"Pressure gradient" as an indicator of plantar skin injury

A method for automated masking and plantar pressure analysis using segmented computed tomography scans

BACKGROUND

Plantar pressure, a common gait and foot biomechanics measurement, is typically analyzed using proprietary commercial software packages. Regional plantar pressure analysis is often reported in terms of underlying bony geometry, and recent advances in image processing and accessibility have made computed tomography, radiographs, magnetic resonance imaging, or other imaging methods more popular for incorporating bone analyses in biomechanics.

RESEARCH QUESTION

Can a computed tomography-based regional mask provide comparable regional analysis to commercial plantar pressure software and can the increased flexibility of an in-house method obtain additional insight from common measurements?

METHODS

A plantar pressure analysis method was developed based on bony geometry from computed tomography scans to calculate peak pressure, pressure time integral incorporating sub-peak values, force time integral, pressure gradient, and pressure gradient angle. Static and dynamic plantar pressure were acquired for 4 subjects (male, 65 ± 2.4 years). Plantar pressure variables were calculated using commercial and computed tomography-based systems.

RESULTS

Dynamic peak pressure, pressure time integral, and force-time integral computed using the bone-based software was 5 % (9kPa), 7 % (0.3kPa-s) and 13 % (0.3 N-s) different than the commercial software on average. Region masks of the metatarsals and toes differed between commercial and computed tomography-based software due to subject-specific bone geometry and toe shape. Pressure time integral values incorporating sub-peak pressure were higher and demonstrated higher relative hindfoot values compared to those without. Removing step-on frames to static pressure analysis decreased forefoot pressures. Regional maps of peak pressure and maximum pressure gradient demonstrate different peak locations.

SIGNIFICANCE

Computed tomography-based regional masks are comparable to commercial masks. Inclusion of static step-on frames and sub-peak pressures may change regional plantar pressure patterns. Differences in location of maximum pressure gradient and peak pressure may be useful for assessing subject specific injury risk.

Coupled effect of load weights and belt use on male shoulder pressure redistribution

Shoulder pressure redistribution is jointly affected by backpack loads and belt support. However, the combined effect of both factors has rarely been fully evaluated. Here, we studied the coupled effect of backpack loads and belt support on shoulder pressure redistribution. All twenty-eight healthy male subjects underwent eight loading conditions with both chest and hip belts fastened (CH) and unfastened (CON) in four conditions where the backpack weighed 7.5, 15, 22.5, and 30% of body weight (BW). Shoulder pressure distribution was quantified through a pressure-sensing vest mat. The results showed that using the hip belt and chest belt was effective in relieving the high pressure in the lateral clavicle and medial trapezius region and strengthening the load-bearing capacity of shoulder. However, the assistance in pressure relief of using belt was weakened when load increased to 30% BW. This study also showed that the belt use can be effective in improving pressure asymmetry on both sides.

Plantar pressure gradient and pressure gradient angle are affected by inner pressure of air insole

Clinically, air insoles may be applied to shoes to decrease plantar pressure gradient (PPG) and increase plantar gradient angle (PGA) to reduce foot ulcers. PPG and PGA may cause skin breakdown. The effects of different inner pressures of inflatable air insoles on dynamic PPG and PGA distributions are largely unknown in non-diabetics and people with diabetes. This study aimed to explore the impact of varying inner air insole pressures on PPG and PGA to establish early mitigation strategies for people at risk of foot ulcers. A repeated measures study design, including three air insoles (80 mmHg, 160 mmHg, and 240 mmHg) and two walking durations (10 and 20 min) for a total of six walking protocols, was tested on 13 healthy participants (height, 165.8 ± 8.4 cm; age, 27.0 ± 7.3 years; and weight, 56.0 ± 7.9 kg, BMI: 20.3 ± 1.7 kg/m^2) over three consecutive weeks. PPG, a measurement of the spatial variation in plantar pressure around the peak plantar pressure (PPP) and PGA, a variation in the gradient direction values at the three plantar regions, big toe (T1), first metatarsal head (M1), and second metatarsal head (M2), were calculated. This study indicated that PPG was lower at 80 mmHg air insoles after 20 min of walking in the M1 region (p = 0.010). The PGA in the M2 increased at an air insole of 80 mmHg compared to 240 mmHg (p = 0.015). Compared to 20 min, the 10 min walking duration at 240 mmHg of air insole had the lowest PPG in the M1 (p = 0.015) and M2 (p = 0.034) regions. The 80 mmHg air insole significantly lowered the PPG compared to a 160 mmHg and 240 mmHg air insole. Moreover, the 80 mmHg air insole significantly decreased PPP and increased PGA compared to the 160 mmHg and 240 mmHg air insole. A shorter walking period (10 min) significantly lowered PPG. The findings of this study suggest that people with a higher risk of foot ulcers should wear softer air insoles to have a lower PPG, as well as an increased PGA.

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability - thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability.

Prediction of Diabetes Mellitus Progression Using Supervised Machine Learning

Diabetic peripheral neuropathy (DN) is a serious complication of diabetes mellitus (DM) that can lead to foot ulceration and eventual amputation if not treated properly. Therefore, detecting DN early is important. This study presents an approach for diagnosing various stages of the progression of DM in lower extremities using machine learning to classify individuals with prediabetes (PD; n = 19), diabetes without (D; n = 62), and diabetes with peripheral neuropathy (DN; n = 29) based on dynamic pressure distribution collected using pressure-measuring insoles. Dynamic plantar pressure measurements were recorded bilaterally (60 Hz) for several steps during the support phase of walking while participants walked at self-selected speeds over a straight path. Pressure data were grouped and divided into three plantar regions: rearfoot, midfoot, and forefoot. For each region, peak plantar pressure, peak pressure gradient, and pressure-time integral were calculated. A variety of supervised machine learning algorithms were used to assess the performance of models trained using different combinations of pressure and non-pressure features to predict diagnoses. The effects of choosing various subsets of these features on the model's accuracy were also considered. The best performing models produced accuracies between 94-100%, showing the proposed approach can be used to augment current diagnostic methods.

Plantar pressure and falling risk in older individuals: a cross-sectional study

BACKGROUND

Falls are commonplace among elderly people. It is urgent to prevent falls. Previous studies have confirmed that there is a difference in plantar pressure between falls and non-falls in elderly people, but the relationship between fall risk and foot pressure has not been studied. In this study, the differences in dynamic plantar pressure between elderly people with high and low fall risk were preliminarily discussed, and the characteristic parameters of plantar pressure were determined.

METHODS

Twenty four high-fall-risk elderly individuals (HR) and 24 low-fall-risk elderly individuals (LR) were selected using the Berg Balance Scale 40 score. They wore wearable foot pressure devices to walk along a 20-m-long corridor. The peak pressure (PP), pressure time integral (PTI), pressure gradient (maximum pressure gradient (MaxPG), minimum pressure gradient (MinPG), full width at half maximum (FWHM)) and average pressure (AP) of their feet were measured for inter-group and intra-group analysis.

RESULTS

The foot pressure difference comparing the high fall risk with low fall risk groups was manifested in PP and MaxPG, concentrated in the midfoot and heel (p < 0.05), while the only time parameter, FWHM, was manifested in the whole foot (p < 0.05). The differences between the left and right foot were reflected in all parameters. The differences between the left and right foot in LR were mainly reflected in the heel (p < 0.05), while it in the HR was mainly reflected in the forefoot (p < 0.05).

CONCLUSIONS

The differences comparing the high fall risk with low fall risk groups were mostly reflected in the midfoot and heel. The HR may have been more cautious when landing. In the intra-group comparison, the difference between the right and left foot of the LR was mainly reflected during heel striking, while it was mainly reflected during pedalling in the HR. The sensitivity of PP, PTI and AP was lower and the newly introduced pressure gradient could better reflect the difference in foot pressure between the two groups. The pressure gradient can be used as a new foot pressure parameter in scientific research.

