Pressure Redistribution Research Articles

Fluid-filled lattices for responsive orthotic insoles

Abstract Orthotic insoles are essential for alleviating discomfort and preventing injuries in the foot caused by high peak pressures in the plantar tissue. Traditional orthotic insoles, often prescribed to address these issues, are designed based on the static foot shape and pressure measurements, lacking responsiveness to dynamic movements. This study explores the behaviour of fluid-filled lattices for improving the functionality of orthotic insoles, focusing on energy dissipation and pressure redistribution capabilities. Using numerical homogenisation, the research integrates hyperelastic and permeability models to simulate the behaviour of Solid–Liquid Composites. Experimental tests validated these models, examining the influence of fluid viscosity and structural variations on energy dissipation and pressure distribution. Results show that fluid-filled lattices provide enhanced energy dissipation and reduce peak pressures by evening out the pressure distribution compared to non-fluid-filled samples. These findings highlight the potential of fluid-filled lattices to improve the performance and comfort of orthotic insoles.

A Comparative Study for Evaluating the Groundwater Inflow and Drainage Effect of Jinzhai Pumped Storage Power Station, China

Various hydrogeological problems like groundwater inflow, water table drawdown, and water pressure redistribution may be encountered in the construction of hydraulic projects. How to accurately predict the occurrence of groundwater inflow and assess the drainage effect during construction are still challenging problems for engineering designers. Taking the Jinzhai pumped storage power station (JPSPS) of China as an example, this paper aims to use different methods to calculate the water inflow rates of an underground powerhouse and evaluate the drainage effect caused by tunnel inflow during construction. The methods consist of the analytical formulas, the site groundwater rating (SGR) method, and the Signorini type variational inequality formulation. The results show that the analytical methods considering stable water table may overestimate the water inflow rates of caverns in drained conditions, whereas the SGR method with available hydro-geological parameters obtains a qualitative hazard assessment in the preliminary phase. The numerical solutions provide more precise and reliable values of groundwater inflow considering complex geological structures and seepage control measures. Moreover, the drainage effects, including a seepage-free surface, pore water pressure redistribution, and hydraulic gradient, have been accurately evaluated using various numerical synthetic cases. Specifically, the faults intersecting on underground caverns and drainage structures significantly change the groundwater flow regime around caverns. This comparative study can not only exactly identify the capabilities of the methods for cavern inflow in drained conditions, but also can comprehensively evaluate the drainage effect during cavern construction.

DEVELOPMENT OF AN EXPRESS ASSESSMENT OF THE RESULTS OF GEOLOGICAL AND TECHNICAL MEASURES TAKEN INTO ACCOUNT OF THE GATHERING SYSTEM

This article provides a rationale for the method of «express» assessment of changes in well flow rate when performing geological and technical measures in an oil field. In view of the cluster configuration of wells that is widespread in Western Siberia, the author identifies two groups of well pads, one of which is influencing, the other is reacting. At the influencing well clusters, as a result of the implementation of geological and technical measures to increase extraction from the productive formation, an increase in the produced fluid occurs. This leads to destabilization of the equilibrium in the “reservoir – well – pipeline” system. The consequence of a violation of this balance is an increase in the load on the reservoir fluid pumped in oil and gas gathering pipelines on individual branches of the field collection system. This leads to a redistribution of wellhead pressures at production wells, which, in turn, also leads to a change in bottomhole pressure and a change in well productivity. The author defines well pads where there is no increase in production, but where there is a change in pressure at the wellheads as reactive. With an increase in linear pressure on the pads, the energy balance in the operating production wells at the reacting well pads shifts towards a decrease in flow rate. Conversely, when wellhead pressure decreases, well productivity increases. These parameters will change until the energy balance of pressures in the wells is achieved. In connection with the above, within the framework of this work, an approach is presented for assessing changes in well operating parameters with increasing production in the field. An example of testing the proposed approach on a complex integrated model is given. To test this approach for adequacy, a comparison was made of theoretical calculations of changes in the operation of real wells with calculations performed on a customized complex integrated model of an oil field. It is worth noting that this type of calculation is characterized as approximate. Its use is advisable exclusively at the stage of preparing programs for performing geological and technical measures to determine reservoir zones in which the negative effect of increasing production will be minimal.

