Monitoring in-shoe plantar pressures, temperature, and humidity: reliability and validity of measures from a portable device

Preventing Diabetic Foot Re-Ulceration Through an Innovative Pressure and Temperature Monitoring Clinical Device

This study compared the outcome of an innovative in-shoe pressure and temperature measuring device as an adjunct to standard clinical care for diabetic foot versus standard clinical care alone. It included 88 participants with Type 2 diabetes mellitus with a history of one or more plantar foot ulceration who were already using prescription orthoses. These were randomly divided into the control group (n = 44, standard care only) and the experimental group (n = 44, standard care plus the innovative device). Both groups were monitored for re-ulceration for one year. Overall, the control group exhibited a higher number of re-ulcerations (n = 14) with 2 amputations in comparison with the experimental group (only 2 ulcerations and no amputations) at the end of the study. In conclusion, this innovative in-shoe pressure and temperature measuring device appears to reduce re-ulcerations by offering objective data for clinical decision making in the management of the diabetic high-risk foot.

In-shoe plantar pressure measurement technologies for the diabetic foot: A systematic review

Introduction

Loss of cutaneous protective sensation and high plantar pressures increase the risk for diabetic foot patients. Trauma and ulceration are imminent threats, making assessment and monitoring essential. This systematic review aims to identify systems and technologies for measuring in-shoe plantar pressures, focusing on the at-risk diabetic foot population.

Methods

A systematic search was conducted across four electronic databases (Scopus, Web of Science, PubMed, Oxford Journals) using PRISMA methodology, covering articles published in English from 1979 to 2024. Only studies addressing systems or sensors exclusively measuring plantar pressures inside the shoe were included.

Results

A total of 87 studies using commercially available devices and 45 articles proposing new systems or sensors were reviewed. The prevailing market offerings consist mainly of instrumented insoles. Emerging technologies under development often feature configurations with four, six or eight resistive sensors strategically placed within removable insoles. Despite some variability due to the inherent heterogeneity of human gait, these devices assess plantar pressure, although they present significant differences between them in measurement results. Individuals with diabetic foot conditions appears exhibit elevated plantar pressures, with reported peak pressures reaching approximately 1000 kPa. The results also showed significant differences between the diabetic and non-diabetic groups.

Conclusion

Instrumented insoles, particularly those incorporating resistive sensor technology, dominate the field. Systems employing eight sensors at critical locations represent a pragmatic approach, although market options extend to systems with up to 960 sensors. Differences between devices can be a critical factor in measurement and highlights the importance of individualized patient assessment using consistent measurement devices.

Plantar pressure thresholds as a strategy to prevent diabetic foot ulcers: A systematic review

Background

The development of ulcers in the plantar region of the diabetic foot originates mainly from sites subjected to high pressure. The monitoring of these events using maximum allowable pressure thresholds is a fundamental procedure in the prevention of ulceration and its recurrence.

Objective

The aim of this review was to identify data in the literature that reveal an objective threshold of plantar pressure in the diabetic foot, where pressure is classified as promoting ulceration. The aim is not to determine the best and only pressure threshold for ulceration, but rather to clarify the threshold values most used in clinical practice and research, also considering the devices used and possible applications for offloading plantar pressure.

Design

A systematic review.

Methods

The search was performed in three electronic databases, by the PRISMA methodology, for studies that used a pressure threshold to minimize the risk of ulceration in the diabetic foot. The selected studies were subjected to eligibility criteria.

Results

Twenty-six studies were included in this review. Seven thresholds were identified, five of which are intended for the inside of the shoe: a threshold of average peak pressure of 200 kPa; 25 % and 40-80 % reduction from initial baseline pressure; 32-35 mm Hg for a capillary perfusion pressure; and a matrix of thresholds based on patient risk, shoe size and foot region. Two other thresholds are intended for the barefoot, 450 and 750 kPa. The threshold of 200 kPa of pressure inside the shoe is the most agreed upon among the studies. Regarding the prevention of ulceration and its recurrence, the efficacy of the proposed threshold matrix and the threshold of reducing baseline pressure by 40-80 % has not yet been evaluated, and the evidence for the remaining thresholds still needs further studies.

Conclusions

Some heterogeneity was found in the studies, especially regarding the measurement systems used, the number of regions of interest and the number of steps to be considered for the threshold. Even so, this review reveals the way forward to obtain a threshold indicative of an effective steppingstone in the prevention of diabetic foot ulcer.

