Plantar Pressure Research Articles

An ex vivo sequential ligament transection model of flatfoot

BackgroundThe ligaments implicated in the earliest stages of developing a progressive collapsing foot deformity are poorly understood. Commonly employed cadaveric flatfoot models are created from simultaneous transection of multiple ligaments, making it difficult to assess early changes in pressure distribution from ligaments critical for maintaining load distribution. A serial transection of ligaments may provide insight into changes in pressure distribution under the foot to identify a potential combination of ligaments that may be involved in early deformities. MethodsSpecimens were loaded using a custom designed axial and tendon loading system. Plantar pressure data for the forefoot and hindfoot were recorded before and after six sequential ligament complex transections. FindingsSectioning the plantar fascia (first) and short/long plantar ligaments (second) failed to generate appreciable differences in load distribution. Dividing the spring ligament (third) led to changes in hindfoot load distribution with a shift towards the lateral column indicative of hindfoot valgus angulation. All subsequent conditions resulted in similar patterns in hindfoot plantar load distribution. An anterior shift in the center of pressure only occurred after transection of all six ligament complexes. InterpretationLoss of the plantar fascia and short/long plantar ligaments are not critical in maintaining plantar load distribution or contact area. However, the additional loss of the spring ligament caused notable changes in hindfoot load distribution, indicating the combination of these three ligament complexes is particularly critical for preventing peritalar subluxation. Minimal changes in load distribution occurred when performing additional transections to reach a complete flatfoot deformity.

Comparative study of the effects of custom-made insole and ordinary insole in adults with flexible flatfoot on different slopes.

Flatfoot (pes planus) is a common foot deformity, and its causes are mainly related to age, gender, weight, and genetics. Previous studies have shown that custom-made insoles could have a positive effect in improving plantar pressure and symptoms in individuals with flexible flatfeet, but it remains to be explored whether they can still show benefits in daily walking on different slopes. This study aims to investigate a custom-made insole based on plantar pressure redistribution and to verify its effectiveness by gait analysis on different slopes. We recruited 10 subjects and compared the peak pressure and impulse in each area between custom-made insole (CI) and ordinary insole (OI) groups. The results illustrate that CI raises the pressure in T area, improves the ability of the subjects to move forward in the slope walking, which was beneficial to gait stability. The redistribution of pressure in MF and MH area is promoted to provide active protection for subjects. Meanwhile, CI could decrease the impulse in MF area during uphill and level walking, which effectively reduces the accumulation of fatigue during gait. Moreover, avoiding downhill walking could be able to protect foot from injury in daily life.

Surgical Offloading versus Medical Conservative Methods in Management of Diabetic Foot Plantar Ulcers (Interventional study)

Abstract Background As a result, peripheral neuropathy is frequently caused by diabetes (DM). Diabetic plantar foot pressure ulcers develop from the lack of protective pain sensibility as a result of recurrent shear and tear pressures. Relieving pressure on the foot's sole is necessary for the ulcers to heal. The purpose of the study is to compare the effectiveness of surgical and nonsurgical unloading procedures in the healing of plantar ulcers. Subjects and Methods 50 diabetic foot ulcer patients who visited Ain Shams University, the national institute of DM, and the endocrinology outpatient clinic participated in this interventional trial (NIDE). We employed mechanical and surgical unloading methods in this trial, and patients were monitored for 6 months to see how long it took for their injuries to recover. Results At the conclusion of the follow-up period, 88% of the surgical group's pressure ulcers were fully healed, compared to 86.7% of the non-surgical patients (6 months). Infection, recurrence, and non-healing were complications we encountered throughout the follow-up period. Regarding the treatment of plantar diabetic foot ulcers, offloading is crucial (DFUs). Compared to using only non-surgical methods, surgical offloading may hasten the recovery time. A well- trained team is necessary to prevent the issues with improperly fitting footwear and to teach the patient how to use them on a regular basis with the non-surgical offloading technique.

