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

Exploring plantar pressure distribution in patients with newly diagnosed diabetes: Implications for foot ulcer prevention in an overweight Mexican population

INTRODUCTION

Elevated plantar pressure (PP) constitutes a risk factor for developing foot ulcers. Once present, elevated PP increases morbidity and mortality in patients with diabetes. Given the high prevalence of overweight and obesity in the Mexican population, this study aimed to describe the magnitudes and the distribution of the PP observed in a sample of newly diagnosed patients with diabetes, adjusting for body mass index (BMI) groups (normal weight, overweight, grade I obesity, and grade II and III obesity).

MATERIALS AND METHODS

A total of 250 volunteers attending a comprehensive care program for the management of type 2 diabetes received foot assessments that included vascular and neurological evaluation, the identification of musculoskeletal changes, and measurements of PP.

RESULTS

Diabetic neuropathy and peripheral arterial disease were present in 21.6% and 11.2% of all participants. Musculoskeletal alterations were present in 70.8% of participants. A positive and significant correlation (p<0.001) was observed between BMI and the peak PP of all anatomical regions assessed. After adjusting for BMI, significant differences (p<0.001) were seen between groups. The metatarsal region, particularly under the third metatarsal head, denoted the highest magnitudes across all BMI.

CONCLUSIONS

Periodic PP assessment is recommended to identify the distribution of high-pressure points along the plantar surface. However, as a preventive measure, it is suggested to encourage patients with diabetes and overweight or obesity to wear appropriate footwear and pressure-relief insoles to relieve high-pressure areas - often seen in these populations - to help prevent foot complications.

What's the Impact of Safety Footwear on Workers Concerning Foot-Related Problems? A Systematic Review

BACKGROUND

This study aims to assess the impact of safety footwear (SF) on workers concerning foot-related problems, especially regarding discomfort, foot pain, and skin lesions.

METHODS

A literature search of PubMed, Embase, Scopus, and Cochrane databases was performed according to PRISMA guidelines. Studies reporting foot-related problems in workers wearing SF were included. Exclusion criteria included non-English papers, reviews, laboratory and animal studies, expert opinions, letters to the editor, and grey literature. The quality assessment was performed using the Newcastle-Ottawa Scale. Descriptive statistic was used to present data.

RESULT

The initial search results yielded 483 articles; 7 articles were included in the review process. Despite the extensive variety of SF, all studies consistently reported symptomatic discomfort and pain. The discomfort factors included heat, sweating, heaviness, and footwear flexibility, with primary issues in the toes, toecaps, or metatarsal-toe crease region. The pain prevalence ranged from 42.3% to 60.8% in various anatomical regions. Irritant Contact Dermatitis was the most common (97.9%) foot dermatosis, but other foot lesions were reported: dry skin (30.2%), calluses (30%), hard nails (28%), corns (27%), and blisters.

CONCLUSIONS

Current SFs are designed to comply with safety regulations but are influenced by the frequent occurrence of discomfort and foot problems. The literature review identified weaknesses in certain design features. Recommendations have been proposed to improve SF development. These include addressing issues such as the selection of specific types and designs of SF based on task performance and the working environment, footwear weight, and breathable materials for moisture permeation. Considerations should also encompass distinct sizing for an optimal fit, insole application, especially for prolonged standing users, and education programs to prevent foot-related issues.

Safety Footwear Impact on Workers' Gait and Foot Problems: A Comparative Study

BACKGROUND

In this study, we hypothesized that safety footwear (SF) impacts gait patterns, potentially contributing to the podiatric symptoms reported by workers. The purpose of this work was to compare the gait analyses of workers wearing SF and sneakers using inertial sensors while also examining the occurrence of foot problems.

METHODS

A consecutive cohort of workers from different occupational sectors who wore SF during their work shifts were prospectively assessed through a gait analysis. The gait analysis was conducted under two conditions: first, while wearing SF, and second, while wearing sneakers. In both conditions, inertial sensors were used (Wiva® MOB). Participants also underwent a podiatric physical examination to evaluate foot problems.

RESULTS

This study shows that SF resulted in a worsening gait pattern compared to sneakers in both genders. The impact was particularly pronounced in female participants, resulting in a significant decline in walking speed and cadence. Discomfort was reported by 83.3% of participants, with a higher prevalence in females (46.6% vs. 36.6%). The SF group exhibited an elevated prevalence of foot problems, with no significant gender variations. It seems that foot problems are more likely to occur when a foot deformity, such as flat or cavus foot or hallux valgus, is present.

CONCLUSIONS

This study suggests that SF may contribute to the reported podiatric symptoms among workers. Certain footwear characteristics, including weight, mis-fit, and inadequate design, may be factors associated with footwear discomfort and adverse gait patterns, potentially leading to increased foot problems among workers.