Dynamic response and damage of pile-geogrid composite reinforced high-speed railway subgrade under seismic actions

In this study, the dynamic response and damage mode of a pile-geogrid composite reinforced high-speed railway subgrade under seismic action were investigated based on a unidirectional shaking table test. Various seismic waves were applied to the subgrade, allowing for an analysis of acceleration, dynamic soil pressure, displacement, and strain responses. The displacement field of the subgrade was visualized using particle image velocimetry (PIV). The study shows that changes in peak ground acceleration (PGA) amplification factors become evident with height due to the presence of geogrid layers. The increase in peak ground motion causes a redistribution of dynamic soil pressures inside the subgrade. The transverse and longitudinal ribs of the geogrids provide an “anchoring effect”. The peak strain of the piles in the center is greater than that of the piles on the sides. The direction of soil particle displacement is closely related to the damage patterns observed in the subgrade. Damage begins to occur once the peak ground motion exceeds 0.4 g, characterized by collapse at the bottom of the subgrade.

Effects on tissue oxygenation in the gluteal region with a smart pressure redistribution wheelchair cushion compared to a pressure relief manoeuvre

Objective The study examines the effects of the air-bladder offloading mode of a smart pressure redistribution wheelchair cushion on tissue oxygenation in the gluteal tissue of non-disabled participants. The hypothesis is that the cushion’s offloading mode, which involves sequentially deflating its five air-bladders one at a time for a specific duration, would improve tissue oxygenation during sitting. Methods Two procedures were conducted. The first compared the cushion’s offloads to a loaded control (LC) with the cushion on static mode, and the second compared the cushion’s offloading mode to a standard manual offload performed by the participant. Three trials of each procedure were performed in randomized order. Tissue oxygenation was continuously monitored with three oxygenation parameters analysed: oxygen saturation (SO2), oxygenated haemoglobin (OxyHb), and deoxygenated haemoglobin (DeoxyHb). Data recordings were segmented in each step of the offloading sequence for analysis. A paired t-test was performed for comparisons with significance considered at α = 0.05. Ten healthy adults participated in the study. Impact Results showed that as the air bladders deflated over time, the three evaluated parameters changed, affecting oxygenation even when other tissue areas were offloaded. The results indicated that the cushion’s sacral offload had the greatest impact on improving tissue oxygenation among the five air-bladders in all ten subjects (p < 0.05). Furthermore, SO2 during the cushion’s offload in the sacral region was similar to a manual offload. The study results suggest that the cushion could benefit tissue oxygenation, especially for individuals unable to change positions independently. Further research is needed to determine its effectiveness for wheelchair users.

Battery-Free, Wireless Multi-Modal Sensor, and Actuator Array System for Pressure Injury Prevention.

Simultaneous monitoring of critical parameters (e.g., pressure, shear, and temperature) at bony prominences is essential for the prevention of pressure injuries in a systematic manner. However, the development of wireless sensor array for accurate mapping of risk factors has been limited due to the challenges in the convergence of wireless technologies and wearable sensor arrays with a thin and small form factor. Herein, a battery-free, wireless, miniaturized multi-modal sensor array is introduced for continuous mapping of pressure, shear, and temperature at skin interfaces. The sensor array includes an integrated pressure and shear sensor consisting of 3D strain gauges and micromachined components. The mechanically decoupled design of the integrated sensor enables reliable data acquisition of pressure and shear at skin interfaces without the need for additional data processing. The sensor platform enables the analysis of interplay among localized pressure, shear, and temperature in response to changes in the patient's movement, posture, and bed inclination. The validation trials using a novel combination of wireless sensor arrays and customized pneumatic actuator demonstrate the efficacy of the platform in continuous monitoring and efficient redistribution of pressure and shear without repositioning, thereby improving the patient's quality of life.

Evolving Trends in the Management of Diabetic Foot Ulcers: A Narrative Review.

The prevalence of diabetic foot ulcers (DFUs) is projected to increase worldwide, which necessitates a review of the current management principles and the development of new approaches to care. The principles of management involve proper glycemic control, infection control, pressure redistribution, wound care debridement, and revascularization. Other modalities of management, such as hyperbaric oxygen therapy and negative wound pressure therapy, are also being explored. While some aspects of DFU care lack high-quality evidence, a multidisciplinary approach incorporating these evolving trends has the potential to improve outcomes and prevent lower extremity amputations in this challenging condition. This review highlights the need for further research to establish definitive treatment protocols for optimal DFU management.

