Development of a research agenda for medical grade footwear in the Netherlands: A multidisciplinary multiphase project to determine the key research questions to advance scientific knowledge in the field.

BACKGROUND: The field of medical grade footwear is dynamic. Originally, a field where individual knowledge, expertise and skills determined the footwear and its outcomes, now becoming a more evidence-based and data-driven field with protocols and systems in place to create appropriate footwear. However, scientific evidence concerning medical grade footwear is still limited. Evidently, all stakeholders, from patients to pedorthists to rehabilitation physicians, will profit from a larger evidence-base in this field. A widely supported research agenda is an essential first step to advance and facilitate new knowledge. METHODS: We formed a multidisciplinary team and followed the methodology from Dutch medical societies for the development of a research agenda on medical grade footwear. This consisted of seven steps: (1) inventory of relevant questions with users and professionals; (2) analyses of responses; (3) analyses of existing knowledge and evidence; (4) formulating research questions; (5) prioritising research questions by users and professionals; (6) finalising the research agenda and (7) implementing the research agenda. RESULTS: In phase 1, 109 participants completed a survey, including 50% pedorthists, 6% rehabilitation physicians and 3% users. Participants provided 228 potential research questions. In phases 2-4, these were condensed to 65 research questions. In phase 5, 152 participants prioritised these 65 research questions, including 50% pedorthists, 13% rehabilitation physicians and 9% users. In phase 6, the final research agenda was created, with 26 research questions, categorised based on the International Classification of Functioning Disability and Health 'process description assistive devices'. In phase 7, an implementation meeting was held with over 50 stakeholders (including users and professionals), resulting in seven applications for research projects based on one or more research questions from the research agenda. CONCLUSIONS: This research agenda structures and guides knowledge development within the field of medical grade footwear in the Netherlands and elsewhere. We expect that this will help to stimulate the field to tackle the research questions prioritised and with that to advance scientific knowledge in this field.

Efficacy of auxetic lattice structured shoe sole in advancing footwear comfort-From the perspective of plantar pressure and contact area.

Introduction: Designing footwear for comfort is vital for preventing foot injuries and promoting foot health. This study explores the impact of auxetic structured shoe soles on plantar biomechanics and comfort, motivated by the integration of 3D printing in footwear production and the superior mechanical properties of auxetic designs. The shoe sole designs proposed in this study are based on a three-dimensional re-entrant auxetic lattice structure, orthogonally composed of re-entrant hexagonal honeycombs with internal angles less than 90 degrees. Materials fabricated using this lattice structure exhibit the characteristic of a negative Poisson's ratio, displaying lateral expansion under tension and densification under compression. Methods: The study conducted a comparative experiment among three different lattice structured (auxetic 60°, auxetic 75° and non-auxetic 90°) thermoplastic polyurethane (TPU) shoe soles and conventional polyurethane (PU) shoe sole through pedobarographic measurements and comfort rating under walking and running conditions. The study obtained peak plantar pressures (PPPs) and contact area across seven plantar regions of each shoe sole and analyzed the correlation between these biomechanical parameters and subjective comfort. Results: Compared to non-auxetic shoe soles, auxetic structured shoe soles reduced PPPs across various foot regions and increased contact area. The Auxetic 60°, which had the highest comfort ratings, significantly lowered peak pressures and increased contact area compared to PU shoe sole. Correlation analysis showed that peak pressures in specific foot regions (hallux, second metatarsal head, and hindfoot when walking; second metatarsal head, third to fifth metatarsal head, midfoot, and hindfoot when running) were related to comfort. Furthermore, the contact area in all foot regions was significantly associated with comfort, regardless of the motion states. Conclusion: The pressure-relief performance and conformability of the auxetic lattice structure in the shoe sole contribute to enhancing footwear comfort. The insights provided guide designers in developing footwear focused on foot health and comfort using auxetic structures.

Recent Innovations in Footwear and the Role of Smart Footwear in Healthcare-A Survey.

Smart shoes have ushered in a new era of personalised health monitoring and assistive technologies. Smart shoes leverage technologies such as Bluetooth for data collection and wireless transmission, and incorporate features such as GPS tracking, obstacle detection, and fitness tracking. As the 2010s unfolded, the smart shoe landscape diversified and advanced rapidly, driven by sensor technology enhancements and smartphones' ubiquity. Shoes have begun incorporating accelerometers, gyroscopes, and pressure sensors, significantly improving the accuracy of data collection and enabling functionalities such as gait analysis. The healthcare sector has recognised the potential of smart shoes, leading to innovations such as shoes designed to monitor diabetic foot ulcers, track rehabilitation progress, and detect falls among older people, thus expanding their application beyond fitness into medical monitoring. This article provides an overview of the current state of smart shoe technology, highlighting the integration of advanced sensors for health monitoring, energy harvesting, assistive features for the visually impaired, and deep learning for data analysis. This study discusses the potential of smart footwear in medical applications, particularly for patients with diabetes, and the ongoing research in this field. Current footwear challenges are also discussed, including complex construction, poor fit, comfort, and high cost.

