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Zhang X, Teng Z, Geng X, Ma X, Chen WM. A fluoroscopic imaging-guided computational analyses to inform internal tissue loads within fat pad of the diabetic foot during gait. J Biomech 2023; 157:111744. [PMID: 37535986 DOI: 10.1016/j.jbiomech.2023.111744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 07/25/2023] [Accepted: 07/28/2023] [Indexed: 08/05/2023]
Abstract
To accurately predict internal tissue loads for early diagnostics of diabetic foot ulcerations, a novel data-driven computational analysis was conducted. A dedicated dual fluoroscopic system was combined with a pressure mat to simultaneously characterize foot motions and soft tissue's material properties during gait. Finite element (FE) models of the heel pad of a diabetic patient were constructed with 3D trajectories of the calcaneus applied as boundary conditions to simulate gait events. The tensile and compressive stresses occurring in the plantar tissue were computed. Predictions of the layered tissue FE model with anatomically-accurate heel pad structures (i.e., fat and skin) were compared with those of the traditional lumped tissue (i.e., homogeneous) models. The influence of different material properties (patient-specific versus generic) on internal tissue stresses was also investigated. The results showed the peak tensile stresses in the layered tissue model were predominantly found in the skin and distributed towards the circumferential regions of the heel, while peak compressive stresses in the fat tissue-bone interface were up to 51.4% lower than those seen in the lumped models. Performing FE analyses at four different phases of walking revealed that ignorance of layered tissue structures resulted in an unphysiological increase of peak-to-peak value of stress fluctuation in the fat and skin tissue components. Thus, to produce more clinical-relevant predictions, foot FE models are suggested to include layered tissue structures of the plantar tissue for an improved estimation of internal stresses in the diabetic foot in gait.
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Affiliation(s)
- Xingyu Zhang
- Institute of Biomedical Engineering and Technology, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai, China
| | - Zhaolin Teng
- Department of Orthopaedics, Huashan Hospital affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China
| | - Xiang Geng
- Department of Orthopaedics, Huashan Hospital affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China
| | - Xin Ma
- Department of Orthopaedics, Huashan Hospital affiliated to Fudan University, 12 Middle Wulumuqi Road, Shanghai, China
| | - Wen-Ming Chen
- Institute of Biomedical Engineering and Technology, Academy for Engineering and Technology, Fudan University, 220 Handan Road, Shanghai, China.
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2
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Gefen A, Brienza DM, Cuddigan J, Haesler E, Kottner J. Our contemporary understanding of the aetiology of pressure ulcers/pressure injuries. Int Wound J 2021; 19:692-704. [PMID: 34382331 PMCID: PMC8874092 DOI: 10.1111/iwj.13667] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/02/2021] [Accepted: 07/25/2021] [Indexed: 12/25/2022] Open
Abstract
In 2019, the third and updated edition of the Clinical Practice Guideline (CPG) on Prevention and Treatment of Pressure Ulcers/Injuries has been published. In addition to this most up‐to‐date evidence‐based guidance for clinicians, related topics such as pressure ulcers (PUs)/pressure injuries (PIs) aetiology, classification, and future research needs were considered by the teams of experts. To elaborate on these topics, this is the third paper of a series of the CPG articles, which summarises the latest understanding of the aetiology of PUs/PIs with a special focus on the effects of soft tissue deformation. Sustained deformations of soft tissues cause initial cell death and tissue damage that ultimately may result in the formation of PUs/PIs. High tissue deformations result in cell damage on a microscopic level within just a few minutes, although it may take hours of sustained loading for the damage to become clinically visible. Superficial skin damage seems to be primarily caused by excessive shear strain/stress exposures, deeper PUs/PIs predominantly result from high pressures in combination with shear at the surface over bony prominences, or under stiff medical devices. Therefore, primary PU/PI prevention should aim for minimising deformations by either reducing the peak strain/stress values in tissues or decreasing the exposure time.