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.

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.

Stability of ischial pressure with 3D thermoplastic elastomer cushion and the characteristics of four types of cushions in pressure redistribution.

Wheelchair cushions are recommended to be used with wheelchair and can protect the buttocks from pain and injury by relieving interface pressure for wheelchair users. However, further investigations are required for proper use in response to the development of new types of wheelchair cushions. The objective of this study was to evaluate physical characteristics of wheelchair cushions by comparing pressure redistributing effects of four types of cushions. The participants were 16 healthy adults who consented to participate in this study. A pressure mapping system (CONFORMat, Nitta Corp.) was used for the measurements. Pressure at ischium was measured immediately after the stabilization of the sitting posture and 10 minutes after. The pressure at ischium significantly decreased with any wheelchair cushions (P < 0.01). A significant negative correlation between body mass index and pressure at ischium was observed without a wheelchair cushion (r = - 0.70), however, the correlation disappeared upon use of a wheelchair cushion. The pressure at ischium increased over time with cushions of urethane, air, and urethane-air hybrid while that with the 3D thermoplastic elastomer cushion did not, and the change in the pressure was statistically less than that in other cushions (P < 0.01). Use of wheelchair cushions was effective in redistribution of the pressure at ischium, and the overtime change in the pressure depends on the type of used cushions.

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.

Plantar pressure distribution using personalised 3D printed lattice insoles with distributed stiffness

This work presents a proof-of-concept study on the use of additive manufacturing for developing customised lattice topology insoles, with the aim of redistributing plantar pressures. Four cubic lattice structures were applied to five sections of the moulded insole contours, which were based in 3D foot scans using Ansys material designer to predict material properties. The variation of the elastic modulus across the sections was controlled via the lattice cell structure volume ratio. The insole lattice structures were made from elastic photosensitive liquid resin resulting in flexible parts. A commercially available shoe was used to compare pressure distribution between the original and customised insole. Plantar pressure distribution and peak pressures were measured during standing, walking, and running. Pressure redistribution varied between insole conditions. During standing, the customised insole reduced peak pressure at the left heel, while the right foot experienced increased peak pressure compared to the control insole. Substantial peak pressure reduction was observed on the left foot during walking and running whilst the reduction was much less for the right foot. The study highlights the potential of additive manufacturing for cost-effective, accurate, and personalized insole production, offering material control and pressure redistribution benefits for various applications like injury prevention and rehabilitation.

Smart seat cushion feasibility pilot study: automated interface pressure modulation of individuals with spinal cord Injury

This study investigates the functionality and feasibility of a novel smart seat cushion system designed for wheelchair users with spinal cord injuries. The cushion, equipped with air cells that serve as both sensors and actuators, was tested on 24 participants for its real-time pressure mapping, automated pressure redistribution, and pressure offloading functions. A commercial pressure mat was concurrently used to validate the cushion’s pressure modulation functions. Additionally, the perceived comfort of the cushion was evaluated using General Discomfort Assessment (GDA) and Discomfort Intensity (DIS) scores, which provided insights into participants’ overall comfort and discomfort levels. Real-time pressure profiles generated by the cushion resembled commercial pressure mat readings. During tests with individuals with spinal cord injury, the cushion was able to dynamically generate and display the real-time pressure profile of a seated individual with strong precision (correlation to commercial pressure mat: r ranging from 0.76 to 0.88), providing effective input into pressure modulation functions. Pressure redistribution algorithms eliminated peak pressure and reduced the overall pressure at the interface. Pressure offloading algorithms automatically identified the regions with the highest interface pressure and subsequently relieved the pressure from those areas. User feedback showed that the cushion was comfortable after redistribution and offloading. This work demonstrated the feasibility of an advanced smart seat cushion system for wheelchair users with spinal cord injuries. The cushion was capable of redistributing pressure evenly across the seating surface, ensuring user’s comfort. Additionally, it identifies and eliminates high-pressure points, further improving comfort and reducing the risk of pressure injuries.

