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Chhikara K, Singh G, Gupta S, Chanda A. Progress of Additive Manufacturing in Fabrication of Foot Orthoses for Diabetic Patients: A Review. ANNALS OF 3D PRINTED MEDICINE 2022. [DOI: 10.1016/j.stlm.2022.100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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DeBerardinis J, Dufek JS, Trabia MB. A viscoelastic ellipsoidal model of the mechanics of plantar tissues. J Biomech 2019; 92:137-145. [DOI: 10.1016/j.jbiomech.2019.05.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/24/2019] [Accepted: 05/27/2019] [Indexed: 10/26/2022]
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3
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Region-specific constitutive modeling of the plantar soft tissue. Biomech Model Mechanobiol 2018; 17:1373-1388. [DOI: 10.1007/s10237-018-1032-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
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Paul S, Vijayakumar R, Mathew L, Sivarasu S. Finite element model-based evaluation of tissue stress variations to fabricate corrective orthosis in feet with neutral subtalar joint. Prosthet Orthot Int 2017; 41:157-163. [PMID: 26979816 DOI: 10.1177/0309364616631344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The subtalar joint position during static stance is a crucial determinant of the peak plantar pressures and forms ideal reference point for any intervention in foot-related problems for leprosy-affected patients. OBJECTIVES The study pursued the hypothesis through a three-dimensional model that stress will be minimal in the distal joints of the foot when the subtalar joint is in neutral static stance position. STUDY DESIGN Finite element model. METHODS The computed tomography images of the feet for five patients suffering from Hansen's disease having no muscle weakness and joint restriction were acquired. The gray intensities corresponding to the bones of the foot from the computed tomography images were three-dimensionally reconstructed. The three-dimensional model of the human foot, incorporating the realistic geometry, and the material properties of the hard tissues were then analyzed using a finite element solver for the stress distribution on bones of the foot. RESULTS The results demonstrate that the position of the calcaneum in the static stance position does contribute to the varying stress in the foot. CONCLUSION The stresses in the bones of the foot are minimal while the subtalar is in neutral position; this position will be suitable for foot orthotic fabrication. Clinical relevance The clinicians, therapists, and podiatrists having less engineering skills can quickly assess the patient and get optimal results on the stress associated with the joints of the foot.
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Affiliation(s)
| | | | - Lazar Mathew
- 3 PSG Institute of Advanced Studies, Coimbatore, India
| | - Sudesh Sivarasu
- 4 Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Finite element modelling of the foot for clinical application: A systematic review. Med Eng Phys 2017; 39:1-11. [DOI: 10.1016/j.medengphy.2016.10.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 10/13/2016] [Accepted: 10/23/2016] [Indexed: 11/20/2022]
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Suzuki R, Ito K, Lee T, Ogihara N. Parameter identification of hyperelastic material properties of the heel pad based on an analytical contact mechanics model of a spherical indentation. J Mech Behav Biomed Mater 2017; 65:753-760. [DOI: 10.1016/j.jmbbm.2016.09.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 09/04/2016] [Accepted: 09/21/2016] [Indexed: 11/26/2022]
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Abstract
In general, diabetic foot ulcers result from abnormal mechanical loading of the foot, such as repetitive moderate pressure applied to the plantar aspect of the foot while walking. Diabetic peripheral neuropathy causes changes in foot structure, affecting foot function and subsequently leading to increased plantar foot pressure, which is a predictive risk factor for the development of diabetic foot ulceration. Prevention of diabetic foot ulceration is possible by early identification of the insensitive foot, therefore a foot “at risk,” and by protecting the foot from abnormal biomechanical loading. Abnormal foot pressures can be reduced using several different approaches, including callus debridement, prescription of special footwear, injection of liquid silicone, Achilles tendon lengthening, and so forth. Off-loading of the diabetic wound is a key factor in successful wound healing, as it is associated with reduced inflammatory and accelerated repair processes. Pressure relief can be achieved using various off-loading modalities including accommodative dressing, walking splints, ankle-foot orthosis, total contact cast, and removable and irremovable cast walkers.