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Affiliation(s)
- Amit Gefen
- The Herbert J. Berman Chair in Vascular Bioengineering, Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - David M Brienza
- Departments of Rehabilitation Science and Technology & Bioengineering and the McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Janet Cuddigan
- College of Nursing, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Emily Haesler
- School of Nursing, Midwifery and Paramedicine, Curtin University, Perth, Australia.,Australian Centre for Evidence Based Aged Care, School of Nursing and Midwifery, LaTrobe University, Melbourne, Victoria, Australia.,Australian National University Medical School, Academic Unit of General Practice, Australian National University, Canberra, ACT, Australia
| | - Jan Kottner
- Charité Center 1 for Health and Human Sciences, Charité-Universitätsmedizin Berlin, Berlin, Germany
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3
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Sidorenko I, Turova V, Botkin N, Kovtanyuk A, Eckardt L, Alves-Pinto A, Felderhoff-Müser U, Rieger-Fackeldey E, Lampe R. Assessing haemorrhage-critical values of cerebral blood flow by modelling biomechanical stresses on capillaries in the immature brain. Sci Rep 2020; 10:14196. [PMID: 32848187 PMCID: PMC7449973 DOI: 10.1038/s41598-020-71087-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/06/2020] [Indexed: 11/09/2022] Open
Abstract
The development of intraventricular haemorrhages (IVH) in preterm newborns is triggered by a disruption of the vessels responsible for cerebral microcirculation. Analysis of the stresses exerted on vessel walls enables the identification of the critical values of cerebral blood flow (CBF) associated with the development of IVH in preterm infants. The purpose of the present study is the estimation of these critical CBF values using the biomechanical stresses obtained by the finite element modelling of immature brain capillaries. The properties of the endothelial cells and basement membranes employed were selected on the basis of published nanoindentation measurements using atomic force microscopes. The forces acting on individual capillaries were derived with a mathematical model that accounts for the peculiarities of microvascularity in the immature brain. Calculations were based on clinical measurements obtained from 254 preterm infants with the gestational age ranging from 23 to 30 weeks, with and without diagnosis of IVH. No distinction between the affected and control groups with the gestational age of 23 to 26 weeks was possible. For infants with the gestational age of 27 to 30 weeks, the CBF value of 17.03 ml/100 g/min was determined as the critical upper value, above which the likelihood of IVH increases.
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Affiliation(s)
- Irina Sidorenko
- Mathematical Faculty, Chair of Mathematical Modelling, Technical University of Munich, Boltzmannstr. 3, 85748, Garching, Germany
| | - Varvara Turova
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Nikolai Botkin
- Mathematical Faculty, Chair of Mathematical Modelling, Technical University of Munich, Boltzmannstr. 3, 85748, Garching, Germany
| | - Andrey Kovtanyuk
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Laura Eckardt
- Department of Pediatrics I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, Department of Pediatrics III, Pediatric Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Ana Alves-Pinto
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Ursula Felderhoff-Müser
- Department of Pediatrics I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, Department of Pediatrics III, Pediatric Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Esther Rieger-Fackeldey
- School of Medicine, Klinikum Rechts Der Isar, Department of Pediatrics, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Renée Lampe
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.