Ultrasensitive and Self-Powered Multiparameter Pressure-Temperature-Humidity Sensor Based on Ultra-Flexible Conductive Silica Aerogel

The application of silica aerogel has been limited because of its poor mechanical properties. In order to expand the application scope of silica aerogel, this study fabricated an ultra-flexible conductive silica aerogel as a multiparameter sensor. The sample is fabricated by introducing poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) on a base of ultra-flexible silica aerogel, which was prepared by a diene synthesis reaction at atmospheric pressure. The pressure, temperature, and humidity can be converted into electrical signals. The pressure sensitivity can reach up to 54.88 kPa^-1, and the detection limit is as low as 5 Pa. The temperature resolution is up to 0.1 K, and the response time of humidity is within 4 s. More importantly, the developed multiparameter sensor can be self-powered to realize multiparameter sensing of pressure, temperature, and humidity. The ultra-flexible conductive silica aerogel is a promising candidate for monitoring human activities and fire-affected areas.

A Technical Review of Foot Temperature Measurement Systems

People suffering from diabetes are at risk of developing foot ulcerations which, if left untreated, could also lead to amputation. Monitoring of the foot temperature can help in the prevention of these foot complications, and various studies have shown that elevated temperatures may be indicative of ulceration. Over the years, there have been various devices that were designed for foot temperature monitoring, for both clinical and home use. The technologies used included infrared thermometry, liquid crystal thermography, infrared thermography, and a vast range of analogue and digital temperature sensors incorporated into different measurement platforms. All these systems are able to collect thermal data from the foot, with some being able to acquire data only when the foot is stationary and others being able to acquire data from the foot in motion, which can give more in-depth insight into any emerging problems. The aim of this review is to evaluate the available literature related to the technologies used in these systems, outlining the benefits of each and what further developments may be required to make the foot temperature analysis more effective.

Footwear microclimate and its effects on the microbial community of the plantar skin

The association between the footwear microclimate and microbial community on the foot plantar skin was investigated by experiments with three participants. Novel methods were developed for measuring in-shoe temperature and humidity at five footwear regions, as well as the overall ventilation rate inside the footwear. Three types of footwear were tested including casual shoes, running shoes, and perforated shoes for pairwise comparison of footwear microclimate and corresponding microbial community on the skin. The major findings are as follows: (1) footwear types make a significant difference to in-shoe temperature at the instep region with the casual shoes sustaining the warmest of all types; (2) significant differences were observed in local internal absolute humidity between footwear types, with the casual shoes sustaining the highest level of humidity at most regions; (3) the perforated shoes provided the highest ventilation rate, followed by running and casual shoes, and the faster the gait, the larger the discrepancy in ventilation rate between footwear types; (4) the casual shoes seemed to provide the most favorable internal environment for bacterial growth at the distal plantar skin; and (5) the bacterial growth at the distal plantar skin showed a positive linear correlation with the in-shoe temperature and absolute humidity, and a negative linear correlation with the ventilation rate. The ventilation rate seemed to be a more reliable indicator of the bacterial growth. Above all, we can conclude that footwear microclimate varies in footwear types, which makes contributions to the bacterial growth on the foot plantar skin.

Wearable Thermoelectric Materials and Devices for Self-Powered Electronic Systems

The emergence of artificial intelligence and the Internet of Things has led to a growing demand for wearable and maintenance-free power sources. The continual push toward lower operating voltages and power consumption in modern integrated circuits has made the development of devices powered by body heat finally feasible. In this context, thermoelectric (TE) materials have emerged as promising candidates for the effective conversion of body heat into electricity to power wearable devices without being limited by environmental conditions. Driven by rapid advances in processing technology and the performance of TE materials over the past two decades, wearable thermoelectric generators (WTEGs) have gradually become more flexible and stretchable so that they can be used on complex and dynamic surfaces. In this review, the functional materials, processing techniques, and strategies for the device design of different types of WTEGs are comprehensively covered. Wearable self-powered systems based on WTEGs are summarized, including multi-function TE modules, hybrid energy harvesting, and all-in-one energy devices. Challenges in organic TE materials, interfacial engineering, and assessments of device performance are discussed, and suggestions for future developments in the area are provided. This review will promote the rapid implementation of wearable TE materials and devices in self-powered electronic systems.

Digital foot health technology and diabetic foot monitoring: A systematic review

BACKGROUND

In diabetic foot ulceration, a correlation between pressure and skin temperature is suspected. The aim of this systematic review is to provide a more rigorous analysis of existing literature related to the various technologies used to read and measure both in-shoe plantar pressures, and in-shoe skin temperatures simultaneously.