Design considerations for protective boots for first responders to hazardous materials incidents.

First responder professionals are at high risk for work-related injuries (e.g., extreme temperatures, chemical and biological threats); boots are essential to ensure body protection since they have full contact with the ground in all scenarios. A substantial body of work has investigated the necessity of improvements in protective boots, but there is limited research conducted on boots with fit-adjustable fasteners for secure and adjustable fit within this context. Thus, this study explored the areas for improvement in boot design for the development of form-fitting and yet comfortable boots focusing on two different boot designs, prototype all-hazards tactical boots (lace-up) and rubber boots (slip-on). Findings indicated that the boot design should address participants' concerns with the material choices of boots, specifically with bulkiness, weight, and flexibility. Our findings provide insights into boot material and design choices to improve protective boots for first responders.

Biomechanical effectiveness of controlled ankle motion boots: A systematic review and narrative synthesis.

INTRODUCTION: Controlled ankle motion (CAM) boots are a below-knee orthotic device prescribed for the management of foot and ankle injuries to reduce ankle range of motion (RoM) and offload the foot and ankle whilst allowing continued ambulation during recovery. There is a lack of clarity within the current literature surrounding the biomechanical understanding and effectiveness of CAM boots. AIMS: To summarise the biomechanical effects of CAM boot wear as an orthotic for restricting ankle RoM and offloading the foot. METHODS: A systematic literature review was conducted in accordance with the PRISMA 2020 guidelines. All papers were independently screened by two authors for inclusion. Methodological quality was appraised using Joanna Briggs Critical Appraisal checklists. A narrative synthesis of all eligible papers was produced. RESULTS: Thirteen studies involving 197 participants (113 male and 84 female) were included. All studies were quasi-randomised and employed a within-study design, of which 12 studies included a control group and a range of CAM boots were investigated. CAM boots can be seen to restrict ankle RoM, however, neighboring joints such as the knee and hip do have kinetic and kinematic compensatory alterations. Plantar pressure of the forefoot is effectively redistributed to the hindfoot by CAM boots. CONCLUSION: The compensatory mechanisms at the hip and knee joint during CAM boot wear could explain the secondary site pain often reported in patients, specifically at the ipsilateral knee and contralateral hip. Although CAM boots can be used to restrict ankle motion, this review has highlighted a lack of in-boot kinematic analyses during CAM boot use, where tracking markers are placed on the anatomical structure rather than on the boot, or through video fluoroscopy, urging the need for a more robust methodological approach to achieve this. There is a need for studies to assess the biomechanical alterations caused by CAM boots in populations living with foot and ankle pathologies. Future research, adopting a longitudinal study design, is required to fully understand the effectiveness of CAM boots for rehabilitation.

The influence of foot muscles exercises and minimalist shoes on lactate threshold velocity in long-distance amateur runners: a randomized controlled trial.

The exercises of plantar foot muscles may have beneficial effects on the performance of the lower extremity muscles. The aim of this study was to compare two methods of foot muscle strengthening: direct short foot muscle exercises and indirect activation through training in minimalist footwear in regard to influence on lactate threshold velocity in long-distance runners. 55 recreational runners aged 21-45 years took part in that study. They were randomly divided into 2 groups: Group 1 (n = 25) with short foot muscle exercises, and Group 2 (n = 30) with training in minimalist shoes. The progressive running test was performed to determine heart rate (HR) and running velocity corresponding to lactate threshold (VLT). Two-way ANOVA was used to determine the significance of the differences regarding the evaluated variables. After the 8-week training program, higher values of VLT were observed in both groups. This change was significant only in Group 1 (p < 0.05). In Group 2, the higher value was noted but the changes were non-significant. Strengthening of the short foot muscles may improve lactate threshold velocity which is connected with running performance. Considering the obtained results, it is worth contemplating the implementation of these methods in the training of long-distance runners.

Textured insoles may improve some gross motor balance measures but not endurance measures in children with motor coordination issues. A randomised controlled feasibility trial.