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Affiliation(s)
- C H M van Schie
- Department of Rehabilitation, University of Amsterdam, the Netherlands.
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GUIOTTO ANNAMARIA, SCARTON ALESSANDRA, SAWACHA ZIMI, GUARNERI GABRIELLA, AVOGARO ANGELO, COBELLI CLAUDIO. GAIT ANALYSIS DRIVEN 2D FINITE ELEMENT MODEL OF THE NEUROPATHIC HINDFOOT. J MECH MED BIOL 2016. [DOI: 10.1142/s0219519416500123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The diabetic foot is one of the most serious complications of diabetes mellitus and it can lead to foot ulcerations and amputations. Finite element analysis quantifies the loads developed in the different anatomical structures and describes how these affect foot tissue during foot–floor interaction. This approach for the diabetic subjects’ foot could provide valuable information in the process of plantar orthosis fabrication and fit. The purpose of this study was to develop two finite element models of the hindfoot, of healthy and diabetic neuropathic subjects. These models accounts for in vivo kinematics, kinetics, plantar pressure (PP) data and magnetic resonance images. These were acquired during gait analysis on 10 diabetic neuropathics and 10 healthy subjects. Validity of the models has been assessed through comparison between the peak PPs of simulated and experimental data: root mean square error (RMSE) in percentage of the experimental peak value was evaluated. Two different finite elements analysis were performed: subject-specific simulations in terms of both geometry and gait analysis, and by adopting the complete gait analysis dataset as boundary conditions. Model predicted plantar pressures were in good agreement with those experimentally measured. Best agreement was obtained in the subject-specific case (RMSE of 13%).
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Affiliation(s)
- ANNAMARIA GUIOTTO
- Department of Information Engineering, University of Padova, Via Gradenigo 6b, 35131 Padova, Italy
| | - ALESSANDRA SCARTON
- Department of Information Engineering, University of Padova, Via Gradenigo 6b, 35131 Padova, Italy
| | - ZIMI SAWACHA
- Department of Information Engineering, University of Padova, Via Gradenigo 6b, 35131 Padova, Italy
| | - GABRIELLA GUARNERI
- Department of Clinical Medicine and Metabolic Disease, University Polyclinic of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - ANGELO AVOGARO
- Department of Clinical Medicine and Metabolic Disease, University Polyclinic of Padova, Via Giustiniani 2, 35128 Padova, Italy
| | - CLAUDIO COBELLI
- Department of Information Engineering, University of Padova, Via Gradenigo 6b, 35131 Padova, Italy
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Telfer S, Erdemir A, Woodburn J, Cavanagh PR. What has finite element analysis taught us about diabetic foot disease and its management? A systematic review. PLoS One 2014; 9:e109994. [PMID: 25290098 PMCID: PMC4188702 DOI: 10.1371/journal.pone.0109994] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 09/12/2014] [Indexed: 11/24/2022] Open
Abstract
Background Over the past two decades finite element (FE) analysis has become a popular tool for researchers seeking to simulate the biomechanics of the healthy and diabetic foot. The primary aims of these simulations have been to improve our understanding of the foot’s complicated mechanical loading in health and disease and to inform interventions designed to prevent plantar ulceration, a major complication of diabetes. This article provides a systematic review and summary of the findings from FE analysis-based computational simulations of the diabetic foot. Methods A systematic literature search was carried out and 31 relevant articles were identified covering three primary themes: methodological aspects relevant to modelling the diabetic foot; investigations of the pathomechanics of the diabetic foot; and simulation-based design of interventions to reduce ulceration risk. Results Methodological studies illustrated appropriate use of FE analysis for simulation of foot mechanics, incorporating nonlinear tissue mechanics, contact and rigid body movements. FE studies of pathomechanics have provided estimates of internal soft tissue stresses, and suggest that such stresses may often be considerably larger than those measured at the plantar surface and are proportionally greater in the diabetic foot compared to controls. FE analysis allowed evaluation of insole performance and development of new insole designs, footwear and corrective surgery to effectively provide intervention strategies. The technique also presents the opportunity to simulate the effect of changes associated with the diabetic foot on non-mechanical factors such as blood supply to local tissues. Discussion While significant advancement in diabetic foot research has been made possible by the use of FE analysis, translational utility of this powerful tool for routine clinical care at the patient level requires adoption of cost-effective (both in terms of labour and computation) and reliable approaches with clear clinical validity for decision making.
