Search Results (111)

Diabetic foot ulcers (DFUs) represent a critical global health issue, necessitating the development of advanced smart, flexible, and wearable sensors for continuous monitoring that are reimbursable within foot orthotics. This study presents the design and characterization of a pressure sensor implemented into a shoe insole to monitor diabetic wound pressures, emphasizing the need for a high sensitivity, durability under cyclic mechanical loading, and a rapid response time. This investigation focuses on the electrical and mechanical properties of carbon nanotube (CNT) composites utilizing Ecoflex and polydimethylsiloxane (PDMS). Morphological characterization was conducted using Transmission Electron Microscopy (TEM), Laser Confocal Microscopy, and Scanning Electron Microscopy (SEM). The electrical and mechanical properties of the CNT/Ecoflex- and the CNT/PDMS-based sensor composites were then investigated. CNT/Ecoflex was then further evaluated due to its lower variability performance between cycles at the same pressure, as well as its consistently higher capacitance values across all trials in comparison to CNT/PDMS. The CNT/Ecoflex composite sensor showed a high sensitivity (2.38 to 3.40 kPa⁻¹) over a pressure sensing range of 0 to 68.95 kPa. The sensor’s stability was further assessed under applied pressures simulating human weight. A custom insole prototype, incorporating 12 CNT/Ecoflex elastomeric matrix-based sensors (as an example) distributed across the metatarsal heads, midfoot, and heel regions, was developed and characterized. Capacitance measurements, ranging from 0.25 pF to 60 pF, were obtained across N = 3 feasibility trials, demonstrating the sensor’s response to varying pressure conditions linked to different body weights. These results highlight the potential of this flexible insole prototype for precise and real-time plantar surface monitoring, offering an approachable avenue for a challenging diabetic orthotics application. Full article

This systematic review, registered in PROSPERO (CRD42025101243), aimed to evaluate how specific badminton shoe design features influence lower-limb biomechanics, injury risk, and sport-specific performance. A comprehensive search in six databases yielded 445 studies, from which 10 met inclusion criteria after duplicate removal and eligibility screening. The reviewed studies focused on modifications involving forefoot bending stiffness, torsional stiffness, lateral-wedge hardness, insole and midsole hardness, sole structure, and heel curvature. The most consistent biomechanical benefits were associated with moderate levels of forefoot and torsional stiffness (e.g., 60D) and rounded heel designs. Increased forefoot bending stiffness was associated with reduced foot torsion and knee loading during forward lunges. Torsional stiffness around 60D provided favorable ankle support and reduced knee abduction, suggesting potential protection against ligament strain. Rounded heels reduced vertical impact forces and promoted smoother knee–ankle coordination, especially in experienced athletes. Lateral-wedge designs improved movement efficiency by reducing contact time and enhancing joint stiffness. Harder midsoles, however, resulted in increased impact forces upon landing. Excessive stiffness in any component may restrict joint mobility and responsiveness. Studies included 127 male-dominated (aged 18–28) competitive athletes, assessing kinematics, impact forces, and coordination during sport-specific tasks. The reviewed studies predominantly involved male participants, with little attention to sex-specific biomechanical differences such as joint alignment and foot structure. Differences in testing methods and movement tasks further limited direct comparisons. Future research should explore real-game biomechanics, include diverse athlete populations, and investigate long-term adaptations. These efforts will contribute to the development of performance-enhancing, injury-reducing badminton shoes tailored to the unique demands of the sport. Full article

Background: Defects of the foot and ankle area pose a significant challenge for both patients and surgeons. While the primary objective of microvascular free flap reconstructions of lower leg defects is limb preservation, there should be an effort to obtain the best functional and aesthetic results possible and to restore the patient’s quality of life. The aim of this study was to investigate the long-term post-operative functional outcome, health-related quality of life, scar quality, and aesthetic satisfaction in patients following microsurgical reconstructions of defects of the foot and ankle area. Methods: We conducted a monocentric, controlled cohort study of adult patients who underwent microsurgical reconstructions for defects of the foot and ankle area between 2006 and August 2022 at our department. As a control, we recruited healthy individuals. Patient-Reported Outcome Measures questionnaires were used to assess long-term results regarding functionality (LEFS: Lower Extremity Functional Scale), health-related quality of life (SF-36: Short-Form 36 Health Survey Questionnaire), scar quality (PSAS: Patient Scar Assessment Scale), aesthetic satisfaction (Aesthetic Likert Scale), pain at rest and activity (10-point Numeric Rating Scale) and usage of footwear. Results: Of the 55 potential patients who had received microvascular free flaps for reconstructions of ankle and foot defects and were eligible for study inclusion, 13 (23.6%) agreed to participate in this study. The study cohort consisted of 84.6% male subjects and the mean follow-up period was 8.6 years (±5.2). Significant moderate limitations were observed with regard to physical function of the lower extremity (LEFS: 42.5 ± 20.5, p = 0.002). Significant limitations were found in the SF-36 subscales of pain (55.8 ± 34.5, p = 0.019), physical functioning (55.0 ± 29.7, p = 0.013), and physical role functioning (38.5 ± 44.0, p = 0.006). The study yielded favorable outcomes with regard to aesthetic satisfaction (14.3 ± 4.4) and scar quality (23.5 ± 13.5). Out of all the patients, 61% were required to wear orthopedic shoes or insoles. Conclusions: Patients undergoing microsurgical reconstructions for ankle and foot defects experience moderate long-term physical limitations and persistent pain during activity. Furthermore, we observed a significant long-term impact on specific physical domains of health-related quality of life, whereas mental health seems less affected. Full article