Quantification of Comfort for the Development of Binding Parts in a Standing Rehabilitation Robot

Human-machine interfaces (HMI) refer to the physical interaction between a user and rehabilitation robots. A persisting excessive load leads to soft tissue damage, such as pressure ulcers. Therefore, it is necessary to define a comfortable binding part for a rehabilitation robot with the subject in a standing posture. The purpose of this study was to quantify the comfort at the binding parts of the standing rehabilitation robot. In Experiment 1, cuff pressures of 10-40 kPa were applied to the thigh, shank, and knee of standing subjects, and the interface pressure and pain scale were obtained. In Experiment 2, cuff pressures of 10-20 kPa were applied to the thigh, and the tissue oxygen saturation and the skin temperature were measured. Questionnaire responses regarding comfort during compression were obtained from the subjects using the visual analog scale and the Likert scale. The greatest pain was perceived in the thigh. The musculoskeletal configuration affected the pressure distribution. The interface pressure distribution by the binding part showed higher pressure at the intermuscular septum. Tissue oxygen saturation (StO₂) increased to 111.9 ± 6.7% when a cuff pressure of 10 kPa was applied and decreased to 92.2 ± 16.9% for a cuff pressure of 20 kPa. A skin temperature variation greater than 0.2 °C occurred in the compressed leg. These findings would help evaluate and improve the comfort of rehabilitation robots.

Plantar pressures values related with appearance of mechanical hyperkeratosis before and after surgery of mild hallux valgus

Background

Hyperkeratoses are thickenings of the stratum corneum, provoked by deviation of the ray and excessive plantar pressures. They are very common under the first metatarsal head (MTH) and on the big toe when there exists hallux valgus. The objective of this study was to assess plantar pressures pre- and post-surgery to try to define the threshold values that could determine the appearance of keratopathies.

Materials and methods

Seventy-nine patients (100 feet) who had undergone percutaneous distal soft-tissue release and the Akin procedure were evaluated prospectively. The BioFoot/IBV^® in-shoe system was used for objective baropodometric functional evaluations of the heel, midfoot, first through fifth MTHs, hallux, and lesser toes. The presence or absence of a hyperkeratosis (HK) or plantar callus under the first MTH or hallux was recorded. The average follow-up time at which the measurements were repeated was 28.1 months.

Results

Pre-surgery, 62 feet presented a painful HK on the big toe, while post-surgery, only 9 of the feet presented the same lesion. Patients who presented a prior HK at the first metatarsophalangeal (MTP) joint had a mean pressure of 417.2 ± 254.5 kPa as against a value of 359.6 ± 185.1 kPa for the rest. Post-surgery, these values dropped to 409.8 and 346.3 kPa, respectively.

Conclusion

Patients with HK presented an 11% greater mean pressure than those without. The values obtained with the BioFoot/IBV^® system in the present study can therefore be considered predictive of the appearance of HK under the first MTH and on the side of the big toe.

Effects of Walking Speeds and Durations on Peak Plantar Pressures

BACKGROUND

Walking at various speeds and durations may result in different peak plantar pressure (PPP). However, there is no study comparing the effect of walking speeds and durations on PPP. The purpose of this study was to explore whether different walking speeds and durations significantly change PPP and establish a normal response in healthy people.

METHODS

An in-shoe plantar pressure system was used to measure PPP under the first toe, first metatarsal, second metatarsal, and heel regions in 12 healthy, young people. All participants performed six walking trials at three speeds (3, 6, and 9 km/h) and for two durations (10 and 20 min). The 3 × 2 two-way analysis of variance was used to examine the main effects of speeds and durations and their interaction.

RESULTS

The results showed that walking speeds significantly affected PPP and that walking duration did not. No interaction between the walking speed and duration was observed. Peak plantar pressure values under the first toe and the first metatarsal head were significantly higher (P < .05) at 9 km/h (509.1 ± 314.2 kPa and 591.4 ± 302.4 kPa, respectively) than at 3 km/h (275.4 ± 168.7 kPa and 369.4 ± 205.4 kPa, respectively) after 10-min walking.

CONCLUSIONS

People at risk for foot ulcers may use slow and brisk walking for exercise to reduce PPP, thus reducing risk for foot ulcers. Our study demonstrated that slow running at 9 km/h significantly increases PPP.

Effects of walking speeds and durations on the plantar pressure gradient and pressure gradient angle

BACKGROUND

Walking exercise has been demonstrated to improve health in people with diabetes. However, it is largely unknown the influences of various walking intensities such as walking speeds and durations on dynamic plantar pressure distributions in non-diabetics and diabetics. Traditional methods ignoring time-series changes of plantar pressure patterns may not fully capture the effect of walking intensities on plantar tissues. The purpose of this study was to investigate the effect of various walking intensities on the dynamic plantar pressure distributions. In this study, we introduced the peak pressure gradient (PPG) and its dynamic patterns defined as the pressure gradient angle (PGA) to quantify dynamic changes of plantar pressure distributions during walking at various intensities.

METHODS

Twelve healthy participants (5 males and 7 females) were recruited in this study. The demographic data were: age, 27.1 ± 5.8 years; height, 1.7 ± 0.1 m; and weight, 63.5 ± 13.5 kg (mean ± standard deviation). An insole plantar pressure measurement system was used to measure plantar pressures during walking at three walking speeds (slow walking 1.8 mph, brisk walking 3.6 mph, and slow running 5.4 mph) for two durations (10 and 20 min). The gradient at a location is defined as the unique vector field in the two-dimensional Cartesian coordinate system with a Euclidean metric. PGA was calculated by quantifying the directional variation of the instantaneous peak gradient vector during stance phase of walking. PPG and PGA were calculated in the plantar regions of the first toe, first metatarsal head, second metatarsal head, and heel at higher risk for foot ulcers. Two-way ANOVA with Fisher's post-hoc analysis was used to examine the speed and duration factors on PPG and PGA.

RESULTS

The results showed that the walking speeds significantly affect PPG (P < 0.05) and PGA (P < 0.05), and the walking durations does not. No interaction between the walking duration and speed was observed. PPG in the first toe region after 5.4 mph for either 10 or 20 min was significantly higher than 1.8 mph. Meanwhile, after 3.6 mph for 20 min, PPG in the heel region was significantly higher than 1.8 mph. Results also indicate that PGA in the forefoot region after 3.6 mph for 20 min was significantly narrower than 1.8 mph.

CONCLUSIONS

Our findings indicate that people may walk at a slow speed at 1.8 mph for reducing PPG and preventing PGA concentrated over a small area compared to brisk walking at 3.6 mph and slow running at 5.4 mph.

Experiences of foot and ankle mobilisations combined with home stretches in people with diabetes: a qualitative study embedded in a proof-of-concept randomised controlled trial

Background

The benefits of exercise and staying active are widely reported in the literature, however adherence and engagement with exercise amongst people with long-term illness and diabetes is poor. Physiotherapy aims to promote independence and physical activity using a range of strategies, including manual therapy and education/advice on exercises. However, low adherence impacts negatively on treatment outcomes. In this study, the practicality of physiotherapy interventions in patients who participate in a proof-of-concept (PoC) randomised controlled trial (RCT) will be considered.

Aim

To explore the experiences of people with diabetes who received an intervention package of foot and ankle mobilisations combined with home stretches for a 6-week period.

Design

An embedded qualitative study in a proof-of-concept RCT using semi-structured interviews and thematic analysis.

Participants

Purposive sample of 16 participants (mean age 73 years) with a diagnosis of diabetes (mean duration 13.4 years) were recruited.