Evaluating the use of a novel low-cost measurement insole to characterise plantar foot strain during gait loading regimes

Introduction: Under plantar loading regimes, it is accepted that both pressure and shear strain biomechanically contribute to formation and deterioration of diabetic foot ulceration (DFU). Plantar foot strain characteristics in the at-risk diabetic foot are little researched due to lack of measurement devices. Plantar pressure comparatively, is widely quantified and used in the characterisation of diabetic foot ulceration risk, with a range of clinically implemented pressure measurement devices on the market. With the development of novel strain quantification methods in its infancy, feasibility testing and validation of these measurement devices for use is required. Initial studies centre on normal walking speed, reflecting common activities of daily living, but evaluating response to differing gait loading regimes is needed to support the use of such technologies for potential clinical translation. This study evaluates the effects of speed and inclination on stance time, strain location and strain response using a low-cost novel strain measurement insole. Methods: The STrain Analysis and Mapping of the Plantar Aspect (STAMPS) insole has been developed, and feasibility tested under self-selected normal walking speeds to characterise plantar foot strain, with testing beyond this limited regime required. A treadmill was implemented to standardise speed and inclination for a range of daily plantar loading conditions. A small cohort, comprising of five non-diabetic participants, were examined at slow (0.75 m/s), normal (1.25 m/s) and brisk (2 m/s) walking speeds and normal speed at inclination (10% gradient). Results: Plantar strain active regions were seen to increase with increasing speed across all participants. With inclination, it was seen that strain active regions reduce in the hindfoot and show a tendency to forefoot with discretionary changes to strain seen. Stance time decreases with increasing speed, as expected, with reduced stance time with inclination. Discussion: Comparison of the strain response and stance time should be considered when evaluating foot biomechanics in diabetic populations to assess strain time interval effects. This study supports the evaluation of the STAMPS insole to successfully track strain changes under differing plantar loading conditions and warrants further investigation of healthy and diabetic cohorts to assess the implications for use as a risk assessment tool for DFU.

Assessing Socket Fit Effects on Pressure and Shear at a Transtibial Residuum/Socket Interface

Fluctuations in residuum volume during daily activities are known to occur in lower-limb amputees. This can cause frequent changes to fit, which cannot be accommodated by commonly-used prosthetic sockets. The real-time effects, if any, of these minor socket fit changes on interface biomechanics have not been studied extensively. Amputees commonly use different layers of socks to accommodate frequent volume fluctuations, enabling adjustment of socket fit. We, thus, altered socket fit levels via addition/removal of sock layers to a transtibial amputee who habitually-donned two-sock layers to mimic relatively looser and tighter socket fits. Interface pressure and shear sensors were placed at known prominent load-bearing sites of the transtibial residuum/socket interface, i.e., patellar tendon (PT), popliteal fossa (PF), and anterior-distal (AD) end, to measure real-time biomechanical interactions during standing and level walking. Although socket fit level was only slightly modified, changes in interface pressure and shear across anatomical sites were still observed. Tighter fit corresponds to notable pressure reduction at AD during early stance and pressure increase at PT during terminal stance due to the residuum being pushed up. Shear-to-pressure ratios were used to assess comfort, while pressure- and shear-time integrals were used to assess tissue health. We observed more notable changes at tissue sites (e.g., AD and PF). Combined evaluation of pressure and shear, including shear-to-pressure ratio and time integrals, may offer insight for residuum care.

A fluoroscopic imaging-guided computational analyses to inform internal tissue loads within fat pad of the diabetic foot during gait

To accurately predict internal tissue loads for early diagnostics of diabetic foot ulcerations, a novel data-driven computational analysis was conducted. A dedicated dual fluoroscopic system was combined with a pressure mat to simultaneously characterize foot motions and soft tissue's material properties during gait. Finite element (FE) models of the heel pad of a diabetic patient were constructed with 3D trajectories of the calcaneus applied as boundary conditions to simulate gait events. The tensile and compressive stresses occurring in the plantar tissue were computed. Predictions of the layered tissue FE model with anatomically-accurate heel pad structures (i.e., fat and skin) were compared with those of the traditional lumped tissue (i.e., homogeneous) models. The influence of different material properties (patient-specific versus generic) on internal tissue stresses was also investigated. The results showed the peak tensile stresses in the layered tissue model were predominantly found in the skin and distributed towards the circumferential regions of the heel, while peak compressive stresses in the fat tissue-bone interface were up to 51.4% lower than those seen in the lumped models. Performing FE analyses at four different phases of walking revealed that ignorance of layered tissue structures resulted in an unphysiological increase of peak-to-peak value of stress fluctuation in the fat and skin tissue components. Thus, to produce more clinical-relevant predictions, foot FE models are suggested to include layered tissue structures of the plantar tissue for an improved estimation of internal stresses in the diabetic foot in gait.

The pressure time integral: An underused, clinically significant parameter as a determinant of neuropathic ulceration in diabetes

BACKGROUND

The purpose of this study was to evaluate plantar pressure dynamics in the occurrence of active diabetic neuropathic ulceration (DNU) and any changes in loadings occurring in individuals with a history of diabetic neuropathic ulceration (DHNU). Since current gold standard offloading strategies are not producing desirable healing outcomes and optimum ulcer prevention, this study aimed to better understand the effect of diabetic peripheral neuropathy (DPN) and ulceration on mean peak plantar pressure (MPPP) and pressure-time integral (PTI) changes.

RESEARCH QUESTION

Is there a redistribution of plantar pressure during gait in the presence of active and history of diabetic neuropathic ulceration?

METHODS

A prospective, cross-sectional study was conducted, in which, eighty adult participants were divided into four groups, namely, the DM, DPN, DNU and DHNU groups. Participants were instructed to walk barefoot over a Tekscan HR Mat™ at self-selected speed. MPPP and PTI data were analysed under five forefoot anatomical landmarks and compared between individuals with and without active neuropathic ulceration.

RESULTS

Minimal MPPP significant changes were observed between ulcerated and non-ulcerated groups, however, PTI values were significantly increased in the ulcerated groups under all plantar ulceration regions. No significant plantar pressure differences were observed between the DNU and DHNU groups. Logistic regression tests demonstrated that as PTIs under the hallux increase, the likelihood of an individual living with DPN developing ulceration increases.