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Affiliation(s)
- Scott Telfer
- Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, United Kingdom
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Ahmet Erdemir
- Computational Biomodeling (CoBi) Core, Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - James Woodburn
- Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, United Kingdom
| | - Peter R. Cavanagh
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
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Guiotto A, Sawacha Z, Guarneri G, Avogaro A, Cobelli C. 3D finite element model of the diabetic neuropathic foot: A gait analysis driven approach. J Biomech 2014; 47:3064-71. [DOI: 10.1016/j.jbiomech.2014.06.029] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 05/20/2014] [Accepted: 06/27/2014] [Indexed: 11/28/2022]
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Periyasamy R, Mishra A, Anand S, Ammini AC. Foot pressure distribution variation in pre-obese and non-obese adult subject while standing. Foot (Edinb) 2012; 22:276-82. [PMID: 23102906 DOI: 10.1016/j.foot.2012.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 08/10/2012] [Accepted: 08/16/2012] [Indexed: 02/04/2023]
Abstract
BACKGROUND To investigate foot pressure distribution parameter-power ratio (PR) difference between pre-obese and non-obese adults subjects during standing and show the correlation between body mass index (BMI) and PR value. METHODS We examined 22 healthy adult subjects aged from 20 to 45 years were classified into two groups according to their BMI values, as 11 non-obese and 11 pre-obese subjects. Foot pressure distribution image during standing was obtained using PedoPowerGraph system. Pedopowergraphic parameters such as percentage medial impulse, forefoot to hind foot pressure distribution ratio and PR were evaluated and compared between the groups. Correlation between BMI value and PR value was assessed. RESULTS Our result shows significant change in contact area between the groups in mid foot regions. Also we found significant differences in mid foot PR values (p<0.05) between the groups, but no significant differences in hind foot and forefoot PR values. In addition BMI value was found to have positive correlation with right and left mid foot PR value (r=0.60 & 0.61) for all the subjects. CONCLUSION This study provides for the first time new insights into foot pressure distribution difference in mid foot among pre-obese subjects as compared to non-obese adult subject while standing. Hence knowledge of high mid foot PR value among pre-obese subjects can provide suitable guidelines for designing orthotic devices.
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Affiliation(s)
- R Periyasamy
- Center for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India.
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Investigation of Shore meter in assessing foot sole hardness in patients with diabetes mellitus - a pilot study. Int J Diabetes Dev Ctries 2012. [DOI: 10.1007/s13410-012-0085-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Periyasamy R, Anand S, Ammini AC. Association of limited joint mobility and increased plantar hardness in diabetic foot ulceration in north Asian Indian: a preliminary study. Proc Inst Mech Eng H 2012; 226:305-11. [PMID: 22611870 DOI: 10.1177/0954411911435613] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this article is to investigate the association of limited joint mobility and foot sole hardness in north Asian Indian type 2 diabetic patients. Limited joint mobility and hardness of the foot sole were measured for 39 subjects attending the AIIMS Endocrinology & Metabolism Clinic. The total subject divided into three groups: 13 control subjects (nondiabetic), 13 diabetic patients without neuropathy and 13 diabetic neuropathy patients. Neuropathy status was assessed using 10 gm Semen's Weinstein monofilament. Joint mobility parameters, such as ankle dorsiflexion/plantar flexion and metatarsophalangeal-1 dorsiflexion/plantar flexion, are measured using a goniometer. Foot sole hardness was measured using a durometer or shore meter. We found that diabetic patients with a neuropathic foot had significantly reduced joint mobility and increased foot sole hardness, placing them at risk for subsequent ulceration. Metatarsophalangeal-1 dorsiflexion/plantar flexion of both feet of diabetic patients had significant correlation (at p < 0.05, p < 0.001, p < 0.001 level) over age and body mass index. Also ankle plantar flexion/dorsiflexion and metatarsophalangeal-1 dorsiflexion/plantar flexion has a significant correlations (at p < 0.01, p < 0.05, p < 0.001, p < 0.001 level) with foot sole hardness in both feet of diabetic neuropathy subjects. Also linear regression analysis showed that duration of diabetes was significantly associated with the joint mobility parameters. In this study we conclude that joint mobility had reduced further if neuropathy and increased foot sole hardness coexisted owing to high plantar pressures. Hence, both limited joint mobility and increased foot sole hardness appears to be important determinants of foot sole ulceration in diabetic neuropathic subject.