Results

Analysis revealed seven themes informing the adherence and non-adherence to the exercise intervention. Themes describing the positive experiences were: 1) support from others to do the exercises; 2) psychological factors to motivate exercise adherence; 2) physical factors contributing to exercise adherence; 4) acceptability of home exercises during and beyond the study. Other themes described barriers: 5) social factors that contributed to exercise disengagement; 6) emotional limitations that influence exercise avoidance; 7) physical circumstances that made exercise participation burdensome. Themes highlighted positive influences by physiotherapists, the motivation of doing exercises while participating in a study, improving the perceived range of motion in their foot and ankle and reducing discomfort in these joints whilst being more active with daily activities.

Conclusion

Our findings highlighted that the intervention of foot and ankle mobilisations combined with home stretches is feasible for study participants. Psycho-social support, self-efficacy, and physiotherapy support are motivational to adhere to the study intervention and might contribute to the success of a full-scale RCT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00512-z.

Predicting Forefoot-Orthosis Interactions in Rheumatoid Arthritis Using Computational Modelling

Foot orthoses are prescribed to reduce forefoot plantar pressures and pain in people with rheumatoid arthritis. Computational modelling can assess how the orthoses affect internal tissue stresses, but previous studies have focused on a single healthy individual. This study aimed to ascertain whether simplified forefoot models would produce differing biomechanical predictions at the orthotic interface between people with rheumatoid arthritis of varying severity, and in comparison to a healthy control. The forefoot models were developed from magnetic resonance data of 13 participants with rheumatoid arthritis and one healthy individual. Measurements of bony morphology and soft tissue thickness were taken to assess deformity. These were compared to model predictions (99th% shear strain and plantar pressure, max. pressure gradient, volume of soft tissue over 10% shear strain), alongside clinical data including body mass index and Leeds Foot Impact Scale–Impairment/Footwear score (LFIS-IF). The predicted pressure and shear strain for the healthy participant fell at the lower end of the rheumatoid models’ range. Medial first metatarsal head curvature moderately correlated to all model predicted outcomes (0.529 < r < 0.574, 0.040 < p < 0.063). BMI strongly correlated to all model predictions except pressure gradients (0.600 < r < 0.652, p < 0.05). There were no apparent relationships between model predictions and instances of bursae, erosion and synovial hypertrophy or LFIS-IF score. The forefoot models produced differing biomechanical predictions between a healthy individual and participants with rheumatoid arthritis, and between individuals with rheumatoid arthritis. Models capable of predicting subject specific biomechanical orthotic interactions could be used in the future to inform more personalised devices to protect skin and soft tissue health. While the model results did not clearly correlate with all clinical measures, there was a wide range in model predictions and morphological measures across the participants. Thus, the need for assessment of foot orthoses across a population, rather than for one individual, is clear.

Unsupervised Generative Adversarial Network for Plantar Pressure Image-to-Image Translation

Analyzing human gait from plantar pressure is critical for human health. The majority of works focus on classifying the healthy plantar pattern from unhealthy ones. Different from previous works, we adopt a generative adversarial network to produce healthy plantar pressure image for individual patients. In this work, we do not have pairs of images for training thus we cast the problem as an unsupervised generative adversarial learning task. Our network benefits from multiple components: an encoder-decoder generator, a convolution-based discriminator, a convolution-based evaluation network, and a new term in the loss function to preserve the person's gait style. Our method achieves high performance (99.8%) on the CAD WALK databases which have patients with hallux valgus disease.

A Novel Low-Cost Wireless Footwear System for Monitoring Diabetic Foot Patients

Diabetic foot is one of the main complications of diabetes with the characteristics of high incidence and difficulty in treatment. Diabetic patients with peripheral neuropathy may develop foot ulcers, and in severe cases amputations are required and some may even die. Plantar pressure can be used to assess the risk of developing diabetic foot, but the existing plantar pressure monitoring methods are not suitable for long-term monitoring in daily life. This study presents a novel low-cost shoe system for daily monitoring of plantar pressure in diabetics. It includes an insole with pressure sensor array, which can dynamically monitor the plantar pressure and display the changes of plantar pressure in real time in the mobile phone to provide early warning for patients with high risk of diabetic foot. As for the sensor, copper and carbon black were adopted as the electrode and conductive filler respectively, enabling a mass production with low price. It was soft and bendable, meeting the performance needs of daily plantar pressure monitoring. All devices were encapsulated in shoes, and the data was transmitted wirelessly through Bluetooth, which did not affect the user's walking. After using random forest for feature selection, five classifiers were used to classify the plantar pressure of healthy people, diabetic patients without peripheral neuropathy, and diabetic patients with peripheral neuropathy collected by this system. The experimental results showed that the accuracy of the random forest classifier was the highest, reaching 94.7%, which indicated that the system could be useful for daily plantar pressure monitoring of diabetic patients.

Lateral pressure equalisation as a principle for designing support surfaces to prevent deep tissue pressure ulcers

When immobile or neuropathic patients are supported by beds or chairs, their soft tissues undergo deformations that can cause pressure ulcers. Current support surfaces that redistribute under-body pressures at vulnerable body sites have not succeeded in reducing pressure ulcer prevalence. Here we show that adding a supporting lateral pressure can counter-act the deformations induced by under-body pressure, and that this 'pressure equalisation' approach is a more effective way to reduce ulcer-inducing deformations than current approaches based on redistributing under-body pressure. A finite element model of the seated pelvis predicts that applying a lateral pressure to the soft tissue reduces peak von Mises stress in the deep tissue by a factor of 2.4 relative to a standard cushion (from 113 kPa to 47 kPa)-a greater effect than that achieved by using a more conformable cushion, which reduced von Mises stress to 75 kPa. Combining both a conformable cushion and lateral pressure reduced peak von Mises stresses to 25 kPa. The ratio of peak lateral pressure to peak under-body pressure was shown to regulate deep tissue stress better than under-body pressure alone. By optimising the magnitude and position of lateral pressure, tissue deformations can be reduced to that induced when suspended in a fluid. Our results explain the lack of efficacy in current support surfaces and suggest a new approach to designing and evaluating support surfaces: ensuring sufficient lateral pressure is applied to counter-act under-body pressure.

Exploring the Influence of Wheelchair-User Interface and Personal Characteristics on Ischial Tuberosity Peak Pressure Index and Gradient in Elite Wheelchair Basketball Players

This pilot study investigated the relationship between personal and wheelchair factors on skin pressures at the ischial tuberosity in wheelchair basketball players. Seventeen wheelchair basketball players (7 male and 10 female) were evaluated during static and dynamic propulsive conditions while peak pressure index and peak pressure gradient were recorded with an interface pressure mat. The results showed that greater seat dump angles and backrest heights were negatively associated with the peak pressure index. Therapeutic cushion use was moderately associated with a reduced peak pressure gradient. Higher-class players used chair configurations associated with augmented pressure; however, classification status alone was not associated with pressure magnitude. Body mass index was negatively correlated with the static peak pressure gradient at levels approaching significance (p < .10). In conclusion, greater seat dump angles and backrest heights may provide pressure relief, whereas greater body mass index and therapeutic cushion use may reduce pressure gradients.

Measuring Plantar Tissue Stress in People With Diabetic Peripheral Neuropathy: A Critical Concept in Diabetic Foot Management

Excessive stress on plantar tissue over time is one of the leading causes of diabetic foot ulcers among people with diabetic peripheral neuropathy. Plantar tissue stress (PTS) is a concept that attempts to integrate several well-known mechanical factors into one measure, including plantar pressure, shear stress, daily weight-bearing activity, and time spent in prescribed offloading interventions (adherence). Despite international diabetic foot guidelines recommending the measure of each of these individual mechanical factors in people with neuropathy, only recently has technology enabled their combined measurement to determine PTS. In this article we review the concept of PTS, the mechanical factors involved, and the findings of pivotal articles reporting measures of PTS in people with neuropathy. We also discuss key existing gaps in this field, including the lack of standards to measure and report PTS, a lack of practical solutions to measure shear stress, and the lack of PTS thresholds that may indicate benefit or detriment to people with neuropathy. To address some of these gaps, we propose recommended clinical and research standards for measuring and reporting PTS in people with neuropathy. Last, we forecast future clinical, research, and technological advancements that may use PTS to highlight the importance of this critical concept in the prevention and management of diabetic foot ulcers.

