Integration of patient-specific biomechanical measurements into the design of therapeutic footwea... more Integration of patient-specific biomechanical measurements into the design of therapeutic footwear has been shown to improve clinical outcomes in patients with diabetic foot disease. The addition of numerical simulations intended to optimise intervention design may help to build on these advances, however at present the time and labour required to generate and run personalised models of foot anatomy restrict their routine clinical utility. In this study we developed second-generation personalised simple finite element (FE) models of the forefoot with varying geometric fidelities. Plantar pressure predictions from barefoot, shod, and shod with insole simulations using simplified models were compared to those obtained from CT-based FE models incorporating more detailed representations of bone and tissue geometry. A simplified model including representations of metatarsals based on simple geometric shapes, embedded within a contoured soft tissue block with outer geometry acquired from a 3D surface scan was found to provide pressure predictions closest to the more complex model, with mean differences of 13.3kPa (SD 13.4), 12.52kPa (SD 11.9) and 9.6kPa (SD 9.3) for barefoot, shod, and insole conditions respectively. The simplified model design could be produced in <1h compared to >3h in the case of the more detailed model, and solved on average 24% faster. FE models of the forefoot based on simplified geometric representations of the metatarsal bones and soft tissue surface geometry from 3D surface scans may potentially provide a simulation approach with improved clinical utility, however further validity testing around a range of therapeutic footwear types is required.
Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to re... more Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to relieve or redistribute high plantar pressures in the region of the metatarsal heads. Few guidelines exist as to how these interventions should be designed and what effect such interventions actually have on the plantar pressure distribution. Finite element analysis has the potential to assist in the design process by refining a given intervention or identifying an optimal intervention without having to actually build and test each condition. However, complete and detailed foot models based on medical image segmentation have proven time consuming to build and computationally expensive to solve, hindering their utility in practice. Therefore, the goal of the current work was to determine if a simplified patient-specific model could be used to assist in the design of foot orthoses to reduce the plantar pressure in the metatarsal head region. The approach is illustrated by a case study of a d...
Peripheral quantitative computed tomography (pQCT) is an established technology that allows for t... more Peripheral quantitative computed tomography (pQCT) is an established technology that allows for the measurement of the material properties of bone. Alterations to bone architecture are associated with an increased risk of fracture. Further pQCT research is necessary to identify regions of interest that are prone to fracture risk in people with chronic diseases. The second metatarsal is a common site for the development of insufficiency fractures, and as such the aim of this study was to assess the reproducibility of a novel scanning protocol of the second metatarsal using pQCT. Eleven embalmed cadaveric leg specimens were scanned six times; three times with and without repositioning. Each foot was positioned on a custom-designed acrylic foot plate to permit unimpeded scans of the region of interest. Sixty-six scans were obtained at 15% (distal) and 50% (mid shaft) of the second metatarsal. Voxel size and scan speed were reduced to 0.40 mm and 25 mm.sec(-1). The reference line was po...
Human Factors: The Journal of the Human Factors and Ergonomics Society, 2009
A novel technique that uses actigraphy, the study of activity involving the use of body-mounted a... more A novel technique that uses actigraphy, the study of activity involving the use of body-mounted accelerometers, to detect the discomfort-related movements of a sitting individual has been proposed as a potential indicator of sitting discomfort, and the purpose of this study was to test its validity. Objective measurement of sitting discomfort has always been challenging for researchers. Electromyographic measurements, pressure mapping, and a wide range of other techniques have all been investigated with limited success. The activity monitor's ability to detect and measure seated movement was assessed, and 12 participants were tested on four different chairs (100-min sessions for each). The activity monitor was able to detect participants' sitting movements (Pearson coefficients > 0.9). The chairs were shown to have significantly different subjective discomfort ratings, all of which increased over time. The movements detected by the activity monitor also increased significantly with time, and the amount measured was greater in the chairs rated as most uncomfortable. Regression analysis indicated that the actigraphy data were able to account for 29.6% of the variation in perceived discomfort ratings. Actigraphy can reliably detect sitting movements and may be of use in measuring sitting discomfort. Potential applications of this technique exist for seating research in the automotive industry, health care, and office and leisure chairs.