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Affiliation(s)
- R Periyasamy
- Centre for Biomedical Engineering, Indian Institute of Technology, New Delhi, India.
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Stucke S, McFarland D, Goss L, Fonov S, McMillan GR, Tucker A, Berme N, Cenk Guler H, Bigelow C, Davis BL. Spatial relationships between shearing stresses and pressure on the plantar skin surface during gait. J Biomech 2011; 45:619-22. [PMID: 22169152 DOI: 10.1016/j.jbiomech.2011.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 11/07/2011] [Accepted: 11/09/2011] [Indexed: 11/16/2022]
Abstract
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. A custom built system was used to collect shear and pressure data simultaneously on 11 subjects using the 2-step method. The peak pressure was found to be 362 kPa ± 106 in the heel and 527 kPa ± 123 in the forefoot. In addition, the average peak shear values were higher in the forefoot than in the heel. The greatest shear on the plantar surface of the forefoot occurred in the anterior direction (mean and std. dev.: 37.7 ± 7.6 kPa), whereas for the heel, peak shear the foot was in the posterior direction (21.2 ± 5 kPa). The results of this study suggest that the interactions of the shear forces caused greater "spreading" in the forefoot and greater tissue "dragging" in the heel. The results also showed that peak shear stresses do not occur at the same site or time as peak pressure. This may be an important factor in locating where skin breakdown occurs in patients at high-risk for ulceration.
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Affiliation(s)
- Samantha Stucke
- Medical Device Development Center, Austen BioInnovation Institute in Akron, Akron, OH 44308, USA
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Parker MD, Taberner AJ, Nielsen PMF. A thermal stereoscope for surface reconstruction of the diabetic foot. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2011:306-309. [PMID: 22254310 DOI: 10.1109/iembs.2011.6090080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have constructed a thermal stereoscope utilizing three digital SLR cameras and an infrared camera for rapid surface reconstruction of diabetic foot geometry and temperature distribution. A structured light pattern is projected on to the foot to provide approximately 2500 reconstructed points. The reconstructed point cloud is then fitted to a finite element model, producing root mean squared errors of less than 0.4 mm.
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Qasaimeh MA, Sokhanvar S, Dargahi J, Kahrizi M. A micro-tactile sensor for in situ tissue characterization in minimally invasive surgery. Biomed Microdevices 2009; 10:823-837. [PMID: 18575981 DOI: 10.1007/s10544-008-9197-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study presents and characterizes a micro-tactile sensor that can be integrated within MIS graspers. The sensor is capable of measuring contact forces and characterizing softness. The grasping forces are distributed normally, though in some cases concentrated loads also appear at the contact surfaces. In the latter case, the position of the concentric load can also be determined. This enables the sensor to detect hidden anatomical features such as embedded lumps or arteries. The microfabricated piezoelectric-based sensor was modeled both analytically and numerically. In a parametric study the influence of parameters such as length, width, and thickness of the sensor was studied using a finite element model. The sensor was microfabricated and tested using elastomeric samples. There is a good conformity between the experimental and theoretical results.
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Affiliation(s)
- M A Qasaimeh
- Tactile Sensing and Medical Robotics Laboratory, Department of Mechanical and Industrial Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC, H3G 1M8, Canada.