SIGNIFICANCE

A significant increase in PTI values in the presence of ulceration highlights the importance of evaluating the duration of loads under forefoot regions during gait rather than just focusing on the magnitude of pressures during ulcer management and prevention. Moreover, results show that PTI values remain high in the presence of a history of neuropathic ulceration, possibly demonstrating the value of PTI as a clinical tool over MPPP in the assessment of the high-risk diabetic foot.

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.

A plantar surface shear strain methodology utilising Digital Image Correlation

The increase in the global diabetic population is leading to an increase in associated complications such as diabetic foot ulceration (DFU), associated amputations, morbidity, which substantial treatment costs. Early identification of DFU risk is therefore of great benefit. International guidelines recommend off-loading is the most important intervention for healing and prevention of DFU, with current research focused on pressure measurement techniques. The contribution of strain to DFU formation is not well understood due to challenges in measurement. The limited data available in the literature suggest that plantar strain is involved in ulcer formation. As a consequence, there is a need for plantar strain measurement systems to advance understanding and inform clinical treatment. A method was developed to determine plantar strain based on a Digital Image Correlation (DIC) approach. A speckle pattern is applied to the plantar aspect of the foot using a low ink transference method. A raised walkway with transparent panels is combined with a calibrated camera to capture images of the plantar aspect throughout a single stance phase. Plantar strain is then determined using 2D DIC and custom analysis summarises these data into clinically relevant metrics. A feasibility study involving six healthy participants was used to assess the efficacy of this new technique. The feasibility study successfully captured plantar surface strain characteristics continuously throughout the stance phase for all participants. Peak mean and averaged mean strains varied in location between participants when mapped into anatomical regions of plantar interest, ranging from the calcaneus to the metatarsal heads and hallux. This method provides the ability to measure plantar skin strain for use in both research and clinical environments. It has the potential to inform improved understanding of the role of strain in DFU formation. Further studies using this technique can support these ambitions and help differentiate between healthy and abnormal plantar strain regimes.

Effects of contoured insoles with different materials on plantar pressure offloading in diabetic elderly during gait

To investigate the effect of contoured insoles constructed of different insole materials, including Nora Lunalastik EVA, Nora Lunalight A fresh, Pe-Lite, and PORON Medical 4708 with Langer Biomechanics longitudinal PPT arch pads on offloading plantar pressure on the foot of the elderly with Type 1 or 2 diabetes during gait. Twenty-two elderly with Type 1 or 2 diabetes participated in the study. Their plantar pressure was measured by using an insole measurement system, while the participants walked 10 m in their bare feet or used each experimental insole in random order. The plantar surface was divided into four specific regions including the toes, forefoot, midfoot, and rearfoot. The mean peak pressure (MPP) and pressure-time integral (PTI) of ten steps with or without wearing one of the four insoles were analyzed on the dominant foot and the four specific plantar regions. After completion of the activities, the participants scored each insole from 1 (the least comfortable) to 10 (the most comfortable). The analysis of variance (ANOVA) factor of the insoles had significant effects on the MPP (P < 0.001) and PTI (P = 0.004) in the dominant foot during gait. Pairwise comparison results showed that the MPP and PTI in the dominant foot were significantly lower (P < 0.001) with PORON Medical 4708 than barefoot, Nora Lunalight A fresh, and Pe-Lite. Additionally, the insole materials had a significant effect for the forefoot (P < 0.001) and rearfoot (P < 0.001) in terms of the MPP and PTI compared with the barefoot condition during gait. Regardless of the plantar region, the MPP and PTI values were the lowest when PORON Medical 4708 was used as the insole material among four insole materials. Meanwhile, a significantly lower MPP and PTI can be found in the forefoot and rearfoot with the use of the four experimental insoles when compared with barefoot. The soft insole materials (i.e., PORON medical 4708 and Nora Lunalastik EVA) had a better performance than the rigid insole materials (i.e., Nora Lunalight A fresh, and Pe-Lite) on plantar pressure offloading for diabetic elderly.

Assessment of in-shoe pressure: Development of a clinical user guide based on a DELPHI-derived consensus

BACKGROUND

The F-Scan (F-Scan System by Tekscan, Boston, USA) is an in-shoe pressure measurement device used to provide dynamic pressure, force and timing information to guide appropriate offloading of plantar foot ulcers. Despite the clinical utility of an in-shoe pressure measuring device there are some limitations in the validity and reliability of the output of the F-Scan. The aim of this study was to develop a consensus-based guideline following information provided by experienced clinicians, synthesis of research evidence and manufacturer's guidelines on the most appropriate use and interpretation of the data generated by the F-Scan to manage plantar foot ulceration.

METHODS

Using the Delphi method a series of sixteen consensus statements were developed following a two-step questionnaire utilising clinicians feedback, a review of evidence and the manufacturer's guidelines.

FINDINGS

Seventeen clinicians responded to the first questionnaire and 11 to the second, that included 8 podiatrists and 9 pedorthists working in the public and private sectors. Of the sixteen statements there was strong consensus for ten and moderate consensus for a further four. Only two statements failed to reach consensus and the feedback from the respondents was of great value providing sound clinical rationale for their rejection.

INTERPRETATION

The objective of this study has been achieved in developing a clear and concise set of guiding statements (Table 1) to standardise use of the F-Scan. The application of the guiding statements will encourage standardisation of practice with the aim of highlighting the limitations of the system and reducing potential systematic error in measurement from output produced.