BACKGROUND: Motor coordination concerns are estimated to affect 5%-6% of school-aged children. Motor coordination concerns have variable impact on children's lives, with gait and balance often affected. Textured insoles have demonstrated positive impact on balance and gait in adults with motor coordination disorders related to disease or the ageing process. The efficacy of textured insoles in children is unknown. Our primary aim was to identify the feasibility of conducting a randomised controlled trial involving children with motor control issues. The secondary aim was to identify the limited efficacy of textured insoles on gross motor assessment balance domains and endurance in children with movement difficulties. METHODS: An assessor-blinded, randomised feasibility study. We advertised for children between the ages of 5-12 years, with an existing diagnosis or developmental coordination disorder or gross motor skill levels assessed as 15th percentile or below on a norm-referenced, reliable and validated scale across two cities within Australia. We randomly allocated children to shoes only or shoes and textured insoles. We collected data across six feasibility domains; demand (recruitment), acceptability (via interview) implementation (adherence), practicality (via interview and adverse events), adaptation (via interview) and limited efficacy testing (6-min walk test and balance domain of Movement ABC-2 at baseline and 4 weeks). RESULTS: There were 15 children randomised into two groups (eight received shoes alone, seven received shoes and textured insoles). We experienced moderate demand, with 46 potential participants. The insoles were acceptable, however, some parents reported footwear fixture issues requiring modification. The 6-min walk test was described as problematic for children, despite all but one child completing. Social factors impacted adherence and footwear wear time in both groups. Families reported appointment locations and parking impacting practicality. Underpowered, non-significant small to moderate effect sizes were observed for different outcome measures. Improvement in balance measures favoured the shoe and insole group, while gait velocity increase favoured the shoe only group. CONCLUSION: Our research indicates that this trial design is feasible with modifications such as recruiting with a larger multi-disciplinary organisation, providing velcro shoe fixtures and using a shorter timed walk test. Furthermore, progressing to a larger well-powered randomised control trial is justified considering our preliminary, albeit underpowered, efficacy findings. TRIAL REGISTRATION: This trial was retrospectively registered with the Australian and New Zealand Clinical Trial Registration: ACTRN12624000160538.

Soft-Tissue Vibrations and Fatigue During Prolonged Running: Does an Individualized Midsole Hardness Play a Role?

Footwear has the potential to reduce soft-tissue vibrations (STV) but responses are highly subject-specific. Recent evidence shows that compressive garments minimizing STV have a beneficial effect on neuromuscular (NM) fatigue. The aim was to determine whether an individualized midsole hardness can minimize STV and NM fatigue during a half marathon. Twenty experienced runners were recruited for three visits: a familiarization session including the identification of midsole minimizing and maximizing STV amplitude (MIN and MAX, respectively), and two half marathon sessions at 95% of speed at the second ventilatory threshold. STV of the gastrocnemius medialis (GM) muscle, running kinetics, foot strike pattern, rating perceived exhaustion (RPE), and midsole liking were recorded every 3 km. NM fatigue was assessed on plantar flexors (PF) before (PRE) and after (POST) the half marathon. At POST, PF central and peripheral alterations and changes in contact time, step frequency, STV median frequency, and impact force frequency as well as foot strike pattern were found in both MIN and MAX. No significant differences in damping, STV main frequency, flight time, duty factor, and loading rate were observed between conditions whatever the time period. During the half marathon, STV amplitude of GM significantly increased over time for the MAX condition (+13.3%) only. Differences between MIN and MAX were identified for RPE and midsole liking. It could be hypothesized that, while significant, the effect of midsole hardness on STV is too low to substantially affect NM fatigue.

Estimation of minimum foot clearance using a single foot-mounted inertial sensor and personalized foot geometry scan.

The real-world measurement of minimum foot clearance (mFC) during the swing phase of gait is critical in efforts to understand and reduce the risk of trip-and-fall incidents in populations with gait impairments. Past research has focused on measuring clearance of a single point on a person's foot, typically the toe-however, this may overestimate mFC and may even be the wrong region of the foot in cases of gait impairments or interventions. In this work, we present a novel method to reconstruct the swing-phase trajectory of an arbitrary number of points on a person's shoe and estimate the instantaneous height and location of whole-foot mFC. This is achieved using a single foot-mounted inertial sensor and personalized shoe geometry scan, assuming a rigid-body IMU-shoe system. This combination allows collection and analysis using out-of-lab tests, potentially including clinical environments. Validation of single marker location using the proposed method vs. motion capture showed height errors with bias less than 0.05 mm, and 95% confidence interval of - 8.18 to + 8.09 mm. The method is demonstrated in an example data set comparing different interventions for foot drop, and it shows clear differences among no intervention, functional electrical stimulation, and ankle-foot orthosis conditions. This method offers researchers and clinicians a rich understanding of a person's gait by providing objective 3D foot kinematics and allowing a unique opportunity to view the regions of the foot where minimum clearance occurs. This information can contribute to a more informed recommendation of specific interventions or assistive technology than is currently possible in standard clinical practice.