- MEMS and NanoDevices Laboratory, Department of Electrical and Computer Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC, H3G 1M8, Canada.
| | - S Sokhanvar
- Tactile Sensing and Medical Robotics Laboratory, Department of Mechanical and Industrial Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC, H3G 1M8, Canada
| | - J Dargahi
- Tactile Sensing and Medical Robotics Laboratory, Department of Mechanical and Industrial Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC, H3G 1M8, Canada
| | - M Kahrizi
- MEMS and NanoDevices Laboratory, Department of Electrical and Computer Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, QC, H3G 1M8, Canada
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Murthy VBN, Poddar R, Periyasamy R. Surveillance and early detection of altered biomechanical parameters help keeping reconstructed ulcer healed. EUROPEAN JOURNAL OF PLASTIC SURGERY 2009. [DOI: 10.1007/s00238-008-0324-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
BACKGROUND AND PURPOSE Patients with diabetes mellitus and peripheral neuropathy are at high risk for plantar skin breakdown due to unnoticed plantar stresses during walking. The purpose of this study was to determine differences in stress variables (peak plantar pressure, peak pressure gradient, peak maximal subsurface shear stress, and depth of peak maximal subsurface shear stress) between the forefoot (where most ulcers occur) and the rear foot in subjects with and without diabetes mellitus, peripheral neuropathy, and a plantar ulcer measured during barefoot walking. SUBJECTS Twenty-four subjects participated: 12 with diabetes mellitus, peripheral neuropathy, and a plantar ulcer (DM+PN group) and 12 with no history of diabetes mellitus or peripheral neuropathy (control group). The subjects (11 men, 13 women) had a mean age (+/-SD) of 54+/-8 years. METHODS Plantar pressures were measured during barefoot walking using a pressure platform. Stress variables were estimated at the forefoot and the rear foot for all subjects. RESULTS All stress variables were higher (127%-871%) in the forefoot than in the rear foot, and the peak pressure gradient showed the greatest difference (538%-871%). All stress variables were higher in the forefoot in the DM+PN group compared with the control group (34%-85%), and the peak pressure gradient showed the greatest difference (85%). The depth (X+/-SD) of peak maximum subsurface shear stress in the forefoot in the DM+PN group was half that in the control group (3.8+/-2.0 versus 8.0+/-4.3 mm, respectively). DISCUSSION AND CONCLUSION : These results indicate that stresses are relatively higher and located closer to the skin surface in locations where skin breakdown is most likely to occur. These stress variables may have additional value in predicting skin injury over the traditionally measured peak plantar pressure, but prospective studies using these variables to predict ulcer risk are needed to test this hypothesis.
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Pressure gradient and subsurface shear stress on the neuropathic forefoot. Clin Biomech (Bristol, Avon) 2008; 23:342-8. [PMID: 18060668 PMCID: PMC2387244 DOI: 10.1016/j.clinbiomech.2007.10.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 09/24/2007] [Accepted: 10/09/2007] [Indexed: 02/07/2023]
Abstract
BACKGROUND Stresses within the neuropathic foot's tissues can be estimated by pressure distributions and may provide information regarding the potential for skin breakdown. The purposes of this study were to: (1) determine the magnitude of peak plantar pressure, pressure time integral, peak pressure gradient, and peak maximum shear stress; and (2) determine the association of these variables with one another. METHODS Forefoot peak plantar pressure, pressure time integral, peak pressure gradient, peak maximal shear stress, and depth of peak maximal shear stress were calculated for 16 controls, 16 people with diabetic neuropathy, and 22 people with diabetic neuropathy and a history of ulceration from pressure assessments. FINDINGS Peak plantar pressure, pressure gradient, and maximal shear stress were greater in subjects with a history of ulceration relative to control subjects (P<0.03), pressure gradient was greater in subjects with diabetic neuropathy and a history of ulceration compared to subjects with diabetic neuropathy and no history of ulceration (P<0.02), and depth of maximal shear stress was less in both groups of subjects with diabetic neuropathy compared to controls (P<0.03). Strong relationships existed between the variables. INTERPRETATION Although these variables are associated with one another, peak pressure gradient and peak maximal shear stress provide information concerning plantar pressure distribution and the potentially injurious internal stresses within the foot's soft tissues. Peak pressure gradient and peak maximal shear stress may perhaps be more discriminating than peak plantar pressure alone in distinguishing between groups of individuals who are at risk for developing a foot ulcer.