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4
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Linking microvascular collapse to tissue hypoxia in a multiscale model of pressure ulcer initiation. Biomech Model Mechanobiol 2019; 18:1947-1964. [PMID: 31203488 DOI: 10.1007/s10237-019-01187-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/05/2019] [Indexed: 12/27/2022]
Abstract
Pressure ulcers are devastating injuries that disproportionately affect the older adult population. The initiating factor of pressure ulcers is local ischemia, or lack of perfusion at the microvascular level, following tissue compression against bony prominences. In turn, lack of blood flow leads to a drop in oxygen concentration, i.e, hypoxia, that ultimately leads to cell death, tissue necrosis, and disruption of tissue continuity. Despite our qualitative understanding of the initiating mechanisms of pressure ulcers, we are lacking quantitative knowledge of the relationship between applied pressure, skin mechanical properties as well as structure, and tissue hypoxia. This gap in our understanding is, at least in part, due to the limitations of current imaging technologies that cannot simultaneously image the microvascular architecture, while quantifying tissue deformation. We overcome this limitation in our work by combining realistic microvascular geometries with appropriate mechanical constitutive models into a microscale finite element model of the skin. By solving boundary value problems on a representative volume element via the finite element method, we can predict blood volume fractions in response to physiological skin loading conditions (i.e., shear and compression). We then use blood volume fraction as a homogenized variable to couple tissue-level skin mechanics to an oxygen diffusion model. With our model, we find that moderate levels of pressure applied to the outer skin surface lead to oxygen concentration contours indicative of tissue hypoxia. For instance, we show that applying a pressure of 60 kPa at the skin surface leads to a decrease in oxygen partial pressure from a physiological value of 65 mmHg to a hypoxic level of 31 mmHg. Additionally, we explore the sensitivity of local oxygen concentration to skin thickness and tissue stiffness, two age-related skin parameters. We find that, for a given pressure, oxygen concentration decreases with decreasing skin thickness and skin stiffness. Future work will include rigorous calibration and validation of this model, which may render our work an important tool toward developing better prevention and treatment tools for pressure ulcers specifically targeted toward the older adult patient population.
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Pinheiro M, Dobson CA, Perry D, Fagan MJ. New insights into the biomechanics of Legg-Calvé-Perthes' disease: The Role of Epiphyseal Skeletal Immaturity in Vascular Obstruction. Bone Joint Res 2018; 7:148-156. [PMID: 29437587 PMCID: PMC5895949 DOI: 10.1302/2046-3758.72.bjr-2017-0191.r1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Objectives Legg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition. Methods Finite element analysis modelling of the blood supply to the juvenile epiphysis was investigated to understand under which circumstances the blood vessels supplying the femoral epiphysis could become obstructed. The identification of these conditions is likely to be important in understanding the biomechanics of LCP. Results The results support the hypothesis that vascular obstruction to the epiphysis may arise when there is delayed ossification and when articular cartilage has reduced stiffness under compression. Conclusion The findings support the theory of vascular occlusion as being important in the pathophysiology of Perthes disease. Cite this article: M. Pinheiro, C. A. Dobson, D. Perry, M. J. Fagan. New insights into the biomechanics of Legg-Calvé-Perthes’ disease: The Role of Epiphyseal Skeletal Immaturity in Vascular Obstruction. Bone Joint Res 2018;7:148–156. DOI: 10.1302/2046-3758.72.BJR-2017-0191.R1.
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Affiliation(s)
- M Pinheiro
- School of Engineering and Computer Science, University of Hull, Cottingham Road, Kingstonupon-Hull HU6 7RX, UK
| | - C A Dobson
- School of Engineering and Computer Science, University of Hull, Cottingham Road, Kingstonupon-Hull HU6 7RX, UK
| | - D Perry
- University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - M J Fagan
- School of Engineering and Computer Science, University of Hull, Cottingham Road, Kingstonupon-Hull HU6 7RX, UK
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Källman U, Bergstrand S, Ek AC, Engström M, Lindgren M. Blood flow responses over sacrum in nursing home residents during one hour bed rest. Microcirculation 2018; 23:530-539. [PMID: 27534925 PMCID: PMC5096247 DOI: 10.1111/micc.12303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/11/2016] [Indexed: 11/29/2022]
Abstract
Objectives To describe individual BF responses in a nursing home resident population for one‐hour periods of bed rest. Methods BF was measured for one hour over the sacrum in 0° supine position and 30° supine tilt position in 25 individuals aged 65 y or older while lying on a pressure‐redistributing mattress. Measurements were made at three tissue depths (1, 2, and 10 mm) using the noninvasive optical techniques, LDF and PPG. Results Eleven participants had a PIV response at 1 mm depth in both positions and seven participants had a lack of this response at this depth and positions. The BF response at 1 mm depth appeared immediately and remained over, or below, baseline for the entire 60 min of loading in both positions. These BF patterns were also seen in deeper tissue layers. Conclusions The cutaneous BF response among the nursing home residents was distinct, appeared early, and remained during the one hour of loading.
