In-shoe Plantar Pressure Measurement Research Articles

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

IntroductionLoss of cutaneous protective sensation and high plantar pressures increase the risk for diabetic foot patients. Trauma and ulceration are imminent threats, making assessment and monitoring essential. This systematic review aims to identify systems and technologies for measuring in-shoe plantar pressures, focusing on the at-risk diabetic foot population. MethodsA systematic search was conducted across four electronic databases (Scopus, Web of Science, PubMed, Oxford Journals) using PRISMA methodology, covering articles published in English from 1979 to 2024. Only studies addressing systems or sensors exclusively measuring plantar pressures inside the shoe were included. ResultsA total of 87 studies using commercially available devices and 45 articles proposing new systems or sensors were reviewed. The prevailing market offerings consist mainly of instrumented insoles. Emerging technologies under development often feature configurations with four, six or eight resistive sensors strategically placed within removable insoles. Despite some variability due to the inherent heterogeneity of human gait, these devices assess plantar pressure, although they present significant differences between them in measurement results. Individuals with diabetic foot conditions appears exhibit elevated plantar pressures, with reported peak pressures reaching approximately 1000 kPa. The results also showed significant differences between the diabetic and non-diabetic groups. ConclusionInstrumented insoles, particularly those incorporating resistive sensor technology, dominate the field. Systems employing eight sensors at critical locations represent a pragmatic approach, although market options extend to systems with up to 960 sensors. Differences between devices can be a critical factor in measurement and highlights the importance of individualized patient assessment using consistent measurement devices.

In-Shoe Pressure Measurements in Diabetic Footwear Practice: Success Rate and Facilitators of and Barriers to Implementation.

We aimed to assess the success rate and facilitators of and the barriers to the implementation of in-shoe plantar pressure measurements in footwear practice for people with diabetes at high risk of foot ulceration. Eleven Dutch footwear practices were partly supported in purchasing a pressure measurement system. Over a 2.5-year period, trained shoe technicians evaluated 1030 people with diabetes (range: 13 to 156 across practices). The implementation success and associated facilitators and barriers were evaluated quantitatively using completed measurement forms and pressure measurement data obtained during four monitoring sessions and qualitatively through semi-structured interviews with technicians. Across the 11 practices, the primary target group (people with diabetes and a healed plantar foot ulcer) represented 25-90% of all the patients measured. The results showed that three practices were successful, five moderately successful, and three not successful. The facilitators included support by the company management board, collaboration with a prescribing physician, measurement sessions separate from the outpatient clinic, and a (dedicated) shoe technician experiencing a learning effect. The barriers included investment costs, usability aspects, and limited awareness among shoe technicians. In-shoe plantar pressure measurements can be implemented to a moderate to large degree in diabetic footwear practice. The barriers to and facilitators of implementation are organizational, logistical, financial, or technical, and the barriers are modifiable, supporting future implementation.

Impact of Fatigue on Ergonomic Risk Scores and Foot Kinetics: A Field Study Employing Inertial and In-Shoe Plantar Pressure Measurement Devices.

(1) Background: Occupational fatigue is a primary factor leading to work-related musculoskeletal disorders (WRMSDs). Kinematic and kinetic experimental studies have been able to identify indicators of WRMSD, but research addressing real-world workplace scenarios is lacking. Hence, the authors of this study aimed to assess the influence of physical strain on the Borg CR-10 body map, ergonomic risk scores, and foot pressure in a real-world setting. (2) Methods: Twenty-four participants (seventeen men and seven women) were included in this field study. Inertial measurement units (IMUs) (n = 24) and in-shoe plantar pressure measurements (n = 18) captured the workload of production and office workers at the beginning of their work shift and three hours later, working without any break. In addition to the two 12 min motion capture processes, a Borg CR-10 body map and fatigue visual analog scale (VAS) were applied twice. Kinematic and kinetic data were processed using MATLAB and SPSS software, resulting in scores representing the relative distribution of the Rapid Upper Limb Assessment (RULA) and Computer-Assisted Recording and Long-Term Analysis of Musculoskeletal Load (CUELA), and in-shoe plantar pressure. (3) Results: Significant differences were observed between the two measurement times of physical exertion and fatigue, but not for ergonomic risk scores. Contrary to the hypothesis of the authors, there were no significant differences between the in-shoe plantar pressures. Significant differences were observed between the dominant and non-dominant sides for all kinetic variables. (4) Conclusions: The posture scores of RULA and CUELA and in-shoe plantar pressure side differences were a valuable basis for adapting one-sided requirements in the work process of the workers. Traditional observational methods must be adapted more sensitively to detect kinematic deviations at work. The results of this field study enhance our knowledge about the use and benefits of sensors for ergonomic risk assessments and interventions.