Integration of patient-specific biomechanical measurements into the design of therapeutic footwea... more Integration of patient-specific biomechanical measurements into the design of therapeutic footwear has been shown to improve clinical outcomes in patients with diabetic foot disease. The addition of numerical simulations intended to optimise intervention design may help to build on these advances, however at present the time and labour required to generate and run personalised models of foot anatomy restrict their routine clinical utility. In this study we developed second-generation personalised simple finite element (FE) models of the forefoot with varying geometric fidelities. Plantar pressure predictions from barefoot, shod, and shod with insole simulations using simplified models were compared to those obtained from CT-based FE models incorporating more detailed representations of bone and tissue geometry. A simplified model including representations of metatarsals based on simple geometric shapes, embedded within a contoured soft tissue block with outer geometry acquired from a 3D surface scan was found to provide pressure predictions closest to the more complex model, with mean differences of 13.3kPa (SD 13.4), 12.52kPa (SD 11.9) and 9.6kPa (SD 9.3) for barefoot, shod, and insole conditions respectively. The simplified model design could be produced in <1h compared to >3h in the case of the more detailed model, and solved on average 24% faster. FE models of the forefoot based on simplified geometric representations of the metatarsal bones and soft tissue surface geometry from 3D surface scans may potentially provide a simulation approach with improved clinical utility, however further validity testing around a range of therapeutic footwear types is required.
Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to re... more Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to relieve or redistribute high plantar pressures in the region of the metatarsal heads. Few guidelines exist as to how these interventions should be designed and what effect such interventions actually have on the plantar pressure distribution. Finite element analysis has the potential to assist in the design process by refining a given intervention or identifying an optimal intervention without having to actually build and test each condition. However, complete and detailed foot models based on medical image segmentation have proven time consuming to build and computationally expensive to solve, hindering their utility in practice. Therefore, the goal of the current work was to determine if a simplified patient-specific model could be used to assist in the design of foot orthoses to reduce the plantar pressure in the metatarsal head region. The approach is illustrated by a case study of a d...
Peripheral quantitative computed tomography (pQCT) is an established technology that allows for t... more Peripheral quantitative computed tomography (pQCT) is an established technology that allows for the measurement of the material properties of bone. Alterations to bone architecture are associated with an increased risk of fracture. Further pQCT research is necessary to identify regions of interest that are prone to fracture risk in people with chronic diseases. The second metatarsal is a common site for the development of insufficiency fractures, and as such the aim of this study was to assess the reproducibility of a novel scanning protocol of the second metatarsal using pQCT. Eleven embalmed cadaveric leg specimens were scanned six times; three times with and without repositioning. Each foot was positioned on a custom-designed acrylic foot plate to permit unimpeded scans of the region of interest. Sixty-six scans were obtained at 15% (distal) and 50% (mid shaft) of the second metatarsal. Voxel size and scan speed were reduced to 0.40 mm and 25 mm.sec(-1). The reference line was po...
Human Factors: The Journal of the Human Factors and Ergonomics Society, 2009
A novel technique that uses actigraphy, the study of activity involving the use of body-mounted a... more A novel technique that uses actigraphy, the study of activity involving the use of body-mounted accelerometers, to detect the discomfort-related movements of a sitting individual has been proposed as a potential indicator of sitting discomfort, and the purpose of this study was to test its validity. Objective measurement of sitting discomfort has always been challenging for researchers. Electromyographic measurements, pressure mapping, and a wide range of other techniques have all been investigated with limited success. The activity monitor's ability to detect and measure seated movement was assessed, and 12 participants were tested on four different chairs (100-min sessions for each). The activity monitor was able to detect participants' sitting movements (Pearson coefficients > 0.9). The chairs were shown to have significantly different subjective discomfort ratings, all of which increased over time. The movements detected by the activity monitor also increased significantly with time, and the amount measured was greater in the chairs rated as most uncomfortable. Regression analysis indicated that the actigraphy data were able to account for 29.6% of the variation in perceived discomfort ratings. Actigraphy can reliably detect sitting movements and may be of use in measuring sitting discomfort. Potential applications of this technique exist for seating research in the automotive industry, health care, and office and leisure chairs.
Uploads
Papers by Scott Telfer