The impact of surgical intervention on statographic parameters of patients with diabetic foot syndrome

Taking into account that the prevalence of diabetes mellitus continues to increase worldwide, secondary complications associated with this endocrine disorder are becoming increasingly common. Disruption of glucose homeostasis and hyperglycemia lead to the activation of several pathological metabolic pathways, contributing to the development of vascular insufficiency and neurodegenerative processes in the lower limbs. These processes are the causes of a condition known as diabetic foot syndrome (DFS), which requires special attention and meticulous treatment. Complications in the form of trophic ulcers of the lower limbs are one of the serious consequences of diabetes mellitus (DM) since they often lead to severe medical and social problems, including high rates of limb amputations. The purpose of the research is to investigate the redistribution of plantar pressure depending on the volume of surgical intervention in patients with diabetic foot syndrome (DFS) by measuring individual statographic parameters. The analysis of a series of parameters from statographic studies in patients with diabetic foot syndrome undergoing various volumes of surgical interventions has allowed for a comprehensive understanding of the features of vertical standing of these patients. In the course of the research, it has been revealed that as the support area of the operated foot decreases, there is an increase in body oscillation in both the sagittal and frontal planes relative to the support area. It has been proven that in cases with a normal support area of the foot, the relative body oscillation decreases.

An observational analysis to evaluate the influence of occlusion on body posture and plantar pressure - An in vivo study.

The aim of this study is to evaluate the influence of occlusion on body posture and plantar arch pressure. An Observational analysis to Analyze the Influence of Occlusion on Plantar Pressure and Body Posture. A total of 30 asymptomatic subjects were selected for the study including 18 females and 12 males from age group 22 years to 28 years with a mean age of 24.83 years. Each subject underwent evaluation of occlusion at MIP using a Digital Occlusal analyzer (T-Scan III). At this point, the subjects were made to stand on a mat scan which consisted of a large postural platform sensor and a computer that displayed the plantar pressure data. The computer connected to the T Scan displayed the occlusal pressure analysis. This was followed by an evaluation of body posture using a posture grid where the photographs were taken and an evaluation of the frontal and lateral photos was done using the APECS - posture analysis app. Statistical package for social sciences (SPSS) for windows version 22.0 Released 2013, Armonk, N Y: IBM Corp., was used to perform Statistical Analysis. A chi-square test was applied for qualitative variables to find the association. Paired t-test was applied to compare the changes in the quantitative parameters in eye-open and eye-closed conditions. The level of significance was set at 5%. As observed from the results, occlusion for 40% of the subjects, where n = 12, was dominant on the right side. Occlusion for 23.3% of subjects, where n = 7, was dominant on the left side. Whereas, for 36.7% of subjects, where n = 11, the pressure distribution was almost equal on both sides. The inclination of body posture for 23.3% of subjects, where n = 7, was towards the right side. The inclination of body posture for 50% of subjects, where n = 11, was towards the left side. And, the inclination of body posture for 26.7% of subjects, where n = 8, was neutral i.e., balanced on the right and left side. Plantar pressure for 6.7% of subjects, where n = 2, was dominant on the right side. Plantar pressure for 36.7% of subjects, where n = 11, was dominant on the left side. Whereas, for 56.7% of subjects, where n = 17, the plantar pressure distribution was almost equal on both sides. On correlating the three parameters, it was found that occlusion for most of the subjects dominated on the right side, while body posture and plantar pressure dominated on the contralateral i.e., left side.