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Affiliation(s)
- Ulrika Källman
- Department of Medical and Health Sciences, Division of Nursing Linköping University, Linköping, Sweden. .,Department of Research, Södra Älvsborgs Sjukhus, Borås, Sweden.
| | - Sara Bergstrand
- Department of Medical and Health Sciences, Division of Nursing Linköping University, Linköping, Sweden
| | - Anna-Christina Ek
- Department of Medical and Health Sciences, Division of Nursing Linköping University, Linköping, Sweden
| | - Maria Engström
- Department of Medical and Health Sciences, Division of Nursing Linköping University, Linköping, Sweden
| | - Margareta Lindgren
- Department of Medical and Health Sciences, Division of Nursing Linköping University, Linköping, Sweden
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7
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A multiscale modeling framework for studying the mechanobiology of sarcopenic obesity. Biomech Model Mechanobiol 2016; 16:275-295. [DOI: 10.1007/s10237-016-0816-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/08/2016] [Indexed: 01/08/2023]
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8
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Yamada H, Inoue Y, Shimokawa Y, Sakata K. Skin stiffness determined from occlusion of a horizontally running microvessel in response to skin surface pressure: a finite element study of sacral pressure ulcers. Med Biol Eng Comput 2016; 55:79-88. [PMID: 27106752 DOI: 10.1007/s11517-016-1500-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 03/27/2016] [Indexed: 11/30/2022]
Abstract
Pressure ulcers occur following sustained occlusion of microvessels at bony prominences under skin surface pressure (SSP). However, the mechanical conditions of the surrounding soft tissue leading to microvascular occlusion are not fully understood. This study determined the stiffness of homogenized skin with microvasculature at the sacrum that occludes microvessels at an SSP of 10 kPa (consistent with a standard mattress) and recovers from occlusion at 5 kPa (consistent with a pressure-redistribution mattress). We conducted two-dimensional finite element analyses under plane stress and plane strain conditions to determine the stiffness of the skin. The results for plane stress conditions show that the microvessel was occluded with a Young's modulus of 23 kPa in response to an SSP of 10 kPa at the center of the sacrum and that the circulation recovered following a reduction in the SSP to 5 kPa. The resulting Young's modulus is consistent with reported data. Our study indicates that the critical value of the SSP for microvascular occlusion is determined not only by the stiffness of homogenized skin with microvasculature but also by the intraluminal pressure, microvascular wall stiffness, and body support conditions.
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Affiliation(s)
- Hiroshi Yamada
- Department of Biological Functions Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
| | - Yoshiaki Inoue
- Department of Biological Functions Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, 808-0196, Japan
| | - Yuki Shimokawa
- Department of Biological Functions Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, 808-0196, Japan
| | - Keisuke Sakata
- Department of Biological Functions Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, 808-0196, Japan
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9
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Bergstrand S, Källman U, Ek AC, Engström M, Lindgren M. Microcirculatory responses of sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses. J Wound Care 2015; 24:346-58. [DOI: 10.12968/jowc.2015.24.8.346] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- S. Bergstrand
- Department of Hand Surgery, Plastic Surgery and Burns and the Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - U. Källman
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
- Department of Dermatology, Södra Älvsborgs Sjukhus, Borås, Sweden
| | - A-C. Ek
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - M. Engström
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - M. Lindgren
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
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10
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Källman U, Bergstrand S, Ek AC, Engström M, Lindgren M. Nursing staff induced repositionings and immobile patients' spontaneous movements in nursing care. Int Wound J 2015; 13:1168-1175. [PMID: 25779932 DOI: 10.1111/iwj.12435] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/30/2015] [Accepted: 02/02/2015] [Indexed: 11/30/2022] Open
Abstract
The aim of this study was to investigate nursing staff induced repositionings and the patients' spontaneous movements during the day and night among older immobile patients in nursing care. Furthermore, the aim was to identify factors associated with the nursing staff induced repositionings and the patients' spontaneous movement frequency. An observational cross-sectional design was used. Spontaneous movements among patients (n = 52) were registered continuously using the MovinSense monitoring system. The nursing staff documented each time they repositioned the patient. Patients spontaneous movements were compared with nursing staff induced repositionings. There were large variations in the patients' spontaneous repositioning frequency during both days and nights, which shows that, although immobilised, some patients frequently reposition themselves. Analgesics were positively related to the movement frequency and psycholeptics were negatively related. The nursing staff more often repositioned the patients who were assessed as high risk than those assessed as low risk, but the patients' spontaneous movement frequency was not correlated to the risk score. This may be important when planning repositioning schedules. A monitoring system may be useful in decision making with regard to planning repositioning and positions used in the prevention of pressure ulcers among elderly immobile patients.
