Shear force

pedCAT(®) (CurveBeam, Warrington, PA) is a technology for 3-dimensional (3D) imaging with full weightbearing that has been proved to exactly visualize the 3D bone position. For the present study, a customized pedography sensor (Pliance; Novel, Munich, Germany) was inserted into the pedCAT(®). The aim of our study was to analyze the correlation of the bone position and force/pressure distribution. A prospective consecutive study of 50 patients was performed, starting July 28, 2014. All patients underwent a pedCAT(®) scan and simultaneous pedography with full weightbearing in the standing position...

Currently, pressure ulcer preventive strategies focus mainly on pressure redistribution. Little attention is paid to reduce the harmful effects of shear-force, because little is known about pathophysiological aspects of shear-force. Even today, no method to measure the effects of shear-force on the skin is available. Therefore, the aim of this study was to investigate the response to shear-forces in terms of analyzing a noninvasive biomarker and reactive hyperemic parameter measured at the skin of healthy participants...

Although the primary risk factors for pressure ulcer development - pressure, shear, skin temperature, moisture, and friction - have been identified for decades, the relative contribution of each to this risk remains unclear. To confirm the results of and expand upon earlier research into the relative contributions of interface pressures, shear stress, and skin temperature among 4 healthy volunteers, a study involving 6 additional healthy 40- to 75-year-old volunteers was conducted and results of the 2 studies were pooled...

GOAL: The objective of this paper is to demonstrate a multiplexed inductive force sensor for simultaneously measuring normal force and shear forces on a foot. METHODS: The sensor measures the normal force and shear forces by monitoring the inductance changes of three planar sensing coils. Resonance frequency division multiplexing was applied to signals from the multiple sensing coils, making it feasible to simultaneously measure the three forces (normal force, shear forces in x- and y-axis) on a foot using only one set of measurement electronics with high sensitivity and resolution...

Measuring shear force is crucial for investigating the pathology and treatment of pressure ulcers. In this study, we introduced a bi-axial shear transducer based on strain gauges as a new shear sensor. The sensor consisted of aluminum and polyvinyl chloride plates placed between quadrangular aluminum plates. On the middle plate, two strain gauges were placed orthogonal to one another. The shear sensor (54 mm × 54 mm × 4.1 mm), which was validated by using standard weights, displayed high accuracy and precision (measurement range, -50 to 50 N; sensitivity, 0...

BACKGROUND: The exact pathology of diabetic foot ulcers remains to be resolved. Evidence suggests that plantar shear forces play a major role in diabetic ulceration. Unfortunately, only a few manuscripts exist on the clinical implications of plantar shear. The purpose of this study was to compare global and regional peak plantar stress values in three groups; diabetic patients with neuropathy, diabetic patients without neuropathy and healthy control subjects. METHODS: Fourteen diabetic neuropathic patients, 14 non-neuropathic diabetic control and 11 non-diabetic control subjects were recruited...

BACKGROUND: Clinical recommendations for the prevention and healing of diabetic foot ulcers (DFUs) are somewhat clear. However, assessment and quantification of the mechanical stress responsible for DFU remain complex. Different pressure variables have been described in the literature to better understand plantar tissue stress exposure. This article reviews the role of pressure and shear forces in the pathogenesis of plantar DFU. METHODS: We performed systematic searches of the PubMed and Embase databases, completed by a manual search of the selected studies...

INTRODUCTION: Forces applied to the skin cause a decrease in regional blood flow. This decrease in blood flow can cause tissue necrosis and lead to the formation of deep, penetrating wounds called pressure ulcers. These wounds are detrimental to individuals with compromised health, such as the elderly and spinal-cord injured. Although surface pressure is known to be a primary risk factor for developing a pressure ulcer, a seated individual rarely experiences pressure alone but rather combined loading which includes pressure as well as shear force on the skin...

BACKGROUND: Many of the physiological changes that lead to diabetic foot ulceration, such as muscle atrophy and skin hardening, are manifested at the foot-ground interface via pressure and shear points. Novel shear-reducing insoles have been developed, but their magnitude of shear stiffness has not yet been compared with regular insoles. The aim of this study was to develop an apparatus that would apply shear force and displacement to an insole's forefoot region, reliably measure deformation, and calculate insole shear stiffness...

Pressure ulcer prevention strategies include the prevention, and early recognition, of deep tissue injury (DTI), which can evolve into a Stage III or Stage IV pressure ulcer. In addition to their role in pressure-induced ischemia, shearing forces are believed to contribute substantially to the risk of DTI. Because the visual manifestation of a DTI may not occur until many hours after tissues were damaged, research to explore methods for early detection is on-going. For example, rhabdomyolysis is a common complication of deep tissue damage; its detection via blood chemistry and urinalysis is explored as a possible diagnostic tool of early DTI in anatomical areas where muscle is present...