Role of midsole hollow structure in energy storage and return in running shoes.

Understanding the relationship between footwear features and their potential influence on running performance can inform the ongoing innovation of running footwear, aimed at pushing the limits of humans. A notable shoe feature is hollow structures, where an empty space is created in the midsole. Presently, the potential biomechanical effect of the hollow structures on running performance remains unknown. We investigated the role of hollow structures through quantifying the magnitude and timing of foot and footwear work. Sixteen male rearfoot runners participated in an overground running study in three shoe conditions: (a) a shoe with a hollow structure in the forefoot midsole (FFHS), (b) the same shoe without any hollow structure (Filled-FFHS) and (c) a shoe with a hollow structure in the midfoot midsole (MFHS). Distal rearfoot power was used to quantify the net power generated by foot and footwear together. The magnitude and timing of distal rearfoot work and ankle joint work were compared across shoe conditions. The results indicated that MFHS can significantly (p = 0.024) delay distal rearfoot energy return (3.4 % of stance) when compared to Filled-FFHS. Additionally, FFHS had the greatest positive (0.425 J/kg) and negative (-0.383 J/kg) distal rearfoot work, and the smallest positive (0.503 J/kg) and negative (-0.477 J/kg) ankle joint work among the three conditions. This showed that the size and location of the midsole hollow structure can affect timing and magnitude of energy storage and return. The forefoot hollow shoe feature can effectively increase distal rearfoot work and reduce ankle joint work during running.

Non-surgical interventions for treating osteoarthritis of the big toe joint.