An integrated personalized assistive devices approach to reduce the risk of foot ulcer recurrence in diabetes (DIASSIST): study protocol for a multicenter randomized controlled trial

BackgroundPreventing foot ulcers in people with diabetes can increase quality of life and reduce costs. Despite the availability of various interventions to prevent foot ulcers, recurrence rates remain high. We hypothesize that a multimodal treatment approach incorporating various footwear, self-management, and education interventions that matches an individual person’s needs can reduce the risk of ulcer recurrence with beneficial cost-utility. The aim of this study is to assess the effect on foot ulcer recurrence, footwear adherence, and cost-utility of an integrated personalized assistive devices approach in high-risk people with diabetes.MethodsIn a parallel-group multicenter randomized controlled trial, 126 adult participants with diabetes mellitus type 1 or 2, loss of protective sensation based on the presence of peripheral neuropathy, a healed plantar foot ulcer in the preceding 4 years, and possession of any type of custom-made footwear will be included. Participants will be randomly assigned to either enhanced therapy or usual care. Enhanced therapy consists of usual care and additionally a personalized treatment approach including pressure-optimized custom-made footwear, pressure-optimized custom-made footwear for indoor use, at-home daily foot temperature monitoring, and structured education, which includes motivational interviewing and personalized feedback on adherence and self-care. Participants will be followed for 12 months. Assessments include barefoot and in-shoe plantar pressure measurements; questionnaires concerning quality of life, costs, disease, and self-care knowledge; physical activity and footwear use monitoring; and clinical monitoring for foot ulcer outcomes. The study is powered for 3 primary outcomes: foot ulcer recurrence, footwear adherence, and cost-utility, the primary clinical, patient-related, and health-economic outcome respectively.DiscussionThis is the first study to integrate multiple interventions for ulcer prevention into a personalized state-of-the-art treatment approach and assess their combined efficacy in a randomized controlled trial in people with diabetes at high ulcer risk. Proven effectiveness, usability, and cost-utility will facilitate implementation in healthcare, improve the quality of life of high-risk people with diabetes, and reduce treatment costs.Trial registrationClinicalTrials.gov NCT05236660. Registered on 11 February 2022.

Reliability of F-Scan® in-shoe plantar pressure measurements in people with diabetes at risk of developing foot ulcers

BackgroundThe provision of therapeutic footwear, to prevent the development of diabetic foot ulcers by re-distributing high peak plantar pressure is frequently prescribed for patients with diabetes. Areas of interest (ROI) are identified by placing boxes on the visualised pressure movie. The aims were to evaluate the inter-reliability of the placements of seven ROI boxes and to explore how the box placement affected peak pressure in the seven ROIs. MethodsPlantar pressure movies from 20 of a total of 40 movies were selected for the analysis. Boxes were placed at ROIs, the heel, the lateral midfoot, the metatarsal phalangeal heads (5, 3–4, 2 and 1) and the hallux. The box placements were registered for the left vertical position (L) and the top horizontal position (T) for each of the ROIs, based on registrations by two certified prosthetists and orthotists. FindingsThe inter correlation coefficient of the placement of the boxes ranged from 1.00 to 0.12 (heel_L and metatarsal phalangeal head 2_L respectively). Of the 14 positions of the boxes; four were excellent, four were good, two were moderate and four were poor. No significant differences in the mean peak pressure corresponding to the box placements were found between the CPOs. InterpretationThe inter-reliability of eight of the 14 registered placements, made by prosthetists and orthotists, of the boxes in Scan® was good to excellent. A variation of 1.00–0.12 was present. Despite the variation, no significant differences in the corresponding mean peak pressure between prosthetists and orthotists was found.

Effectiveness of Shock-Absorbing Insole for High-Heeled Shoes on Gait: Randomized Controlled Trials.