The fundamental cause of lower-extremity complications in diabetes is chronic hyperglycemia leading to diabetic foot ulcer pathology. While the relationship between abnormal plantar pressure distribution and plantar ulcers has been widely investigated, little is known about the role of shear stress. Moreover, the mutual relationship among plantar pressure, shear stress, and abnormal kinematics in the etiology of diabetic foot has not been established. This lack of knowledge is determined by the lack of commercially available instruments which allow such a complex analysis...

Based on the hypothesis that diabetic foot lesions have a mechanical etiology, extensive efforts have sought to establish a relationship between ulcer occurrence and plantar pressure distribution. However, these factors are still not fully understood. The purpose of this study was to simultaneously record shear and pressure distributions in the heel and forefoot and to answer whether: (i) peak pressure and peak shear for anterior-posterior (AP) and medio-lateral (ML) occur at different locations, and if (ii) peak pressure is always centrally located between sites of maximum AP and ML shear stresses...

BACKGROUND: According to the latest pressure ulcer definition provided by the EPUAP and NPUAP pressure and shear are named as factors causing pressure ulcers. Empirical evidence suggests that pressure forces in combination with shear seem to be primarily responsible for deeper tissue injuries leading to category III or IV pressure ulcers. Superficial frictional forces seem to cause skin lesion resembling category II pressure ulcers. OBJECTIVES: The objective of this study was to explore the empirical relationships between friction forces and category II pressure ulcers and between pressure forces and categories III and IV pressure ulcers...

Surface pressures and shear forces were measured in order to clarify the mechanism leading to the development of a pressure ulcer at five sites on the body during the operation of a bed (bed) using a device for simultaneously measuring pressure and shear force. Changes of shear force and pressure when three body types adopted different supine positions, with or without raising/bending the knees (raising the knees), were investigated and analyzed. The results are as follows: a slender body type tends to have the highest shear force at the coccygeal bone site and also has a higher surface pressure at the coccygeal and at the lateral sacral bone sites than an obese body type...

Pressure ulcers are serious health problems. Although a vast amount of literature addresses prevention and treatment strategies, conceptual difficulties persist regarding pressure ulcer definitions, classifications, and distinction from other tissue lesions. Based on a review of terminologies as well as current state of knowledge on pathophysiology and etiology, questions as to what pressure ulcers are and what they are not are addressed. Because pressure forces seem to play a minor role in the development of superficial ulcers, the authors suggest these types of wounds no longer be termed pressure ulcers...

Shear forces under the human foot are thought to be responsible for various foot pathologies such as diabetic plantar ulcers and athletic blisters. Frictional shear forces might also play a role in the metatarsalgia observed among hallux valgus (HaV) and rheumatoid arthritis (RA) patients. Due to the absence of commercial devices capable of measuring shear stress distribution, a number of linear models were developed. All of these have met with limited success. This study used nonlinear methods, specifically neural network and fuzzy logic schemes, to predict the distribution of plantar shear forces based on vertical loading parameters...

Diabetic foot ulcers are known to have a biomechanical etiology. Among the mechanical factors that cause foot lesions, shear stresses have been either neglected or underestimated. The purpose of this study was to determine various plantar pressure and shear variables in the diabetic and control groups and compare them. Fifteen diabetic patients with neuropathy and 20 non-diabetic subjects without foot symptoms were recruited. Subjects walked on a custom-built platform capable of measuring local normal and tangential forces simultaneously...

No abstract text is available yet for this article.

Plantar shear stresses are believed to play a major role in diabetic ulceration. Due to the lack of commercial devices that can measure plantar shear distribution, a number of mathematical models have been developed to predict plantar frictional forces. This study assessed the accuracy of these models using a custom-built platform capable of measuring plantar stresses simultaneously. A total of 48 (38 healthy and 10 diabetic) human subjects (75+/-20 kg, 41+/-20 years, 32 males, 16 females) were recruited in the study...

OBJECTIVE: We compared the shear forces exerted over the heel between a pressure ulcer preventive dressing and a thin-film dressing in a clinical setting. Interface pressures were measured as well. DESIGN: Quasi-experimental clinical trial. SETTING AND SUBJECTS: Participants were 30 elderly patients (5 men, 25 women; mean age, 86.4 +/- 8.0 years) hospitalized in a geriatrics hospital in Japan; all had a Braden score of less than 14 (mean, 10...