The relationship between Foot Posture Index and plantar pressure in a community-dwelling adult population with Type 2 diabetes

AimsTo investigate the contribution of foot type to plantar pressures in a community-dwelling adult population with type 2 diabetes. MethodsFoot Posture Index-6 (FPI-6) as a measure of foot type, barefoot plantar pressure (peak pressures and pressure-time integrals), presence of forefoot deformities, peripheral neuropathy, ankle and first metatarsophalangeal joint (MTPJ) dorsiflexion range of motion (ROM), and demographic variables were measured. Standard multiple regression models were used to investigate the independent contribution of FPI-6 on plantar pressure variables at the hallux, forefoot, and rearfoot. Results122 adults (mean age 70.9 ± 9.3, n = 58 female) with type 2 diabetes were recruited. A lower (more supinated) FPI-6 significantly contributed to an increased forefoot pressure-time integral (β = −0.285, p = 0.04). FPI-6 was not a statistically significant independent predictor of peak pressure at the hallux, forefoot or rearfoot. ConclusionsWhen screening for at-risk sites of elevated plantar pressure in adults with type 2 diabetes, clinicians should consider performing the FPI-6 along with other clinical measures that have been shown to be associated with increased plantar pressures including first MTPJ dorsiflexion ROM, and presence of digital deformities. Evidence-based treatments to offload these areas should then be considered.

Effects of tendon elongation on plantar pressure and clinical outcomes: A comparative analysis between open repair and minimally invasive surgery.

The aim of this study was to assess whether variances in Achilles tendon elongation are linked to dissimilarities in the plantar pressure distribution following two different surgical approaches for an Achilles tendon rupture (ATR). All patients who were treated with open or minimally invasive surgical repair (MIS) and were over 2 years post their ATR were eligible for inclusion. A total of 65 patients with an average age of 43 ± 11 years were included in the study. Thirty-five patients were treated with open repair, and 30 patients were treated with MIS. Clinical outcomes were evaluated using the American Orthopedic Foot and Ankle Society (AOFAS) and ATR Score (ATRS). Achilles tendon elongation was measured using axial and sagittal magnetic resonance imaging scans. Plantar pressure measurements for the forefoot, midfootand hindfoot during gait were divided into percentages based on total pressure, measured in g/cm2 for each area. The average AOFAS score was found 'excellent' (93 ± 2.8) in the MIS group, while it was found 'good' (87.4 ± 5.6) in the open repair group. In addition, the MIS group showed significantly superior ATRS scores (78.8 ± 7.4) compared to the open repair group (56.4 ± 15.4) (p < 0.001). The average tendon elongation in the MIS group was 11.3 ± 2 mm, while it was 17.3 ± 4.3 mm(p < 0.001) in the open repair group. While the open repair group showed significantly higher plantar pressure distribution in the initial contact and preswing phases compared to uninjured extremities, there was no significant difference between the uninjured extremities and the MIS group. In conclusion, the findings of this study demonstrated that minimally invasive surgery was associated with less tendon elongation, more proximity to the plantar pressure distributions of the uninjured extremity and superior clinical outcomes compared to open surgical repair. Therefore, minimally invasive surgery may be considered a more suitable option for acute Achilles tendon repair to achieve overall better outcomes. Level III.

Surgical management of severe planovalgus foot deformity in children with generalised joint hypermobility

BackgroundThis study aimed to evaluate the outcomes of calcaneal lengthening osteotomy (CLO) and double arthrodesis of the talonavicular and calcaneocuboid joints (DA) for correcting planovalgus foot deformity exclusively in patients with generalised joint hypermobility. MethodsWe retrospectively reviewed 29 feet in 17 consecutive patients who underwent either CLO or DA. The mean age at surgery was 11.3 ± 2.3 years, and the mean follow-up duration was 7.7 ± 3.2 years. Preoperative and final follow-up radiographs and dynamic foot-pressure measurements were analysed. ResultsBoth operations significantly improved the radiographic parameters, except for the lateral talocalcaneal angle in the CLO group. Pedobarographic study demonstrated an elevation of the medial longitudinal arch and an improved foot-pressure distribution after both surgeries. The plantar pressure in the lateral forefoot significantly increased only in the DA group, while the pressures exerted on the medial forefoot and hindfoot and the arch index improved only in the CLO group. ConclusionsBoth CLO and DA effectively improve the foot alignments of the deformity in patients with generalised joint hypermobility. However, differences were observed in the changes in the lateral talocalcaneal angle and plantar pressure distribution between the two procedures. Level of evidenceTherapeutic Level III.