BACKGROUND: Osteoarthritis (OA) affecting the first metatarsophalangeal joint (hallux rigidus) is common and painful. Several non-surgical treatments have been proposed; however, few have been adequately evaluated. Since the original 2010 review, several studies have been published necessitating this update. OBJECTIVES: To determine the benefits and harms of non-surgical treatments for big toe OA. SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search was February 2023. SELECTION CRITERIA: We included randomised trials that compared any type of non-surgical treatment versus placebo (or sham), no treatment (such as wait-and-see) or other treatment. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. The major outcomes were pain, function, quality of life, radiographic joint structure, adverse events and withdrawals due to adverse events. The primary time point was 12 weeks. We used GRADE to assess the certainty of evidence. MAIN RESULTS: This update includes six trials (547 participants). The mean age of participants ranged from 32 to 62 years. Trial durations ranged from 4 to 52 weeks. Treatments were compared in single trials as follows: arch-contouring foot orthoses versus sham inserts; shoe-stiffening inserts versus sham inserts; intra-articular injection of hyaluronic acid versus saline (placebo) injection; arch-contouring foot orthoses versus rocker-sole footwear; peloid therapy versus paraffin therapy; and sesamoid mobilisation, flexor hallucis longus strengthening and gait training plus physical therapy versus physical therapy alone. Certainty of the evidence was limited by the risk of bias and imprecision. Meta-analysis was not performed due to the heterogeneity of interventions. We reported numerical data for the 12-week time point for the three trials that used a placebo/sham control group. Arch-contouring foot orthoses versus sham inserts One trial (88 participants) showed that arch-contouring foot orthoses probably lead to little or no difference in pain, function, or quality of life compared to sham inserts (moderate certainty). Mean pain (0-10 scale, 0 no pain) with sham inserts was 3.9 points compared to 3.5 points with arch-contouring foot orthoses; a difference of 0.4 points better (95% (CI) 0.5 worse to 1.3 better). Mean function (0-100 scale, 100 best function) with sham inserts was 73.3 points compared to 65.5 points with arch-contouring foot orthoses; a difference of 7.8 points worse (95% CI 17.8 worse to 2.2 better). Mean quality of life (-0.04-100 scale, 100 best score) with sham inserts was 0.8 points compared to 0.8 points with arch-contouring foot orthoses group (95% CI 0.1 worse to 0.1 better). Arch-contouring foot orthoses may show little or no difference in adverse events and withdrawal due to adverse events compared to sham inserts (low certainty). Adverse events (mostly foot pain) were reported in 6 out of 41 people with sham inserts and 4 out of 47 people with arch-contouring foot orthoses (RR 0.58, 95% CI 0.18 to 1.92). Withdrawals due to adverse events were reported in 0 out of 41 people with sham inserts and 1 out of 47 people with arch-contouring foot orthoses (Peto OR 6.58, 95% CI 0.13 to 331). Shoe-stiffening inserts versus sham inserts One trial (100 participants) showed that shoe-stiffening inserts probably lead to little or no difference in pain, function, or quality of life when compared to sham inserts (moderate certainty). Mean pain (0-100 scale, 0 no pain) with sham inserts was 63.8 points compared to 70.1 points with shoe-stiffening inserts; a difference of 6.3 points better (95% CI 0.5 worse to 13.1 better). Mean function (0-100 scale, 100 best function) with sham inserts was 81.0 points compared to 84.9 points with shoe-stiffening inserts; a difference of 3.9 points better (95% CI 3.3 worse to 11.1 better). Mean quality of life (0-100 scale, 100 best score) with sham inserts was 53.2 points compared to 53.3 points with shoe-stiffening inserts; a difference of 0.1 points better (95% CI 3.7 worse to 3.9 better). Shoe-stiffening inserts may show little or no difference in adverse events and withdrawal due to adverse events, compared to sham inserts (low certainty). Adverse events (mostly foot pain, blisters, and spine/hip pain) were reported in 31 out of 51 people with sham inserts and 29 out of 49 people with shoe-stiffening inserts (RR 0.94, 95% CI 0.42 to 2.08). Withdrawals due to adverse events were reported in 1 out of 51 people with sham inserts and 2 out of 49 people with shoe-stiffening inserts (Peto OR 2.08, 95% CI 0.19 to 22.23). Hyaluronic acid versus placebo One trial (151 participants) showed that a single intra-articular injection of hyaluronic acid probably leads to little or no difference in pain or function compared to placebo (moderate certainty). Mean pain (0-100 scale, 0 no pain) with placebo was 72.5 points compared to 68.2 points with hyaluronic acid; a difference of 4.3 points better (95% CI 2.1 worse to 10.7 better). Mean function (0-100 scale, 100 best function) was 83.4 points with placebo compared to 85.0 points with hyaluronic acid; a difference of 1.6 points better (95% CI 4.6 worse to 7.8 better). Hyaluronic acid may provide little or no difference in quality of life (0-100 scale, 100 best score) which was 79.9 points with placebo compared to 82.9 points with hyaluronic acid; a difference of 3.0 better (95% CI 1.4 worse to 7.4 better; low certainty). There may be fewer adverse events with hyaluronic acid compared to placebo. Adverse events (mostly pain at the injection site) were reported in 43 out of 76 people with placebo compared with 27 out of 75 people with hyaluronic acid (RR 0.64, 95% CI 0.44 to 0.91; low certainty). No participants withdrew from either group due to adverse events. The effects on radiographic joint structure were not reported in any study. AUTHORS' CONCLUSIONS: The existing evidence regarding the benefits and harms of non-surgical treatments for big toe OA is limited. There is moderate-certainty evidence, based upon three single placebo/sham-controlled trials, that there are no clinically important benefits of arch-contouring foot orthoses, shoe-stiffening inserts, or a single intra-articular injection of hyaluronic acid. Further placebo-controlled trials are needed to evaluate the effectiveness of non-surgical treatments for big toe OA.

A four-week minimalist shoe walking intervention influences foot posture and balance in young adults-a randomized controlled trial.

