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Objective To compare biomechanical characteristics of the knee joint during forward walking and backward walking. Methods Temporal-spatial, kinematics, kinetics parameters of 13 healthy young male volunteers were collected and compared by 3D motion capture system Vicon T40 and force platforms AMTI OR6-7. Results Compared with forward walking, the speed, cadence and stride length significantly decreased, while the gait cycle and stance phase percentage in gait cycle significantly increased during backward walking. In the sagittal plane, the range of motion (ROM), the maximum flexion/extension moment of the knee were smaller during backward walking. In the frontal plane, the ROM of knee varus/valgus during backward walking decreased, and the peak value of knee adduction moment significantly reduced in the early stance phase while significantly increased in the late stance phase of backward walking. The peak value of ground reaction force (GRF) was significantly larger in the early stance phase while smaller in the late stance phase during backward walking than that during forward walking. Conclusions The biomechanical characteristics of the knee joint during forward walking and backward walking are significantly different. Compared with forward walking, backward walking is helpful to reduce the medial compartment load in the early stance phase. Further study will be needed to investigate the effects of backward walking on knee joint loading in the late stance phase.
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Objective To assess the injury risks and affecting factors of spinal loads at L5/S1 joint for caregivers during manual patient-handling tasks, so as to find a suitable handling way to effectively reduce such risks. Methods Kinetic data were collected from nine female caregivers performing six patient handling tasks on three agent ‘patients’ with different weight. Peak L5/S1 force was calculated based on a multi-segment three-dimensional model to investigate the characteristics of injury risks, and the correlations between the peak L5/S1 force and six affecting factors were specifically analyzed. Results Peak compression of the tasks all exceeded the safe thresholds of 3.4 kN; Peak anterior-posterior force for those repositioning tasks were above the threshold of 0.5 kN. Different tasks showed different biomechanical characteristics for risk of injury and affecting factors, and there was a significant correlation between the L5/S1 loads and the moving distance of center of gravity, and the ground reaction force as well (P<0.01). Conclusions Manual patient handling tasks could cause different injury risks by high loads on spinal low back. Decreasing the range of motion of the whole body and avoiding jerk movement during the patient handling tasks would help caregiver to reduce the injury risks.
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The mechanism of balance controlling and maintaining during human motion is quite complex, and many physiological and non-physiological factors such as aging, apoplexy and limb disability can lead to balance dysfunctions.Thus, the functional tests and evaluation on balance plays a vital role in the diagnosis and evaluation of many diseases. The common equipment and methods for investigating balance funciton of human body, as well as their limitations were summarized, and the design and method of serveral light-weight, low-cost, novel systems such as wearable motion capture systems based on microelectronic sensors and human balance measuring and training systems based on somatosensory games were also proposed in this paper.
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Objective To investigate the gait stability of healthy old and young adult volunteers during walking using the nonlinear time series analysis method so as to comprehensively assess the dynamic balance of human and provide important references for the prediction of fall risk. Methods The Vicon motion capture system was used to collect three-dimensional kinematic data of healthy volunteers (seven old subjects and ten young subjects) at different walking speed (80%, 100%, 120% of the natural walking speed). The anterior-posterior and medio-lateral motions of the seventh cervical and tenth thoracic vertebrae, as well as the flexion-extension and abduction-adduction angles of the lower extremity joints, were obtained from 30 consecutive gait cycles to calculate the largest Lyapunov exponents and analyze the difference of gait stability between the old and young group and the influence of walking speed on gait stability. Results The gait stability in the young group was better than that in the old group, and there were significant differences in certain motion segments (P＜0.01). The gait stability in both groups were reduced with the increase of speed (P＜0.05). Conclusions The largest Lyapunov exponent based on nonlinear time series analysis method can be used to effectively and quantitatively analyze the gait stability of each motion segment in human during walking.
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<p><b>OBJECTIVE</b>To set up three-dimensional reconstruction of acetabulum bone structure from CT scanned image in computer with software of CAD and study quantitatively the morphologic features of the acetabulum.</p><p><b>METHODS</b>Through the process of CT scanning, and edge recording of the CT image, we made use of CAD software and Unigraphics software to reconstruct the 40 normal acetabulum bones for the radius of acetabulum (R), minimum thickness of medial wall of acetabulum (L), depth of Harris fossa (D) and maximum opening rim width in cross-sectional plane (W).</p><p><b>RESULTS</b>The average R was 30.48 +/- 2.05 mm. The average L was 2.35 +/- 1.13 mm. The average D was 5.71 +/- 1.21 mm. The average W was 63.06 +/- 2.05 mm. There was a linear relationship between the R and the W, but no correlation between the R, the L and the D.</p><p><b>CONCLUSIONS</b>There was a significance linear relationship between the R and the W in normal adult acetabulum. However no correlation between the R, the L and the D.</p>