The effects of altering attentional demands of gait control on the variability of temporal and kinematic parameters

Analysis of dynamic elbow flexion deformity in children with hemiplegic cerebral palsy

BACKGROUND

Cerebral palsy affects 1 per 1.000 children, and in 83% of the cases upper extremity is involved. Dynamic elbow flexion deformity is a movement disorder observed in individuals with hemiparesis secondary to cerebral palsy. We sought to determine whether children with hemiplegic cerebral palsy exhibit dynamic elbow flexion deformity during daily activities and its influence to reaching function.

METHODS

Sixteen children with upper limb hemiparesis and cerebral palsy (age 11y 7mo (SD 3y 2mo); 11 boys, 5 girls; Gross Motor Function Classification System level I or II) were included in this observational descriptive study. Manual Ability Classification System, Children's Hand-use Experience Questionnaire and Shriners Hospital for Children Upper Extremity Evaluation were used to evaluate affected upper extremity function. Spasticity was assessed with Modified Ashworth scale. Involuntary elbow flexion was recorded in eight daily activities. Elbow motion during reach function was measured.

FINDINGS

Fifteen out of 16 individuals showed dynamic elbow flexion deformity. There was a significative increase of involved median elbow flexion in all the activities studied, except for "high speed stairs climbing" evaluation. Children's Hand-use Experience Questionnaire showed that children were independent in most of the daily activities (21 out of 29). Correlation between dynamic elbow flexion deformity and Shriners Hospital for Children Upper Extremity Evaluation was observed only in sitting-standing activity (Spearman's ρ 0.549, P = 0.028).

INTERPRETATION

Dynamic elbow flexion deformity is very common in hemiplegic cerebral palsy and occurs proportionally to the degree of the effort demanded by the activities. Despite of presenting this movement disorder, it does not affect in children participation in daily activities.

Variability in trunk and pelvic movement of transfemoral amputees using a C-leg system compared to healthy controls

OBJECTIVE

Gait variability is a measure of gait disturbance, and therefore constitutes a useful parameter for gait assessment as well as planning of therapeutic and medical interventions. To date, variability during walking has not been adequately analyzed in amputees. The aim of this examination was to evaluate trunk and pelvic movement variability in transfemoral amputees. The effect of different types of walking surfaces on variability in trunk and pelvic movement was also studied.

METHOD

This prospective clinical examination compares 20 transfemoral amputees (17 ♂, 42 ± 16 years; 3 ♀, 48 ± 3 years) with a group of 20 age and mass matched healthy controls regarding the extent of variability in trunk and pelvic movement. Kinematic data of trunk and pelvic movement during walking on level, uneven ground and slope was captured by eight infrared cameras (Vicon Nexus ™, Oxford, UK). Variability in trunk and pelvic movement was analyzed. Univariate ANCOVA and ANOVA with repeated measures and post hoc tests were used for statistical comparison. Fall history was retrospectively collected from medical history to assess the association between falls and variability in trunk and pelvic movement.

RESULTS

Trunk and pelvic movement variability in amputees was significantly higher during walking on uneven ground and slope compared to healthy controls (p ≤ 0.05). Variability in trunk and pelvic movement was increased during walking on uneven ground and slope compared to even ground for both groups (p ≤ 0.05).

CONCLUSION

Amputees showed increased trunk and pelvic movement variability during walking on uneven ground and slope, indicating an affected gait pattern in comparison to healthy controls. Therefore, trunk and pelvic movement variability could be a potential marker for gait quality with diagnostic implications.

Fractal properties and short-term correlations in motor control in cycling: influence of a cognitive challenge

Fluctuations in cyclic tasks periods is a known characteristic of human motor control. Specifically, long-range fractal fluctuations have been evidenced in the temporal structure of these variations in human locomotion and thought to be the outcome of a multicomponent physiologic system in which control is distributed across intricate cortical, spinal and neuromuscular regulation loops. Combined with long-range correlation analyses, short-range autocorrelations have proven their use to describe control distribution across central and motor components. We used relevant tools to characterize long- and short-range correlations in revolution time series during cycling on an ergometer in 19 healthy young adults. We evaluated the impact of introducing a cognitive task (PASAT) to assess the role of central structures in control organization. Autocorrelation function and detrending fluctuation analysis (DFA) demonstrated the presence of fractal scaling. PSD in the short range revealed a singular behavior which cannot be explained by the usual models of even-based and emergent timing. The main outcomes are that (1) timing in cycling is a fractal process, (2) this long-range fractal behavior increases in persistence with dual-task condition, which has not been previously observed, (3) short-range behavior is highly persistent and unaffected by dual-task. Relying on the inertia of the oscillator may be a way to distribute more control to the periphery, thereby allocating less resources to central process and better managing additional cognitive demands. This original behavior in cycling may explain the high short-range persistence unaffected by dual-task, and the increase in long-range persistence with dual-task.

Lower limb kinematics during the swing phase in patients with knee osteoarthritis measured using an inertial sensor

BACKGROUND

During gait, the swing limb requires flexible control to adapt to ever changing environmental circumstances. However, few studies have focused on the mechanics of swing limb control in patients with knee osteoarthritis (OA). Investigating the variability of swing limb kinematics, which can be represented by variables such as the peak shank angular velocity during the swing phase obtained from an inertial sensor, provides insights into the adaptability of swing limb control. The purpose of this study was to investigate how patients with knee OA control the swing limb and whether the degree of impairment and disability due to knee OA affects swing limb control.

METHODS

Twelve subjects diagnosed with knee OA and 11 healthy control subjects participated in this study. Subjects walked on a treadmill for 10min. The mean, coefficient of variation, and fractal scaling exponent α of the peak shank angular velocity during the swing phase were calculated.

FINDINGS

There were no significant differences between the groups for any of the kinematic parameters. The Knee Injury and Osteoarthritis Outcome Score (KOOS) activities of daily living (ADL) subsection correlated with the coefficient of variation (r=-0.677, p=0.016) and the scaling exponent α (r=0.604, p=0.037) of the peak shank angular velocity.

INTERPRETATION

Control of the swing limb was associated with the degree of impairment and disability. Larger and more random variability of peak shank angular velocity may indicate decreased ADL ability in patients with knee OA.