INTRODUCTION: Minimalist shoes (MS) are beneficial for foot health. The foot is a part of the posterior chain. It is suggested that interventions on the plantar foot sole also affect the upper segments of the body. This study aimed to investigate the local and remote effects along the posterior chain of four weeks of MS walking in recreationally active young adults. METHODS: 28 healthy participants (15 female, 13 male; 25.3 ± 5.3 years; 70.2 ± 11.9 kg; 175.0 ± 7.8 cm) were randomly assigned to a control- or intervention group. The intervention group undertook a four-week incremental MS walking program, which included 3,000 steps/day in the first week, increasing to 5,000 steps/day for the remaining three weeks. The control group walked in their preferred shoe (no MS). We assessed the following parameters in a laboratory at baseline [M1], after the four-week intervention [M2], and after a four-week wash-out period [M3]: Foot parameters (i.e., Foot Posture Index-6, Arch Rigidity Index), static single-leg stance balance, foot-, ankle-, and posterior chain range of motion, and muscle strength of the posterior chain. We fitted multiple hierarchically built mixed models to the data. RESULTS: In the MS group, the Foot Posture Index (b = -3.72, t(51) = -6.05, p < .001, [-4.94, 2.51]) and balance (b = -17.96, t(49) = -2.56, p = .01, [-31.54, 4.37]) significantly improved from M1 to M2, but not all other parameters (all p >.05). The improvements remained at M3 (Foot Posture Index: b = -1.71, t(51) = -2.73, p = .009, [-4,94,0.48]; balance: b = -15.97, t(49) = -2.25, p = .03, [-29.72, 2.21]). DISCUSSION: Walking in MS for four weeks might be advantageous for foot health of recreationally active young adults but no chronic remote effects should be expected.

Human-in-the-loop optimization of rocker shoe to reduce plantar pressure and collision work simultaneously.

BACKGROUND: Rocker shoes can be used to reduce foot pressure and adjust lower limb kinetics for various patient population, such as people with diabetic peripheral neuropathy. Selecting adequate properties of the rocker sole is of great importance for its efficacy. This study investigated the capability of human-in-the-loop optimization (HILO) to individually optimize apex position and angle of rocker shoe to reduce peak pressure and collision work simultaneously. METHODS: Peak pressure, kinetic, and kinematic data were recorded from 10 healthy participants while walking at preferred speed wearing rocker shoes with adjustable apex position and angle. An evolutionary algorithm was used to find optimal apex parameters to reduce both peak pressure in medial forefoot and collision work. The optimized shoe (HILO shoe) was compared with generic optimal rocker settings (Chapman settings) and normal shoe. FINDINGS: Compared to normal shoe, the HILO shoe had lower plantar pressure (pHILO = 0.007; pChapman = 0.044) and Chapman shoe showed higher collision work (pHILO = 0.025; pChapman = 0.014). Both HILO and Chapman shoe had smaller push-off work than normal shoe (pHILO = 0.001; pChapman < 0.001) with the Chapman shoe exhibited earlier push-off onset (pHILO = 0.257; pChapman = 0.016). INTERPRETATION: The Human-in-the-loop optimization approach resulted in individualized apex settings which performed on average similar to Chapman settings but, were superior in selected cases. In these cases, medial forefoot could be further offloaded with apex angles larger than generic settings. The larger apex angle might increase the external ankle moment arm and push-off work. However, there is limited room for improvement on collision work compared to generic settings.

Plantar pressure reduction in the heel region through self-adjusting insoles with a heel cup in standard and individualized rocker shoes.

BACKGROUND: Effectiveness of therapeutic footwear in reducing peak pressure in persons with diabetes and loss of protective sensation to prevent diabetic foot ulcers varies due to manual production and possible changing foot structure. A previous two-way approach to address this issue, featuring individualized 3D-printed rocker midsoles and self-adjusting insoles, proved effective in the forefoot but less in the heel. To address this, new insoles incorporating a heel cup are developed. METHODS: In-shoe pressure was measured, while persons with diabetes and loss of protective sensation with high peak pressure (≥ 200 kPa) in the heel walked on a treadmill with control and individualized rocker shoe paired with control and new insole. FINDINGS: Generalized estimating equations revealed significant decrease in peak pressure in the proximal heel with the new insole alone and combined with rocker shoe compared to rocker shoe alone. For the distal heel, significant decrease in peak pressure is shown with the combination of new insole and rocker shoe compared to control shoe. For the forefoot and toes (excluding hallux) significant decrease in peak pressure is shown using the rocker shoe alone or combined with the heel cup compared to control shoe. INTERPRETATION: The new insole paired with rocker shoe is effective in reducing peak pressure in the distal heel. To have similar (or more) success in proximal heel, one could replace the rocker midsole with more compliant materials. The rocker shoe used separately or combined with a heel cup effectively reduces the peak pressure in the forefoot and other toes.

Upcycling of industrial footwear waste into nonwoven fibrous structures with thermal and acoustic insulation properties.