This study was carried out to identify the influence of a shock-absorbing insole, developed by the author for use with high-heeled shoes, on walking. The research design included single-blind randomized parallel groups; namely, a group of 26 participants who wore the shock-absorbing insoles and another group of 26 participants who did not wear the insoles, both carried out walking while wearing 7 cm high-heels. During walking, plantar pressure analysis (via in-shoe plantar pressure measurements), surface electrode electromyography (surface EMG), gait analysis, subjective comfort evaluation, and functional movement (functional mobility) analysis were carried out. In order to compare the two groups, statistical verification (paired t-test) was performed. Wearing the shock-absorbing insole with the high-heeled shoes improved posture stability during walking, as well as increasing the walking speed. In addition, the heel pressure, the pressure of the front foot at the inner side, and the shock ability were decreased. For these reasons, the wearers reported higher comfort. Changes in the muscle activities of the tibialis anterior muscle (TA) and the gastrocnemius muscle (GA) heightened the stability of the ankle joints. Overall, the proposed shock-absorbing insole for use with high-heeled shoes improved the postural stability when walking, as well as improving the distribution of pressure on the soles. A decrease in the diverse side-effects of wearing high-heeled shoes can thus be expected.

Evaluation of novel plantar pressure-based 3-dimensional printed accommodative insoles - A feasibility study

BackgroundCustom insoles are commonly prescribed to patients with diabetes to redistribute plantar pressure and decrease the risk of ulceration. Advances in 3D printing have enabled the creation of 3D-printed personalized metamaterials whose properties are derived not only from the base material but also the lattice microstructures within the metamaterial. Insoles manufactured using personalized metamaterials have both patient-specific geometry and stiffnesses. However, the safety and biomechanical effect of the novel insoles have not yet been tested clinically. MethodsIndividuals without ulcer, neuropathy, or deformity were recruited for this study. In-shoe walking plantar pressure at baseline visit was taken and sensels with pressure over 200 kPa was used to define offloading region(s). Three pairs of custom insoles (two 3D printed insoles with personalized metamaterials (Hybrid and Full) designed based on foot shape and plantar pressure mapping and one standard-of-care diabetic insole as a comparator). In-shoe plantar pressure measurements during walking were recorded in a standardized research shoe and the three insoles and compared across all four conditions. FindingsTwelve individuals were included in the final analysis. No adverse events occurred during testing. Maximum peak plantar pressure and the pressure time integral were reduced in the offloading regions in the Hybrid and Full but not in the standard-of-care compared to the research shoe. InterpretationThis feasibility study confirms our ability to manufacture the 3D printed personalized metamaterials insoles and demonstrates their ability to reduce plantar pressure. We have demonstrated the ability to modify the 3D printed design to offload certain parts of the foot using plantar pressure data and a patient-specific metamaterials in the 3D printed insole design. The advance in 3D printed technology has shown its potential to improve current care.

Footsteps required for reliable and valid in-shoe plantar pressure assessment during gait per foot region in people with hallux valgus

BackgroundPlantar pressure assessment is commonly performed to identify pathognomonic gait characteristics and evaluate therapeutics against them in people with various foot disorders. Little is known about the reliability and validity of this assessment in people with hallux valgus (HV) per foot region. Research questionThis study aimed to assess the reliability and validity of the in-shoe plantar pressure measurement method during gait in people with HV and the required number of footsteps, as an intra-subject sample size, to ensure a reliable and valid use of this method. MethodsWith an inserted disposable insole plantar pressure sensor in shoes, 17 females with HV (HV angle > 15°) completed three gait trials over the ground at a comfortable speed. Peak plantar pressure data and its distribution in 15 stance phases on the foot clinically diagnosed with HV in each participant were extracted by dividing the foot into eight regions. The intraclass correlation coefficient per foot region and the number of footsteps required to produce a valid peak plantar pressure and distribution (intraclass correlation coefficient > 0.90) were used to measure reliability. Based on the limit of agreement analysis, the coefficient of variation between the averaged value from each incremental footstep (2–14 footsteps) and 15 reference footsteps was calculated. ResultsThe intraclass correlation coefficient of plantar pressure assessment with the in-shoe sensor was 0.606–0.847 in the eight foot regions in people with HV. Additionally, the number of steps required for a valid assessment ranged from two to nine. Hence, the application of averaged values from more than nine footsteps is recommended for this evaluation. SignificanceThis reference sample size is intended to be used in future studies and clinical settings to determine the efficacy of HV treatment.