Altered body balance and plantar pressure distribution in young adults with forward head posture

BackgroundForward head posture (FHP), a common postural issue, affects balance and may be linked to altered muscle activity and cervical spine alignment. This study investigated the impact of FHP on static balance and plantar pressure distribution in adults. We hypothesized that FHP would be associated with poorer balance and altered pressure distribution. MethodsThis case-control study investigated the impact of FHP on static balance and plantar pressure distribution in adults (n = 52). Participants were categorized based on craniovertebral angle (CVA), into FHP (CVA <47°) and control (CVA ≥47°) groups. Static balance was assessed using a NeuroCom® Balance Manager System, evaluating parameters like center of gravity sway and directional control. Plantar pressure distribution was measured with an Emed Pedobarography system during walking, analyzing maximum force, peak pressure, and contact area. ResultsParticipants with FHP showed poorer balance with eyes closed on foam compared to the control group. Additionally, the FHP group exhibited lower total maximum force and altered force distribution in both feet during walking. Correlations suggested that higher CVA degrees were associated with decreased balance and altered plantar pressure distribution. Despite, linear regression analyses revealed no significant predictive relationships between CVA and specific balance measures, it showed significant associations with several plantar pressure distribution parameters, including total maximum force exerted on both feet, maximum force on the forefoot, and peak pressure on the hindfoot. ConclusionThese findings suggest that FHP may influence balance and plantar pressure distribution, with a potentially stronger effect on plantar pressure than balance parameters.

Texture differences of microchambers and macrochambers in heel pads between the elderly with and without diabetes

ObjectiveThis study aims to use the texture analysis of ultrasound images to distinguish the features of microchambers (a superficial thinner layer) and macrochambers (a deep thicker layer) in heel pads between the elderly with and without diabetes, so as to preliminarily explore whether texture analysis can identify the potential injury characteristics of deep tissue under the influence of diabetes before the obvious injury signs can be detected in clinical management. MethodsUltrasound images were obtained from the right heel (dominant leg) of eleven elderly people with diabetes (DM group) and eleven elderly people without diabetes (Non-DM group). The TekScan system was used to measure the peak plantar pressure (PPP) of each participant. Six gray-level co-occurrence matrix (GLCM) features including contrast, correlation, dissimilarity, energy, entropy, homogeneity were used to quantify texture changes in microchambers and macrochambers of heel pads. ResultsSignificant differences in GLCM features (correlation, energy and entropy) of macrochambers were found between the two groups, while no significant differences in all GLCM features of microchambers were found between the two groups. No significant differences in PPP and tissue thickness in the heel region were observed between the two groups. ConclusionsIn the elderly with diabetes who showed no significant differences in PPP and plantar tissue thickness compared to those without diabetes, several texture features of ultrasound images were found to be significantly different. Our finding indicates that texture features (correlation, energy and entropy) of macrochambers could be used for early detection of soft tissue damage associated with diabetes.

Primary Isolated Arthrodesis of the First Metatarsophalangeal Joint for Hallux Rigidus: Clinical, Radiologic, and Pedobarographic Evaluation.

Arthrodesis of the first metatarsophalangeal joint is an effective treatment of advanced hallux rigidus. Numerous options have been described for performing this intervention. The aim of this study was to evaluate the outcomes following a consistent surgical technique of joint preparation with hand tools and fixation with 2 crossed screws and a dorsal compression plate. Thirteen patients (16 feet) who underwent primary isolated arthrodesis of the first metatarsophalangeal joint between March 2019 and June 2021 were available for clinical, radiologic, and pedobarographic evaluation at a minimum of 12 months after surgery. American Orthopaedic Foot & Ankle Society scores, numerical pain rating scale, the radiologic hallux valgus and intermetatarsal 1-2 angles as well as the distribution of plantar pressure during gait were compared between the pre- and postoperative conditions. After an average follow-up period of 26 months, union was achieved in all cases and the mean AOFAS score raised significantly by 39 points. All the patients were satisfied with the result. Only 1 patient complained of mild residual pain at walk. Hardware removal was performed in 2 cases. The mean hallux valgus angle dropped from 12.3 to 6.3 degrees. The mean postoperative dorsiflexion angle was 21.6 degrees. After the procedure, peak pressure was significantly higher beneath the first metatarsal head and heel, whereas pressure-time integral was significantly lower beneath the hallux and medial lesser toes. Arthrodesis of the first metatarsophalangeal joint with 2 crossed screws and a dorsal compression plate is a safe and effective treatment of advanced hallux rigidus. This procedure provides adequate pain relief and functional improvement of gait. Level IV, therapeutic, retrospective case series.