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Lott DJ, Hastings MK, Commean PK, Smith KE, Mueller MJ. Effect of footwear and orthotic devices on stress reduction and soft tissue strain of the neuropathic foot. Clin Biomech (Bristol, Avon) 2007; 22:352-9. [PMID: 17182156 PMCID: PMC1847616 DOI: 10.1016/j.clinbiomech.2006.10.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 09/25/2006] [Accepted: 10/24/2006] [Indexed: 02/07/2023]
Abstract
BACKGROUND Ground reaction forces from walking result in stress (pressure) and soft tissue strain at the plantar aspect of the foot. Excessive plantar pressure and tissue strain on the insensate foot may lead to ulceration. Our study investigated the effect of therapeutic footwear and custom-made orthotic inserts on pressure and tissue strain along the second ray of the plantar foot, and how these two variables are associated. METHODS Twenty subjects (mean age 57.3 [SD 9.3] years, 12 male, 8 female, body mass index 32.5 [SD 7.4] kg/m2) with diabetes mellitus, peripheral neuropathy, and a history of a plantar ulcer participated. Plantar pressure data were recorded during computed tomography scans for four conditions (barefoot, shoe, shoe+total contact insert, and shoe+total contact insert+metatarsal pad). For each condition tested, tissue strain and plantar pressure were determined at the second metatarsal head and at 15 other points along the second ray. FINDINGS Differences were noted between the 4 conditions for pressure (P<0.004) and soft tissue strain (P<0.042) at the second metatarsal head. Correlation coefficients demonstrated an association between pressure and strain (Barefoot r=0.81, Shoe r=0.75, Shoe+total contact insert r=0.73, and Shoe+total contact insert+metatarsal pad r=0.44). INTERPRETATION Footwear and orthotic devices tested in this study decreased pressure and soft tissue strain at the second ray of the foot, and these two variables were strongly related. A better understanding of the role tissue strain plays in distributing plantar forces may lead to improvements in the design of orthotic devices.
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Affiliation(s)
- Donovan J Lott
- Movement Science Program, Washington University, St. Louis, MO 63108, USA.
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Budhabhatti SP, Erdemir A, Petre M, Sferra J, Donley B, Cavanagh PR. Finite Element Modeling of the First Ray of the Foot: A Tool for the Design of Interventions. J Biomech Eng 2007; 129:750-6. [PMID: 17887901 DOI: 10.1115/1.2768108] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Disorders of the first ray of the foot (defined as the hard and soft tissues of the first metatarsal, the sesamoids, and the phalanges of the great toe) are common, and therapeutic interventions to address these problems range from alterations in footwear to orthopedic surgery. Experimental verification of these procedures is often lacking, and thus, a computational modeling approach could provide a means to explore different interventional strategies. A three-dimensional finite element model of the first ray was developed for this purpose. A hexahedral mesh was constructed from magnetic resonance images of the right foot of a male subject. The soft tissue was assumed to be incompressible and hyperelastic, and the bones were modeled as rigid. Contact with friction between the foot and the floor or footwear was defined, and forces were applied to the base of the first metatarsal. Vertical force was extracted from experimental data, and a posterior force of 0.18 times the vertical force was assumed to represent loading at peak forefoot force in the late-stance phase of walking. The orientation of the model and joint configuration at that instant were obtained by minimizing the difference between model predicted and experimentally measured barefoot plantar pressures. The model were then oriented in a series of postures representative of push-off, and forces and joint moments were decreased to zero simultaneously. The pressure distribution underneath the first ray was obtained for each posture to illustrate changes under three case studies representing hallux limitus, surgical arthrodesis of the first ray, and a footwear intervention. Hallux limitus simulations showed that restriction of metatarsophalangeal joint dorsiflexion was directly related to increase and early occurrence of hallux pressures with severe immobility increasing the hallux pressures by as much as 223%. Modeling arthrodesis illustrated elevated hallux pressures when compared to barefoot and was dependent on fixation angles. One degree change in dorsiflexion and valgus fixation angles introduced approximate changes in peak hallux pressure by 95 and 22 kPa, respectively. Footwear simulations using flat insoles showed that using the given set of materials, reductions of at least 18% and 43% under metatarsal head and hallux, respectively, were possible.