Plantar pressure during gait: norm-referenced measurement for Brazilian healthy adults using the Footwork Pro® System

Abstract Introduction The measurement of plantar pressure is an important component in the evaluation of the locomotive system. However, the absence of norm-referenced measurement poses limitations to its use. Objective To verify the influence of gender on plantar pressure during gait in healthy adults and to propose norm-referenced measurement that may be used as a reference for monitoring. Methods The study included 353 healthy participants (158 females and 195 males), aged between 20 and 64 years, and with a normal foot posture. Using a pressure platform, the peak plantar pressure and pressure-time integrals were measured in three areas of the foot: forefoot, midfoot, and hindfoot. Results Both indicators of plantar pressure showed no significant differences between genders (p ≤ 0.05). Higher peak plantar pressure was found in the forefoot region, while a higher pressure-time integral was found in the hindfoot region. Percentile distribution values were made available for the data set of females and males. Conclusion The available norm-referenced measurement may be used to identify pathological gait parameters, monitor the efficacy of therapeutic interventions, and detect individuals in need of referral for a more sophisticated and detailed evaluation.

Predictive values of foot plantar pressure assessment in patients with midfoot deformity secondary to Charcot neuroarthropathy

AIMS

The principal aim of this study was to identify a cut-off point along the spectrum of peak plantar midfoot pressure that has an optimum combination of sensitivity and specificity to screen for neuropathic ulceration in patients with Charcot neuroarthropathy (CN).

METHODS

A 1-year outcome study was performed in twenty-five patients with diabetes, affected with chronic CN midfoot deformity. Peak plantar pressure (PPP) and pressure/time Integral (PTI) in the midfoot region were registered. For selecting the optimal diagnostic cut-off points on the scale of pressure measurement, ROC curves were used.

RESULTS

Twelve (48%) patients developed a plantar midfoot ulcer. Baseline PPP (24.04 ± 6.33 Vs. 12.85 ± 3.29 N/cm²) and PTI (11.89 ± 4.60 Vs. 5.42 ± 2.26 N/cm²/s) were significantly higher in the ulcerated group (p < .001 and p < .001, respectively). Using ROC analyses, optimal cut-off point for PPP was 16.45 N/cm², yielding a sensitivity of 92% and a specificity of 85%; and for PTI, optimal cut-off point was 7.2 N/cm²/s, yielding a sensitivity of 92% and a specificity of 77%.

CONCLUSIONS

Patients with CN midfoot deformity with cut-off values for PPP of 16.45 N/cm² and PTI of 7.2 N/cm²/s showed an elevated risk of neuropathic ulceration in the plantar area of the midfoot.

Effects of Exercise on Plantar Pressure during Walking in Children with Overweight/Obesity

PURPOSE

To investigate the effect of a 13-wk exercise program, based on "movement quality" and "multigames" work, on plantar pressure during walking in children with overweight/obesity (OW/OB).

METHOD

Seventy children (10.8 ± 1.2 yr, 58.5% girls) with OW/OB, as defined by the World Obesity Federation, were assigned to either a 13-wk exercise program (intervention group [EG]; n = 39), or to a usual lifestyle control group (CG) (n = 31). Children underwent assessments of basic anthropometry (weight and height) and plantar pressure during walking before and after the intervention period, recording plantar surface area (cm), maximum force (N), and force-time integrals (N·s).

RESULTS

After the 13-wk intervention period, the EG participants showed no significant change in total plantar surface area, while the CG participants experienced an increase in this variable (small effect size, -2.5 SD; P = 0.015). Compared with the GC participants, the EG participants showed a greater increase in the maximum force supported beneath the forefoot during walking at the end of the intervention period (small effect size, 0.33 SD; P = 0.012), specifically under the lateral and medial forefoot (both P < 0.05). Force-time changed similarly in both groups by the end of the intervention period (all regions P > 0.05).

CONCLUSIONS

These results suggest the exercise program led to positive structural and functional changes in plantar pressure during walking. The increase in maximum force supported by the forefoot in the EG children might indicate a change toward a more normal foot rollover pattern and a more adult gait.

Arm-pull thrust in human swimming and the effect of post-activation potentiation

The aim of this study was to analyse the front-crawl arm-pull kinetics and kinematics, comparing it before and after post-activation potentiation (PAP), and the associations between variables describing of the arm-pull kinetics. Twelve male competitive swimmers were randomly assigned to perform two different warm-ups in a crossover manner: (i) non-PAP (control condition); and (ii) PAP (experimental condition). PAP consisted of 2 × 5 arm-pulls with resistance bands by both upper-limbs. Eight minutes later, participants underwent a 25 m all-out trial in front-crawl arm-pull. Kinetics (i.e., peak thrust, mean thrust and thrust-time integral) and kinematics (i.e., speed and speed fluctuation) were collected by an in-house customised system composed of differential pressure sensors, speedo-meter and underwater camera. There was a significant and large improvement of the arm-pull kinetics after completing the warm-up with PAP sets (0.010 < P < 0.054, 0.50 < d < 0.74). There were non-significant and small effects of PAP on speed (P = 0.307, d = 0.18) and speed fluctuation (P = 0.498, d = 0.04). Correlation coefficients among kinetic variables were significant with large associations (0.51 < R < 0.90, 0.001 < P < 0.088). In conclusion, warm-ups including PAP conditioning sets elicit a large improvement in the thrust, but with small improvement in performance. Variables used to characterise thrust are strongly correlated and hence can be used interchangeably.