Plantar Pressure Differences between Nordic Walking Techniques

High plantar pressure has been associated with increased risk of injury. The characteristics of each physical activity determine the load on the lower limbs. The influence of Nordic Walking (NW) technique on plantar pressure is still unknown. The aim of this study was to analyze the differences between plantar pressure during NW with the Diagonal technique (DT) versus Alpha technique (AT) and compare them with the pressure obtained during normal walking (W). The normality and sphericity of the plantar pressure data were checked before performing a two-way repeated measures ANOVA in order to find differences between speeds (preferred, fast) and the gait (NW, W) as within-subject factors. Then, a t-test for independent measures was used to identify the specific differences between NW techniques. The strength of the differences was calculated by means of the effect size (ES). The results demonstrated that during NW with AT at preferred speed the pressure was lower under the Calcaneus, Lateral Metatarsal and Toes compared to the DT group (p = 0.046, ES = 1.49; p = 0.015, ES = 1.44; p = 0.040, ES = 1.20, respectively). No differences were found at the fast speed (p > 0.05). Besides the increase in walking speed during NW (p < 0.01), both technique groups showed lower pressure during NW compared to W under the Hallux and Central Metatarsal heads (F = 58.321, p = 0.000, ES = 2.449; F = 41.917, p = 0.012, ES = 1.365, respectively). As a practical conclusion, the AT technique may be the most effective of the NW techniques at reducing plantar pressure while allowing NW practitioners to achieve the physiological benefits of NW.

Discrete sensors distribution for accurate plantar pressure analyses

The aim of this study was to determine the distribution of discrete sensors under the footprint for accurate plantar pressure analyses. For this purpose, two different sensor layouts have been tested and compared, to determine which was the most accurate to monitor plantar pressure with wireless devices in research and/or clinical practice. Ten healthy volunteers participated in the study (age range: 23-58 years). The barycenter of pressures (BoP) determined from the plantar pressure system (W-inshoe®) was compared to the center of pressures (CoP) determined from a force platform (AMTI) in the medial-lateral (ML) and anterior-posterior (AP) directions. Then, the vertical ground reaction force (vGRF) obtained from both W-inshoe® and force platform was compared for both layouts for each subject. The BoP and vGRF determined from the plantar pressure system data showed good correlation (SCC) with those determined from the force platform data, notably for the second sensor organization (ML SCC= 0.95; AP SCC=0.99; vGRF SCC=0.91). The study demonstrates that an adjusted placement of removable sensors is key to accurate plantar pressure analyses. These results are promising for a plantar pressure recording outside clinical or laboratory settings, for long time monitoring, real time feedback or for whatever activity requiring a low-cost system.

Quantifying Dynamic Changes in Plantar Pressure Gradient in Diabetics with Peripheral Neuropathy

Diabetic foot ulcers remain one of the most serious complications of diabetes. Peak plantar pressure (PPP) and peak pressure gradient (PPG) during walking have been shown to be associated with the development of diabetic foot ulcers. To gain further insight into the mechanical etiology of diabetic foot ulcers, examination of the pressure gradient angle (PGA) has been recently proposed. The PGA quantifies directional variation or orientation of the pressure gradient during walking and provides a measure of whether pressure gradient patterns are concentrated or dispersed along the plantar surface. We hypothesized that diabetics at risk of foot ulceration would have smaller PGA in key plantar regions, suggesting less movement of the pressure gradient over time. A total of 27 participants were studied, including 19 diabetics with peripheral neuropathy and 8 non-diabetic control subjects. A foot pressure measurement system was used to measure plantar pressures during walking. PPP, PPG, and PGA were calculated for four foot regions – first toe (T1), first metatarsal head (M1), second metatarsal head (M2), and heel (HL). Consistent with prior studies, PPP and PPG were significantly larger in the diabetic group compared with non-diabetic controls in the T1 and M1 regions, but not M2 or HL. For example, PPP was 165% (P = 0.02) and PPG was 214% (P < 0.001) larger in T1. PGA was found to be significantly smaller in the diabetic group in T1 (46%, P = 0.04), suggesting a more concentrated pressure gradient pattern under the toe. The proposed PGA may improve our understanding of the role of pressure gradient on the risk of diabetic foot ulcers.

Application of DCT-derived parameters for early detection of polyneuropathy in diabetic patients

Diabetic foot is one of the most severe complications of diabetes. Early diagnosis of this syndrome can ensure proper medical care and adequate treatment. Various image analysis methods can be used to speed up the diagnosis process, and automated diagnosis can be applied as a screening technique to reduce its cost. Introducing auxiliary diagnostic parameters may help to detect polyneuropathy or neuropathy, both of which often precede the appearance of diabetic foot syndrome. The present paper describes a study performed on a group of diabetic patients by analyzing plantar pressure distribution images. As part of this study, 2D discrete cosine transform (DCT) is computed for the forefoot and rearfoot regions of each diabetic subject in a group of 37 patients. Three new DCT-based parameters are introduced to help to detect polyneuropathy or at least indicate that the patient may have polyneuropathy without a time-consuming examination. The results indicate a certain relationship between these parameters and the presence of polyneuropathy. This information could be used in further diagnosis to prevent foot ulcers from developing in patients with diabetes.

Pedorthic management of the diabetic foot

BACKGROUND

Conservative pedorthic management of the diabetic foot has been shown to be an effective method to prevent ulcers, amputations, and re-amputations. This article exhibits why and how pedorthics plays such an important role via modalities such as footwear, shoe modifications, custom foot orthoses, and partial foot prostheses.

OBJECTIVE

The objective of this article is to demonstrate how pedorthics has been shown to be an integral part of conservative diabetic foot care. The authors' goal was to educate the reader about the different modalities that are available for use.

STUDY DESIGN

This article is based largely on review of previously published research and scholarly articles, augmented by the more than 60 years of pedorthic and orthotic clinical experience of the authors.

METHODS

Approximately 60 journal articles and book chapters were reviewed by the authors. Articles were located via online resources such as PubMed as well as the authors' own libraries.

RESULTS

It was repeatedly noted that pedorthic modalities such as shoes, foot orthoses, and shoe modifications may be utilized in the treatment and prevention of diabetic foot wounds and other complications.

CONCLUSION

Pedorthic devices may be successfully integrated into a comprehensive treatment plan for patients with diabetes and foot ulcers.

CLINICAL RELEVANCE

This information is of special interest to those who treat patients with diabetes. The article demonstrates the efficacy of pedorthic intervention through the compilation and review of relevant previously published data.

Plantar pressure as a risk assessment tool for diabetic foot ulceration in egyptian patients with diabetes

BACKGROUND

Diabetic foot ulceration is a preventable long-term complication of diabetes. In the present study, peak plantar pressures (PPP) and other characteristics were assessed in a group of 100 Egyptian patients with diabetes with or without neuropathy and foot ulcers. The aim was to study the relationship between plantar pressure (PP) and neuropathy with or without ulceration and trying to clarify the utility of pedobarography as an ulceration risk assessment tool in patients with diabetes.