Influence of Different Breathing Strategies on Plantar Pressure Distribution in Ballet Movements

PURPOSE This study investigated the differences in plantar pressure distribution when using three breathing techniques during heel raises.METHODS The subjects were 29 professional dancers aged 20 to 30 years with more than 10 years of experience. Pressure distribution according to breathing method during heel raise was measured for 10 seconds while controlling the raise speed and gaze. The three breathing techniques were randomly ordered. Peak pressure, contact area and time, displacement, and absolute velocity of the center of pressure trajectory were measured using Emed&lt;sup&gt;®&lt;/sup&gt;-le from Novel GMBH. Plantar pressure was analyzed by dividing it into a total of 12 areas (masks): five toes, five metatarsals, the midfoot, and the hindfoot.RESULTS Using the teeth occlusion breathing technique, the peak pressure on the first metatarsal was significantly reduced, the contact time of the second metatarsal was significantly longer, and the displacement of the center of pressure trajectory was significantly shorter. Additionally, during the phase of the forefoot retainer, the velocity of the center of pressure trajectory was significantly reduced.CONCLUSIONS The teeth occlusion technique reduces peak pressure, increases contact time and area, and decreases the displacement and velocity of the center of pressure trajectory, demonstrating an efficient method for maintaining balance in ballet movements. This technique can potentially enhance stability and prevent injuries in ballet dancers.

A Preliminary Study on the Effects of 4-Week Training Program with Interactive Floor Support on Plantar Pressure Distribution in Sedentary Individuals

Objective: Our purpose was to investigate on the effects of foot exercises by using interactive floor support as a modality of rehabilitation technology on plantar pressure distribution in sedentary individuals. Methods: Participants who were aged between 18-35, who agreed to participate voluntarily and had no pathology developed in the lower extremities in the past 6 months were included in this study. In order to determine the plantar pressure distribution change of all participants, the first and last evaluation was measured with Emed® Pedobarography. Balance and proprioception exercises on both lower extremities for 12 sessions (for four weeks, three sessions per week, lasts 15 minutes each) were performed with an interactive floor device. Results: A total of 15 healthy and sedentary subjects (12 female, 3 male, with a mean of 20,27±0,961 years and 21,31 ± 3,027 kg/m2 BMI) completed the four-week training protocol. Maximum force of total and hindfoot in both feet significantly decreased after 4-week training (p.05). Conclusion: Based on our results, the present study revealed that the 4-week training programme with interactive floor support for ankle joint could decrease maximum force of total and hindfoot on the bottom of the dominant and non-dominant side feet in healthy and sedentary individuals. Future investigation should be conducted to clarify the effects of long-term training programs with interactive floor support on plantar pressure distribution in patients with foot deformities.

Extended finite element analysis for the 2nd and 3rd metatarsals stress fracture during push-off