Outcomes and potential mechanism of a protocol to optimize foot orthoses in patients with rheumatoid arthritis

BackgroundFoot problems are highly prevalent in patients with rheumatoid arthritis. Treatment of foot problems related to rheumatoid arthritis often consists of custom made foot orthoses. One of the assumed working mechanisms of foot orthoses is redistribution of plantar pressure by creating a larger weight bearing area. Overall, the reported treatment effect of foot orthoses on foot pain in rheumatoid arthritis is small to medium. Therefore, we developed a foot orthoses optimization protocol for evaluation and adaptation of foot orthoses by using the feedback of in-shoe plantar pressure measurements. The objectives of the present study were: 1) to evaluate the 3-months outcomes of foot orthoses developed according to the protocol on pain, physical functioning and forefoot plantar pressure in patients with foot problems related to rheumatoid arthritis, and 2) to determine the relationship between change in forefoot plantar pressure and change in pain and physical functioning.MethodsForty-five patients with foot problems related to rheumatoid arthritis were included and received foot orthoses developed according to the protocol. Outcome measures were assessed at baseline and after three months of wearing foot orthoses in 38 patients. Change scores and effect sizes (ES) were calculated for pain, physical functioning and plantar pressure. In a subgroup of patients with combined forefoot pain and high plantar pressure, the relationship between change in plantar pressure and change in pain and physical functioning was analyzed.ResultsIn the total group of 38 patients, statistically significant changes in pain (ES 0.69), physical functioning (ES 0.82) and forefoot plantar pressure (ES 0.35) were found. In the subgroup (n = 23) no statistically significant relationships were found between change in plantar pressure and change in pain or physical functioning.ConclusionFoot orthoses developed according to a protocol for improving the plantar pressure redistribution properties lead to medium to large improvements in pain and physical functioning. The hypothesis that more pressure reduction would lead to better clinical outcomes could not be proven.

Effects of metatarsal domes on plantar pressures in older people with a history of forefoot pain

BackgroundForefoot pads such as metatarsal domes are commonly used in clinical practice for the treatment of pressure-related forefoot pain, however evidence for their effects is inconsistent. This study aimed to evaluate the effects on plantar pressures of metatarsal domes in different positions relative to the metatarsal heads.MethodsParticipants in this study included 36 community-dwelling adults aged 65 or older with a history of forefoot pain. Standardised footwear was used and plantar pressures were measured using the pedar®-X in-shoe plantar pressure measurement system. Peak pressure, maximum force and contact area were analysed using an anatomically-based masking protocol that included three forefoot mask sub-areas (proximal to, beneath, and distal to the metatarsal heads). Data were collected for two different types of prefabricated metatarsal domes of different densities (Emsold metatarsal dome and Langer PPT metatarsal pad) in three different positions relative to the metatarsal heads. Seven conditions were tested in this study: (i) control (no pad) condition, (ii) Emsold metatarsal dome positioned 5 mm proximal to the metatarsal heads, (iii) Emsold metatarsal dome positioned in-line with the metatarsal heads, (iv), Emsold metatarsal dome positioned 5 mm distal to the metatarsal heads, (v) Langer PPT metatarsal pad positioned 5 mm proximal to the metatarsal heads, (vi) Langer PPT metatarsal pad positioned in-line with the metatarsal heads, and (vii) Langer PPT metatarsal pad positioned 5 mm distal to the metatarsal heads.ResultsWhen analysed with the mask that was distal to the metatarsal heads, where the plantar pressure readings were at their highest, all metatarsal dome conditions led to significant reductions in plantar pressure at the forefoot compared to the control (no pad) condition (F3.9, 135.6 = 8.125, p < 0.001). The reductions in plantar pressure were in the order of 45–60 kPa. Both the Emsold metatarsal dome and the Langer PPT metatarsal pad, when positioned proximal to the metatarsal heads, managed to achieve this without adversely increasing plantar pressure proximally where the pad was positioned, however the Emsold metatarsal dome was most effective.ConclusionsMetatarsal domes reduce plantar pressure in the forefoot in older people with a history of forefoot pain. All metatarsal dome conditions significantly reduced peak pressure in the forefoot, however metatarsal domes that were positioned 5 mm proximal to the metatarsal heads provided the best balance of reducing plantar pressure distal to the metatarsal heads, where the pressure is at its greatest, but not adversely increasing plantar pressure proximally, where the bulk of the pad is positioned. In this proximal position, the Emsold metatarsal dome was more effective than the Langer PPT metatarsal pad and we cautiously recommend this forefoot pad for alleviating forefoot pressure in older people with forefoot pain.

