SLIP PREVENTION IN WALKING -LOWER EXTREMITY BIOMECHANICS

This study investigated the human slip prevention strategies when walking on slippery surfaces. Fifteen male subjects performed, level walking without slips under sixteen simulated construction site environments. Kinematics, kinetics and electromyography parameters were collected. The slipperiness of the walkway conditions were quantified by the dynamic coefficient of friction (DCOF). Gait changes in slippery condition included prolonged force and pressure exertion in hallux and lateral toes. more ankle plantarflexion moment during 30-50% stance, less knee extension moment during 1030% stance, higher muscle activity at rectus femoris in late stance, and in gastrocnemius in swing phase. These strategies helped achieving walking without slips by reducing the RCOF from 0.188 to 0.092, which was just lower to the dropped available friction (DCOF=0.107)

BIOMECHANICAL ANALYSIS OF FOOT MOVEMENT DURING A SET OF TAl CHI CHUAN EXERCISE

A set of the 42-form Tai Chi Chuan movements performed by a TCC master were studied using 3-D video filming and Pedar insole pressure measurement. The results showed that TCC exercise is full with the transform of foot positions among the single leg support, single leg support with the opposite leg semi support and double leg support in three dimensions and is full with the transform of different weight bearing patterns associated with the open and closed kinetic chain movement. There was the highest pressure in the hallux area during the single leg support phases, suggesting the training effects of TCC on hallus' muscle

Mirror Metrology Using Nano-Probe Supports

Thin, lightweight mirrors are needed for future x-ray space telescopes in order to increase x-ray collecting area while maintaining a reduced mass and volume capable of being launched on existing rockets. However, it is very difficult to determine the undistorted shape of such thin mirrors because the mounting of the mirror during measurement causes distortion. Traditional kinematic mounts have insufficient supports to control the distortion to measurable levels and prevent the mirror from vibrating during measurement. Over-constrained mounts (non-kinematic) result in an unknown force state causing mirror distortion that cannot be determined or analytically removed. In order to measure flexible mirrors, it is necessary to over-constrain the mirror. Over-constraint causes unknown distortions to be applied to the mirror. Even if a kinematic constraint system can be used, necessary imperfections in the kinematic assumption can lead to an unknown force state capable of distorting the mirror. Previously, thicker, stiffer, and heavier mirrors were used to achieve low optical figure distortion. These mirrors could be measured to an acceptable level of precision using traditional kinematic mounts. As lighter weight precision optics have developed, systems such as the whiffle tree or hydraulic supports have been used to provide additional mounting supports while maintaining the kinematic assumption. The purpose of this invention is to over-constrain a mirror for optical measurement without causing unacceptable or unknown distortions. The invention uses force gauges capable of measuring 1/10,000 of a Newton attached to nano-actuators to support a thin x-ray optic with known and controlled forces to allow for figure measurement and knowledge of the undeformed mirror figure. The mirror is hung from strings such that it is minimally distorted and in a known force state. However, the hanging mirror cannot be measured because it is both swinging and vibrating. In order to stabilize the mirror for measurement, nano-probes support the mirror, causing the mirror to be over-constrained

A systematic review on ankle injury and ankle sprain in sports

This article systematically reviews epidemiological studies on sports injury from 1977 to 2005 in which ankle injury was included. A total of 227 studies reporting injury pattern in 70 sports from 38 countries were included. A total of 201 600 patients were included, with 32 509 ankle injuries. Ankle injury information was available from 14 098 patients, with 11 847 ankle sprains. Results show that the ankle was the most common injured body site in 24 of 70 included sports, especially in aeroball, wall climbing, indoor volleyball, mountaineering, netball and field events in track and field. Ankle sprain was the major ankle injury in 33 of 43 sports, especially in Australian football, field hockey, handball, orienteering, scooter and squash. In sports injuries throughout the countries studied, the ankle was the second most common injured body site after the knee, and ankle sprain was the most common type of ankle injury. The incidence of ankle injury and ankle sprain was high in court games and team sports, such as rugby, soccer, volleyball, handball and basketball. This systematic review provides a summary of the epidemiology of ankle injury in sports

ANKLE LIGAMENT STRAIN DURING SUPINATION SPRAIN INJURY – A COMPUTATIONAL BIOMECHANICS STUDY

This study presents ankle ligament strain data during a grade I mild anterior talofibular ligamentous sprain. Kinematics data obtained during the injury and a 3BW were imported to a validated dynamic foot model. Four simulations were done: (1) inversion, (2) inversion plus plantarflexion, (3) inversion plus internal rotation, and (4) inversion, plantarflexion and internal rotation. Results showed that in situation (1), the calcaneofibular ligament was strained the most (12%), followed by the anterior talofibular ligament (10%). In situations (2) and (3), both ligaments were strained to about 14-16%. In situation (4), the anterior talofibular ligament was strained to 20%. This study suggested that plantarflexion and internal rotation, together with inversion, may have greatly strained and torn the anterior talofibular ligament during the reported injury event