SUBJECTS AND METHODS

A total of 100 patients having diabetes were selected. All patients had a comprehensive foot evaluation, including assessment for neuropathy using modified neuropathy disability score (MNDS), for peripheral vascular disease using ankle brachial index, and for dynamic foot pressures using the MAT system (Tekscan). The studied patients were grouped into: (1) diabetic control group (DC), which included 37 patients who had diabetes without neuropathy or ulceration and MNDS ≤2; (2) diabetic neuropathy group (DN), which included 33 patients who had diabetes with neuropathy and MNDS >2, without current or a history of ulceration; and (3) diabetic ulcer group (DU), which included 30 patients who had diabetes and current ulceration, seven of those patients also gave a history of ulceration.

RESULTS

PP parameters were significantly different between the studied groups, namely, forefoot peak plantar pressure (FFPPP), rearfoot peak plantar pressure (RFPPP), forefoot/rearfoot ratio (F/R), forefoot peak pressure gradient (FFPPG) rearfoot peak pressure gradient (RFPPG), and forefoot peak pressure gradient/rearfoot peak pressure gradient (FFPPG/RFPPG) (P < 0.05). FFPPP and F/R were significantly higher in the DU group compared to the DN and DC groups (P < 0.05), with no significant difference between DN and DC. FFPPG was significantly higher in the DU and DN groups compared to the DC group (P < 0.05). RFPPP and FFPPG/RFPPG were significantly higher in the DU and DN groups compared to the DC group (P < 0.05) with no significant difference between the DN and DU groups (P > 0.05). FFPPP, F/R ratio, FFPPG, and FFPPG/RFPPG correlated significantly with the severity of neuropathy according to MNDS (P < 0.05). These same variables as well as MNDS were also significantly higher in patients with foot deformity compared to those without deformity (P < 0.05). Using the receiver operating characteristic analysis, the optimal cut-point of PPP for ulceration risk, as determined by a balance of sensitivity, specificity, and accuracy was 335 kPa and was found at the forefoot. Multivariate logistical regression analysis for ulceration risk was statistically significant for duration of diabetes (odds ratio [OR] = 0.8), smoking (OR = 9.7), foot deformity (OR = 8.7), MNDS (OR = 1.5), 2-h postprandial plasma glucose (2 h-PPG) (OR = 0.9), glycated hemoglobin (HbA1c) (OR = 2.1), FFPPP (OR = 1.0), and FFPPG (OR = 1.0).

CONCLUSION

In conclusion, persons with diabetes having neuropathy and/or ulcers have elevated PPP. Risk of ulceration was highly associated with duration of diabetes, smoking, severity of neuropathy, glycemic control, and high PP variables especially the FFPPP, F/R, and FFPPG. We suggest a cut-point of 355 kPa for FFPPP to denote high risk for ulceration that would be more valid when used in conjunction with other contributory risk factors, namely, duration of diabetes, smoking, glycemic load, foot deformity, and severity of neuropathy.

Plantar shear stress measurements - A review

BACKGROUND

Mechanical stress at the plantar surface has two components, pressure acting normal to the surface and shear stress acting tangential to the surface. Typically only pressure is measured and reported. However, plantar shear stress also plays a major role, especially in diabetic ulceration.

METHODS

During the last few decades, a variety of methods have been developed for the measurement of plantar shear stress. This paper reviews the technologies used in plantar shear stress measurements.

FINDINGS

Several technologies have been used, e.g. magneto-resistors, strain gauges, optical methods, piezoelectric materials and capacitive sensors. Examples of plantar shear stress values measured with the developed devices are also collected here and the relationship between sensor characteristics and the measured plantar shear stress distribution is discussed.

INTERPRETATION

Even with the limitations of current plantar shear stress measurement technologies, they can provide useful information on the plantar stress distribution.

Plantar pressures, plantar forces, and their influence on the pathogenesis of diabetic foot ulcers: a review

BACKGROUND

Clinical recommendations for the prevention and healing of diabetic foot ulcers (DFUs) are somewhat clear. However, assessment and quantification of the mechanical stress responsible for DFU remain complex. Different pressure variables have been described in the literature to better understand plantar tissue stress exposure. This article reviews the role of pressure and shear forces in the pathogenesis of plantar DFU.

METHODS

We performed systematic searches of the PubMed and Embase databases, completed by a manual search of the selected studies. From 535 potentially relevant references, 70 studies were included in the full-text review.

RESULTS

Variables of plantar mechanical stress relate to vertical pressure, shear stress, and temporality of loading. At this time, in-shoe peak plantar pressure (PPP) is the only reliable variable that can be used to prevent DFU. Although it is a poor predictor of in-shoe PPP, barefoot PPP seems complementary and may be more suitable when evaluating patients with diabetes mellitus and peripheral neuropathy who seem noncompliant with footwear. An in-shoe PPP threshold value of 200 kPa has been suggested to prevent DFU. Other variables, such as peak pressure gradient and peak maximal subsurface shear stress and its depth, seem to be of additional utility.

CONCLUSIONS

To better assess the at-risk foot and to prevent ulceration, the practitioner should integrate quantitative models of dynamic foot plantar pressures, such as in-shoe and barefoot PPPs, with the regular clinical screening examination. Prospective studies are needed to evaluate causality between other variables of mechanical stress and DFUs.

How effective is orthotic treatment in patients with recurrent diabetic foot ulcers?

BACKGROUND

We assessed the efficacy of customized foot orthotic therapy by comparing reulceration rates, minor amputation rates, and work and daily living activities before and after therapy. Peak plantar pressures and peak plantar impulses were compared with the patients not wearing and wearing their prescribed footwear.

METHODS

One hundred seventeen patients with diabetes were prescribed therapeutic insoles and footwear based on the results of a detailed biomechanical study and were followed for 2 years. All of the patients had a history of foot ulcers, but none had undergone previous orthotic therapy.

RESULTS

Before treatment, the reulceration rate was 79% and the amputation rate was 54%. Two years after the start of orthotic therapy, the reulceration rate was 15% and the amputation rate was 6%. Orthotic therapy reduced peak plantar pressures in patients with reulcerations and in those without (P < .05), although a significant decrease in peak plantar impulses was achieved only in patients not experiencing reulceration. Sick leave was reduced from 100% to 26%.

CONCLUSIONS

Personalized orthotic therapy targeted at reducing plantar pressures by off-loading protects high-risk patients against reulceration. Treatment reduced the reulceration rate and peak plantar pressures, leading to patients' return to work or other activities.

Offloading of the diabetic foot: orthotic and pedorthic strategies

The diabetic foot is more susceptible than the non-diabetic foot to collapse. This frequently leads to bony prominences followed by ulceration. Offloading of areas of increased pressure is paramount to ulcer prevention and healing. Several devices and accommodations can aid practitioners in saving patients' extremities and allow them to ambulate. A team approach works best, and patient education is a must. Regular assessment and modifications are required for longevity of each device. In this article, different therapeutic options are detailed. A variety of presentations and situations are discussed and the authors' best tips for avoiding complications are offered.

Intrinsic foot muscle deterioration is associated with metatarsophalangeal joint angle in people with diabetes and neuropathy

BACKGROUND

Metatarsophalangeal joint deformity is associated with skin breakdown and amputation. The aims of this study were to compare intrinsic foot muscle deterioration ratios (ratio of adipose to muscle volume), and physical performance in subjects with diabetic neuropathy to controls, and determine their associations with 1) metatarsophalangeal joint angle and 2) history of foot ulcer.

METHODS

23 diabetic, neuropathic subjects [59 (SD 10) years] and 12 age-matched controls [57 (SD 14) years] were studied. Radiographs and MRI were used to measure metatarsophalangeal joint angle and intrinsic foot muscle deterioration through tissue segmentation by image signal intensity. The Foot and Ankle Ability Measure evaluated physical performance.