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Affiliation(s)
- Sachin P Budhabhatti
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Actis RL, Ventura LB, Smith KE, Commean PK, Lott DJ, Pilgram TK, Mueller MJ. Numerical simulation of the plantar pressure distribution in the diabetic foot during the push-off stance. Med Biol Eng Comput 2006; 44:653-63. [PMID: 16937207 DOI: 10.1007/s11517-006-0078-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Accepted: 05/31/2006] [Indexed: 11/25/2022]
Abstract
The primary objective of conservative care for the diabetic foot is to protect the foot from excessive pressures. Pressure reduction and redistribution may be achieved by designing and fabricating orthotic devices based on foot structure, tissue mechanics, and external loads on the diabetic foot. The purpose of this paper is to describe the process used for the development of patient-specific mathematical models of the second and third rays of the foot, their solution by the finite element method, and their sensitivity to model parameters and assumptions. We hypothesized that the least complex model to capture the pressure distribution in the region of the metatarsal heads would include the bony structure segmented as toe, metatarsal and support, with cartilage between the bones, plantar fascia and soft tissue. To check the hypothesis, several models were constructed with different levels of details. The process of numerical simulation is comprised of three constituent parts: model definition, numerical solution and prediction. In this paper the main considerations relating model selection and computation of approximate solutions by the finite element method are considered. The fit of forefoot plantar pressures estimated using the FEA models and those explicitly tested were good as evidenced by high Pearson correlations (r=0.70-0.98) and small bias and dispersion. We concluded that incorporating bone support, metatarsal and toes with linear material properties, tendon and fascia with linear material properties, soft tissue with nonlinear material properties, is sufficient for the determination of the pressure distribution in the metatarsal head region in the push-off position, both barefoot and with shoe and total contact insert. Patient-specific examples are presented.
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Affiliation(s)
- Ricardo L Actis
- Engineering Software Research and Development, Inc., 111 West Port Plaza, Suite 825, St. Louis, MO 63146, USA.
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Zou D, Mueller MJ, Lott DJ. Effect of peak pressure and pressure gradient on subsurface shear stresses in the neuropathic foot. J Biomech 2006; 40:883-90. [PMID: 16677657 DOI: 10.1016/j.jbiomech.2006.03.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Accepted: 03/09/2006] [Indexed: 11/24/2022]
Abstract
The pressure distribution on the plantar surface of the foot may provide insights into the stresses within the subsurface tissues of patients with diabetes mellitus and peripheral neuropathy (PN) who are at risk for skin breakdown. The purposes of this study were to (1) estimate the stress distribution in the subsurface soft tissue from a measured surface pressure distribution and determine any differences between values in the forefoot and rearfoot, and (2) determine the relationship between maximum shear stress (MSS) (magnitude and depth) and characteristics of the pressure distribution. The measured in-shoe pressure distributions during walking characterized by the peak plantar pressure and maximum pressure gradient on the plantar surface of the feet for 20 subjects with diabetes, PN and history of a mid foot or forefoot plantar ulcer were analyzed. The effects of peak pressure and maximum pressure gradient at the peak pressure location on the stress components in the subsurface soft tissue were studied using a potential function method to estimate the subsurface tissue stress. The calculated MSSs are larger in magnitude and located closer to the surface in the forefoot, where most skin breakdown occurs, compared to the rearfoot. In addition, the MSS (magnitude and depth) is highly correlated with the pressure gradient (r=-0.77 & 0.61) and the peak pressure (r=-0.61 & 0.91). The peak pressure and the maximum pressure gradient obtained from the surface pressure distribution appear to be important variables to identify where MSSs are located in the subsurface tissues on the plantar foot that may lead to skin break down.