Metatarsal stress fractures (MSF), particularly the 2nd and 3rd MSF, are common injuries among athletes. Although there are several practices to reduce foot and ankle injuries, there is no injury prevention program specifically designed to minimize MSF. This is mainly due to the lack of information about the loadings/postures that cause MSF. Therefore, this study aimed to investigate dangerous loadings/postures potentially causing MSF during push-off (PO). The analysis was conducted with Finite Element Modelling (FEM), calibrated with the three-point bending test, and validated with peak plantar pressure (PPP) and fracture force measurement. Extended Finite Element Method was used for MSF simulation such that ten different foot and ankle configurations were designed, with five for each of the 2nd and 3rd MSF under pure vertical loadings. A more complex loading, ankle eversion/inversion during PO, was also examined for the MSF. The average error percentage for the calibration of the model with the three-point bending test was 3.05%. The average error percentages for the validation of the model with PPP and fracture force measurements were 18% and 30%, respectively. The outcomes of pure vertical loadings indicated the higher potential for the 2nd and 3rd MSF at 30% PO and 70% PO, respectively. The results of ankle eversion/inversion loadings represented that the most dangerous posture for MSF was 30° ankle eversion for the 3rd metatarsal at 70% PO. These results provide a guide, including what postures to avoid for the 2nd and 3rd MSF among people who are at high risk of MSF.

Implications of plantar static pressure distribution among bilateral flatfoot patients: An analytical case-control research

BackgroundAdult pes planus is a highly prevalent condition characterized by the gradual or sudden appearance of fallen arches in adulthood, which is a recognized cause of difficulty with balance and stability, discomfort, pain, swelling, tired and achy feet and impairment. Accordingly, the main purpose of this analytical, case-control study was to evaluate the characteristics in foot morphology related to static plantar pressure distribution in adults with and without a bilateral condition. MethodsSixty-eight subjects were recruited by a laboratory in this analytical case-control study, involving thirty-four adults with a bilateral condition and thirty-four healthy controls. Static plantar pressure was measured in all participants using a specific portable pressure platform with multiple resistive sensors which was placed on the floor. ResultsStatic plantar pressure distribution in the cases group showed significant increases in the right and left surface areas, in the right heel surface area and also in the left foot mean peak pressure (p < 0.001), as well as in the left heel surface area (p = 0.003). ConclusionsAdults with bilateral flatfoot showed changes in the surface areas in both feet and recorded higher levels in static plantar pressures with respect to the control group, a feature which can be associated with this common bilateral condition.

A cross sectional pilot study utilising STrain Analysis and Mapping of the Plantar Surface (STAMPS) to measure plantar load characteristics within a healthy population

BackgroundNo in-shoe systems, measuring both components of plantar load (plantar pressure and shear stress) are available for use in patients with diabetes. The STAMPS (STrain Analysis and Mapping of the Plantar Surface) system utilises digital image correlation (DIC) to determine the strain sustained by a deformable insole, providing a more complete understanding of plantar shear load at the foot-surface interface. Research questionsWhat is the normal range and pattern of strain at the foot-surface interface within a healthy population as measured by the STAMPS system? Is STAMPS a valid tool to measure the effects of plantar load? MethodsA cross-sectional study of healthy participants was undertaken. Healthy adults without foot pathology or diabetes were included. Participants walked 20 steps with the STAMPS insole in a standardised shoe. Participants also walked 10 m with the Novel Pedar® plantar pressure measurement insole within the standardised shoe. Both measurements were repeated three times. Outcomes of interest were global and regional values for peak resultant strain (SMAG) and peak plantar pressure (PPP). ResultsIn 18 participants, median peak SMAG and PPP were 35.01 % and 410.6kPa respectively. The regions of the hallux and heel sustained the highest SMAG (29.31 % (IQR 24.56–31.39) and 20.50 % (IQR 15.59–24.12) respectively) and PPP (344.8kPa (IQR 268.3 – 452.5) and 279.3kPa (IQR 231.3–302.1) respectively). SMAG was moderately correlated with PPP (r= 0.65, p < 0.001). Peak SMAG was located at the hallux in 55.6 % of participants, at the 1st metatarsal head (MTH) in 16.7 %, the heel in 16.7 %, toes 3–5 in 11.1 % and the MTH2 in 5.6 %. SignificanceThe results demonstrate the STAMPS system is a valid tool to measure plantar strain. Further studies are required to investigate the effects of elevated strain and the relationship with diabetic foot ulcer formation.