FINDINGS

The diabetic, neuropathic group had a higher muscle deterioration ratio [1.6 (SD 1.2) vs. 0.3 (SD 0.2), P<0.001], and lower Foot and Ankle Ability Measure scores [65.1 (SD 24.4) vs. 98.3 (SD 3.3) %, P<0.01]. The correlation between muscle deterioration ratio and metatarsophalangeal joint angle was r=-0.51 (P=0.01) for all diabetic, neuropathic subjects, but increased to r=-0.81 (P<0.01) when only subjects with muscle deterioration ratios >1.0 were included. Muscle deterioration ratios in individuals with diabetic neuropathy were higher for those with a history of ulcers.

INTERPRETATION

Individuals with diabetic neuropathy had increased intrinsic foot muscle deterioration, which was associated with second metatarsophalangeal joint angle and history of ulceration. Additional research is required to understand how foot muscle deterioration interacts with other impairments leading to forefoot deformity and skin breakdown.

Effect of viscoelastic properties of plantar soft tissues on plantar pressures at the first metatarsal head in diabetics with peripheral neuropathy

Diabetic foot ulcers are one of the most serious complications associated with diabetes mellitus. Current research studies have demonstrated that biomechanical alterations of the diabetic foot contribute to the development of foot ulcers. However, the changes of soft tissue biomechanical properties associated with diabetes and its influences on the development of diabetic foot ulcers have not been investigated. The purpose of this study was to investigate the effect of diabetes on the biomechanical properties of plantar soft tissues and the relationship between biomechanical properties and plantar pressure distributions. We used the ultrasound indentation tests to measure force-deformation relationships of plantar soft tissues and calculate the effective Young's modulus and quasi-linear viscoelastic parameters to quantify biomechanical properties of plantar soft tissues. We also measured plantar pressures to calculate peak plantar pressure and plantar pressure gradient. Our results showed that diabetics had a significantly greater effective Young's modulus and initial modulus of quasi-linear viscoelasticity compared to non-diabetics. The plantar pressure gradient and biomechanical properties were significantly correlated. Our findings indicate that diabetes is linked to an increase in viscoelasticity of plantar soft tissues that may contribute to a higher peak plantar pressure and plantar pressure gradient in the diabetic foot.

The association between skin blood flow and edema on epidermal thickness in the diabetic foot

BACKGROUND

Skin blood flow plays an important role in maintaining the health of the skin. The development of interstitial edema may impede oxygen diffusion to the skin. The aim of this study was to evaluate the association of skin blood flow and edema and epidermal thickness in the feet of people with and without diabetic neuropathy compared with a healthy control group.

SUBJECTS AND METHODS

Eighty-seven subjects (19 people with diabetic neuropathy and foot ulceration, 35 people with diabetes but without neuropathy, and 33 healthy controls without diabetes) participated in the study. High-frequency ultrasonography was used to measure the epidermal thickness and edema in papillary skin at the big toe as reflected by the thickness of the subepidermal low echogenic band (SLEB). The capillary nutritive blood flow was measured by the use of video capillaroscopy, and skin blood flux was monitored by laser Doppler flowmetry.

RESULTS

There was a 7.2% increase in epidermal thickness in those with diabetes but without neuropathy and a 16.5% decrease in people with diabetic neuropathy and foot ulceration compared with the healthy controls (all P<0.05). The SLEB thickness increased in all subjects with diabetes to a greater degree in those with neuropathy and ulceration than in those without (64.7% vs. 11.8%, P<0.001). Skin blood flux was shown to be higher in the diabetes groups than in the controls (all P<0.05), but no significant differences were found in the resting nutritive capillary blood flow (P>0.05). A significant negative correlation (P=0.002, r=-0.366) was demonstrated between the SLEB and epidermal thickness at the pulp of the big toe, whereas no significant correlation was demonstrated between skin blood flow and epidermal thickness (all P>0.05).

CONCLUSIONS

An increase in subepidermal edema was demonstrated in people with diabetic neuropathy and ulceration, which may partly contribute to reduced epidermal thickness at the pulp of the big toe. This may subsequently lead to the breaking down of skin in the diabetic foot.

Priorities in offloading the diabetic foot

Biomechanical factors play an important role in diabetic foot disease. Reducing high foot pressures (i.e. offloading) is one of the main goals in healing and preventing foot ulceration. Evidence-based guidelines show the strong association between the efficacy to offload the foot and clinical outcome. However, several aspects related to offloading are underexposed. First, in the management of foot complications, offloading is mostly studied as a single entity, whereas it should be analysed in a broader perspective of contributing factors to better predict clinical outcome. This includes assessment of patient behavioural factors such as type and intensity of daily physical activity and adherence to prescribed treatment. Second, a large gap exists between evidence-based recommendations and clinical practice in the use of offloading for ulcer treatment, and this gap needs to be bridged. Possible ways to achieve this are discussed in this article. Third, our knowledge about the efficacy and role of offloading in treating complicated and non-plantar neuropathic foot ulcers needs to be expanded because these ulcers currently dominate presentation in multidisciplinary foot practice. Finally, foot ulcer prevention is underexposed when compared with ulcer treatment. Prevention requires a larger focus, in particular regarding the efficacy of therapeutic footwear and its relative role in comparison with other preventative strategies. These priorities need the attention of clinicians, scientists and professional societies to improve our understanding of offloading and to improve clinical outcome in the management of the diabetic foot.

Spatial relationships between shearing stresses and pressure on the plantar skin surface during gait

Based on the hypothesis that diabetic foot lesions have a mechanical etiology, extensive efforts have sought to establish a relationship between ulcer occurrence and plantar pressure distribution. However, these factors are still not fully understood. The purpose of this study was to simultaneously record shear and pressure distributions in the heel and forefoot and to answer whether: (i) peak pressure and peak shear for anterior-posterior (AP) and medio-lateral (ML) occur at different locations, and if (ii) peak pressure is always centrally located between sites of maximum AP and ML shear stresses. A custom built system was used to collect shear and pressure data simultaneously on 11 subjects using the 2-step method. The peak pressure was found to be 362 kPa ± 106 in the heel and 527 kPa ± 123 in the forefoot. In addition, the average peak shear values were higher in the forefoot than in the heel. The greatest shear on the plantar surface of the forefoot occurred in the anterior direction (mean and std. dev.: 37.7 ± 7.6 kPa), whereas for the heel, peak shear the foot was in the posterior direction (21.2 ± 5 kPa). The results of this study suggest that the interactions of the shear forces caused greater "spreading" in the forefoot and greater tissue "dragging" in the heel. The results also showed that peak shear stresses do not occur at the same site or time as peak pressure. This may be an important factor in locating where skin breakdown occurs in patients at high-risk for ulceration.

Randomised clinical trial comparing pressure characteristics of pelvic circumferential compression devices in healthy volunteers

INTRODUCTION

The role of pelvic circumferential compression devices (PCCDs) is to temporarily stabilise a pelvic fracture, reduce the volume and tamponade the bleeding. Tissue damage may occur when PCCDs are left in place longer than a few hours. The aim of this randomised clinical trial was to quantify the pressure at the region of the greater trochanters (GTs) and the sacrum, induced by PCCDs in healthy volunteers.

MATERIALS AND METHODS

In a crossover study, the Pelvic Binder(®), SAM-Sling(®) and T-POD(®) were applied successively onto 80 healthy participants in random order. The pressure was measured using a pressure mapping system, with the volunteers in supine position on a spine board and on a hospital bed. Data were analysed using Mixed Linear Modelling.

RESULTS

On a spine board, the pressure exceeded the tissue damaging threshold at the GTs and the sacrum. Pressure at the GTs was highest with the Pelvic Binder(®), and lowest with the SAM-Sling(®). Pressure at the sacrum was highest with the Pelvic Binder(®). The pressure at the GTs and sacrum was reduced significantly for all three PCCDs upon transfer to a hospital bed.

