Insole Research Articles

Impact of Silicone Arch Support on Energy Expenditure in Flexible Flatfeet Employees

Background: Flat feet, or pes planus, is a common condition affecting approximately 20-30% of the general population, leading to muscle tension and instability that can impact energy expenditure during walking. Objective: To evaluate the effectiveness of Silicone Medial Arch Support in reducing energy expenditure during walking in individuals with flat feet compared to a control group. Methods: A total of 32 participants with flexible flat feet were selected through random sampling. This study employed a quasi-experimental design with a control group using a sham insole and an intervention group using silicone medial arch support for two months. Energy expenditure was measured using VO? max. The average energy expenditure before using silicone medial arch support was 36.76 ± 5.03 ml/kg/min, which increased to 39.75 ± 4.05 ml/kg/min post-intervention (p < 0.001). For the sham insole group, the energy expenditure was 34.67 ± 2.44 ml/kg/min before and 34.87 ± 2.20 ml/kg/min after the intervention (p = 0.183). Results: The use of silicone medial arch support resulted in a significant increase in energy expenditure compared to the sham insole group (p < 0.001). Conclusion: The study concludes that silicone medial arch support can reduce energy expenditure during walking in individuals with flat feet. These results suggest that incorporating well-designed arch support interventions can significantly improve biomechanical efficiency and comfort for individuals with flat feet. Future interventions should consider individual variations in foot morphology and activity levels to optimize support design, potentially integrating adjustable or customizable insoles to better address the diverse needs of this population.

Clinical Efficacy of a Contralateral Shoe Lift in Patients with Diabetic Foot Ulcers and Induced Limb-Length Discrepancies: A Randomized Controlled Trial.

Objective: To evaluate the clinical efficacy of combining an offloading device with a contralateral shoe lift to compensate for induced limb-length discrepancies in participants with plantar diabetes-related foot ulcers. Approach: Between March 2021 and December 2023, 42 consecutive patients with active plantar diabetic foot ulcers (DFUs) were randomly assigned (1:1) to the treatment group (limb-length discrepancy compensation with a shoe lift in the therapeutic footwear of the contralateral limb) or a control group that did not receive limb-length discrepancy compensation. Primary outcomes included the 20-week wound-healing rate and wound area reduction. Secondary outcomes included minor amputation, new ulcers in the contralateral limb, perceived comfort, and hip pain. Results: On an intention-to-treat basis, 15 participants in the control and 19 in the treatment group showed ulcer healing (p = 0.0023). In those with >80% adherence to the offloading device, multivariate analysis showed that the shoe lifts improved ulcer healing time. The use of a shoe lift reduced the number of minor amputations and the occurrence of new ulcers in the contralateral limb (p = 0.035; p = 0.033 respectively). Hip pain and perceived comfort improved with the use of shoe lifts (p < 0.001). Innovation: It validates the use of shoe lifts for patients with DFUs, as it is the first largest study of its kind to establish a clear reference standard to guide clinician decision-making. Conclusion: The use of shoe lifts reduced healing time in participants with diabetes and active plantar foot ulcers. Shoe lifts reduce late complications, including new ulcers in the contralateral limb and minor amputations.

An Innovative Approach to Enhance the Durability and Sustainability of Shoe Insoles

This study presents an innovative approach to designing a shoe insole with enhanced durability, sustainability, and antibacterial properties. Needle-punched non-woven recycled polyester fabrics with three different GSMs (100, 200, and 300) were developed. The composite shoe insole was developed using non-woven fabric laminated with a polyurethane sheet to enhance durability. The fabrics were treated with an antibacterial finish with three different concentrations (5%, 10%, and 15%) and subjected to 5 and 10 washing cycles. The developed composites were evaluated against their relative hand value, abrasion resistance, tensile strength, antibacterial activity, and overall moisture management capability. Overall results reveal that the developed composite shoe insole is durable, sustainable, and presents no bacterial growth, demonstrating the insole’s hygienic effectiveness.