Determining the changes in morphology and loading status following medial displacement calcaneal osteotomy for flatfoot using patient-specific finite element models

Medial displacement calcaneal osteotomy (MDCO) is the standard procedure for flatfoot. We investigated the effect of MDCO on the foot using a finite element analysis. Foot models were created from computed tomography data of 8 patients with flat feet. MDCO was performed on each model with bone translation distance of 4, 8, and 12 mm. The morphological changes, plantar pressures, and stress percentage on the talocrural and subtalar joints were evaluated before and after surgery. Morphological evaluation showed improvement in the medial longitudinal arch. The stress percentage of plantar pressure in the medial area decreased, and the stress percentage of plantar pressure in the mid- and lateral forefoot area increased. At the talocrural joint, the medial and middle stress percentage increased, while the lateral and posterior stress percentage decreased. In the subtalar joint, the stress percentage in the middle subtalar joint increased and that in the posterior subtalar joint decreased. Within the posterior subtalar joint, the anterior and medial stress percentage increased, while the posterior and lateral stress percentage decreased. Preoperative simulation using the finite element analysis may be useful in understanding postoperative morphological changes and loading conditions to perform patient-specific surgery.

Graphene Sterically-Wrapped textile piezoresistive Sensors: A spray coating path for synergistically advancing sensitivity and response range

Trade-off between a high sensitivity and a broad sensing range remains a persistent challenge for flexible pressure sensors. Not to suffer from this dilemma, a flexible textile piezoresistive sensor sterically-wrapped with graphene by spray coating is reported, which constructs enriched three-dimensional conductive networks from leather fabric’s inherent fibers and pore structures, synergistically advancing the sensitivity and response range. Such a sensor renders bulky spatial deformation and augmented pressure-induced conducting paths, and hence affords an ultra-high sensitivity of 259.6 kPa−1(0–100 kPa) and an exceptional response range of up to 1 MPa. Besides, the graphene/textile sensor demonstrates outstanding durability (>12000 cycles). With these advantages, real-time monitoring of human physiological activities such as wrist pulses and throat swallowing is successfully achieved. Benefitting from the scalability of the spraying methodology, a large-size 45 × 45 cm2 sensing array with a 32 × 32 matrix is facilely fabricated to map the spatial pressure of human interactive behaviors for ergonomics. And smart insoles incorporating graphene/textile sensors can capture plantar pressure distribution and provide effective analysis for diverse static/dynamic movements of feet. Such spray-coated textile sensors could not only find potential applications in wearable electronics and intelligent robotics, but also open the possibility of monitoring complex heavy machinery and large-scale infrastructures.

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

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. 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. 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. 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.

Pressure-Reducing Design of 3D-Printed Diabetic Shoe Midsole Utilizing Auxetic Lattice Structure

With the global rise in the prevalence of diabetes, diabetic patients need innovative footwear designs to reduce the risk of foot ulcers. This study examined the mechanical properties of diabetic shoe midsoles featuring auxetic lattice structures. Through the construction of finite element models and simulation, this research compared the biomechanical parameter differences in the plantar regions of the metatarsal head, midfoot, and hindfoot when wearing two types of auxetic midsoles with internal angles of 60° and 75° and a non-auxetic midsole with an internal angle of 90° under both walking and running conditions. Compared to the non-auxetic midsole, the auxetic midsoles significantly reduced the peak plantar pressure and optimized the pressure distribution across various plantar regions. Notably, the auxetic 60° midsole reduced the peak plantar pressure by 19.68–55.25% and 16.19–54.39% compared to the non-auxetic 90° midsole during walking and running, respectively. This study also verified that the auxetic midsoles exhibited greater adaptability and compliance to the plantar foot shape, contributing to reductions in plantar pressure in comparisons of deformation values and plantar contact areas across the different midsoles. Auxetic midsoles manufactured using 3D printing technology have significant potential to prevent diabetic foot ulcers and maintain human foot health. This research integrates insights and techniques from materials science and ergonomics, offering a new direction for footwear design.