METHODS

A systematic review of the literature related to the topic was searched in database sources such as Medline OVID, Cochrane Library, PubMed, CONAHL, PROSPERO, and Elsevier. Outcome measures of interest included validity, reliability and responsiveness of in-shoe temperature and/or pressure mapping device used, and characteristics and quantity of sensors used, anatomical landmarks and statistical analysis used to interpret the data. Quality of evidence and risk of bias was evaluated using the QUADAS-2.

RESULTS

Nineteen studies were identified and included in this review. The majority of studies used a small sample size (mean n = 17) and recruited healthy participants. All studies have shown excellent validity but only a few tested for the reliability of the device. None of the studies tested for responsiveness of the device. Quality assessment results scored high risk in view of 'patient selection', 'use of reference standard' and 'applicability', and low risk in view of 'use if index test' and 'flow and timing'.

CONCLUSIONS

The data outlined in this review confirms that further improvement, reliability testing and clinical validation of the developed systems is required despite the results of excellent performance in detecting changes of in-shoe skin temperature and pressure.

Novel design of smart sleep-lighting system for improving the sleep environment of children

BACKGROUND

Children struggle to fall asleep by themselves because of their physiological characteristics. Therefore, research has been carried on various devices (such as a smartphone) to assist in improving the sleep quality of children. However, all such devices need to be controlled by parents and do not have functions for monitoring the sleep environment.

OBJECTIVE

In this paper, a smart sleep-lighting system that includes a sleep-lighting device and a smartphone dongle is developed to improve the sleep environment of children.

METHODS

The temperature, humidity, and luminance of the sleep environment are monitored and analyzed by the sleep-lighting device to control multi-color light and audio components. The colored light emitted by the multi-color light can be adjusted to improve the sleep atmosphere. Also, the audio component can play white noise to induce sleep. In addition, parents can use a smartphone dongle with a multi-channel wireless communication method to monitor and control one or more lighting devices in different locations in real time.

RESULTS

For environmental monitoring, average difference between proposed device and commercial sensor from chamber setting temperature 15∘C to 35∘C was 0.588∘C ± 0.10∘C, and average error value of the humidity measurement was 0.74% at 40% ∼ 60% RH. Also, the manufactured sleep-lighting device shows good performance in multi-color light emission, and playing of white noise. As result, the smartphone connected to the proposed smartphone dongle enables monitoring and control of the proposed lighting device in a wireless well.

CONCLUSIONS

The manufactured sleep-lighting device has a high-precision temperature and humidity sensor and a luminance sensor that can accurately monitor the sleeping environment. The lighting device can play white noise to induce sleep in children. Also, a multi-color LED light is operated via a smartphone application to improve the sleep atmosphere. The measured data will be sent to the lighting device and processed together with sleep environment data in order to improve the sleep quality. Additionally, the final system will be tested for real end-users with clinical experiments by sleep research center of a university hospital.

Prediction of Diabetic Foot Ulceration: The Value of Using Microclimate Sensor Arrays

BACKGROUND

Accurately predicting the risk of diabetic foot ulceration (DFU) could dramatically reduce the enormous burden of chronic wound management and amputation. Yet, the current prognostic models are unable to precisely predict DFU events. Typically, efforts have focused on individual factors like temperature, pressure, or shear rather than the overall foot microclimate.

METHODS

A systematic review was conducted by searching PubMed reports with no restrictions on start date covering the literature published until February 20, 2019 using relevant keywords, including temperature, pressure, shear, and relative humidity. We review the use of these variables as predictors of DFU, highlighting gaps in our current understanding and suggesting which specific features should be combined to develop a real-time microclimate prognostic model.

RESULTS

The current prognostic models rely either solely on contralateral temperature, pressure, or shear measurement; these parameters, however, rarely reach 50% specificity in relation to DFU. There is also considerable variation in methodological investigation, anatomical sensor configuration, and resting time prior to temperature measurements (5-20 minutes). Few studies have considered relative humidity and mean skin resistance.

CONCLUSION

Very limited evidence supports the use of single clinical parameters in predicting the risk of DFU. We suggest that the microclimate as a whole should be considered to predict DFU more effectively and suggest nine specific features which appear to be implicated for further investigation. Technology supports real-time in-shoe data collection and wireless transmission, providing a potentially rich source of data to better predict the risk of DFU.