Design and Development of a Novel Transtibial Cycling Prosthesis

ABSTRACT Introduction This article describes the design methodology, creation, and testing of a bespoke transtibial prosthesis, manufactured in part using three-dimensional (3D) printing technology, to enable more effective transmission of dynamic pressure through pedals during cycling. Asymmetry in motion can occur during cycling between the affected and contralateral lower limb. This pilot study was devised to enable development of a prototype prosthesis using a flexible ankle joint design for people with transtibial lower-limb absence for use when participating in amateur sports cycling. Materials and Methods Gait laboratory analysis and in-shoe plantar pressure measurement were used to simultaneously measure heel/ankle kinematics, plus pressure magnitude/distribution applied during cycling. A volunteer subject cycled on a static rig wearing either a standard unilateral transtibial prosthesis or a prototype prosthesis, which incorporated a simulated Achilles tendon. An able-bodied volunteer acted as a control. Results The results indicate that cycling with the prototype prosthesis reduced bilateral ankle and heel kinematic misalignment by 64% and reduced unwanted pedal pressure during the cycling recovery phase from 60 N to 50 N. Conclusions The use of 3D printing is a feasible option in the design and manufacture of lower-limb prostheses designed for cycling. Further research is needed to confirm this in a larger cohort of patients.

Design of wireless device to measure plantar pressure and gait analysis

Foot plantar pressure is the pressure field that acts between the plantar region of the foot and supporting ground. The pressure exerted on the variable region of the foot can be determined using discrete pressure sensors. Information obtained from these sensors is useful in the measurement of gait and posture for diagnosing various problems associated with a lower limb, footwear design, and sports biomechanics. This project is aimed to design a portable in-shoe plantar pressure and gyroscope-based gait angle measurement system. Six Force Sensitive Resistor (FSR) placed in the sole (hallux, 1st, 5th metatarsal, midfoot lateral, midfoot medial and heel respectively) detects the plantar pressure and gyroscope placed at the ankle, knee and hip help measure the orientation and angle of joint movement during various phases of gait. The study among 16 male and 16 female subjects illustrated the significant pressure variation (p&lt;0.0001, t=5.17 with α=95%). Similarly, there was a significant difference in pressure between normal and fast walking speed (p&lt;0.0001, t=5.88) with mean values of 353Kpa and 426Kpa respectively. The mean pressure value for slow walking speed was 423Kpa while there was no significant variation between slow and normal walking speeds (p=0.62, t=1.98). Plantar pressure increased linearly with an increase in the body weight of a person as well. The mean pressure for the 45-50 age group was 313.25Kpa and that for 70-75 was 449Kpa. The study among 10 diabetics and 10 non-diabetic subjects illustrated significantly higher pressure on 1st and 5th metatarsal on diabetic subjects (p=0.0207 and t=2.536). The movement of ankle, knee and hip joint is visualized using the 3D model of a lower limb through processing software. The study illustrated the range of ankle joint movement between -60(dorsiflexion) to 200(plantarflexion), for knee joint was 00 to 300 (flexion) and that for hip joint was -50(extension) to 400(flexion). There was a significant difference in angular values for all three joints while climbing up and down the staircase as compared to walk in a level surface.

The design and development of a foot plantar pressure measurement based on the mechanically induced long period fiber grating

The aim of this study is to design and develop an alternative in-shoe foot plantar pressure measurement based on an optical fiber sensor. The foot plantar pressure distributions from human feet is considered to be important and essential information required by clinicians to plan a proper management on some foot problems of diabetic patients. Advantages of using the optical fiber include the immunity to electromagnetic interference, structural flexibility, light weight and low-cost assembly. The main component of the sensor is the long period fiber grating (LPFG) which is composed of a strand of single mode fiber (SMF, 9/125 μm) with a cut-off wavelength at 800 nm and plastic grooved plates with grating periods less than 1 mm. The gratings with different periods are placed at different regions in a foot platform whereby a patient’s fore-foot, mid-foot and hind-foot are supported. The LPFG mechanically induced by the plantar pressure applied from each region can be observed from the resonance wavelength shift as a part of the transmission spectrum from the sensor. The data reveal both magnitude and position where the pressure is applied. Experimental results show that this system has a stable and reliable performance for measuring the foot plantar pressure distribution.

P 125 – An anatomically-based protocol for the assessment of in-shoe plantar pressure measurement of the forefoot

Rapid cold hardening (RCH) is a central physiological adaptation in which brief chilling significantly enhances the cold tolerance ability of insects. However, the mechanism of rapid cold stress response remains unknown for rice water weevils. To elucidate the mechanism, a comparative proteomic analysis was applied with two-dimensional gel electrophoresis (2-DE) between RCH and control treatment samples. A total of 21 protein spots were found to be up-regulated in rice water weevil adults for the RCH condition. As an initial work, 16 of these proteins were identified using MALDI TOF/TOF MS. In addition, the expression patterns of 9 proteins (including 2 HSPs that were not identified in the 2-DE experiment) were confirmed by qPCR analysis. Using the geneMANIA app in cytoscape, we constructed a protein-protein interaction network analysis of these up-regulated proteins. Gene ontology (GO) function annotation shows that a “response to heat process,” including 6 HSPs, was related to the identified proteins. These up-regulated, RCH responsive proteins could possibly serve as potential biomarkers to study the molecular mechanisms of the L. oryzophilus response to cold stress.