The role of foot pressure measurement in the prediction and prevention of diabetic foot ulceration-A comprehensive review

The predominant risk factor of diabetic foot ulcers (DFU), peripheral neuropathy, results in loss of protective sensation and is associated with abnormally high plantar pressures. DFU prevention strategies strive to reduce these high plantar pressures. Nevertheless, several constraints should be acknowledged regarding the research supporting the link between plantar pressure and DFUs, which may explain the low prediction ability reported in prospective studies. The majority of studies assess vertical, rather than shear, barefoot plantar pressure in laboratory-based environments, rather than during daily activity. Few studies investigated previous DFU location-specific pressure. Previous studies focus predominantly on walking, although studies monitoring activity suggest that more time is spent on other weight-bearing activities, where a lower "peak" plantar pressure might be applied over a longer duration. Although further research is needed, this may indicate that an expression of cumulative pressure applied over time could be a more relevant parameter than peak pressure. Studies indicated that providing pressure feedback might reduce plantar pressures, with an emerging potential use of smart technology, however, further research is required. Further pressure analyses, across all weight-bearing activities, referring to location-specific pressures are required to improve our understanding of pressures resulting in DFUs and improve effectiveness of interventions.

Gait analysis - Available platforms for outcome assessment

Movement or gait analysis has become a viable assessment tool not only used in sports science or basic biomechanical research, but has also expanded to be a very valuable instrument in clinical diagnostics, monitoring functional recovery and musculoskeletal rehabilitation. In this context, this method has long been an integral part solely in neurological disorders such as cerebral palsy. However, in the meantime the benefits have also become apparent in other medical areas, such as foot surgery, orthopaedic technology, or in patients after lower limb amputation. These procedures proved to better understand, objectify and quantify the individual causes of gait and movement disorders in order to optimize patient-specific therapy. Currently we are able to rely on a multitude of available measurement systems. These can either be used in everyday life for simple monitoring of one's own activity or to complement therapeutic approaches in the clinical and scientific environment. The following review highlights the various fields of movement analysis, including markerless motion capture, marker-based analysis, pedobarography and wearable sensors. Each of these areas presents its own field of application and potential usage as well as the advantages and disadvantages arising in this context. The following article will give an overview of the type of measurement technology used, the respective fields of application, and the selected parameters and their interpretation possibilities for each of the areas mentioned.

Effect of shaft stiffness and sole flexibility on perceived comfort and the plantar pressures generated when walking on a simulated underground coal mining surface

The structural features of work boots worn by underground coal miners affect comfort, foot motion and, in turn, loading of the plantar surface of miners' feet. Although shaft stiffness and sole flexibility appear to be boot design features that could influence perceived comfort and plantar pressures, no study has systematically altered these boot design features to truly understand how they affect these parameters. This study aimed to systematically investigate the effect of changes to shaft stiffness and sole flexibility on perceived comfort and plantar pressures when 20 males walked on a simulated gravel coal mining surface under four different work boot conditions. There were no significant effects of shaft stiffness or sole flexibility on perceived comfort. However, shaft stiffness and sole flexibility each significantly affected the plantar pressures generated under the medial midfoot, heel, middle metatarsals and hallux and, in combination, affected plantar pressures generated beneath the lateral midfoot, medial and lateral metatarsals and lesser toes. Participants preferred a boot with a flexible shaft combined with a stiff sole, citing properties such as fit, moveability, walking effort and support to explain why they perceived one boot as more comfortable than another. We therefore recommend that underground coal mining work boots should be designed to incorporate different flexibility and stiffness between the shaft and sole of the boot to optimise foot movement and, in turn, walking efficiency.

Index of Plantar Pressure Alters with Prolonged Diabetes Duration

INTRODUCTION

Diabetic foot ulcers develop with deviations in the distribution of plantar pressure. It is difficult to interpret any alteration in plantar pressure under different conditions of type 2 diabetes mellitus (T2DM). The aim of this study was to gain a better insight into the variations in plantar pressure with increased duration of diabetes.

METHODS

Plantar pressure was examined in 1196 participants with or without T2DM. Subjects with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) were assigned to control groups, and those with T2DM were divided into five groups according to diabetes duration (< 2 years, 2-5 years, 5-10 years, 10-15 years, and > 15 years). The clinical characteristics, plantar peak pressure, and pressure-time integral (PTI) were compared among the seven study groups, and factors associated with peak pressure and the PTI were analyzed.

RESULTS

At the hallux, peak pressure exhibited an upward trend in patients with T2DM within 5 years of diabetes duration, followed by a distinct downward slope with further progression of the disease (trend analysis, p  < 0.05). An uneven distribution of peak pressure was found at other locations, but this unevenness was ultimately lower than that in the two control groups (p  < 0.05). No obvious trend was noted for PTI among patients with different diabetes duration; however, those with diabetes for > 10 years manifested a significantly sharper increase in the PTI at the metatarsus (11.63 Ns/cm², p  < 0.05) and heel (14.12 Ns/cm², p  < 0.05) than at the hallux (8.76 Ns/cm²). A fluctuation in the PTI was also detected at the hallux and midfoot of diabetes patients, which was broadly flat when compared with that of the two control groups. The stepwise multiple regression analysis revealed that the variation in plantar pressure was independently associated with age, body mass index, and vibration perception threshold (VPT) (p  < 0.05).

CONCLUSIONS

There would appear to be an association between longer diabetes duration and decreased peak pressure for the hallux, suggesting that individuals with diabetes for > 10 years will have an increased PTI for the metatarsus and heel. The reduced pressure on the hallux is believed to be transferred to the metatarsus. Age, BMI, and VPT are distinct risk factors of abnormal plantar pressure.

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.

Pressure distribution under the contralateral limb in Charcot arthropathy with different walking speeds

BACKGROUND

The total contact cast has been recognized as the "gold standard" for treatment of Charcot neuro-osteoarthropathy (CN). However, removable cast walkers (RCWs) became an alternative option especially after resolution of the acute stage. RCWs with an elevated sole construction often induce leg length discrepancy (LLD) that could significantly affects plantar pressure (PP) distribution in diabetic patients with neuropathy.