A Review of Wearable Sensor Systems to Monitor Plantar Loading in the Assessment of Diabetic Foot Ulcers

Diabetes is highly prevalent throughout the world and imposes a high economic cost on countries at all income levels. Foot ulceration is one devastating consequence of diabetes, which can lead to amputation and mortality. Clinical assessment of diabetic foot ulcer (DFU) is currently subjective and limited, impeding effective diagnosis, treatment and prevention. Studies have shown that pressure and shear stress at the plantar surface of the foot plays an important role in the development of DFUs. Quantification of these could provide an improved means of assessment of the risk of developing DFUs. However, commercially-available sensing technology can only measure plantar pressures, neglecting shear stresses and thus limiting their clinical utility. Research into new sensor systems which can measure both plantar pressure and shear stresses are thus critical. Our aim in this paper is to provide the reader with an overview of recent advances in plantar pressure and stress sensing and offer insights into future needs in this critical area of healthcare. Firstly, we use current clinical understanding as the basis to define requirements for wearable sensor systems capable of assessing DFU. Secondly, we review the fundamental sensing technologies employed in this field and investigate the capabilities of the resultant wearable systems, including both commercial and research-grade equipment. Finally, we discuss research trends, ongoing challenges and future opportunities for improved sensing technologies to monitor plantar loading in the diabetic foot.

A Multiparameter Pressure-Temperature-Humidity Sensor Based on Mixed Ionic-Electronic Cellulose Aerogels

Pressure (P), temperature (T), and humidity (H) are physical key parameters of great relevance for various applications such as in distributed diagnostics, robotics, electronic skins, functional clothing, and many other Internet-of-Things (IoT) solutions. Previous studies on monitoring and recording these three parameters have focused on the integration of three individual single-parameter sensors into an electronic circuit, also comprising dedicated sense amplifiers, signal processing, and communication interfaces. To limit complexity in, e.g., multifunctional IoT systems, and thus reducing the manufacturing costs of such sensing/communication outposts, it is desirable to achieve one single-sensor device that simultaneously or consecutively measures P-T-H without cross-talks in the sensing functionality. Herein, a novel organic mixed ion-electron conducting aerogel is reported, which can sense P-T-H with minimal cross-talk between the measured parameters. The exclusive read-out of the three individual parameters is performed electronically in one single device configuration and is enabled by the use of a novel strategy that combines electronic and ionic Seebeck effect along with mixed ion-electron conduction in an elastic aerogel. The findings promise for multipurpose IoT technology with reduced complexity and production costs, features that are highly anticipated in distributed diagnostics, monitoring, safety, and security applications.

Normal foot loading parameters and repeatability of the Footscan® platform system

Background

The Footscan® platform system is one of the most commonly used clinical tools for the measurement of the foot pressure. The present study was designed to assess the repeatability of the system and identify the range of loading parameters observed in the normal foot.

Methods

Measurements were collected from 32 healthy participants, 15 females and 17 males, twice at an interval of 1 week. Peak pressure (PP), contact time (CT), contact area (CA), pressure-time integral (PTI), and maximum force (MaF) were recorded; these parameters were investigated in 10 areas of the foot: medial heel, lateral heel, midfoot, first to fifth metatarsals, hallux, and toes 2–5. The intra-session repeatability was evaluated by calculating the intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) across the three repeated trials within the same session. The inter-session repeatability was assessed using the average of the three trials in each session to determine the ICCs and CVs.

Results

The ICCs showed moderate to good repeatability for every variable of interest, and the CVs were all <28%. The highest zones of PP were found under the second and third metatarsals, followed by the medial heel. The CT was 68.5–82.8% of the total stance time under the metatarsal heads. CA was highest under the midfoot, PTI was highest under the second metatarsal, and MaF was highest under the medial heel.

Conclusions

Footscan® platform system was found to be repeatable. Thus, it can be used as a valuable tool in the assessment of plantar pressure distribution, and the normal values of the foot loading parameters identified in this study can be employed to provide a reference range for the gait analysis performed by the Footscan® system.