Background/Objectives: Orthoses are commonly used in the treatment of various foot and ankle injuries and deformities. An effective technology in foot orthoses is a vacuum system to improve the fit and function of the orthosis. Recently, a new technology was designed to facilitate the wearing of the foot orthoses while maintaining function without the need for vacuum suction. Methods: A plantar dynamic pressure distribution measurement was carried out in 25 healthy subjects (13 w/12 m, age 23–58 y) using capacitive measuring insoles in two differently designed inlays within the VACOpedes^® orthosis (Group A: vacuum inlay vs. Group B: XELGO^® inlay) and a regular off-the-shelf shoe (Group C, OTS). The peak plantar pressure, mean plantar pressure and maximum force were analyzed in the entire foot and in individual regions of the medial and lateral forefoot, the midfoot and the hindfoot. Finally, the wearing comfort was compared using a visual analog scale from 1 to 10 (highest comfort). Results: The peak pressure of both inlays was significantly lower than in the OTS shoe (A: 230.6 ± 44.6 kPa, B: 218.0 ± 49.7 kPa, C: 278.6 ± 50.5 kPa; p < 0.001). In a sub-analysis of the different regions, the XELGO^® inlay significantly reduced plantar pressure in the medial forefoot compared to the vacuum orthosis (A: 181.7 ± 45.7 kPa, B: 158.6 ± 51.7 kPa, p < 0.002). The wearing comfort was significantly higher with the XELGO^® inlay compared to the vacuum inlay (A: 5.68/10, B: 7.24/10; p < 0.001). Conclusions: The VACOpedes^® orthosis with a new XELGO^® inlay showed at least equivalent relief in all pressure distribution measurements analyzed and greater relief in the forefoot area than the VACOpedes^® orthosis with a vacuum inlay, as well as increased wearing comfort. Full article

Post-op shoes (POSs) are commonly used after forefoot surgery to protect the surgical site. However, there are insufficient data on their impact on forefoot load during the rollover phase of walking. This study aims to analyze the effects of a commonly used POS on plantar pressures under the forefoot and to assess whether improper usage could affect pressure patterns. Sixteen healthy volunteers underwent three different walking tests on a straight tartan track. The test setting included walking barefoot, as well as normal walking and a modified heel-accentuated “limping” gait while wearing a common POS. The pressure distribution over the forefoot regions of interest was measured using sensor insoles and a pressure-measuring plate on the ground. Results show that only the heel-accentuated “limping” gait in the POS led to a significant reduction in pressure values over all anatomical regions compared to the normal barefoot gait. Furthermore, higher pressure values were found over the lesser toes during normal walking in the POS compared to normal barefoot walking. The findings highlight that the protective function of a POS relies on proper use, specifically the correct gait pattern. If used incorrectly, POS may even have unfavorable effects on the pressure on the operated forefoot and possibly even increase the risk of delayed healing or complications in comparison to barefoot walking. Therefore, strategies such as patient training in proper walking techniques should be incorporated into postoperative care. Full article

Background and Objectives: Weight-bearing activities exacerbate pain and fatigue in functional flat foot, with uphill walking presenting additional challenges due to increased external loads. The current study investigates whether 3D-printed customized arch-support insoles can enhance gait variables and ankle alignment during uphill walking. Materials and Methods: Twenty healthy young adults, divided into two groups (normal foot condition (control, n = 10), functional flat foot (FF, n = 10)), walked on a treadmill at a 10% incline under two conditions: wearing shoes alone (shoe) or wearing shoes with 3D-printed customized arch-support insoles (SI). Gait pattern, center of force (COF), and ankle joint angles were analyzed by OptoGait, Tekscan, and Kinovea, respectively. Results: The foot flat phase of the gait pattern was prolonged in individuals with FF compared to the control under both shoe and SI conditions, whereas the propulsive phase was shortened with the SI. Medial deviation of the COF during the propulsive phase, observed in individuals with FF under the shoe condition, was corrected to a more lateral alignment with the SI, resembling the COF alignment of the control. Additionally, individuals with FF under the shoe condition exhibited increased ankle pronation compared to the control, whereas the SI moderated pronation, achieving alignment closer to that of the control. Conclusions: These findings indicate that the 3D-printed customized arch-support insoles can improve gait mechanics and ankle alignment in individuals with FF, particularly under challenging conditions such as uphill walking. Full article