AIM

To study the additional effect of walking speed on PP abnormalities induced by LLD.

METHOD

The study included 16 patients with diabetes (59±8.8years; 8 men and 8 women), with unilateral CN offloaded by RCW. In-shoe PP distribution was measured using F-scan (Tekscan Inc.), whilst patients walked at their normal speed (53±4 steps/min), versus short slow steps (24±3/min) under the two walking conditions: (1) neglected LLD, and (2) corrected LLD.

RESULTS

The greatest reduction in PP was seen during reduction of walking speed, with corrected LLD, followed by corrected LLD with normal walking speed, followed by neglected LLD with slowing of walking speed. The highest PP was found when the patient remain on their normal walking speed and LLD was neglected.

CONCLUSION

The contralateral foot of CN offloaded with RCW, is subjected to high pressure loads beneath the hallux, 1st, 2nd, 3rd, and 5th metatarsal heads. As such, care should be taken not only to avoid minor LLD, but to also advise the patient to practice short slow steps while walking, so that pressure overload on contralateral limb and its possible contribution to the development of bilateral Charcot, could be minimized.

Reliability of peak foot pressure in patients with previous diabetic foot ulceration

BACKGROUND

Previous reliability studies on peak plantar pressure measurements in patients with previous diabetic foot ulceration (DFU) did not stratify their analyses according to whether the foot had a previous ulcer.

RESEARCH QUESTION

Does test-retest reliability of peak foot pressure measurements from the various foot regions differ between the ulcerated and non-ulcerated feet?

METHODS

Data from 23 participants with peripheral neuropathy and healed plantar DFU were analysed in this test-retest reliability comparison study. Plantar pressure was evaluated on two sessions using Pedar^®-X in-shoe system, with a mean of 7.2 days (SD = 1.6) between sessions.

RESULTS

The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for 10 foot regions. Overall, test-retest reliability was excellent (ICCs, 0.82 to 0.95) for all peak pressure variables. CV ranged between 6.3% and 18.3%, and exceeded 15% over the hallux and medial forefoot regions in the ulcer foot (18.3% and 16.4%, respectively). Hallux peak pressure CV was significantly higher over the ulcer foot than over the non-ulcer foot (5.7%, 95% CI, 1.7%-10.2%). Peak pressure CV over the forefoot also tended to be higher over the ulcer foot (medial forefoot: 6.1%, 95% CI, -0.5%-14.5%; lateral forefoot: 4.1%, 95%CI, -0.7%-11.1%).

SIGNIFICANCE

Peak plantar foot pressure may be useful to distinguish between groups of patients with peripheral neuropathy and healed plantar DFU. However, clinical decisions based on ulcer foot hallux and forefoot peak pressure measurements should be interpreted with caution.

Distribution of the Highest Plantar Pressure Regions in Patients with Diabetes and Its Association with Peripheral Neuropathy, Gender, Age, and BMI: One Centre Study

The abnormal plantar pressure distribution and value play a key role in the formation of plantar calluses and diabetic foot ulcer. The prevalence of the highest pressure different distribution and its association with various factors among patients with diabetes is not well known. The study purpose was to evaluate the prevalence of different regions for the highest pressure on the sole and its association with selected factors among patients with diabetes. Medical records of nonulcer patients were retrospectively analysed. The relationship between pressure patterns on the sole obtained during a pedobarographic test as a semiquantitative assessment with colourful print analysis and neuropathy, gender, age, and BMI was searched. The most common location of the highest pressure was the central part of the forefoot. No association was found between the different highest pressure regions and age, sensory neuropathy, calluses, and foot deformities. The highest pressure on the lateral part of the foot and midfoot was observed more often in females and in patients with a BMI ≥ 35. The prevalence of the highest pressure on the forefoot was more common in patients with a BMI < 35. Conclusions. The most frequent regions of the highest pressure on the sole in patients with diabetes were the central part of the forefoot (2-3 metatarsal heads) with no simple relationship to the assessed variables other than BMI < 35. Female gender and higher BMI seem to be responsible for shifting the place of the highest pressure to other places of the foot.

Foot Kinetic and Kinematic Profile in Type 2 Diabetes Mellitus with Peripheral Neuropathy A Hospital-Based Study from South India

BACKGROUND

A kinetic change in the foot such as altered plantar pressure is the most common etiological risk factor for foot ulcers in people with diabetes mellitus. Kinematic alterations in joint angle and spatiotemporal parameters of gait have also been frequently observed in participants with diabetic peripheral neuropathy (DPN). Diabetic peripheral neuropathy leads to various microvascular and macrovascular complications of the foot in type 2 diabetes mellitus. There is a gap in the literature for biomechanical evaluation and assessment of type 2 diabetes mellitus with DPN in the Indian population. We sought to assess and determine the biomechanical changes, including kinetics and kinematics, of the foot in DPN.

METHODS

This cross-sectional study was conducted at a diabetic foot clinic in India. Using the purposive sampling method, 120 participants with type 2 diabetes mellitus and DPN were recruited. Participants with active ulceration or amputation were excluded.

RESULTS

The mean ± SD age, height, weight, body mass index, and diabetes duration were 57 ± 14 years, 164 ± 11 cm, 61 ± 18 kg, 24 ± 3 kg/m², and 12 ± 7 years, respectively. There were significant changes in the overall biomechanical profile and clinical manifestations of DPN. The regression analysis showed statistical significance for dynamic maximum plantar pressure at the forefoot with age, weight, height, diabetes duration, body mass index, knee and ankle joint angle at toe-off, pinprick sensation, and ankle reflex ( R = 0.71, R² = 0.55, F_12,108 = 521.9 kPa; P = .002).

