Dataset supporting: Mcgrath, Michael et al. (2016) Development of a residuum/socket interface sim... more Dataset supporting: Mcgrath, Michael et al. (2016) Development of a residuum/socket interface simulator for lower limb prosthetics. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine.Embargoed until 2020 for commercial reasons.
There are many situations where the skin and underlying soft tissues are compromised by mechanica... more There are many situations where the skin and underlying soft tissues are compromised by mechanical loading in the form or pressure, or pressure in combination with shear. If sustained, this can lead to damage in the tissues particularly adjacent to bony prominences, resulting in chronic wounds. An array of bioengineering technologies have been adopted to assess the integrity of loaded soft tissues. This paper aims to review these approaches for the quantification, simulation and early detection of mechanically-induced skin damage. The review considers different measurements at the interface between the skin and support surface/medical device, involving pressure, shear, friction and the local microclimate. The potential of the techniques to monitor the physiological response of the skin to these external stimuli including biophysical measurement devices and sampling of biofluids are critically analysed. In addition, it includes an analysis of medical imaging technologies and computat...
Journal of applied physiology (Bethesda, Md. : 1985), 2018
Early diagnosis of deep tissue injury remains problematic due to the complicated and multi-factor... more Early diagnosis of deep tissue injury remains problematic due to the complicated and multi-factorial nature of damage induction, and the many processes involved in damage development and recovery. In this paper we present a comprehensive assessment of deep tissue injury development and remodeling in a rat model by multi-parametric magnetic resonance imaging (MRI) and histopathology. The tibialis anterior muscle of rats was subjected to mechanical deformation for 2 h. Multi-parametric in vivo MRI, consisting of T, T∗, mean diffusivity (MD), and angiography measurements, was applied before, during, and directly after indentation, as well as at several time points during a 14 days follow-up. MRI readouts were linked to histological analyses of the damaged tissue. The results showed dynamic change in various MRI parameters, reflecting the histopathological status of the tissue during damage induction and repair. Increased T corresponded with edema, muscle cell damage, and inflammation. ...
Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 2017
Mechanical coupling at the interface between lower limb residua and prosthetic sockets plays an i... more Mechanical coupling at the interface between lower limb residua and prosthetic sockets plays an important role in assessing socket fitting and tissue health. However, most research lab-based lower limb prosthetic simulators to-date have implemented a rigid socket coupling. This study describes the fabrication and implementation of a lower limb residuum/socket interface simulator, designed to reproduce the forces and moments present during the key loading phases of amputee walking. An artificial residuum made with model bones encased in silicone was used, mimicking the compliant mechanical loading of a real residuum/socket interface. A 6-degree-of-freedom load cell measured the overall kinetics, having previously been incorporated into an amputee's prosthesis to collect reference data. The developed simulator was compared to a setup where a rigid pylon replaced the artificial residuum. A maximum uniaxial load of 850 N was applied, comparable to the peak vertical ground reaction f...
Dynamic loading is known to be essential in the biosynthesis and maintenance of healthy matabolis... more Dynamic loading is known to be essential in the biosynthesis and maintenance of healthy matabolism in articular cartilage and chondrocyte-seeded hydrogels. This is thought to be a result of a range of factors, including cell deformation. However, the nature of this deformation remains elusive. This study utilises the well-characterized chondrocyte seeded agarose model and finite element analysis based on a viscoelastic model to demonstrate the cell deformation duringboth static and dynamic compression in the stage of initial culture. The prony series viscoelastic models were adopted to model agarose and chondrocyte which have been implemented in finite element analysis. The findings suggest that cell strain during loaded phase and unloaded phase strongly depends on the frequency and number of cycles, both of which have been implicated in various mechanotransduction pathway. Due to the mechanical properties mismatch between the cell and agarose construct, the cell strain is amplified through-out the cyclic compression.
Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distr... more Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distribution of pressure over a prolonged period. They can have devastating effects on the patients' well-being and in extreme conditions can prove fatal. In addition to traditional wisdom implicating mechanically induced ischaemia, there is strong evidence that other mechanisms play a role in the cascade of events which can initiate the PU damage process at the cellular level. Some of these refer to a metabolic imbalance with compromised delivery of nutrients and accumulation of waste products in the local environment of the cells. The approach of much research has focused on the measure of oxygen in compressed tissues as a means of predicting early damage. However, the present review adopting a hierarchical approach, using length scales ranging from cells through to human models, has revealed compelling evidence which highlights the importance of carbon dioxide levels and associated con...
Design and fitting of artificial limbs to lower limb amputees are largely based on the subjective... more Design and fitting of artificial limbs to lower limb amputees are largely based on the subjective judgement of the prosthetist. Understanding the science of three-dimensional (3D) dynamic coupling at the residuum/socket interface could potentially aid the design and fitting of the socket. A new method has been developed to characterise the 3D dynamic coupling at the residuum/socket interface using 3D motion capture based on a single case study of a trans-femoral amputee. The new model incorporated a Virtual Residuum Segment (VRS) and a Socket Segment (SS) which combined to form the residuum/socket interface. Angular and axial couplings between the two segments were subsequently determined. Results indicated a non-rigid angular coupling in excess of 10° in the quasi-sagittal plane and an axial coupling of between 21 and 35 mm. The corresponding angular couplings of less than 4° and 2° were estimated in the quasi-coronal and quasi-transverse plane, respectively. We propose that the co...
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, 2015
Currently, pressure ulcer preventive strategies focus mainly on pressure redistribution. Little a... more 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 analysing a non-invasive biomarker and reactive hyperaemic parameter measured at the skin of healthy participants. A physical model was developed to produce a combination of pressure and shear or pressure alone on the skin. Ten healthy male participants were included and pressure (3.9 kPa) and a combined loading of pressure and shear (2.4 kPa + 14.5 N) was applied at the volar aspect of the forearms for 15 and 30 minutes. A Sebutape sample was used to collect IL-1α and total protein non- invasively. The reactive hyperaemic parameter was derived from a Laser Doppler flowmeter. T...
Dataset supporting: Mcgrath, Michael et al. (2016) Development of a residuum/socket interface sim... more Dataset supporting: Mcgrath, Michael et al. (2016) Development of a residuum/socket interface simulator for lower limb prosthetics. Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine.Embargoed until 2020 for commercial reasons.
There are many situations where the skin and underlying soft tissues are compromised by mechanica... more There are many situations where the skin and underlying soft tissues are compromised by mechanical loading in the form or pressure, or pressure in combination with shear. If sustained, this can lead to damage in the tissues particularly adjacent to bony prominences, resulting in chronic wounds. An array of bioengineering technologies have been adopted to assess the integrity of loaded soft tissues. This paper aims to review these approaches for the quantification, simulation and early detection of mechanically-induced skin damage. The review considers different measurements at the interface between the skin and support surface/medical device, involving pressure, shear, friction and the local microclimate. The potential of the techniques to monitor the physiological response of the skin to these external stimuli including biophysical measurement devices and sampling of biofluids are critically analysed. In addition, it includes an analysis of medical imaging technologies and computat...
Journal of applied physiology (Bethesda, Md. : 1985), 2018
Early diagnosis of deep tissue injury remains problematic due to the complicated and multi-factor... more Early diagnosis of deep tissue injury remains problematic due to the complicated and multi-factorial nature of damage induction, and the many processes involved in damage development and recovery. In this paper we present a comprehensive assessment of deep tissue injury development and remodeling in a rat model by multi-parametric magnetic resonance imaging (MRI) and histopathology. The tibialis anterior muscle of rats was subjected to mechanical deformation for 2 h. Multi-parametric in vivo MRI, consisting of T, T∗, mean diffusivity (MD), and angiography measurements, was applied before, during, and directly after indentation, as well as at several time points during a 14 days follow-up. MRI readouts were linked to histological analyses of the damaged tissue. The results showed dynamic change in various MRI parameters, reflecting the histopathological status of the tissue during damage induction and repair. Increased T corresponded with edema, muscle cell damage, and inflammation. ...
Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 2017
Mechanical coupling at the interface between lower limb residua and prosthetic sockets plays an i... more Mechanical coupling at the interface between lower limb residua and prosthetic sockets plays an important role in assessing socket fitting and tissue health. However, most research lab-based lower limb prosthetic simulators to-date have implemented a rigid socket coupling. This study describes the fabrication and implementation of a lower limb residuum/socket interface simulator, designed to reproduce the forces and moments present during the key loading phases of amputee walking. An artificial residuum made with model bones encased in silicone was used, mimicking the compliant mechanical loading of a real residuum/socket interface. A 6-degree-of-freedom load cell measured the overall kinetics, having previously been incorporated into an amputee's prosthesis to collect reference data. The developed simulator was compared to a setup where a rigid pylon replaced the artificial residuum. A maximum uniaxial load of 850 N was applied, comparable to the peak vertical ground reaction f...
Dynamic loading is known to be essential in the biosynthesis and maintenance of healthy matabolis... more Dynamic loading is known to be essential in the biosynthesis and maintenance of healthy matabolism in articular cartilage and chondrocyte-seeded hydrogels. This is thought to be a result of a range of factors, including cell deformation. However, the nature of this deformation remains elusive. This study utilises the well-characterized chondrocyte seeded agarose model and finite element analysis based on a viscoelastic model to demonstrate the cell deformation duringboth static and dynamic compression in the stage of initial culture. The prony series viscoelastic models were adopted to model agarose and chondrocyte which have been implemented in finite element analysis. The findings suggest that cell strain during loaded phase and unloaded phase strongly depends on the frequency and number of cycles, both of which have been implicated in various mechanotransduction pathway. Due to the mechanical properties mismatch between the cell and agarose construct, the cell strain is amplified through-out the cyclic compression.
Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distr... more Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distribution of pressure over a prolonged period. They can have devastating effects on the patients' well-being and in extreme conditions can prove fatal. In addition to traditional wisdom implicating mechanically induced ischaemia, there is strong evidence that other mechanisms play a role in the cascade of events which can initiate the PU damage process at the cellular level. Some of these refer to a metabolic imbalance with compromised delivery of nutrients and accumulation of waste products in the local environment of the cells. The approach of much research has focused on the measure of oxygen in compressed tissues as a means of predicting early damage. However, the present review adopting a hierarchical approach, using length scales ranging from cells through to human models, has revealed compelling evidence which highlights the importance of carbon dioxide levels and associated con...
Design and fitting of artificial limbs to lower limb amputees are largely based on the subjective... more Design and fitting of artificial limbs to lower limb amputees are largely based on the subjective judgement of the prosthetist. Understanding the science of three-dimensional (3D) dynamic coupling at the residuum/socket interface could potentially aid the design and fitting of the socket. A new method has been developed to characterise the 3D dynamic coupling at the residuum/socket interface using 3D motion capture based on a single case study of a trans-femoral amputee. The new model incorporated a Virtual Residuum Segment (VRS) and a Socket Segment (SS) which combined to form the residuum/socket interface. Angular and axial couplings between the two segments were subsequently determined. Results indicated a non-rigid angular coupling in excess of 10° in the quasi-sagittal plane and an axial coupling of between 21 and 35 mm. The corresponding angular couplings of less than 4° and 2° were estimated in the quasi-coronal and quasi-transverse plane, respectively. We propose that the co...
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, 2015
Currently, pressure ulcer preventive strategies focus mainly on pressure redistribution. Little a... more 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 analysing a non-invasive biomarker and reactive hyperaemic parameter measured at the skin of healthy participants. A physical model was developed to produce a combination of pressure and shear or pressure alone on the skin. Ten healthy male participants were included and pressure (3.9 kPa) and a combined loading of pressure and shear (2.4 kPa + 14.5 N) was applied at the volar aspect of the forearms for 15 and 30 minutes. A Sebutape sample was used to collect IL-1α and total protein non- invasively. The reactive hyperaemic parameter was derived from a Laser Doppler flowmeter. T...
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Papers by Dan Bader