Effect of knee unloading shoes on regional plantar pressures in people with symptomatic knee osteoarthritis

Purpose: Knee ‘unloading’ footwear can reduce joint loading in people with knee osteoarthritis, yet effects of these shoes on regional plantar pressures are unknown. Measurement of regional plantar pressures permits an increased understanding of how unloading footwear changes regional plantar loading, and may yield important insights into why some people with knee osteoarthritis respond to unloading footwear, while others do not. We evaluated the effects of unloading shoes on in-shoe regional plantar pressures, and whether measures of foot posture and/or mobility moderate these effects in people with symptomatic knee osteoarthritis. Methods: Twenty-one participants with medial compartment knee osteoarthritis underwent in-shoe plantar pressure measurements (Novel Pedar) while wearing knee unloading shoes (ASICS GEL-Melbourne OA) and standard conventional walking shoes (ASICS) in random order. The knee unloading shoes were commercially available unloading walking shoes with triple-density midsoles (stiffer laterally than medially) and mild (5-degree) lateral wedge insoles attached to the underside of the sock liners. Peak total forces were compared across conditions for: entire foot, lateral heel, medial heel, lateral forefoot, and medial forefoot. Arch index, center of pressure position and medial-lateral heel peak force ratio were also evaluated. Foot posture (neutral or pronated) was assessed using the Foot Posture Index. Vertical and medial-lateral mobility of the midfoot was assessed with the foot mobility magnitude. Foot mobility was also assessed using the navicular drop test. Foot posture, foot mobility magnitude and navicular drop were separately added to the mixed linear model to investigate if these modified the effect of footwear on outcomes. Results: Patient characteristics are presented in Table 1. The effects of unloading shoes on in-shoe regional plantar pressures, relative to conventional shoes, are summarized in Table 2. Unloading shoes significantly increased total, lateral heel and lateral forefoot force (+6.4%, +12.9% and +20.2% respectively, all P < 0.001), with concurrent decreases in the medial heel (−8.9%, P = 0.001) and medial forefoot (−9.9%, P = 0.005). As a result of these changes, the medial-lateral heel force ratio also decreased significantly with unloading shoes (−20.0%, P < 0.001). Unloading shoes significantly shifted the center of pressure anteriorly (+4.7%, P < 0.001) and laterally (+5.6%, P = 0.034), but did not affect the arch index (−8.7%, P = 0.093). Whilst all but three participants demonstrated an increase in lateral heel force with unloading shoes relative to conventional shoes (Figure 1), there was a large degree of individual variation in response. Despite this, no significant interaction effect was observed for foot posture, foot mobility magnitude and navicular drop on the effect of footwear on regional plantar pressures. Conclusions: Compared to conventional shoes, unloading shoes cause a lateral shift in foot pressure and force patterns. These findings may explain why a small proportion of people with knee osteoarthritis experience foot problems when wearing unloading footwear. Foot posture/mobility did not moderate effects of footwear on plantar pressures.Table 1Characteristics of participants (n = 21)Age, years63.4 (7.0)Male, n (%)9 (43)Body mass index, kg/m229.8 (3.6)Mild radiographic disease (grade 2), n (%)16 (29)Moderate radiographic disease (grade 3), n (%)19 (43)Severe radiographic disease (grade 4), n (%)16 (29)Foot Posture Index Classification, n (%)(Highly) supinated (scores less than 0)0 (0)Normal (scores from 0 to +5)9 (43)(Highly) pronated (scores greater than +5)12 (57)Foot mobility magnitude, mm9.6 (3.8)Navicular drop, mm7.6 (3.1)Pain while walking (NRS)23.7 (3.0)Physical function (WOMAC)318.5 (13.2)Values are reported as mean (SD) unless otherwise indicated.1Using the Kellgren-Lawrencegrading system; NRS = numerical rating scale; WOMAC = Western Ontario and McMasterUniversities OsteoarthritisIndex. 2Ranges from 0 to 10 (higher scores indicate worse pain); 3Ranges from 0 to 68 (higher scores indicate worse function). Open table in a new tab Table 2The effect of unloading shoes on plantar forces relative to conventional shoes.Plantar force measurementsConventional shoes, Mean (SD)Unloading shoes, Mean (SD)Difference (95%CI)P valuePeak foot force, N806.8 (152.7)858.7 (155.8)52.0 (37.6 to 66.4)<0.001Peak lateral heel force, N233.0 (68.3)263.0 (69.6)30.0 (18.1 to 42.0)<0.001Peak medial heel force, N229.4 (62.5)208.9 (57.7)−20.5 (−32.3 to −8.7)0.001Peak lateral forefoot force, N204.1 (44.4)245.4 (52.3)41.3 (21.5 to 61.0)<0.001Peak medial forefoot force, N246.1 (74.8)221.8 (63.9)−24.3 (−41.2 to −7.4)0.005Arch index (midstance)0.23 (0.04)0.21 (0.03)−0.01 (−0.03 to 0.00)0.093CoP x-position [ML](25%stance), mm53.0 (5.0)55.5 (4.9)2.5 (1.4 to 3.6)<0.001CoP y-position [AP](25%stance), mm78.9 (15.5)83.3 (14.7)4.4 (0.3 to 8.5)0.034Medial - lateral heel peakforce ratio1.0 (0.3)0.8 (0.3)−0.2 (−0.3 to −0.1)<0.001CoP = center of pressure Open table in a new tab Values are reported as mean (SD) unless otherwise indicated.1Using the Kellgren-Lawrencegrading system; NRS = numerical rating scale; WOMAC = Western Ontario and McMasterUniversities OsteoarthritisIndex. 2Ranges from 0 to 10 (higher scores indicate worse pain); 3Ranges from 0 to 68 (higher scores indicate worse function). CoP = center of pressure