Investigation on tunnelling-induced soil pressure changes, a modified trapdoor test study

To investigate the failure mechanics and soil pressure redistribution in cohesive soil during the formation of the arching effect after tunnel excavation, a series of trapdoor tests were conducted on similarity material, and the tunnelling-induced soil movement was modeled. In addition, the moveable soil on the two sides of a tunnel was replicated by modifying the boundary condition of the classic trapdoor. Results indicated that as the trapdoor descended, the cracks extended outward to the ground when the cover ratio (depth to width) was 2, and extended upwards below the ground when the cover ratio was over 2. After the descent of the trapdoor, the unloading effect and arching effect were formed. Therefore, above the trapdoor, the vertical stress (radial stress for the trapdoor) decreased significantly while the tangential stress for the trapdoor increased. Due to the arching effect, the lateral pressure coefficient (K) at the central axis of the trapdoor increased, while it decreased above the two sides of the trapdoor. In the modified trapdoor device, the arching effect was weaker, and reduced the angle between the outermost crack and the horizontal plane, the tangential stress, and the K at the central axis of the trapdoor, and increased the K above both sides of the trapdoor and the range of the soil arch. In addition, in the classic trapdoor device, the arching effect was underestimated at small trapdoor displacements while it was overestimated at large trapdoor displacements. Therefore, the influence of boundary conditions in trapdoor devices should be considered when investigating underground excavation-induced soil deformation and stress redistribution. When calculating the soil pressure, the K should be determined according to the parameters of the soil, the span of the tunnel, and the deformation of the tunnel lining.

Effects of Excess Pore Pressure Redistribution in Liquefiable Layers

Effects of Excess Pore Pressure Redistribution in Liquefiable Layers

349 Addressing the Gaps in Diabetic Foot Ulcer Management: Prediction and Prevention

OBJECTIVES/GOALS: Globally, diabetes affects 537 million people and 15-25% will develop a foot ulcer in their lifetime. Diabetic foot ulcers (DFU) tend to be chronic and non-healing due to the poor wound healing environment, leading to infection or amputation. Our study aims to develop a method to predict and prevent DFU formation. METHODS/STUDY POPULATION: Our preliminary plan is to develop a method to detect high plantar pressures, coupled with the ability to automatically adjust an orthotic device to offload excess pressure. Our current aim is to create a “smart orthotic” which will link with foot mapping technology to automatically offload high pressure areas, reducing the need for a separate clinic visit for orthotic adjustment. We aim to prove that our device will normalize plantar pressure distribution, which will prevent callus and subsequent DFU formation. The current target population includes those with diagnosed diabetes and are ambulatory. RESULTS/ANTICIPATED RESULTS: With our technology, we anticipate normalization of plantar pressure distribution in a more frequent fashion than is currently done. Because annual orthotic fittings, which is current standard of care, do not provide regular enough adjustments to match the rate of diabetic foot structural changes and peak plantar pressure redistribution, our device will address two gaps in management. One, patients will receive near-instantaneous changes in plantar pressure offloading, allowing for near continuous orthotic customization. Secondly, our device would reduce the clinical appointment burden, which would be especially important for patients with multiple medical comorbidities or experience other barriers to accessing healthcare. DISCUSSION/SIGNIFICANCE: While DFUs are commonplace and their complications are well recognized, there still exists a gap in ulcer prevention. Our proposed solution will redistribute pathologic plantar pressures, allow for more frequent monitoring, automatic therapy, and aid in the management of high ulcer risk patients.

Explore the effect of pressure and time of compression on the risk of intraoperatively acquired pressure injury based on theoretical framework: A prospective study.

Surgery is a high risk factor for the occurrence of pressure injury (PI). On the basis of theoretical research, pressure and duration of pressure are key factors affecting PI. Pressure is affected by the individual pressure redistribution capacity. So our study aims to explore how the surgery time and pressure intensity affect the occurrence of PI and what are the risk factors. A prospective study. A total of 250 patients who underwent elective surgery in a grade-A general hospital from November 2021 to February 2023 were selected and divided into a group of 77 patients with IAPI (intraoperatively acquired pressure injury) and a group of 173 patients with no IAPI. Visual pressure inductive feedback system and body composition analysis technology were used to record the local pressure value and change of patients before and after anaesthesia. Relevant data of the patients were collected to explore the influencing factors. The maximum pressure and average pressure at the pressure site of the same patient changed before and after anaesthesia, and the pressure after anaesthesia was significantly higher than that before anaesthesia. There was no statistical difference in the average pressure after anaesthesia (p > 0.05), but the maximum pressure in the IAPI group was higher than that in the non-occurrence group (p < 0.05). The average pressure multiplied by the operation time in IAPI group is significantly higher than that in the non-IAPI group (p < 0.01). Multiple linear regression analysis (stepwise regression) showed that fat-free weight, age, waist circumference, body mass index (BMI) and gender were taken as independent variables into the regression model, affecting the maximum pressure. In addition, operation time ≥4 h may be a high risk factor for IAPI. In future studies, more objective research tools can be applied to improve the accuracy of predicting the risk of IAPI. In addition to gender and BMI, follow-up studies may consider including measures such as waist circumference and fat-free body weight in IAPI risk assessment to guide the clinical nursing work more scientifically.