Portable System for Monitoring the Microclimate in the Footwear-Foot Interface

A new, continuously-monitoring portable device that monitors the diabetic foot has shown to help in reduction of diabetic foot complications. Persons affected by diabetic foot have shown to be particularly sensitive in the plantar surface; this sensitivity coupled with certain ambient conditions may cause dry skin. This dry skin leads to the formation of fissures that may eventually result in a foot ulceration and subsequent hospitalization. This new device monitors the micro-climate temperature and humidity areas between the insole and sole of the footwear. The monitoring system consists of an array of ten sensors that take readings of relative humidity within the range of 100% ± 2% and temperature within the range of −40 °C to 123.8 ± 0.3 °C. Continuous data is collected using embedded C software and the recorded data is processed in Matlab. This allows for the display of data; the implementation of the iterative Gauss-Newton algorithm method was used to display an exponential response curve. Therefore, the aim of our system is to obtain feedback data and provide the critical information to various footwear manufacturers. The footwear manufactures will utilize this critical information to design and manufacture diabetic footwear that reduce the risk of ulcers in diabetic feet.

Effect of gait on formation of thermal environment inside footwear

In this study, the relationship between the gait condition and foot temperature distributions inside footwear was investigated using subject experiments. Mechanical, physical, and physiological variables such as the foot contact force, landing speed, and metabolic heat generation were also measured. Gait motion measurements showed that a large contact force was concentrated in the small area of the heel at the initial contact and later at the forefoot. A faster gait produced a larger contact force, higher landing velocity, higher skin temperature, and larger metabolism during gait. The temperature at the bottom of the foot increased, and the temperature on the upper side decreased. The metabolic heat generation had a basic impact on the temperature profile, and skin temperatures tended to increase gradually. In addition, high-temperature-elevation regions such as the big toe and heel coincided with regions with high-contact loads, which suggested a relationship between the temperature elevation and contact load.

Skin Temperature Prediction in Lower Limb Prostheses

Increased temperature and perspiration within a prosthetic socket is a common complaint of many amputees. The heat dissipation in prosthetic sockets is greatly influenced by the thermal conductive properties of the socket and interface liner materials. These materials influence the body's temperature regulation mechanism and might be the reason for thermal discomfort in prosthetic sockets. Monitoring interface temperature at skin level is notoriously complicated. The problem might be considered notorious because embedding wires and sensors in an elastomer eventually results in elastomer failures because of the high strain induced when donning a liner (amputees roll the liners onto their limbs). Another reason is because placing sensors and wires directly against the skin could cause irritation and chaffing over just a short period of time. We describe a route wherein if the thermal properties of the socket and liner materials are known, the in-socket residual limb temperature could be accurately predicted by monitoring the temperature between socket and liner rather than skin and liner using the Gaussian process technique.

Real-time human ambulation, activity, and physiological monitoring: taxonomy of issues, techniques, applications, challenges and limitations

Automated methods of real-time, unobtrusive, human ambulation, activity, and wellness monitoring and data analysis using various algorithmic techniques have been subjects of intense research. The general aim is to devise effective means of addressing the demands of assisted living, rehabilitation, and clinical observation and assessment through sensor-based monitoring. The research studies have resulted in a large amount of literature. This paper presents a holistic articulation of the research studies and offers comprehensive insights along four main axes: distribution of existing studies; monitoring device framework and sensor types; data collection, processing and analysis; and applications, limitations and challenges. The aim is to present a systematic and most complete study of literature in the area in order to identify research gaps and prioritize future research directions.

Personalized foot orthoses with embedded temperature sensing: Proof of concept and relationship with activity

Plantar foot surface temperature has been identified as a clinically relevant physiological variable. Embedding sensors in foot orthoses (FOs) may allow long term monitoring of these temperatures, with compliance via the detection of periods of activity being a potential clinical utilization. This study aimed to test novel designs for FOs with embedded sensing that were produced via additive manufacturing and determine if foot temperature measurements could be used to detect periods of increased activity. FOs with embedded temperature sensors were developed and tested in 10 healthy participants over four day wear periods. Activity monitoring was used to estimate energy expenditure during testing. A threshold-based algorithm was developed to identify time periods of high activity from foot temperature data. Group differences in estimated energy expenditure between time periods below and above the threshold were significant in both the training and validation sets (p<0.001). Significant differences were also seen at individual participant level (p<0.001 in all cases). These results demonstrate the feasibility of using FOs with embedded sensing to monitor plantar surface foot temperatures during normal daily activities and for extended periods and show that periods of increased activity can be identified using foot temperature data.

The value of reporting pressure-time integral data in addition to peak pressure data in studies on the diabetic foot: a systematic review

BACKGROUND

In plantar pressure studies on the diabetic foot, pressure-time integral data is often analyzed and reported next to peak pressure data, mostly because of its assumed additional value. The aim was to assess this additional value by systematically reviewing the relevant literature.

