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This study aimed to investigate obstacle crossing in 7-9-year-old children with Down syndrome (DS). Fifteen children with DS, age- and gender-matched with 15 typically developing (TD) children, were recruited to walk and cross obstacles with heights of 10%, 20% and 30% of their leg lengths. End-point and kinematic variables of obstacle crossing were obtained using a three-dimensional motion analysis system. The results showed that children with DS tend to adopt a lower speed and larger step width when they perceive instability. Moreover, unlike TD children, children with DS adopt a pelvic strategy (i.e., greater pelvic leading-side listing and forward rotation) to achieve a higher leading toe clearance with a longer step length, presumably for safety reasons. This pelvic strategy increased the frontal plane motion of the whole leg and trunk, and thus possibly stability, during obstacle crossing. However, this strategy may be inefficient. Trailing toe clearance did not differ significantly between two groups. The results of this study suggest that children with DS tend to use inefficient and conservative strategies for obstacle crossing. Knowledge of both end-point and kinematic control of obstacle crossing in children with DS is useful for understanding the mechanisms of obstacle-related falls. Moreover, obstacle crossing can be used as a task-oriented rehabilitation program for children with DS. [ABSTRACT FROM AUTHOR]

Background: Kinematic analysis has been used to objectively evaluate movement patterns, quality, and strategies during reaching tasks. However, no study has investigated whether kinematic variables during unilateral and bilateral reaching tasks predict a patient's perceived arm use during activities of daily living (ADL) after an intensive intervention. Therefore, this study investigated whether kinematic measures during unilateral and bilateral reaching tasks before an intervention can predict clinically meaningful improvement in perceived arm use during ADL after intensive poststroke rehabilitation. Methods: The study was a secondary analysis of 120 subjects with chronic stroke who received 90-120 min of intensive intervention every weekday for 3-4 weeks. Reaching kinematics during unilateral and bilateral tasks and the Motor Activity Log (MAL) were evaluated before and after the intervention. Results: Kinematic variables explained 22 and 11 % of the variance in actual amount of use (AOU) and quality of movement (QOM), respectively, of MAL improvement during unilateral reaching tasks. Kinematic variables also explained 21 and 31 % of the variance in MAL-AOU and MAL-QOM, respectively, during bilateral reaching tasks. Selected kinematic variables, including endpoint variables, trunk involvement, and joint recruitment and interjoint coordination, were significant predictors for improvement in perceived arm use during ADL (P < 0.05). Conclusions: Arm-trunk kinematics may be used to predict clinically meaningful improvement in perceived arm use during ADL after intensive rehabilitation. Involvement of interjoint coordination and trunk control variables as predictors in bilateral reaching models indicates that a high level of motor control (i.e., multijoint coordination) and trunk stability may be important in obtaining treatment gains in arm use, especially for bilateral daily activities, in intensive rehabilitation after stroke. [ABSTRACT FROM AUTHOR]

Abstract: Fifteen young and 15 older healthy adults walked and crossed obstacles with heights of 10%, 20% and 30% of their leg lengths while their kinematic data were measured with a three-dimensional (3D) motion analysis system. End-point variables together with 3D joint kinematics of both the leading and trailing limbs were obtained. The results showed that the older group adopted a swing hip flexion strategy to achieve a higher leading toe clearance than the young group. With increasing obstacle height, the older group increased linearly the leading toe clearance by changing fewer joint angular components than the young group, allowing the maintenance of the necessary stability of the body with minimum control effort. When the trailing limb was crossing, the older group showed no significant difference in the trailing toe clearance compared to the young group, although different joint kinematic patterns were evident. The older group seemed to use a more conservative strategy for obstacle-crossing. Failure to implement this strategy during obstacle negotiation may increase the risk of falls owing to an inability to recover from unexpected tripping or stumbling. The results of this study suggest that existing knowledge of the kinematic control of obstacle-crossing based on young subjects may serve as a baseline for further studies on older people for a better understanding of the mechanisms and for the prevention of falls in the elderly. [Copyright &y& Elsevier]