Coupled effect of load weights and belt use on male shoulder pressure redistribution

Shoulder pressure redistribution is jointly affected by backpack loads and belt support. However, the combined effect of both factors has rarely been fully evaluated. Here, we studied the coupled effect of backpack loads and belt support on shoulder pressure redistribution. All twenty-eight healthy male subjects underwent eight loading conditions with both chest and hip belts fastened (CH) and unfastened (CON) in four conditions where the backpack weighed 7.5, 15, 22.5, and 30% of body weight (BW). Shoulder pressure distribution was quantified through a pressure-sensing vest mat. The results showed that using the hip belt and chest belt was effective in relieving the high pressure in the lateral clavicle and medial trapezius region and strengthening the load-bearing capacity of shoulder. However, the assistance in pressure relief of using belt was weakened when load increased to 30% BW. This study also showed that the belt use can be effective in improving pressure asymmetry on both sides.

Modeling and comfort analysis of arrayed air cushion mattress for pressure ulcer prevention and assisted repositioning

Assisting immobile individuals with regular repositioning to adjust pressure distribution on key prominences such as the back and buttocks is the most effective measure for preventing pressure ulcers. However, compared to active self-repositioning, passive assisted repositioning results in distinct variations in force distribution on different body parts. This incongruity can affect the comfort of repositioning and potentially lead to a risk of secondary injury, for certain trauma or critically ill patients. Therefore, it is of considerable practical importance to study the passive turning comfort and the optimal turning strategy. Initially, in this study, the load-bearing characteristics of various joints during passive repositioning were examined, and a wedge-shaped airbag configuration was proposed. The airbags coupled layout on the mattress was equivalently represented as a spring-damping system, with essential model parameters determined using experimental techniques. Subsequently, different assisted repositioning strategies were devised by adjusting force application positions and sequences. A human-mattress force-coupled simulation model was developed based on rigid human body structure and equivalent flexible springs. This model provided the force distribution across the primary pressure points on the human body. Finally, assisted repositioning experiments were conducted with 15 participants. The passive repositioning effectiveness and pressure redistribution was validated based on the simulation results, experimental data, and questionnaire responses. Furthermore, the mechanical factors influencing comfort during passive assisted repositioning were elucidated, providing a theoretical foundation for subsequent mattress design and optimization of repositioning strategies.

Tuning the Tensile and Shear Properties of a Scar Healing Composite for Mechanotherapy

Conventional scar treatment options of single pressure garment therapy (PGT) or silicone gel sheeting (SGS, Cica-Care®, Smith and Nephew, London, UK) alone lack mechanical property tunability. This article discusses a scar healing composite (PGF-Biopor®AB, Dreve Otoplastik GmbH, Unna, Germany) and how its mechanical properties can be tuned for improved mechanotherapy. A balance between compression and tension was achieved by tuning the tensile and shear properties, facilitating tension shielding and pressure redistribution for scar therapeutics. Biopor®AB-wrapping on biaxial-tensioned pressure garment fabric (PGF) allowed compression therapy and internal pressure redistribution. The Biopor®AB surface, with a coefficient of friction close to 1, strategically localizes stress for effective tension shielding. A substantial five-fold reduction in silicone tension, amounting to 1.060 N, achieves tension shielding and pressure redistribution. Simultaneously, a dynamic internal pressure-sharing mechanism distributes 0.222 kPa from each SPK-filament bundle, effectively managing internal pressure. Alongside the principle compression-silicone dual therapy, this composite design with dynamic internal pressure sharing and mechanical property tunability provides an additional pressure-relieving strategy for multiple scar therapeutics.