The footwear industry significantly impacts the environment, from raw material extraction to waste disposal. Transforming waste into new products is a viable option to mitigate the environmental consequences, reducing the reliance on virgin raw materials. This work aims to develop thermal and acoustic insulation materials using polyester waste from footwear industry. Two nonwoven and two compressed nonwoven structures, comprising 80% polyester waste and 20% commercial recycled polyester (matrix), were produced. The materials were created through needle-punching and compression molding techniques. The study included the production of sandwich and monolayer nonwoven structures, which were evaluated considering area weight, thickness, air permeability, mechanical properties, morphology using field emission scanning electron microscopy, and thermal and acoustic properties. The nonwoven samples presented high tensile strength (893 kPa and 629 kPa) and the highest strain (79.7% and 73.3%) and compressed nonwoven structures showed higher tensile strength (2700 kPa and 1291 kPa) but reduced strain (25.8% and 40.8%). Nonwoven samples showed thermal conductivity of 0.041 W/K.m and 0.037 W/K.m. Compressed nonwoven samples had higher values at 0.060 W/K.m and 0.070 W/K.m. While the sample with the highest conductivity exceeds typical insulation levels, other samples are suitable for thermal insulation. Nonwoven structures exhibited good absorption coefficients (0.640-0.644), suitable for acoustic insulation. Compressed nonwoven structures had lower values (0.291-0.536), unsuitable for this purpose. In summary, this study underscores the potential of 100% recycled polyester structures derived from footwear and textile industry waste, showcasing remarkable acoustic and thermal insulation properties ideal for the construction sector.

AI-Assisted Insole Sensing System for Multifunctional Plantar-Healthcare Applications.

The pervasive global issue of population aging has led to a growing demand for health monitoring, while the advent of electronic wearable devices has greatly alleviated the strain on the industry. However, these devices come with inherent limitations, such as electromagnetic radiation, complex structures, and high prices. Herein, a Solaris silicone rubber-integrated PMMA polymer optical fiber (S-POF) intelligent insole sensing system has been developed for remote, portable, cost-effective, and real-time gait monitoring. The system is capable of sensitively converting the pressure of key points on the sole into changes in light intensity with correlation coefficients of 0.995, 0.952, and 0.910. The S-POF sensing structure demonstrates excellent durability with a 4.8% variation in output after 10,000 cycles and provides stable feedback for bending angles. It also exhibits water resistance and temperature resistance within a certain range. Its multichannel multiplexing framework allows a smartphone to monitor multiple S-POF channels simultaneously, meeting the requirements of convenience for daily care. Also, the system can efficiently and accurately provide parameters such as pressure, step cadence, and pressure distribution, enabling the analysis of gait phases and patterns with errors of only 4.16% and 6.25% for the stance phase (STP) and the swing phase (SWP), respectively. Likewise, after comparing various AI models, an S-POF channel-based gait pattern recognition technique has been proposed with a high accuracy of up to 96.87%. Such experimental results demonstrate that the system is promising to further promote the development of rehabilitation and healthcare.

Gait classification of knee osteoarthritis patients using shoe-embedded internal measurement units sensor.

BACKGROUND: Knee osteoarthritis negatively affects the gait of patients, especially that of elderly people. However, the assessment of wearable sensors in knee osteoarthritis patients has been under-researched. During clinical assessments, patients may change their gait patterns under the placebo effect, whereas wearable sensors can be used in any environment. METHODS: Sixty patients with knee osteoarthritis and 20 control subjects were included in the study. Wearing shoes with an IMU sensor embedded in the insoles, the participants were required to walk along a walkway. The sensor data were collected during the gait. To discriminate between healthy and knee osteoarthritis patients and to classify different subgroups of knee osteoarthritis patients (patients scheduled for surgery vs. patients not scheduled for surgery; bilateral knee osteoarthritis diagnosis vs. unilateral knee osteoarthritis diagnosis), we used a machine learning approach called the support vector machine. A total of 88 features were extracted and used for classification. FINDINGS: The patients vs. healthy participants were classified with 71% accuracy, 85% sensitivity, and 56% specificity. The "patients scheduled for surgery" vs. "patients not scheduled for surgery" were classified with 83% accuracy, 83% sensitivity, and 81% specificity. The bilateral knee osteoarthritis diagnosis vs. unilateral knee osteoarthritis diagnosis was classified with 81% accuracy, 75% sensitivity, and 79% specificity. INTERPRETATION: Gait analysis using wearable sensors and machine learning can discriminate between healthy and knee osteoarthritis patients and classify different subgroups with reasonable accuracy, sensitivity, and specificity. The proposed approach requires no complex gait factors and is not limited to controlled laboratory settings.

Biomechanical Investigation of Lower Limbs during Slope Transformation Running with Different Longitudinal Bending Stiffness Shoes.