An expository analysis of biomechanical and subjective impacts induced by shoe inserts in asymptomatic subjects: A systematic review on functionality and mechanisms of action

AbstractThis systematic review explores the biomechanical and subjective effects of shoe inserts, including foot orthotics (FOs) and insoles, in asymptomatic subjects. Aimed at understanding their implications, the review poses two key research questions: (i) the influence of shoe inserts on lower extremity biomechanics and subjective perception and (ii) the effects of different design characteristics on these aspects. Following Preferred Reporting of Systematic Reviews and Meta‐Analysis guidelines, a meticulous search of Scopus and PubMed from August 2022 to March 2023 yielded 34 articles, with 26 focusing on biomechanical effects and eight on comfort effects. The studies, conducted during static and dynamic activities, such as standing, walking, jogging, running, jumping, and cycling, reveal significant reductions in rearfoot eversion, knee joint forces, and lower extremity muscle forces through postings and wedging in FOs. Changes in stiffness impact rearfoot kinematics, plantar pressure distribution, and ankle–foot power distribution. Conversely, surface texture and arch variations demonstrate limited significance. FOs and shoe inserts, characterized by geometric, material, location, size, and fabrication features, effectively regulate forces and moments on the lower extremity. This control promotes uniform plantar pressure distribution and enhances comfort during various activities. These insights benefit manufacturers, clinicians, and stakeholders, providing a deeper understanding of the positive benefits of FOs and shoe inserts. However, further well‐designed studies on clinical populations are necessary to validate these findings and establish their clinical efficacy, as the current focus remains on healthy subjects.

Contribution of the plantar fascia and long plantar ligaments to the stability of the longitudinal arch of the foot

The contribution of the Plantar Fascia (PF) and Long Plantar Ligament (LPL), two ligaments extending from the hindfoot to the forefoot, to arch stability has been studied in the past using in vivo, in vitro, and in silico methodologies. In silico studies were based on one single model obtained from one single subject and did not account for the known inter-subject morphological and biomechanical variations. In the present study, we developed computational dynamic models of nine different legs obtained from nine different individuals to evaluate the role of the LPL and PF in arch support, accounting for biological differences between subjects. These models were validated by comparing the simulation results against experimental results from the corresponding cadaver legs. After validation, we simulated body weight conditions for each model by applying a vertical load to the tibia, starting from zero and increasing linearly to 720 N. Kinematic and dynamic parameters, including the variation of the medial arch angle and of the navicular height, as well as the passive forces developed by the LPL and PF, were used to evaluate the contribution of these ligaments to arch support under body weight. The results indicate that a total collapse of the medial longitudinal arch occurred only when both the LPL and PF were absent, but a stable arch was maintained when either one of these two ligament structures were present. The results varied significantly among the specific models, highlighting the importance of using multiple models to account for inter-subject morphological differences.

Electrifying waste textiles: Transforming fabric scraps into high-performance triboelectric nanogenerators for biomechanical energy harvesting

Textiles are an integral part of daily life globally, but their widespread use leads to significant waste generation. Repurposing these discarded fabrics for energy harvesting offers a sustainable solution to both energy demand and textile waste management. In this study, Textile-based Triboelectric Nanogenerators (T-TENGs) were developed using recycled cloth as tribopositive layers and polyvinyl chloride (PVC) film as the tribonegative layer, with aluminum foil tape serving as electrodes. Five different recycled textiles were evaluated, and Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) analysis revealed a correlation between yarn structure and carbon content, leading to enhanced triboelectric performance. Silk-based TENG (S-TENG) demonstrated the highest output, with 320.76 V and 8.73 µA, while exhibiting stable performance over 10,000 cycles. Practical applications were explored by integrating T-TENGs into shoe insoles for energy harvesting during walking and jumping, with rayon-based TENG generating up to 208.52 V on a PVC coil mat. This work highlights the dual benefits of waste reduction and sustainable energy applications, making a compelling case for advanced technologies where recycled textiles function as frictional materials to harvest mechanical energy from human motion and convert it into electrical energy for use in flexible sensors and wearable devices.