CONCLUSION

The results of this randomised clinical trial in healthy volunteers showed that patients with pelvic fractures, temporarily stabilised with a PCCD, are at risk for developing pressure sores. The pressure on the skin exceeded the tissue damaging threshold and is, besides PCCD type, influenced by BMI, waist size and age. Regardless with which PCCD trauma patients are stabilised, early transfer from the spine board is of key importance to reduce the pressure to a level below the tissue damaging threshold. Clinicians should be aware of the potential deleterious effects associated with the application of a PCCD, and every effort must be made to remove the PCCD once haemodynamic resuscitation has been established.

Epidermal thickness and biomechanical properties of plantar tissues in diabetic foot

Diabetic foot is a common complication for people with diabetes but it is unclear whether the change is initiated from the skin surface or underneath plantar tissues. This study compared the thickness of epidermis and the thickness and stiffness of the total plantar soft tissue among people with diabetes with or without complications. Seventy-two people with diabetes, including 22 people with neuropathies, 16 foot ulcerations, 34 pure diabetics without complications and 40 healthy controls participated in the study. The thickness of the epidermal layer of the plantar skin was examined using high-frequency ultrasonography; the thickness and stiffness of the total plantar soft tissue were measured by using tissue ultrasound palpation system at the big toe, the first, third and fifth metatarsal heads; and the heel pad. Compared with the control group, the average epidermal thickness of plantar skin was reduced by 15% in people with diabetic foot ulceration and 9% in people with neuropathy, but was increased by 6% in pure diabetics. There was an 8% increase in total thickness of plantar soft tissue in the 3 diabetic groups at all testing sites (all p < 0.05), except the first metatarsal head. The stiffness of plantar soft tissue was increased in all diabetic groups at all testing sites compared with the control (all p < 0.05). The epidermal plantar skin becomes thinner and plantar soft tissues stiffen in people with diabetes, particularly in persons who have neuropathy or ulceration, which increases the risk of tissue breakdown and ulceration formation.

Walking speed and peak plantar pressure distribution during barefoot walking in persons with diabetes

BACKGROUND

The impact of walking speed has not been evaluated as a feasible outcome measure associated with peak plantar pressure (PPP) distribution, which may result in tissue damage in persons with diabetic foot complications. The objective of this pilot study was to determine the walking speed and PPP distribution during barefoot walking in persons with diabetes. 

METHODS

 Nine individuals with diabetes and nine age-gender matched individuals without diabetes participated in this study. Each individual was marked at 10 anatomical landmarks for vibration and tactile pressure sensation tests to determine the severity of sensory deficits on the plantar surface of the dominant limb foot. A steady state walking speed, PPP, the fore and rear foot (F/R) PPP ratio and gait variables were measured during barefoot walking. 

RESULTS

 Persons with diabetes had a significantly slower walking speed than the age-gender matched group resulting in a significant reduction of PPP at the F/R foot during barefoot walking (p < 0.05). There was no significant difference in F/R foot PPP ratio in the diabetic group compared with the age-gender matched group during barefoot walking (p > 0.05). There was a significant difference between the diabetic and non-diabetic groups for cadence, step time, toe out angle and the anterior-posterior excursion (APE) for centre of force (p < 0.05). 

CONCLUSION

 Walking speed may be a potential indicator for persons with diabetes to identify PPP distribution during barefoot walking in a diabetic foot. However, the diabetic group demonstrated a more cautious walking pattern than the age-gender matched group by decreasing cadence, step length and APE, and increasing step time and toe in/out angle. People with diabetes may reduce the risk of foot ulcerations as long as they are able to prevent severe foot deformities such as callus, hammer toe or charcot foot.

Dressing plantar wounds with foam dressings, is it too much pressure?

Diabetes and its associated complications have become a major concern locally, nationally and internationally. One such complication is lower extremity amputation, commonly preceded by chronic ulceration. The cause of this tissue breakdown is multi-faceted, but includes an increase in pressure, particularly plantar pressure. As such, the choice of dressing to be applied to a plantar wound should ideally not increase this pressure further. A commonly used and possibly more bulky dressing is the foam dressing. This pilot study investigates the plantar pressures associated with three common foam dressings (Allevyn(®), Lyofoam(®) and Mepilex(®)) compared with a control dressing (Melolin(®)). Twelve healthy males and 19 females [SD] age 36.6 [10.4] were measured using the F-scan plantar pressure measurement system. Substantial variations in individual pressure changes occurred across the foot. No significant differences were identified, once a Bonferroni correction was applied. In healthy adults, it could be concluded that foam dressings do not have any effect on the plantar pressures of the foot. However, the need remains for a robust trial on a pathological population.

Shoes, orthoses, and prostheses for partial foot amputation and diabetic foot infection

Amputations in patients with diabetes, while often preventable, are unfortunately a far too common outcome. The roles of the certified or licensed pedorthist, certified orthotist, and the certified prosthetist should not be undervalued in the prevention of diabetic foot complications (eg, amputations, revisions, and foot infections secondary to skin ulcerations) and in returning the patient a normal, active, and productive lifestyle in the event of an amputation. This article highlights the roles these specialists play in treating patients with partial foot amputation.

Diabetic foot biomechanics and gait dysfunction

BACKGROUND

Diabetic foot complications represent significant morbidity and precede most of the lower extremity amputations performed. Peripheral neuropathy is a frequent complication of diabetes shown to affect gait. Glycosylation of soft tissues can also affect gait. The purpose of this review article is to highlight the changes in gait for persons with diabetes and highlight the effects of glycosylation on soft tissues at the foot-ground interface.

METHODS

PubMed, the Cochrane Library, and EBSCOhost on-line databases were searched for articles pertaining to diabetes and gait. Bibliographies from relevant manuscripts were also searched.

FINDINGS

Patients with diabetes frequently exhibit a conservative gait strategy where there is slower walking speed, wider base of gait, and prolonged double support time. Glycosylation affects are observed in the lower extremities. Initially, skin thickness decreases and skin hardness increases; tendons thicken; muscles atrophy and exhibit activation delays; bones become less dense; joints have limited mobility; and fat pads are less thick, demonstrate fibrotic atrophy, migrate distally, and may be stiffer.

INTERPRETATION

In conclusion, there do appear to be gait changes in patients with diabetes. These changes, coupled with local soft tissue changes from advanced glycosylated end products, also alter a patient's gait, putting them at risk of foot ulceration. Better elucidation of these changes throughout the entire spectrum of diabetes disease can help design better treatments and potentially reduce the unnecessarily high prevalence of foot ulcers and amputation.

Biomechanical properties of the forefoot plantar soft tissue as measured by an optical coherence tomography-based air-jet indentation system and tissue ultrasound palpation system

BACKGROUND

The forefoot medial plantar area withstand high plantar pressure during locomotion, and is a common site that develops foot lesion problems among elderly people. The aims of the present study were to (1) determine the correlation between the biomechanical properties of forefoot medial plantar soft tissue measured by a newly developed optical coherence tomography-based air-jet indentation system and by tissue ultrasound palpation system, and (2) to compare the biomechanical properties of plantar soft tissues of medial forefoot between a young and old adult group.

METHODS

Thirty healthy subjects were classified as the young or older group. The biomechanical properties of plantar soft tissues measured at the forefoot by the air-jet indentation system and tissue ultrasound palpation system were performed, and the correlation of the findings obtained in the two systems were compared.

FINDINGS

A strong positive correlation was obtained from the findings in the two systems (r=0.88, P<0.001). The forefoot plantar soft tissue of the older group was significantly stiffer at the second metatarsal head and thinner at both metatarsal heads than that of the young group (all P<0.05). The stiffness coefficient at the second metatarsal head was 28% greater than that at the first metatarsal head in both study groups.