METHODS

The MEDLINE database was searched for original articles that report both pressure-time integral and peak pressure data measured in the diabetic foot. Eligible articles were assessed according to differences in reported results between both parameters, the quality of discussion and specific conclusions drawn on pressure-time integral data, and the added value of the pressure-time integral data.

FINDINGS

All 35 eligible papers described studies on gait. Differences in reported results between parameters were found to be clear, minimal, or absent in 15, 8, and 12 papers, respectively. In 15 papers, the pressure-time integral results were discussed with respect to the peak pressure results, but in only 5 papers the explanation given for reported differences was considered meaningful. Specific conclusions were drawn in 11 papers. Some added value was found in 10 papers, but in all papers one or more limitations to this value applied.

INTERPRETATION

The study findings suggest that the added value of reporting pressure-time integral data is limited. Unless clear benefit can be shown such, as that ulceration can be better predicted using pressure-time integral than using peak pressure data, the reporting of pressure-time integral data seems redundant to express the plantar loading in the diabetic foot.

Test-retest reliability of the Win-Track platform in analyzing the gait parameters and plantar pressures during barefoot walking in healthy adults

The Win-Track platform is an instrument used to measure plantar pressures and gait parameters during barefoot walking. The objective of this study was to determine the test-retest reliability of the system in assessing plantar pressures and temporal gait variables between 1-step and 3-step gait protocols. A total of 30 healthy participants (18 women and 12 men; age 23.7 ± 4.75 years) were recruited for the study. The 1-step gait protocol exhibited good reliability in terms of single stance, step duration and swing duration of the left foot; stride duration of the right foot; stride length; and step length of the right foot, with intraclass correlation coefficients (ICCs) ranging from 0.75 to 0.88. The 3-step gait protocol showed good reliability, with ICC values ranging between 0.75 and 0.90 in cadence; step duration of the right foot; double-stance duration and swing duration of the right foot; stride length of the right foot; step length and gait cycle length of the right and the left foot; and the area covered by the first, second, and third foot. The authors concluded that the Win-Track platform provided reliable plantar pressures and temporal gait measures, and the 3-step gait protocol showed better reliability compared with the 1-step gait protocol.

Reliability of the TekScan MatScan(R) system for the measurement of plantar forces and pressures during barefoot level walking in healthy adults

Background

Plantar pressure systems are increasingly being used to evaluate foot function in both research settings and in clinical practice. The purpose of this study was to investigate the reliability of the TekScan MatScan^® system in assessing plantar forces and pressures during barefoot level walking.

Methods

Thirty participants were assessed for the reliability of measurements taken one week apart for the variables maximum force, peak pressure and average pressure. The following seven regions of the foot were investigated; heel, midfoot, 3^rd-5^th metatarsophalangeal joint, 2^nd metatarsophalangeal joint, 1^st metatarsophalangeal joint, hallux and the lesser toes.

Results

Reliability was assessed using both the mean and the median values of three repeated trials. The system displayed moderate to good reliability of mean and median calculations for the three analysed variables across all seven regions, as indicated by intra-class correlation coefficients ranging from 0.44 to 0.95 for the mean and 0.54 to 0.97 for the median, and coefficients of variation ranging from 5 to 20% for the mean and 3 to 23% for the median. Selecting the median value of three repeated trials yielded slightly more reliable results than the mean.

Conclusions

These findings indicate that the TekScan MatScan^® system demonstrates generally moderate to good reliability.

Gait analysis using a shoe-integrated wireless sensor system

We describe a wireless wearable system that was developed to provide quantitative gait analysis outside the confines of the traditional motion laboratory. The sensor suite includes three orthogonal accelerometers, three orthogonal gyroscopes, four force sensors, two bidirectional bend sensors, two dynamic pressure sensors, as well as electric field height sensors. The "GaitShoe" was built to be worn in any shoe, without interfering with gait and was designed to collect data unobtrusively, in any environment, and over long periods. The calibrated sensor outputs were analyzed and validated with results obtained simultaneously from the Massachusetts General Hospital, Biomotion Laboratory. The GaitShoe proved highly capable of detecting heel-strike and toe-off, as well as estimating foot orientation and position, inter alia.

Reducing plantar pressure in rheumatoid arthritis: a comparison of running versus off-the-shelf orthopaedic footwear

BACKGROUND

Foot pain in patients with rheumatoid arthritis is common and can be associated with excessive forefoot plantar pressure loading. Running and off-the-shelf orthopaedic footwear are commonly recommended to manage foot pain and discomfort in these patients. The aim of this study was to evaluate the effect of running footwear as an alternative to off-the-shelf orthopaedic footwear on plantar pressure loading characteristics in people with forefoot pain associated with rheumatoid arthritis.