Physical characteristics inducing Sever's disease in junior gymnasts

ObjectiveThis prospective cohort study aimed to determine characteristics contributing to the development of Sever's disease in junior gymnasts. MethodsThis study included 74 limbs from 37 junior gymnasts. The Baseline demographic data, flexibility measurements, foot alignments, trunk function tests, and functional balancing tests were used for evaluation. The incidence of Sever's disease among this cohort was assessed for six months after the first evaluations. We categorized those diagnosed by medical specialists as having Sever's disease into a Sever's disease group, while those with no foot pain or other diagnosed pathologies were in a no-symptom group. ResultsThe Junior gymnasts with Sever's disease had a lower arch height ratio and lower anterior star excursion balance test values. ConclusionsSever's disease in junior gymnasts may be potentially prevented through using a medial longitudinal arch support and/or undertaking dynamic postural balance training.

Weaving fiber-based triboelectric nanogenerators and yarn-based sweat-activated batteries for dry-wet bimodal power supply in textile electronics

Textile-based energy systems, which can provide sustainable power in both dry and wet conditions, are ideal for wearable devices, especially electronic textiles used for motion monitoring, and have attracted much interest in recent years. In this work, we developed a hybrid energy fabric woven with fiber-based triboelectric nanogenerators (F-TENGs) and yarn-based sweat-activated batteries (Y-SABs) to achieve a dry-wet bimodal power supply. Single-electrode core-sheath F-TENGs were fabricated as dry-state energy harvesters, which could respond sensitively to repeated skin contact to produce transient spikes of open-circuit voltage and short-circuit current at 30 V and 2 µA, respectively. Since the wetting of the F-TENGs could result in a remarkable degradation of the triboelectric performance, coaxial Y-SABs with the output voltage of 0.58 V (external load=2 kΩ) were manufactured to supply power in the wet state sustainably. Both devices withstood 1500 times bending/twisting and 20 times machine washing. The F-TENGs and the Y-SABs were integrated with the conventional weaving technique to obtain a plain structured fabric, in which the TENG and SAB regions could successively generate electricity to power electronic devices under repeated skin contacts in the dry state and NaCl-solution activation in the wet state, respectively, without affecting each other. The hybrid energy fabric was further integrated into a shoe insole and a T-shirt for the on-body trials. During the volunteer’s running process, the system could provide electricity to charge a capacitor or illuminate LEDs in sweatless and sweaty conditions, demonstrating its great potential as a reliable and sustainable dry-wet bimodal power source in wearable applications.

Biomechanical effect between conventional and 3-dimensional printed customized foot orthoses on medial longitudinal arch support and rearfoot angle in adults with flexible flatfeet.

Customized foot orthoses are used to treat flexible flatfoot regarding medial longitudinal arch (MLA) support, alignment correction, and pain management. Recently, 3-dimensional (3D) printing orthosis has become the focus of discussion regarding function and manufacturing. We aimed to investigate differences in biomechanical effects between flat insole (Flat), conventional foot orthosis (Cinsole), and 3D printed foot orthosis (3Dinsole) use on MLA support and rearfoot alignment during walking in adult flexible flatfeet. Twelve men with flexible flatfoot were recruited. Data were collected and analyzed using a Vicon motion capture system under 3 trial conditions: Flat and >1 month after using Cinsole and 3Dinsole. Repeated-measures analysis of variance with Bonferroni post hoc tests was used to compare kinematics variables, foot pain, and satisfaction. Dynamic navicular drop significantly reduced with the use of the Cinsole and 3Dinsole compared with Flat (P < 0.001; ηp2 = 0.65). The maximum rearfoot eversion angle with the use of the Cinsole and 3Dinsole significantly reduced from Flat (P < 0.001; ηp2 = 0.56). Foot pain score significantly decreased after using foot orthoses; satisfaction between Cinsole and 3Dinsole was not significantly different. Thus, Cinsole and 3Dinsole are effective alternative treatments of MLA support and rearfoot alignment in adults with flexible flatfoot. 3D printing is a future technology with potential to replace conventional production methods. However, material characteristics, design, and manufacturing process can affect treatment outcomes; hence, our results may not represent all variations of 3D printed foot orthoses.