BACKGROUND: During city running or marathon races, shifts in level ground and up-and-down slopes are regularly encountered, resulting in changes in lower limb biomechanics. The longitudinal bending stiffness of the running shoe affects the running performance. PURPOSE: This research aimed to investigate the biomechanical changes in the lower limbs when transitioning from level ground to an uphill slope under different longitudinal bending stiffness (LBS) levels in running shoes. METHODS: Fifteen male amateur runners were recruited and tested while wearing three different LBS running shoes. The participants were asked to pass the force platform with their right foot at a speed of 3.3 m/s ± 0.2. Kinematics data and GRFs were collected synchronously. Each participant completed and recorded ten successful experiments per pair of shoes. RESULTS: The range of motion in the sagittal of the knee joint was reduced with the increase in the longitudinal bending stiffness. Positive work was increased in the sagittal plane of the ankle joint and reduced in the keen joint. The negative work of the knee joint increased in the sagittal plane. The positive work of the metatarsophalangeal joint in the sagittal plane increased. CONCLUSION: Transitioning from running on a level surface to running uphill, while wearing running shoes with high LBS, could lead to improved efficiency in lower limb function. However, the higher LBS of running shoes increases the energy absorption of the knee joint, potentially increasing the risk of knee injuries. Thus, amateurs should choose running shoes with optimal stiffness when running.

Curved carbon-plated shoe may further reduce forefoot loads compared to flat plate during running.

Using a curved carbon-fiber plate (CFP) in running shoes may offer notable performance benefit over flat plates, yet there is a lack of research exploring the influence of CFP geometry on internal foot loading during running. The objective of this study was to investigate the effects of CFP mechanical characteristics on forefoot biomechanics in terms of plantar pressure, bone stress distribution, and contact force transmission during a simulated impact peak moment in forefoot strike running. We employed a finite element model of the foot-shoe system, wherein various CFP configurations, including three stiffnesses (stiff, stiffer, and stiffest) and two shapes (flat plate (FCFP) and curved plate (CCFP)), were integrated into the shoe sole. Comparing the shoes with no CFP (NCFP) to those with CFP, we consistently observed a reduction in peak forefoot plantar pressure with increasing CFP stiffness. This decrease in pressure was even more notable in a CCFP demonstrating a further reduction in peak pressure ranging from 5.51 to 12.62%, compared to FCFP models. Both FCFP and CCFP designs had a negligible impact on reducing the maximum stress experienced by the 2nd and 3rd metatarsals. However, they greatly influenced the stress distribution in other metatarsal bones. These CFP designs seem to optimize the load transfer pathway, enabling a more uniform force transmission by mainly reducing contact force on the medial columns (the first three rays, measuring 0.333 times body weight for FCFP and 0.335 for CCFP in stiffest condition, compared to 0.373 in NCFP). We concluded that employing a curved CFP in running shoes could be more beneficial from an injury prevention perspective by inducing less peak pressure under the metatarsal heads while not worsening their stress state compared to flat plates.

Heart rate and heart rate variability in horses undergoing hot and cold shoeing.

Heart rate variability (HRV) is a frequently used indicator of autonomic responses to various stimuli in horses. This study aimed to investigate HRV variables in horses undergoing cold (n = 25) or hot (n = 26) shoeing. Multiple HRV variables were measured and compared between horses undergoing cold and hot shoeing, including the time domain, frequency domain, and nonlinear variables pre-shoeing, during shoeing, and at 30-minute intervals for 120 minutes post-shoeing. The shoeing method interacted with time to change the HRV variables standard deviation of RR intervals (SDNN), root mean square of successive RR interval differences (RMSSD), very-low-frequency band, low-frequency band (LF), the LF to high-frequency band ratio, respiratory rate, total power, standard deviation perpendicular to the line of identity (SD1), and standard deviation along the line of identity (SD2). SDNN, RMSSD, and total power only increased 30 minutes after hot shoeing (all p < 0.05). Triangular interpolation of normal-to-normal intervals (TINN) and the HRV triangular index increased during and up to 120 minutes after hot shoeing (p < 0.05-0.001). TINN increased only during cold shoeing (p < 0.05). LF increased 30 and 60 minutes after hot shoeing (both p < 0.05). SD1 and SD2 also increased 30 minutes after hot shoeing (both p < 0.05). SDNN, TINN, HRV triangular index, LF, total power, and SD2 were higher in hot-shoed than cold-shoed horses throughout the 120 minutes post-shoeing. Differences in HRV were found, indicating increased sympathovagal activity in hot shoed horses compared to cold shoed horses.