Polymer Optical Fiber for In-Shoe Monitoring of Ground Reaction Forces During the Gait

Ground reaction force (GRF) measurement is usually made by means of force platforms, which can lead to errors when the foot is not precisely placed inside the platform boundaries. Although electronic in-shoe plantar pressure sensors solve this problem, they lack in stability, robustness to impact loads and also can present some errors and inconsistencies. Polymer optical fibers (POF) present high elastic strain limits, fracture toughness, flexibility in bend, and relative low cost and are not influenced by electromagnetic fields, which enable their application for in-shoe plantar pressure measurements. This paper presents an in-shoe system to measure the vertical GRF during the gait cycle. The system comprises of four POF sensors in an insole. Since the polymer does not have a constant response with stress or strain due to its viscoelasticity, a compensation technique for this effect is also proposed. The proposed insole is compared with a commercial force platform, and a root mean squared error of 5.30 N was obtained. Results also show the feasibility of the system to measure the GRF during the gait and the identification of all subdivisions of the stance phase with the additional advantages of full portability, lower cost, and higher flexibility than the one presented by commercial force platforms and fiber Bragg gratings-based insoles.

An anatomically-based masking protocol for the assessment of in-shoe plantar pressure measurement of the forefoot

BackgroundThe area beneath the metatarsal heads is a common location of foot pain, which is often associated with high plantar pressures. Current plantar pressure assessment protocols focus mainly on the gross area of the forefoot with minimal attention paid to specific areas such as the metatarsal heads. The aim of this study was to develop and assess a new anatomically-based masking protocol that is clinically relevant to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads.MethodsInitially, we developed a masking protocol to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads. This new masking protocol divided the forefoot into three sub-areas (proximal, beneath, and distal to the metatarsal heads) as determined by the position of each metatarsal head. Following development of the new masking protocol, we compared the new protocol against a traditional protocol, which defines the forefoot as between 51 and 81% of the foot length. To compare the two masking protocols, we tested two experimental conditions: (i) a control condition (i.e. no metatarsal pad), and (ii) a metatarsal pad condition. We then compared plantar pressure differences between the two experimental conditions for the two masking protocols. Participants for this component of the study included 36 community dwelling older adults (mean age 75.6 years ±5.4) with a history of forefoot pain. Forefoot plantar pressure data were measured while walking using the pedar®-X in-shoe system. Peak pressure, maximum force and contact area at the time of peak pressure were determined and results were compared between the two masking protocols.ResultsThe traditional masking protocol showed that the metatarsal pad significantly decreased peak pressure and increased contact area in the forefoot area (i.e. within the entire mask area), but maximum force was not significantly different between the two conditions. In contrast, the newly developed anatomically-based masking protocol indicated that the metatarsal pad decreased peak plantar pressures distal to and beneath the metatarsal heads by increasing force and contact area proximal to the metatarsal heads.ConclusionsAn anatomically-based masking protocol that is clinically relevant was developed to assess forefoot plantar pressure during shod conditions based on the anatomical positions of metatarsal heads. We propose that the new forefoot masking protocol will provide greater interpretability of forefoot plantar pressure data, which will aid clinicians and researchers for diagnostic, prognostic and therapeutic purposes.