Monitoring plantar foot temperatures is essential for assessing foot health, particularly in individuals with diabetes at increased risk of complications. Traditional thermographic imaging measures foot temperatures in unshod individuals lying down, which may not reflect thermal characteristics of feet in shod, active, real-world conditions. These controlled settings limit understanding of dynamic foot temperatures during daily activities. Recent advancements in wearable technology, such as insole-based sensors, overcome these limitations by enabling continuous temperature monitoring. This study leverages a data-driven clustering approach, independent of pre-selected foot regions or models like the angiosome concept, to explore normative thermal patterns in shod feet with insole-based sensors. Data were collected from 27 healthy participants using insoles embedded with 21 temperature sensors. The data were analysed using clustering algorithms, including k-means, fuzzy c-means, OPTICS, and hierarchical clustering. The clustering algorithms showed a high degree of similarity, with variations primarily influenced by clustering granularity. Six primary thermal patterns were identified, with the “butterfly pattern” (elevated medial arch temperatures) predominant, representing 51.5% of the dataset, aligning with findings in thermographic studies. Other patterns, like the “medial arch + metatarsal area” pattern, were also observed, highlighting diverse yet consistent thermal distributions. This study shows that while normative thermal patterns observed in thermographic imaging are reflected in insole data, the temperature distribution within the shoe may better represent foot behaviour during everyday activities, particularly when enclosed in a shoe. Unlike thermal imaging, the proposed in-shoe system offers the potential to capture dynamic thermal variations during ambulatory activities, enabling richer insights into foot health in real-world conditions. Full article

Foot disorders affect approximately 10% of adults, with plantar heel pain significantly impacting foot-related quality of life and altering walking patterns. Flat feet, characterized by a lack of longitudinal arches, can lead to fatigue during walking. This study aims to develop 3D-printed shoe insoles tailored to the needs of patients. The design process incorporates Quality Function Deployment (QFD), Theory of Inventive Problem Solving (TRIZ), and Analytic Hierarchy Process (AHP) methods to create insoles that alleviate concentrated loads while meeting patient requirements. The AHP analysis indicated that patients prioritize insoles that effectively manage pressure distribution to achieve optimal functionality. QFD and TRIZ facilitated the identification of four product alternatives and production specifications. The analysis indicated that 3D-printed insoles made from TPU filament with 20% auxetic infill best align with patient preferences. This auxetic TPU option emerged as the top choice, achieving a priority value of 0.2506 due to its superior functionality and comfort. Load distribution measurements confirmed that TPU with auxetic infill resulted in the lowest load distribution, with a standard deviation of 0.1434 and a 25.4% reduction in maximum load compared to conditions without the insole. Full article

The purpose of this study was to compare the mechanical properties of a non-cushioned minimalistic shoe and cushioned shoe during walking at 6 and running at 10 and 14 km∙h⁻¹ in habituated female runners. Twelve habituated female runners completed two trials (cushioned shoe vs. minimalist shoe) with three within-trial speeds (6, 10, and 14 km∙h⁻¹) in a counter-balanced design. Flexible pressure insole sensors were used to determine kinetic variables (peak vertical impact force, average loading rate, active vertical peak force, time to active peak vertical force, and impulse) and spatiotemporal variables (stride duration, cadence, ground contact time, swing time, and time to midstance). Cushioned running shoes exhibited greater energy absorption (690%), recovered energy (920%), and heat dissipation (350%). The cushioned shoes significantly reduced peak vertical impact (~12%) and average loading rate (~11%) at running speeds 10–14 km∙h⁻¹. However, these effects were not observed during walking, nor did the cushioned shoes influence peak active force, impulse, stride duration, ground contact or swing time. Cushioned running shoes provide significant benefits in energy absorption, energy recovery, and heat dissipation, which decrease impact-related forces and loading rates in female runners without changing the spatiotemporal variables of gait. Full article