METHODS

Twenty participants diagnosed with rheumatoid arthritis reporting chronic forefoot pain participated in this experimental, randomised, single-blind, cross-over trial of three footwear conditions: control, running and off-the-shelf orthopaedic. Outcome measures included measurement of peak pressure and pressure-time integral, with an in-shoe plantar pressure measurement system, beneath the total foot, forefoot, midfoot and rearfoot. Furthermore, perceived comfort and footwear acceptability were determined for each footwear condition.

FINDINGS

Compared to the control footwear, forefoot peak pressures were reduced by 36% in the running footwear and by 20% in the orthopaedic footwear, compared to the control (P<0.001). Forefoot pressure-time integrals were reduced by 33% in the running footwear and by 23% in the orthopaedic footwear (P<0.001). The largest reductions were achieved with the running footwear across the whole plantar surface of the foot. Perceived comfort did not differ between running and orthopaedic footwear, although both were significantly more comfortable than the control footwear. Overall, more participants nominated the running footwear as the most acceptable footwear condition.

INTERPRETATION

The results of this preliminary study show that running footwear was most effective at reducing plantar pressure loading and was regarded as a comfortable and acceptable footwear alternative by participants with forefoot pain associated with rheumatoid arthritis.

An evaluation of accuracy and repeatability of a novel gait analysis device

INTRODUCTION

Restoration of gait is a particularly important patient-based functional outcome following lower extremity trauma. A new portable device which measures gait parameters, the IDEEA, may be particularly useful in evaluating post-traumatic gait parameters in the office setting, but the accuracy and repeatability of this device relative to standard gait laboratory footswitches are unknown.

MATERIAL AND METHODS

Twelve healthy subjects were tested simultaneously using the IDEEA device and standard gait laboratory footswitches, at slow, medium, and fast speeds. Parameters evaluated were single-limb support time (SLS), double-limb support time (DLS), swing phase duration (SPD), cycle duration, and cadence.

RESULTS

The repeatability between right and left measurements tended to be better for the IDEEA, and was at least as good as the foot switches. The absolute differences of the timed gait parameters between the two devices were all in the range of 0.03 s, which is within the data sampling resolution of the gait laboratory foot switches (0.04 s). Furthermore, assuming a 1-s gait cycle, these differences account for only 3% of the gait cycle, which is also well within the clinical parameters for evaluating and differentiating between treatments.

CONCLUSION

This device is accurate and repeatable, and may facilitate the evaluation of gait function in post-traumatic patients in settings outside of the traditional gait laboratory.

Quantification of human motion: gait analysis-benefits and limitations to its application to clinical problems

The technology supporting the analysis of human motion has advanced dramatically. Past decades of locomotion research have provided us with significant knowledge about the accuracy of tests performed, the understanding of the process of human locomotion, and how clinical testing can be used to evaluate medical disorders and affect their treatment. Gait analysis is now recognized as clinically useful and financially reimbursable for some medical conditions. Yet, the routine clinical use of gait analysis has seen very limited growth. The issue of its clinical value is related to many factors, including the applicability of existing technology to addressing clinical problems; the limited use of such tests to address a wide variety of medical disorders; the manner in which gait laboratories are organized, tests are performed, and reports generated; and the clinical understanding and expectations of laboratory results. Clinical use is most hampered by the length of time and costs required for performing a study and interpreting it. A "gait" report is lengthy, its data are not well understood, and it includes a clinical interpretation, all of which do not occur with other clinical tests. Current biotechnology research is seeking to address these problems by creating techniques to capture data rapidly, accurately, and efficiently, and to interpret such data by an assortment of modeling, statistical, wave interpretation, and artificial intelligence methodologies. The success of such efforts rests on both our technical abilities and communication between engineers and clinicians.