Microwave Radiation Assisted Construction of Fused Deposition Modeling 3D Printing Flexible Sensors

AbstractWith the rapid development of the internet of things, the simple preparation of sensors has become a challenge. The present work presents the simple preparation of flexible sensors by using the fused deposition modeling (FDM) 3D printing combined with the microwave radiation‐assisted treatment of the thermoplastic polyurethane (TPU) with carbon nanotubes (CNTs) as conductive fillers to create the flexible sensors. The as‐prepared TPU/CNT composites exhibit the 7.27 MPa tensile strength and 401% elongation at break, similar to those of the pure TPU. After 200 tensile cycles, the TPU/CNT composites can still stably convert pressure into electrical signals, which can be used as flexible sensors with high sensitivity (0.879 kPa−1). In addition, shoe insoles and finger cover with sensing performance are fabricated through the FDM 3D printing technology, demonstrating the potential of the sensors to monitor human gait, finger straightening, and bending movements. The as‐proposed method involves the embedding CNTs as conductive fillers on the surface of TPU to form the TPU/CNT composite conductive layers on the surface of TPU, which is beneficial for maintaining the elasticity of the polymer matrix. The challenges in preparing stable, low‐cost, and scalable flexible sensors and highlights of the advantages of 3D printing technology in manufacturing flexible piezoresistive sensors are also deeply discussed.

Effect of Medial Arch Support Foot Orthosis on Pressure Distribution and Peak Pressure in Women with Hallux Valgus

Effect of Medial Arch Support Foot Orthosis on Pressure Distribution and Peak Pressure in Women with Hallux Valgus

Antibacterial Efficiency of Quaternary Ammonium Silane-Coated Shoe Insoles Using the Sol-Gel Technique

Antibacterial Efficiency of Quaternary Ammonium Silane-Coated Shoe Insoles Using the Sol-Gel Technique

Prefabricated contoured foot orthoses to reduce pain and increase physical activity in people with hip osteoarthritis: A randomised feasibility trial.

Hip osteoarthritis (OA) is a prevalent and burdensome condition that leads to impaired quality of life and a substantial economic burden. Encouraging physical activity, particularly walking, is crucial for OA management, but many individuals with hip OA fail to meet recommended activity levels. Prefabricated contoured foot orthoses have shown promise in improving hip muscle efficiency during walking in laboratory settings, but their real-world feasibility and efficacy remain uncertain. The aim of this study was to assess the feasibility of conducting a fully powered randomised controlled trial (RCT) to evaluate the effectiveness of prefabricated contoured foot orthoses, prescribed via telehealth, in people with hip OA. This feasibility trial randomised 27 participants with hip OA into two groups: prefabricated contoured foot orthoses or flat shoe inserts. Feasibility outcomes were assessed, including recruitment rate, adherence, logbook completion, and dropout rate. Patient-reported outcomes and accelerometer-measured physical activity were collected as secondary outcomes. While the recruitment rate was low (0.88 people/week), adherence to the intervention (59%), logbook completion (93%), and dropout rates (7%) met or exceeded our predefined feasibility parameters. Participants found the intervention acceptable, and practicality was demonstrated with minor adverse events. Preliminary efficacy testing indicated that prefabricated contoured foot orthoses positively affected physical activity (adjusted mean difference=2590 [260 to 4920] steps/day), with comparable outcomes for hip-related quality of life and pain. This trial supports proceeding to a fully powered RCT to assess the effect of teleheath prescribed prefabricated contoured foot orthoses on physical activity in people with hip OA. National Institutes of Health Trial Registry (NCT05138380).

