine children with CP (GMFCS II-IV) participated in LBPPS treadmill training 2 days per week for 6 weeks. Pre and post training measures of preferred walking speed, spatiotemporal kinematics, lower extremity strength, and the BESTest were used to assess potential improvements from LBPPS treadmill training.

RESULTS

LBPPS treadmill training resulted in significantly faster walking speed, less time in double support, improved overall balance, and strength of the lower extremity antigravity musculature.

CONCLUSIONS

It is feasible to use LBPPS treadmill training to improve the walking performance, balance, and strength of children with CP.

Trunk and hip muscle activation patterns are different during walking in young children with and without cerebral palsy

BACKGROUND

Poor control of postural muscles is a primary impairment in people with cerebral palsy (CP).

OBJECTIVE

The purpose of this study was to investigate differences in the timing characteristics of trunk and hip muscle activity during walking in young children with CP compared with children with typical development (TD).

METHODS

Thirty-one children (16 with TD, 15 with CP) with an average of 28.5 months of walking experience participated in this observational study. Electromyographic data were collected from 16 trunk and hip muscles as participants walked at a self-selected pace. A custom-written computer program determined onset and offset of activity. Activation and coactivation data were analyzed for group differences.

RESULTS

The children with CP had greater total activation and coactivation for all muscles except the external oblique muscle and differences in the timing of activation for all muscles compared with the TD group. The implications of the observed muscle activation patterns are discussed in reference to existing postural control literature.

LIMITATIONS

The potential influence of recording activity from adjacent deep trunk muscles is discussed, as well as the influence of the use of an assistive device by some children with CP.

CONCLUSIONS

Young children with CP demonstrate excessive, nonreciprocal trunk and hip muscle activation during walking compared with children with TD. Future studies should investigate the efficacy of treatments to reduce excessive muscle activity and improve coordination of postural muscles in CP.