INTERPRETATION

Older subjects showed a loss of elasticity and reduced thickness in their forefoot plantar soft tissue, with the second metatarsal head displaying stiffer and thicker plantar tissue than the first metatarsal head. The air-jet indentation system is a useful instrument for characterizing the biomechanical properties of soft tissue.

Role of ankle mobility in foot rollover during gait in individuals with diabetic neuropathy

BACKGROUND

The purpose of this study was to investigate the ankle range of motion during neuropathic gait and its influence on plantar pressure distribution in two phases during stance: at heel-strike and at push-off.

METHODS

Thirty-one adults participated in this study (control group, n=16; diabetic neuropathic group, n=15). Dynamic ankle range of motion (electrogoniometer) and plantar pressures (PEDAR-X system) were acquired synchronously during walking. Plantar pressures were evaluated at rearfoot, midfoot and forefoot during the two phases of stance. General linear model repeated measures analysis of variance was applied to investigate relationships between groups, areas and stance phases.

FINDINGS

Diabetic neuropathy patients walked using a smaller ankle range of motion in stance phase and smaller ankle flexion at heel-strike (P=0.0005). Peak pressure and pressure-time integral values were higher in the diabetic group in the midfoot at push-off phase when compared to heel-strike phase. On the other hand, the control group showed similar values of peak pressure in midfoot during both stance phases.

INTERPRETATION

The ankle mobility reduction observed could be associated to altered plantar pressure distribution observed in neuropathic subjects. Results demonstrated that midfoot and forefoot play a different role in subjects with neuropathy by receiving higher loads at push-off phase that are probably due to smaller ankle flexion at stance phase. This may explain the higher loads in anterior areas of the foot observed in diabetic neuropathy subjects and confirm an inadequate foot rollover associated to the smaller ankle range of motion at the heel-strike phase.

Utilization of the foot load monitor for evaluating deep plantar tissue stresses in patients with diabetes: proof-of-concept studies

The purposes of the present study were to (1) determine the internal plantar mechanical stresses in diabetic and healthy subjects during everyday activities, and (2) identify stress parameters potentially capable of distinguishing between diabetic and healthy subjects. A self-designed, portable, real-time and subject-specific foot load monitor which employs the Hertz contact theory was utilized to determine the internal dynamic plantar tissue stresses in 10 diabetic patients and 6 healthy subjects during free walking and outdoors stair climbing. Internal stress parameters and average stress-doses were evaluated, and the results obtained from the two groups were compared. Internal plantar stresses and averaged stress-doses during free walking and outdoors stairs climbing in the diabetic group were 2.5-5.5-fold higher than in the healthy group (p<0.001; stair climbing comparisons incorporated data from five diabetic patients). The interfacial pressures measured during free walking were slightly higher ( approximately 1.5-fold) in the diabetic group (p<0.05), but there was no significant difference between the two groups during stairs climbing. We conclude that during walking and stair climbing, internal plantar tissue stresses are considerably higher than foot-shoe interface pressures, and in diabetic patients, internal stresses substantially exceed the levels in healthy. The proposed method can be used for rating performances or design of footwear for protecting sub-dermal plantar tissues in patients who are at risk for developing foot ulcers. It may also be helpful in providing biofeedback to neuropathic diabetic patients.

Plantar stresses on the neuropathic foot during barefoot walking

BACKGROUND AND PURPOSE

Patients with diabetes mellitus and peripheral neuropathy are at high risk for plantar skin breakdown due to unnoticed plantar stresses during walking. The purpose of this study was to determine differences in stress variables (peak plantar pressure, peak pressure gradient, peak maximal subsurface shear stress, and depth of peak maximal subsurface shear stress) between the forefoot (where most ulcers occur) and the rear foot in subjects with and without diabetes mellitus, peripheral neuropathy, and a plantar ulcer measured during barefoot walking.

SUBJECTS

Twenty-four subjects participated: 12 with diabetes mellitus, peripheral neuropathy, and a plantar ulcer (DM+PN group) and 12 with no history of diabetes mellitus or peripheral neuropathy (control group). The subjects (11 men, 13 women) had a mean age (+/-SD) of 54+/-8 years.

METHODS

Plantar pressures were measured during barefoot walking using a pressure platform. Stress variables were estimated at the forefoot and the rear foot for all subjects.

RESULTS

All stress variables were higher (127%-871%) in the forefoot than in the rear foot, and the peak pressure gradient showed the greatest difference (538%-871%). All stress variables were higher in the forefoot in the DM+PN group compared with the control group (34%-85%), and the peak pressure gradient showed the greatest difference (85%). The depth (X+/-SD) of peak maximum subsurface shear stress in the forefoot in the DM+PN group was half that in the control group (3.8+/-2.0 versus 8.0+/-4.3 mm, respectively).

DISCUSSION AND CONCLUSION

: These results indicate that stresses are relatively higher and located closer to the skin surface in locations where skin breakdown is most likely to occur. These stress variables may have additional value in predicting skin injury over the traditionally measured peak plantar pressure, but prospective studies using these variables to predict ulcer risk are needed to test this hypothesis.

The effect of surface electric stimulation of the gluteal muscles on the interface pressure in seated people with spinal cord injury

OBJECTIVE

To study effects of surface electric stimulation of the gluteal muscles on the interface pressure in seated persons with spinal cord injury (SCI).

DESIGN

One session in which alternating and simultaneous surface electric stimulation protocols were applied in random order.

SETTING

Research laboratory of a rehabilitation center.

PARTICIPANTS

Thirteen subjects with SCI.

INTERVENTION

Surface electric stimulation of the gluteal muscles.

MAIN OUTCOME MEASURES

Interface pressure, maximum pressure, pressure spread, and pressure gradient for the stimulation measurement. Variables were compared using 2-tailed paired t tests.

RESULTS

Alternating and simultaneous stimulation protocol caused a significant (P<.01) decrease in interface pressure (-17+/-12 mmHg, -19+/-14 mmHg) and pressure gradient (-12+/-11 mmHg, -14+/-12 mmHg) during stimulation periods compared with rest periods. There was no significant difference in effects between the 2 protocols.

CONCLUSIONS

Surface electric stimulation of the gluteal muscles in persons with SCI causes a decrease in interface pressure. This might restore blood flow in compressed tissue and help prevent pressure ulcers.

Pressure gradient and subsurface shear stress on the neuropathic forefoot

BACKGROUND

Stresses within the neuropathic foot's tissues can be estimated by pressure distributions and may provide information regarding the potential for skin breakdown. The purposes of this study were to: (1) determine the magnitude of peak plantar pressure, pressure time integral, peak pressure gradient, and peak maximum shear stress; and (2) determine the association of these variables with one another.

METHODS

Forefoot peak plantar pressure, pressure time integral, peak pressure gradient, peak maximal shear stress, and depth of peak maximal shear stress were calculated for 16 controls, 16 people with diabetic neuropathy, and 22 people with diabetic neuropathy and a history of ulceration from pressure assessments.

FINDINGS

Peak plantar pressure, pressure gradient, and maximal shear stress were greater in subjects with a history of ulceration relative to control subjects (P<0.03), pressure gradient was greater in subjects with diabetic neuropathy and a history of ulceration compared to subjects with diabetic neuropathy and no history of ulceration (P<0.02), and depth of maximal shear stress was less in both groups of subjects with diabetic neuropathy compared to controls (P<0.03). Strong relationships existed between the variables.

INTERPRETATION

Although these variables are associated with one another, peak pressure gradient and peak maximal shear stress provide information concerning plantar pressure distribution and the potentially injurious internal stresses within the foot's soft tissues. Peak pressure gradient and peak maximal shear stress may perhaps be more discriminating than peak plantar pressure alone in distinguishing between groups of individuals who are at risk for developing a foot ulcer.