Self-Powered Wearable Pressure Sensor System for Smart Healthcare Applications

Wearable sensors mark a groundbreaking advancement in the realm of health monitoring technology. However, traditional wearable devices lack comprehensive solutions for tracking sports exercise behaviors and providing feedback on rehabilitation for those undergoing home-based recovery. To bridge this gap, a self-powered triboelectric nanogenerator (TENG)-based wearable sensing system has been developed with in-house monitoring capabilities. The wearable sensor system is composed of triboelectric pressure sensors with an electro-conductive silicone sheet and patterned Ecoflex film as the contact layers. Highly sensitive TENG sensors have been successfully embedded into a bicycle saddle and human shoe insole for real-time pressure monitoring. Experimental results demonstrate that biomechanical energy, originating from both the pelvic-saddle interactions on bicycle and human gait movements, has been successfully converted into electrical energy. The generated sensor voltage remains stable under frequency variations and external environmental conditions, such as temperature and humidity variations. Utilizing distinctive information contained in individual body mass imbalances and gait characteristics, a smart healthcare monitoring system is envisioned to extract essential biomechanical insights via artificial intelligence, facilitating a pivotal role in in-house monitoring and tracking of sports rehabilitation exercises. The as-designed low-cost, highly scalable self-powered wearable sensor system offers an accessible, user-friendly point-of-care solution for gait detection and rehabilitation monitoring for individuals with various physical impairments, with considerable potential for commercialization. Figure 1

Modeling of Human-Induced Dynamic Bouncing Force Using a Self-Sustained Nonlinear Oscillator

This paper proposed a single-degree-of-freedom self-sustained nonlinear oscillator capable of precisely predicting the bouncing force induced by a person during bouncing activity on a flat and rigid surface. A bouncing person produces essential internal energy required to maintain its motion, so it can be modeled as a self-sustained oscillator that can generate (i) the stable limit cycle, (ii) the periodic bouncing force signal, and (iii) the self-sustained motion. A hybrid Van der Pol–Rayleigh oscillator added with two quadratic and one cubic nonlinear terms has been derived to yield desired softening and hardening effects as well as even and odd harmonics, as observed from the analysis of experimental bouncing force data. The force applied on the surface corresponds to its restoring force. The stability analysis of the oscillator has been performed using the energy balance and perturbation methods. The model parameters are extracted from the experimental bouncing force data resulting from a bouncing test on a group of seven subjects with shoe insoles at six different frequencies guided by a metronome. The bootstrapping method has been performed to examine the convergence of mean values of each model parameter by increasing the cardinality of the experimental set. The bouncing force signals produced by the proposed model and experimental results demonstrate an excellent agreement.

Comparison by ultrasound shear wave elastography of toe flexor muscle contraction during MTP flexion exercise and short-foot exercise.

The intrinsic foot muscles play an important role in medial longitudinal arch support, as well as several extrinsic foot muscles. While various strength training methods specific to intrinsic foot muscles have been conducted, these exercises are associated with certain concerns regarding their effectiveness and difficulty. We developed a new exercise for the intrinsic muscles (MTP flexion exercise). The aim was to compare the shear modulus of the toe flexors as the muscle contraction activity during MTP flexion and short-foot exercises using ultrasound shear wave elastography. Eleven healthy participants were included in this study. The shear modulus of the toe flexor muscles was measured during MTP flexion and short-foot exercises using ultrasound shear wave elastography. The muscle shear modulus was statistically compared between the resting phase, and during the two exercises. The shear modulus during MTP flexion exercise was significantly greater than in the resting phase in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, and flexor digitorum longus. The flexor digitorum longus showed greater shear modulus during MTP flexion exercise than during short-foot exercise. MTP flexion exercise showed equivalent or greater contraction activity in certain intrinsic and extrinsic foot muscles when compared with short-foot exercise. This exercise is considered one of the training options for strengthening the intrinsic muscles of the foot.

Application of ARIZ-85C to Solve Shoe Insole Problems

Application of ARIZ-85C to Solve Shoe Insole Problems

Determination of the type of arched carbon fiber reinforced fastening of the preparatory opening for the conditions of the «Dniprovska» mine in weakly metamorphized rocks