ESTIMATING COMPLETE GROUND REACTION FORCES AND ANKLE JOINT TORQUES FROM PRESSURE INSOLE DATA IN WALKING AND RUNNING

This study described a method to estimate complete ground reaction forces and ankle joint torques from only pressure insole sensor data. One subject performed 56 valid steps during heel-toe walking and running in canvas shoes at different speeds (0.85-4.00m/s). Motion data, ground reaction force data and plantar pressure data were simultaneously recorded. Six parameters of ground reaction forces and ankle joint torques were obtained, and were trimmed from touchdown to takeoff. Pressure values at each of the 99 sensors were used to predict these six parameters by linear stepwise regression. Prediction models with 80% or more explained variance were constructed. Estimated values were obtained from these models, and the prediction accuracy was reported. Comparison to a previously developed method was done

AN IN-SHOE ANKLE SUPINATION TORQUE MEASURING METHOD IN RUNNING

This study presented an in-shoe ankle supination torque measuring method in running. One subject performed 56 valid steps during heel-toe walking and running in canvas shoe at different speeds (0.85-4.00m/s). Motion data, ground reaction force data and plantar pressure data were simultaneously recorded. Ankle joint torques in dorsiflexion / plantarflexion and inversion / eversion directions were obtained, and were trimmed from touchdown to takeoff. Pressure values at each of the 99 sensors were used to predict these two parameters by linear stepwise regression. Prediction models with 80%, 85%, 90% and 95% explained variance were constructed. A 9-sensor system is suggested for further development of an in-shoe ankle supination torque measuring device

A three-pressure-sensor (3PS) system for monitoring ankle supination torque during sport motions

This study presented a three-pressure-sensor (3PS) system for monitoring ankle supination torque during sport motions. Five male subjects wore a pair of cloth sport shoes and performed 10 trials of walking, running, cutting, vertical jump-landing and stepping-down motions in a random sequence. A pair of pressure insoles (Novel Pedar model W, Germany) was inserted in the shoes for the measurement of plantar pressure at 100 Hz. The ankle joint torque was calculated by a standard lower extremity inverse dynamic calculation procedure with the data obtained by a motion capture system (VICON, UK) and a force plate (AMTI, USA), and was presented in a supination/pronation plane with an oblique axis of rotation at the ankle joint. Stepwise linear regression analysis suggested that pressure data at three locations beneath the foot were essential for reconstructing the ankle supination torque. Another group of five male subjects participated in a validation test with the same procedure, but with the pressure insoles replaced by the 3PS system. Estimated ankle supination torque was calculated from the equation developed by the regression analysis. Results suggested that the correlation between the standard and estimated data was high (R=0.938). The overall root mean square error was 6.91 N m, which was about 6% of the peak values recorded in the five sport motions (113 N m). With the good estimation accuracy, tiny size and inexpensive cost, the 3PS system is readily available to be implanted in sport shoe for the estimation and monitoring of ankle supination torque during dynamic sport motions

Catheter Migration After Implantationan Intrathecal Baclofen Infusion Pump for Severe Spasticity: A Case Report

We report a case of intrathecal baclofen infusion pump implantation complicated by migration of the catheter tip. A 55-year-old man required an intrathecal baclofen infusion for severe spasticity 4 years after a cervical spinal cord injury with incomplete tetraparesis. Twelve months after initial implantation of the device, the patient began to experience a recurrence of trunk tightness and spasticity. Subsequent X-ray and computed tomography evaluations of the catheter system revealed pooling of contrast medium outside of the intrathecal distribution in the lumbar subcutaneous region of the back and therefore migration of the pump catheter tip. At surgical revision, emphasis was placed on minimizing the length of catheter outside of the spine and securing the catheter in the supraspinous fascia with a right-angled anchor. The distance between the anchors and the entry point of the catheter into the supraspinous fascia was also reduced to prevent slipping when the patient bends forward. After surgery, the patient's spasticity improved and, 1 year later, he has experienced no further complications during follow-up, requiring an average baclofen dose of 150 mg/day. Here, we describe several surgical methods intended to secure the intrathecal catheter and prevent catheter migration. Other complications related to catheter failure are also highlighted

Reflective Coating for Lightweight X-Ray Optics

X-ray reflective coating for next generation's lightweight, high resolution, optics for astronomy requires thin-film deposition that is precisely fine-tuned so that it will not distort the thin sub-mm substrates. Film of very low stress is required. Alternatively, mirror distortion can be cancelled by precisely balancing the deformation from multiple films. We will present results on metallic film deposition for the lightweight optics under development. These efforts include: low-stress deposition by magnetron sputtering and atomic layer deposition of the metals, balancing of gross deformation with two-layer depositions of opposite stresses and with depositions on both sides of the thin mirrors