Tendon Achilles lengthening for the treatment of neuropathic ulcers causes a temporary reduction in forefoot pressure associated with changes in plantar flexor power rather than ankle motion during gait

The purposes of this study were to determine the effects of tendon Achilles lengthening (TAL) on ambulatory plantar pressures and ankle range of motion, moment, and power, and to determine whether changes in forefoot pressure after treatment of a neuropathic ulcer are related to changes in ankle dorsiflexion range of motion (DFROM) or plantar flexor (PF) power during gait. Pressure and gait tests were performed before treatment, and at 3 weeks and 8 months after treatment in two randomly assigned groups of subjects with diabetes, equinus deformity, and a neuropathic forefoot ulcer treated with TAL and total contact casting (TAL group, n=14), or total contact casting alone (TCC group, n=14). The TAL group had an initial decrease in forefoot peak pressure (PP) (27%), forefoot pressure-time integral (PTI) (42%), PF moment (53%), and PF power (65%), along with an initial increase in rear foot PP (34%), rear foot PTI (48%), and DFROM (74%). Post-surgical changes in rear foot pressure and DFROM were maintained up to 8 months after treatment with TAL, whereas forefoot pressure and PF moment and power increased significantly. Changes in forefoot pressure after treatment in either group were correlated with changes in PF power (r=0.45-0.60), but not with changes in DFROM during gait (r=-0.02-0.08). Results suggest TAL causes a temporary reduction in forefoot pressure primarily by reducing PF power during gait. The initial decrease in forefoot pressure, followed by progressive reloading of forefoot tissues as PF muscles regain strength after TAL, may help reduce the risk of ulcer recurrence in patients with diabetes.

Foot pressures during level walking are strongly associated with pressures during other ambulatory activities in subjects with diabetic neuropathy

OBJECTIVE

To assess the relationship between foot pressures measured during level walking and other types of ambulatory activity in subjects with diabetes mellitus (DM) and peripheral neuropathy (PN).

DESIGN

Descriptive survey with repeated measures.

SETTING

University medical center.

PARTICIPANTS

Convenience sample of 16 ambulatory subjects with DM and PN.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Peak pressure and pressure-time integral (PTI) at the heel, great toe, first metatarsal head (MT1), and third metatarsal head (MT3) during level walking, ramp climbing, stair climbing, and turning at a self-selected speed.

RESULTS

Peak pressure and PTI during level walking correlated highly with pressures during ramp climbing (r range,.85-.97) and turning (r range,.75-.96) at all regions examined and with pressures during stair climbing at MT1 and MT3 (r range,.84-.91). Correlations between pressures during level walking and stair climbing were moderate at the great toe (r range,.46-.57) and poor at the heel (r range, -.12 to -.06). With few exceptions, pressures during ramp climbing, stair climbing, and turning were less than (P<.008) or equal to pressures during level walking. We found no activity-related differences in peak pressure or PTI independent of the effects of preferred walking speed.

CONCLUSIONS

Results support the clinical evaluation of peak pressure during level walking as an efficient method to screen for maximum levels of stress on the foot as patients with DM and PN perform their daily activities.

Novel Award 2002. Comparison of physical activity and cumulative plantar tissue stress among subjects with and without diabetes mellitus and a history of recurrent plantar ulcers

OBJECTIVES

To compare the amount of weight-bearing activity and estimates of cumulative plantar tissue stress between subjects with and without diabetes mellitus and a history of recurrent plantar ulcers.

DESIGN

Cross-sectional study with matched groups.

BACKGROUND

Weight-bearing activity among individuals with diabetes is likely to influence the amount of mechanical trauma accumulated by plantar tissues, yet activity levels have not been accounted for in previous measurements of plantar tissue stress or predictions of plantar tissue injury.

METHODS

Study groups included subjects with diabetes mellitus and peripheral neuropathy, either with or without a history of recurrent plantar ulcers, and non-diabetic control subjects (n=10 per group). Pressure on the plantar foot was assessed as subjects walked at their preferred speed in the shoes they reported wearing most often each day. Physical activity was monitored over seven consecutive days using an accelerometer. The product of mean daily strides and forefoot pressure-time integral was used to estimate daily cumulative stress on the plantar forefoot.

RESULTS

Subjects with diabetes and a history of recurrent plantar ulcers were 46% less active than subjects without diabetes (mean (SD)=2727 (1345) versus 5037 (2624) strides/day, P=0.04), and accumulated 41% less daily stress on the forefoot than non-diabetic and diabetic control subjects without a history of plantar ulcers (mean (SD)= 210 (134) versus 354 (118) and 354 (148) MPas/day respectively, P=0.03).

CONCLUSIONS

Subjects with diabetes and a history a previous ulcers may be susceptible to plantar tissue injury even at relatively low levels of cumulative tissue stress.

RELEVANCE

Changes in weight-bearing activity following plantar tissue injury in patients with diabetes may influence plantar tissue adaptation and the risk of ulcer recurrence.

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.