Abstract: Twenty young healthy adults walked and crossed obstacles of heights of 10%, 20% and 30% of their leg lengths and kinematics and kinetics of their gait analysed. Three-dimensional joint moments of the lower limb were calculated with inverse dynamics analysis. Peak moments and crossing moments (joint moments at the time when the swing foot is above the obstacle) were obtained. Most of the peak moments of the supporting limb joints did not show the same height effects as the corresponding crossing moment components. This suggests that the true effects of obstacle heights on the joint kinetics during obstacle crossing cannot be obtained solely through comparisons of peak moments. For inter-limb comparisons the peak and crossing moments were different, suggesting that the leading and trailing limb adopted different kinetic strategies during obstacle crossing. The findings may help to shed light on further investigation on the motor control strategies of the central nervous system for obstacle crossing. [Copyright &y& Elsevier]

Abstract: With the advances in stroke care, the number of high-functioning patients after stroke is increasing. However, existing clinical tools may not be sensitive enough to identify the residual deficits in these patients. The current study aimed to investigate the control of the pelvis, and the joints and end-point of the lower limbs in high-functioning older patients post-stroke during obstacle-crossing using motion analysis techniques. Twenty-four high-functioning older patients following unilateral stroke and fifteen healthy controls walked and crossed obstacles of three different heights. End-point variables (leading toe-clearance and trailing toe-obstacle distance) and crossing pelvic and joint angles were obtained for both limbs during leading limb crossing. Whether leading with the contralesional or ipsilesional limb, the stroke group exhibited significantly different joint kinematics from the controls mainly in the frontal and transverse planes, with greater leading toe-clearance, trailing toe-obstacle distance, and posterior pelvic tilt. None of the end-point and joint variables were significantly different between limbs. High-functioning patients post-stroke appeared to have acquired a specific symmetric kinematic strategy with increased leading toe-clearance during obstacle-crossing, most likely in order to prevent tripping. This symmetric strategy, possibly a consequence of brain reorganization, may help in performing functional activities during which symmetric performance between the contralesional and ipsilesional sides is required. Obstacle-crossing training with both limbs leading alternately may be helpful for the development of this symmetric strategy. It is suggested that computerized motion analysis of obstacle-crossing can be a sensitive assessment tool for distinguishing the motor performance between normal and high-functioning patients post-stroke. [Copyright &y& Elsevier]

Abstract: Patients with type II diabetes mellitus (DM) have been reported to be at high risk of falls that may be further increased by the effects of challenging activities such as obstacle-crossing. The purpose of this study was to compare the end-point trajectory and joint kinematic and kinetic patterns of the lower extremities between healthy subjects and individuals with DM during obstacle-crossing with the leading limb. Fourteen patients with type II DM, with no to minimal peripheral neuropathy (PN), and 14 healthy controls walked and crossed obstacles of three different heights (10%, 20% and 30% of leg length) while kinematic and kinetic data were measured using a motion analysis system and two forceplates. Compared to normal, the DM group had similar walking speeds and horizontal footobstacle distances but significantly reduced leading toe-obstacle clearances, suggesting an increased risk of tripping over the obstacle. When the swing toe was above the obstacle, the DM group showed greater pelvic anterior tilt, stance ankle dorsiflexion, and smaller swing hip abduction, with reduced hip abductor moments but greater knee flexor and ankle plantarflexor and adductor moments. It is suggested that patients with type II DM, with no or minimal PN, should also be targeted for prevention of falls. Possible therapeutic interventions to decrease falls for those with DM may include strengthening of the knee flexors and ankle plantarflexor muscles, together with proprioception and balance training. [Copyright &y& Elsevier]

Abstract: Measurement of the changes of the three-dimensional (3D) motion and surface kinematics of the knee under different external loading conditions is essential for the understanding and evaluation of the function of the joint, as well as for relevant clinical applications. Knee extension exercise (KEE) has been applied extensively in the rehabilitation programs of patients with various knee disorders. This study measured the 3D knee kinematics of eight normal subjects during active knee extension for unloaded and loaded conditions using a voxel-based method for the registration of fluoroscopic images with CT bone data. The knee kinematics during unloaded conditions were found to be similar to previous findings. A mass of 5kg at the ankle did not affect the joint angles but significantly altered the lateral contact positions during knee extension, especially at knee flexion angles higher than 75°, and also reduced the asymmetry of the surface kinematics between the medial and lateral condyles. The results of the current study may be useful for knee replacement design and for developing guidelines for the use of KEEs for the rehabilitation of patients with knee disorders. [Copyright &y& Elsevier]