The object of study is an arched carbon fiber-reinforced support of constant cross-section in a layered massif of weakly metamorphosed rocks. The article presents an analysis of the possible use of arched fiber-reinforced support of constant cross-section in a layered massif of weakly metamorphosed rocks for the conditions of the «Dniprovska» mine (Ukraine) around the preparatory opening. An analysis of the stability of mine openings in Western Donbas mines has shown that it is necessary to modernize the support system by introducing carbon fiber. The main reason for the low stability of the opening is the insufficient load-bearing capacity of the support, while its technical characteristics do not take into account the complex mining and geological conditions. The increase in stresses at mining depth is associated with impact safety, which is a serious problem during mining. Metal arch supports are deformable and have high rock loads and require a high level of energy absorption, i. e., to be very strong and flexible to withstand significant loads and avoid large displacements of the opening walls. Carbon fiber-reinforced plastic is able to ensure the stability of the fastening system and eliminate the existing disadvantages of typical metal arch fasteners, namely, high labour intensity, low production speed and high weight of the structure. In this article, the stress-strain state for the specified conditions and the carbon fiber-reinforced plastic arch support of constant cross-section was analyzed using the SolidWorks software product, taking into account the physical and mechanical properties of carbon fiber-reinforced plastic and layered rocks. Taking into account the results of laboratory tests of an equivalent layered array on a press made of PLA and carbon fiber, the dependence of deformations of the equivalent array with increasing load was established. The use of arched carbon fiber supports of various cross-sections can ensure the opening stability by reducing the intensity of stresses around its contour. On the basis of this study, a rational arched composite support of constant cross-section was proposed for the conditions of the «Dniprovska» mine. The obtained results indicate the need for further research, which will be considered in the author's future works.

Ferroelectric catalytic BaTiO3‐based composite insoles to promote healing of infected wounds: Analysis of antibacterial efficacy and angiogenesis

AbstractOur feet are often subjected to moist and warm environments, which can promote the growth of harmful bacteria and the development of severe infection in wounds located in the foot. As a result, there is a need for new and innovative strategies to safely sterilize feet, when shoes are worn, to prevent any potential foot‐related diseases. In this paper, we have produced a non‐destructive, biocompatible and convenient‐to‐use insole by embedding a BaTiO3 (BT) ferroelectric material into a conventional polydimethylsilane (PDMS) insole material to exploit a ferroelectric catalytic effect to promote the antibacterial and healing of infected wounds via the ferroelectric charges generated during walking. The formation of reactive oxygen species generated through a ferroelectric catalytic effect in the PDMS‐BT composite is shown to increase the oxidative stress on bacteria and decrease both the activity of bacteria and the rate of formation of bacterial biofilms. In addition, the ferroelectric field generated by the PDMS‐BT insole can enhance the level of transforming growth factor‐beta and CD31 by influencing the endogenous electric field of a wound, thereby promoting the proliferation, differentiation of fibroblasts and angiogenesis. This work therefore provides a new route for antimicrobial and tissue reconstruction by integrating a ferroelectric biomaterial into a shoe insole, with significant potential for health‐related applications.

Does plantar pressure in short-term standing differ between modular insoles selected based upon preference or matched to self-reported foot shape?

Prolonged workplace standing is commonplace and associated with a range of lower limb issues. Evaluating footwear interventions aiming to modify plantar pressure during standing is essential as the body is static, creating a different requirement for footwear. Previous research associates medial midfoot pressure with greater perceived comfort and identifies arch height as the most variable element of foot shape. Targeting footwear mass customization within this area may better address differences within the target wearers. This study aims to evaluate a modular insole system for its ability to modify plantar pressure during standing. Twenty-five participants completed a static and dynamic standing protocol for 60 seconds whilst measuring in-shoe peak and mean plantar pressure (KPa) and contact area (%). Individuals wore three insole options targeted towards different medial arch shapes (A– low arch, B– medium arch, C– high arch) and rated them for comfort. Participants received guidance to self-identify foot shape (low, medium, or high arch). Comparisons were drawn across the three insole profiles and between the insole rated as most comfortable (preferred), and the insole that matched the self-identified foot shape (matched). As insole arch height increased, medial midfoot pressure and contact area significantly increased, alongside significant reductions in first metatarsal pressure and contact. Preference was spread across insoles A, B, and C (56%, 32%, 12% of participants, respectively). Sixteen participants had different matched and preferred insoles, with significantly greater medial midfoot pressure and contact in the matched insole. The modular insole enabled different wear experiences, however, results suggest that individuals selected insoles lower than their foot shape. Providing adequate medial arch support enables redistribution of pressure which may enable greater comfort during the workday.