CONCLUSIONS

People with type 2 diabetes mellitus and DPN have significant changes in their foot kinetic and kinematic parameters. Therefore, they could be at higher risk for foot ulceration, with underlying neuropathy and biomechanically associated problems.

Foot function and strength of patients with diabetes grouped by ulcer risk classification (IWGDF)

BACKGROUND

The stratification system from the International Working Group on the Diabetic Foot (IWGDF) was used to classify the participants as to the ulcer risk. However, it is not yet known what the classification groups' individual deficits are regarding sensitivity, function, and musculoskeletal properties and mechanics. This makes it difficult to design proper ulcer prevention strategies for patients. Thus, this study aimed to investigate the foot function, foot strength and health of people with diabetes mellitus (DM)-with or without DPN-while considering the different ulcer risk classifications determined by the IWGDF.

METHODS

The subject pool comprised 72 people with DM, with and without DPN. The patients were divided into three groups: Group 0 (G0), which comprised diabetic patients without DPN; Group 1 (G1), which comprised patients with DPN; and Group 2 (G2), which comprised patients with DPN who had foot deformities. The health and foot function of the subjects' feet were assessed using a foot health status questionnaire (FHSQ-BR) that investigated four domains: foot pain, foot function, footwear, and general foot health. The patients' foot strength was evaluated using the maximum force under each subject's hallux and toes on a pressure platform (emed q-100, Novel, Munich, Germany).

RESULTS

Moderate differences were found between G0 and G1 and G2 for the foot pain, foot function, general foot health, and footwear. There was also a small but significant difference between G0 and G2 in regards to hallux strength.

CONCLUSION

Foot health, foot function and strength levels of people with DM and DPN classified by the ulcer risk are different and this must be taken into account when evaluating and developing treatment strategies for these patients.

Prevalence of ankle equinus and correlation with foot plantar pressures in people with diabetes

BACKGROUND

An association between equinus and plantar pressure may be important for people with diabetes, as elevated plantar pressure has been linked with foot ulcer development. To determine the prevalence of equinus in community dwelling people with diabetes and to examine any association between presence of equinus and forefoot plantar pressures.

METHODS

Barefoot (Tekscan HR Mat™) and in-shoe (Novel Pedar-X®) plantar pressure variables, non-weight bearing ankle range of motion and neuropathy status were assessed in 136 adults with diabetes (52.2% male; 47.8% with neuropathy; mean (standard deviation) age and diabetes duration: 68.4 (11.5) and 14.6 (11.1) years respectively).

FINDINGS

Equinus, when measured as ≤5° dorsiflexion, was present in 66.9% of the cohort. There was a significant correlation between an equinus and barefoot (r = 0.247, p = 0.004) and in-shoe forefoot pressure time integrals (r = 0.214, p = 0.012) and in-shoe forefoot alternate pressure time integrals (r = 0.246, p = 0.004). Significantly more males (p < 0.01) and people with neuropathy (p = 0.02) or higher glycated haemoglobin levels (p < 0.01) presented with an equinus.

INTERPRETATION

Community dwelling adults with diabetes have a high rate of ankle equinus which is associated with increased forefoot pressure time integrals and a two-fold increased risk of high in-shoe peak pressures. Clinical assessment of an ankle equinus may be a useful screening tool to identify adults at increased risk of diabetic foot complications.

Peak pressure data and pressure-time integral in the contralateral limb in patients with diabetes and a trans-tibial prosthesis

BACKGROUND

Clinicians currently rely on observational clinical data pertaining to the biomechanics of the diabetic foot. However, advances in technology can objectively describe this. A thorough understanding of the functional and mechanical consequences following trans-tibial amputations is lacking.

RESEARCH QUESTION

Does a trans-tibial prostheses significantly increase peak plantar pressures and pressure time integrals in the intact foot of patients with type-2 diabetes and neuropathy?

METHODS

A prospective quantitative matched-subject design was employed. Twenty participants living with diabetes and peripheral sensory neuropathy were recruited. Ten participants presented with a trans-tibial amputation and 10 had intact feet. Participants were matched for gender, age, foot type and BMI. Peak plantar pressure and pressure time integral data were recorded using the Tekscan HR™ pressure mat system, using the two-step gait protocol. The Shapiro-Wilk test was used to determine normality of data. The Independent Samples t-test and the Mann Whitney U test were carried out to reject the null hypothesis.

RESULTS

Although no significant differences (p < 0.05) in mean peak plantar pressures were observed in all the foot masks analysed between the amputee and the control group, a significant difference (p = 0.002) in mean pressure time integrals was recorded with highest pressure time integral (PTI) values under the 2nd-4th metatarsophalangeal joint (MTP joint) for the trans-tibial amputee group.

SIGNIFICANCE

Cumulative exposure of both pressure and time can lead to tissue damage. PTI could be considered as an important contributory factor in determining ulcer formation. Elevated PTI under the 2nd-4th MTP joints sustained in the intact contralateral limb in patients using below knee prosthesis could possibly be due to gait alterations in this population. The preservation of the contralateral limb is of great concern and importance as this might impact patient's mobility and quality of life.