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Affiliation(s)
- Ulrika Källman
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Department of Dermatology, Södra Älvsborgs Sjukhus, Borås, Sweden
| | - Sara Bergstrand
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.,Department of Hand Surgery, Plastic Surgery, and Burns, Linköping University, Linköping, Sweden.,Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - Anna-Christina Ek
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Maria Engström
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Margareta Lindgren
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
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11
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Bergstrand S, Källman U, Ek AC, Lindberg LG, Engström M, Sjöberg F, Lindgren M. Pressure-induced Vasodilation and Reactive Hyperemia at Different Depths in Sacral Tissue Under Clinically Relevant Conditions. Microcirculation 2014; 21:761-71. [DOI: 10.1111/micc.12160] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 07/31/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Sara Bergstrand
- Department of Hand Surgery, Plastic Surgery and Burns and Department of Medical and Health Sciences; Linköping University; Linköping Sweden
| | - Ulrika Källman
- Department of Medical and Health Sciences; Linköping University; Linköping Sweden
- Department of Dermatology; Södra Älvsborgs Sjukhus; Borås Sweden
| | - Anna-Christina Ek
- Department of Medical and Health Sciences; Linköping University; Linköping Sweden
| | - Lars-Göran Lindberg
- Department of Biomedical Engineering; Linköping University; Linköping Sweden
| | - Maria Engström
- Department of Medical and Health Sciences; Linköping University; Linköping Sweden
| | - Folke Sjöberg
- Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Margareta Lindgren
- Department of Medical and Health Sciences; Linköping University; Linköping Sweden
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12
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Tang K, Sharpe W, Schulz A, Tam E, Grosse I, Tis J, Cullinane D. Determining bruise etiology in muscle tissue using finite element analysis. J Forensic Sci 2013; 59:371-4. [PMID: 24313678 DOI: 10.1111/1556-4029.12349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 01/07/2013] [Accepted: 02/03/2013] [Indexed: 11/29/2022]
Abstract
Bruising, the result of capillary failure, is a common physical exam finding due to blunt trauma and, depending on location and severity, a potential indicator of abuse. Despite its clinical relevance, few studies have investigated the etiology of capillary failure. The goal of this study was to determine whether capillaries primarily fail under shear stress or hydraulic-induced tensile stress. An arteriole bifurcating into four capillaries was modeled using ANSYS 14.0 (®) . The capillaries were embedded in muscle tissue and a pressure of 20.4 kPa was applied. Any tensile stress exceeding 8.4 × 10(4) Pa was considered failure. Results showed that failure occurred directly under the impact zone and where capillaries bifurcated, rather than along the line of greatest shear stress, indicating that internal tensile stress is likely the primary mode of capillary failure in bruising. These results are supported by the concept that bruising can occur via blunt trauma in which no shearing lacerations occur.
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Affiliation(s)
- Kevin Tang
- Biomechanics Laboratory, Deerfield Academy, 7 Boyden Lane Deerfield, Deerfield, MA 01342
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13
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Shoham N, Gefen A. Deformations, mechanical strains and stresses across the different hierarchical scales in weight-bearing soft tissues. J Tissue Viability 2012; 21:39-46. [DOI: 10.1016/j.jtv.2012.03.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/03/2012] [Accepted: 03/25/2012] [Indexed: 01/23/2023]
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