Lower-extremity dynamics of walking in neuropathic diabetic patients who wear a forefoot-offloading shoe

BackgroundA forefoot-offloading shoes has a negative-heel rocker outsole and is used to treat diabetic plantar forefoot ulcers, but its mechanisms of action and their association with offloading and gait stability are not sufficiently clear. MethodsTen neuropathic diabetic patients were tested in a forefoot-offloading shoe and subsequently in a control shoe with no specific offloading construction, both worn on the right foot (control shoe on left), while walking at 1.2m/s. 3D-instrumented gait analysis and simultaneous in-shoe plantar pressure measurements were used to explain the shoe's offloading efficacy and to define centre-of-pressure profiles and left-to-right symmetry in ankle joint dynamics (0–1, 1:maximum symmetry), as indicators for gait stability. FindingsCompared to the control shoe, peak forefoot pressures, vertical ground reaction force, plantar flexion angle, and ankle joint moment, all in terminal stance, and the proximal-to-distal centre-of-pressure trajectory were significantly reduced in the forefoot-offloading shoe (P<0.01). Peak ankle joint power was 51% lower in the forefoot-offloading shoe compared to the control shoe: 1.61 (0.35) versus 3.30 (0.84) W/kg (mean (SD), P<0.001), and was significantly associated with forefoot peak pressure (R2=0.72, P<0.001). Left-to-right symmetry in the forefoot-offloading shoe was 0.39 for peak ankle joint power. InterpretationBy virtue to their negative-heel rocker-outsole design, forefoot-offloading shoes significantly alter a neuropathic diabetic patient's gait towards a reduced push-off power that explains the shoe's offloading efficacy. However, gait symmetry and stability are compromised, and may be factors in the low perceived walking discomfort and limited use of these shoes in clinical practice. Shoe modifications (e.g. less negative heel, a more cushioning insole) may resolve this trade-off between efficacy and usability.

A Graphene-Based Flexible Pressure Sensor with Applications to Plantar Pressure Measurement and Gait Analysis.

In the present study, we propose and develop a flexible pressure sensor based on the piezoresistive effect of multilayer graphene films on polyester textile. The pressure response results from the deformation of graphene conductive network structure and the changes in resistance. Here, we show that the graphene pressure sensor can achieve a sensitivity value of 0.012 kPa, the measurement range can be as high as 800 kPa, and the response time can reach to 50 ms. Subsequently, a stable in-shoe wireless plantar pressure measurement system is developed and dynamic pressure distribution is acquired in real-time. Overall, the graphene textile pressure sensor has the advantage of wide dynamic range, flexibility and comfort, which provides the high possibility for footwear evaluation, clinical gait analysis and pathological foot diagnosis.

In-Shoe Plantar Pressure Profiles in Amateur Basketball Players Implications for Footwear Recommendations and Orthosis Use.

Biomechanical analysis of foot loading characteristics may provide insights into the injury mechanisms and guide orthotic prescription for basketball players. This study aimed to quantify in-shoe plantar pressure profiles in amateur players when executing typical basketball movements. Twenty male university basketball players performed four basketball-specific movement tasks-running, maximal forward sprinting, maximal 45° cutting, and layup-in a pair of standardized basketball shoes fitted with an in-shoe plantar pressure measurement system. Peak pressure (PP) and pressure-time integral (PTI) data were extracted from ten plantar regions. One-way repeated-measures analysis of variance was performed across the tasks, with significance set at P < .05. Distinct plantar pressure distribution patterns were observed among the four movements. Compared with running, significantly higher ( P < .05) PP and PTI of up to approximately 55% were found in sprinting and layup, particularly at the forefoot region. Similarly, significantly higher ( P < .05) PPs and PTIs, ranging from approximately 23% to 90%, were observed in 45° cutting compared with running at most foot regions. Compared with running, sprinting and layup demonstrated higher plantar loading in the forefoot region, and 45° cutting yielded increased plantar loading in most regions of the foot. Understanding the plantar pressure characteristics of different movements may be useful in optimizing footwear designs, orthosis use, or training strategies to minimize regional plantar loading during amateur basketball play.