The effect of foot orthoses with forefoot cushioning or metatarsal pad on forefoot peak plantar pressure in running

Background

Foot orthoses are frequently used in sports for the treatment of overuse complaints with sufficient evidence available for certain foot-related overuse pathologies like plantar fasciitis, rheumatoid arthritis and foot pain (e.g., metatarsalgia). One important aim is to reduce plantar pressure under prominent areas like metatarsal heads. For the forefoot region, mainly two common strategies exist: metatarsal pad (MP) and forefoot cushioning (FC). The aim of this study was to evaluate which of these orthosis concepts is superior in reducing plantar pressure in the forefoot during running.

Methods

Twenty-three (13 female, 10 male) asymptomatic runners participated in this cross-sectional experimental trial. Participants ran in a randomised order under the two experimental (MP, FC) conditions and a control (C) condition on a treadmill (2.78 ms⁻¹) for 2 min, respectively. Plantar pressure was measured with the in-shoe plantar pressure measurement device pedar-x®-System and mean peak pressure averaged from ten steps in the forefoot (primary outcome) and total foot was analysed. Insole comfort was measured with the Insole Comfort Index (ICI, sum score 0–100) after each running trial. The primary outcome was tested using the Friedman test (α = 0.05). Secondary outcomes were analysed descriptively (mean ± SD, lower & upper 95%-CI, median and interquartile-range (IQR)).

Results

Peak pressure [kPa] in the forefoot was significantly lower wearing FC (281 ± 80, 95%-CI: 246–315) compared to both C (313 ± 69, 95%-CI: 283–343; p = .003) and MP (315 ± 80, 95%-CI: 280–350; p = .001). No significant difference was found between C and MP (p = .858). Peak pressures under the total foot were: C: 364 ± 82, 95%-CI: 328–399; MP: 357 ± 80, 95%-CI: 326–387; FC: 333 ± 81 95%-CI: 298–368. Median ICI sum scores were: C 50, MP 49, FC 64.

Conclusions

In contrast to the metatarsal pad orthosis, the forefoot cushioning orthosis achieved a significant reduction of peak pressure in the forefoot of recreational runners. Consequently, the use of a prefabricated forefoot cushioning orthosis should be favoured over a prefabricated orthosis with an incorporated metatarsal pad in recreational runners with normal height arches.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-016-0176-z) contains supplementary material, which is available to authorized users.

Plantar pressures in individuals with normal and pronated feet according to static squat depths

[Purpose] The purpose of the present study was to investigate differences in plantar pressure between individuals with normal and pronated feet according to 3 static squat depths. [Subjects and Methods] Study subjects were 10 young adults with normal and pronated feet. Plantar pressures were measured in the standing position and static squat positions at 45° (semi-squat) and 90° (half-squat) knee flexion using the F-Mat. Subjects’ plantar pressures were analyzed by dividing the foot into 4 areas: forefoot medial, forefoot lateral, midfoot, and heel. [Results] In the half-squat position, the pronated foot group showed a higher foot pressure in the forefoot medial than was seen in the normal group, whereas the normal group exhibited a higher foot pressure in the heel than was seen in the pronated foot group. [Conclusion] An increase in squat depth led to the transfer of plantar pressure to the heel in normal feet and to the forefoot medial in pronated feet.

Plantar loading reflects ulceration risks of diabetic foot with toe deformation

Diabetes has been one of the most common chronic diseases all over the world. The purpose of this study was to quantitatively assess the foot loading characteristics of diabetic patients with fifth-toe deformity through a comparative analysis with diabetic patients with healthy and normal feet. Six neuropathic diabetic female subjects with the fifth-toe deformation and six age-matched neuropathic diabetic controls without any feet deformities participated in the walking test. Dynamic barefoot plantar pressure was measured with Novel EMED force plate. Peak pressure and pressure-time integral for all 7 foot regions (rearfoot, midfoot, lateral forefoot, central forefoot, medial forefoot, great toe, and other toes) were collected. Peak pressure was significantly higher in the patients with toe deformity in rearfoot, central forefoot, and great toe regions compared with the control group. Meanwhile, loading sustaining period extended longer in great toe region of deformed group than in that of the control group, and the center of pressure was nearly in the big toe region during toe offstage. Diabetic patients with fifth-toe deformity could have plantar contact area reduction in the other toes part and increased loading to the great toe part. The result showed that fifth-toe deformity was associated with potential ulceration risk especially in hallux region.

Effect of rocker shoe design features on forefoot plantar pressures in people with and without diabetes

BACKGROUND

There is no consensus on the precise rocker shoe outsole design that will optimally reduce plantar pressure in people with diabetes. This study aimed to understand how peak plantar pressure is influenced by systematically varying three design features which characterise a curved rocker shoe: apex angle, apex position and rocker angle.

METHODS

A total of 12 different rocker shoe designs, spanning a range of each of the three design features, were tested in 24 people with diabetes and 24 healthy participants. Each subject also wore a flexible control shoe. Peak plantar pressure, in four anatomical regions, was recorded for each of the 13 shoes during walking at a controlled speed.

FINDINGS

There were a number of significant main effects for each of the three design features, however, the precise effect of each feature varied between the different regions. The results demonstrated maximum pressure reduction in the 2nd-4th metatarsal regions (39%) but that lower rocker angles (<20°) and anterior apex positions (>60% shoe length) should be avoided for this region. The effect of apex angle was most pronounced in the 1st metatarsophalangeal region with a clear decrease in pressure as the apex angle was increased to 100°.

INTERPRETATION

We suggest that an outsole design with a 95° apex angle, apex position at 60% of shoe length and 20° rocker angle may achieve an optimal balance for offloading different regions of the forefoot. However, future studies incorporating additional design feature combinations, on high risk patients, are required to make definitive recommendations.