Tibia shaft fractures are common lower extremity fractures that can require surgery and rehabilitation. However, patient recovery is often poor, partly due to clinicians’ inability to monitor bone loading, which is critical to stimulating healing. We envision a future of patient care that includes at-home monitoring of tibia loading using pressure-sensing insoles. However, one issue is missing portions of daily loading due to limited insole wear time (e.g., not wearing shoes all day). Here, we introduce a method for overcoming this issue with a wrist-worn fitness tracker that can be worn all day. We developed a model to estimate tibia loading from fitness tracker data and evaluated its accuracy during 10-h remote data collections (N = 8). We found that a fitness tracker, with trained and calibrated models, could effectively supplement insole-based estimates of bone loading. Fitness tracker-based estimates of loading stimulus—the minute-by-minute weighted impulse of tibia loading—showed a strong fit relative to insole-based estimates (R² = 0.74). However, insoles needed to be worn for a minimum amount of time for accurate estimates. We found daily loading stimulus errors less than 5% when insoles were worn at least 25% of the day. These findings suggest that a multi-sensor approach—where insoles are worn intermittently and a fitness tracker is worn continuously throughout the day—could be a viable strategy for long-term, remote monitoring of tibia loading in daily life. Full article

Background: Lacing techniques are often viewed as a functional necessity, but recent research has highlighted their role as a customization tool for foot health and comfort. This review synthesizes findings from studies examining the biomechanical effects of different lacing patterns on pressure distribution, tendon loading, and foot mechanics. Methods: We analyzed studies that investigated various lacing techniques, including tightness and patterns. Objective measurements, such as pressure insoles and cadaveric models, were used to quantify the effects. Diverse study populations, including individuals with foot health concerns and athletes, were considered. This study was conducted as a scoping review following the JBI methodology, adhering to the PRISMA-ScR guidelines. Results: The studies collectively reveal that lacing patterns significantly influence dorsal pressure distribution during activities like running. Customized lacing can optimize foot biomechanics, reducing the risk of injuries related to abnormal pressure distribution. A total of 27 records were identified from the initial search. After removing duplicates and screening, four articles were included in the final review. Additionally, certain lacing configurations were found to reduce peak Achilles tendon tension, a crucial finding for injury-prone individuals. Conclusions: Proper lacing techniques are not just a functional aspect but a means to enhance foot health and prevent injuries. Healthcare professionals can provide personalized lacing recommendations to patients, with implications for those with specific foot conditions, athletes, and individuals at risk of injuries. The importance of patient education on the significance of lacing techniques cannot be overstated, emphasizing the need for informed choices when lacing shoes. These findings underscore the multifaceted role of lacing techniques in promoting foot health and well-being. Full article

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. Full article

Pressure-relieving footwear helps prevent foot ulcers in people with diabetes. The footwear design contributes to this effect and includes the insole top cover. We aimed to assess the offloading effect of materials commonly used as insole top cover. We measured 20 participants with diabetes and peripheral neuropathy for in-shoe peak pressures while walking in their prescribed footwear with the insole covered with eight different materials, tested in randomized order. Top covers were a 3 mm or 6 mm thick open or closed-cell foam or a 6 mm thick combination of open- and closed-cell foams. We re-assessed pressures after one month of using the top cover. Peak pressures were assessed per anatomical foot region and a region of interest (i.e., previous ulceration or high barefoot pressure). Walking comfort was assessed using a 10-point Likert scale. Mean peak pressure at the region of interest varied between 167 (SD:56) and 186 (SD:65) kPa across top covers (p < 0.001) and was significantly higher for the 3 mm thick PPT than for four of the seven 6 mm thick top covers. Across 6 mm thick top covers, only two showed a significant peak pressure difference between them. Over time, peak pressures changed non-significantly from −2.7 to +47.8 kPa across top cover conditions. Comfort ratings were 8.0 to 8.4 across top covers (p = 0.863). The 6 mm thick foams provided more pressure relief than the 3 mm thick foam during walking in high-risk people with diabetes. Between the 6 mm thick foams and over time, only small differences exist. The choice of which 6 mm thick insole top cover to use may be determined more by availability, durability, ease of use, costs, or hygienic properties than by superiority in pressure-relief capacity. Full article

An optoelectronic sensor was developed to measure the in-plane displacement between two parallel surfaces. This sensor used a photodetector, which was placed on one of the parallel surfaces, to measure the intensity of the red (R), green (G), blue (B), and white/clear (C) light spectra of a broad-spectrum light that was reflected off a color grid on the opposing surface. The in-plane displacement between these two surfaces caused a change in the reflected RGB and C light intensity, allowing the prediction of the displacement direction and magnitude by using a polynomial regression prediction algorithm to convert the RGB and C light intensity to in-plane displacement. Results from benchtop experiments showed that the sensor can achieve accurate displacement predictions with a coefficient of determination R² > 0.97, a root mean squared error (RMSE) < 0.3 mm, and a mean absolute error (MAE) < 0.36 mm. By measuring the in-plane displacement between two surfaces, this sensor can be applied to measure the shear of a flexible layer, such as a shoe’s insole or the lining of a limb prosthesis. This sensor would allow slippage detection in wearable devices such as orthotics, prostheses, and footwear to quantify the overfitting or underfitting of these devices. Full article