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Affiliation(s)
- Dequan Zou
- Program in Physical Therapy, Washington University School of Medicine, 4444 Forest Park Blvd., Campus Box 8502, St. Louis, MO 63108, USA.
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Dai XQ, Li Y, Zhang M, Cheung JTM. Effect of sock on biomechanical responses of foot during walking. Clin Biomech (Bristol, Avon) 2006; 21:314-21. [PMID: 16298465 DOI: 10.1016/j.clinbiomech.2005.10.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 10/02/2005] [Accepted: 10/06/2005] [Indexed: 02/07/2023]
Abstract
BACKGROUND Except the plantar pressure and gross joint motion, we know little about the mechanical state of a foot during walking. This study aimed at investigating the effect of wearing socks with different frictional properties on plantar shear, which is a possible mechanical risk factor of foot lesion development. METHOD A 3-D finite element model for simulating the foot-sock-insole contact was developed to investigate the biomechanical effects of wearing socks with different combinations of frictional properties on the plantar foot contact. The dynamic plantar pressure and shear stress during the stance phases of gait were studied through finite element computations. Three cases were simulated, a barefoot with a high frictional coefficient against the insole (0.54) and two socks, one with a high frictional coefficient against the skin (0.54) and a low frictional coefficient against the insole (0.04) and another with an opposite frictional properties assignment. FINDINGS Wearing sock of low friction against the insole to allow more relative sliding between the plantar foot and footwear was found to reduce the shear force significantly: at the rearfoot from 3.1 to 0.88 N, and at the forefoot from 10.61 to 1.61 N. The shear force can be further reduced to 0.43 N at the rearfoot, and 1.18 N at the forefoot, when wearing the sock with low friction against the foot skin and high friction set against the insole. INTERPRETATION Wearing sock with low friction against the foot skin was found to be more effective in reducing plantar shear force on the skin than the sock with low friction against the insole. The risk of barefoot walking in developing plantar shear related blisters and ulcers might be reduced by socks wearing especially those with low friction against the foot skin.
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Affiliation(s)
- Xiao-Qun Dai
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
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Puri M, Patil KM, Balasubramanian V, Narayanamurthy VB. Texture analysis of foot sole soft tissue images in diabetic neuropathy using wavelet transform. Med Biol Eng Comput 2005; 43:756-63. [PMID: 16594303 DOI: 10.1007/bf02430954] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The paper presents a new method of characterisation of texture changes in foot sole soft tissue ultrasound (US) images, as observed to occur in diabetic subjects, using wavelet transforms. US images of the soft tissue subcutaneous layer were taken with a 7.5 MHz linear transducer probe placed parallel to the skin surface. The foot sole hardness was characterised by Shore level. A 2D discrete wavelet transform was performed on the US images to extract features that encode the internal state of the foot sole soft tissue. The global energy feature computed at the output of each wavelet channel was found to achieve excellent delineation between the normal and the diabetic groups. An important finding was a strong correlation, in the order of 0.84 and above, between the feature values that reflect changes in the internal arrangement of the tissue, and the externally measurable hardening of the skin, characterised by the Shore levels, with the latter known to be high for diabetics. A comparison drawn between diabetic ulcer and non-ulcer groups established a change in the order of 122-311% in the textural parameter, as influenced by a corresponding 66.7-200% change in the respective Shore values. Thus US examination of foot sole soft tissue and its texture analysis may serve as sources of valuable information regarding the internal changes taking place with progressive hardening of the soft tissue and thereby help the clinician in taking appropriate preventive measures.
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Affiliation(s)
- M Puri
- Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology, Madras
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