A Holter-type microprocessor-based rehabilitation instrument for acquisition and storage of plantar pressure data in children with cerebral palsy

Sensor architectural tradeoff for diabetic foot ulcer monitoring

The diabetic foot complications constitute a tremendous challenge for patients, caregivers, and the healthcare system. Studies show up to 25% of diabetic individuals will develop a foot ulcer during their lifetime and many of these patients eventually must undergo amputation as a result of infection due to untreated foot ulcers. With current technology, in-shoe monitoring systems can be implemented to continuously monitor at-risk ulceration sites based on known indicators such as peak pressure. The important parameters in designing a pressure-sensing insole include the number, location and size of sensors. In this paper, we aim at showing the criticality of sensor architectural tradeoff in developing the in-shoe plantar pressure monitoring systems. We evaluate this tradeoff by using our custom-made platform for data collection during normal walking.

Characterization of postural stability in a simulated environment of an earthquake using in-shoe plantar pressure measurement

An abled individual is believed to be capable of withstanding and overcoming the severe tremors of an earthquake as has been ascertained in a previous study. However, the event-related physiological mechanisms of human postural stability during an earthquake are subject to further investigation. Accordingly, the objective of this study is to further characterize postural stability in a simulated environment of an earthquake using a pedar-x (novel gmbh, Munich, Germany) in-shoe dynamic plantar pressure measurement system. A foot mask, dividing each of the insoles into seven plantar loading regions, was employed in this study. This paper reports preliminary results obtained from a normal adult female test subject with right side dominance and a normal foot arch. The test trial was comprised of 12 stages, ranging from quiet standing to simulated earthquake magnitude of 6.7 degrees on the Richter's scale, which is considered to be violent. The study metrics included: mean plantar pressure, foot-to-ground contact duration, insole loading area, and the position, displacement, and instantaneous velocity of the center of pressure. The study showed bilateral quantifiable changes in these metrics by foot-mask-region as a result of increasing magnitudes of simulated tremors. The subject was able to defy the overwhelming perturbations and maintain her balance and postural stability throughout the test period. The significance of this study lies in its ability to determine the threshold of falling within different subject populations in the event of an earthquake.

Wearable accelerometer system for measuring the temporal parameters of gait

A small and wireless accelerometer system was developed for the estimation of temporal gait parameters. The new system was built using two 3-axis accelerometers. Measurement's accuracy was assessed using as a criterion standard provided by foot switches. To assess the consistency of this system, estimates of heel contact and toe off time based on accelerometers and those based on footswitches were compared for 20 steps from 8 individual healthy subjects. Accelerometers and footswitches had high consistency in the temporal gait parameters. The stance, swing, single support, and double support time of gait cycle revealed ICCs values of 0.95, 0.93, 0.86, and 0.75 on the right and 0.96, 0.86, 0.93, 0.84 on the left, respectively. Therefore, this system proved to be a reliable tool for identification of temporal gait parameters.

Redistribution of foot pressure in healthy adults during sideslope walking

Normal adult plantar pressures were measured during both level and sideslope walking. Sideslope pressures increased, depending on the relative position of the foot on the slope. With upslope placement, pressures increased significantly at the midfoot (approximately 20%) and fifth metatarsal (approximately 16%). With downslope placement, pressure increased predominantly beneath the first metatarsal (approximately 11%). Pressure changes were relatively small at the heel (approximately 3%) and central metatarsals (approximately 4%). Significant increases occurred on sideslopes as small as 2 degrees. Since gradients of this size are likely to be encountered commonly in outdoor daily activities, this finding may have substantial implications for individuals with peripheral neuropathy.

In-shoe multisensory data acquisition system

Patients with diabetes and peripheral neuropathy are susceptible to unnoticed trauma on the foot that can cause skin breakdown. We have designed an electronic system in a shoe that monitors temperature, pressure, and humidity, storing the data in a battery-powered device for later uploading to a host computer for data analysis. The pressure sensors are located at the heel, and under three metatarsal heads. Temperature sensors are located under the medial metatarsal head and under the heel. The humidity sensor is located in the toe of the shoe. Correlations of data from pressure sensors with known values were high (r > 0.85), even after extended use. Although data currently are being collected for descriptive purposes, the design potentially can be used to provide feedback to patients.

Surgical rehabilitation of the planovalgus foot in cerebral palsy

The objectives of this study were to quantitatively determine the effects of subtalar arthrodesis on the planovalgus foot using three-dimensional (3-D) gait analysis and plantar pressure measurements. Twelve children and adolescents with planovalgus foot deformity secondary to spastic cerebral palsy participated in this outcome study. The pediatric population were evaluated preoperatively and following subtalar fusion. Seventeen feet were operated for the correction of the planovalgus foot deformity. A Holter-type microprocessor-based portable in-shoe data acquisition system was used in this study to collect the multistep dynamic plantar pressure history, while a five-camera Vicon-based gait analysis system was used to track the lower extremity joint kinematics. The results obtained from the plantar pressure measurement showed significant increases in mean peak vertical plantar pressures postoperatively at the lateral midfoot and lateral metatarsal heads. Mean contact durations and mean pressure-time integrals were also significantly increased at these plantar locations following foot surgery. This redistribution in pressure metrics suggests the formation of new lateral plantar weight bearing areas. The 3-D gait analysis system, using standardized lower extremity measurements, was unable to reveal any significant changes in joint kinematics, particularly at the foot and ankle where the surgery was performed. This suggests the need for a more refined system to track the complex motion of the pediatric foot and ankle during gait.