Showing papers by "David Howard published in 2014"
TL;DR: Low dorsiflexion stiffness generally improved gait performance seemingly due to easier tibial progression during stance, but observed differences were small, suggesting that a wider range of walking and stiffness conditions would be useful to fully explore these effects in future studies.
61 citations
TL;DR: The results showed that the number of steps required for both acclimatisation and to ensure data quality are dependent on shoe type and the foot region being investigated.
34 citations
TL;DR: It was found that the forces in the intrinsic muscles (interosseus group and lumbrical) are significantly reduced by 22% to 61% due to the action of the extensor mechanism, with the greatest reductions in more flexed postures, which suggests that theextensor mechanism may help to reduce the risk of injury at the finger joints and also to moderate the forces of intrinsic muscles.
Abstract: This study investigated the effects of the finger extensor mechanism on the bone-to-bone contact forces at the interphalangeal and metacarpal joints and also on the forces in the intrinsic and extrinsic muscles during finger pressing. This was done with finger postures ranging from very flexed to fully extended. The role of the finger extensor mechanism was investigated by using two alternative finger models, one which omitted the extensor mechanism and another which included it. A six-camera three-dimensional motion analysis system was used to capture the finger posture during maximum voluntary isometric pressing. The fingertip loads were recorded simultaneously using a force plate system. Two three-dimensional biomechanical finger models, a minimal model without extensor mechanism and a full model with extensor mechanism (tendon network), were used to calculate the joint bone-to-bone contact forces and the extrinsic and intrinsic muscle forces. If the full model is assumed to be realistic, then the results suggest some useful biomechanical advantages provided by the tendon network of the extensor mechanism. It was found that the forces in the intrinsic muscles (interosseus group and lumbrical) are significantly reduced by 22% to 61% due to the action of the extensor mechanism, with the greatest reductions in more flexed postures. The bone-to-bone contact force at the MCP joint is reduced by 10% to 41%. This suggests that the extensor mechanism may help to reduce the risk of injury at the finger joints and also to moderate the forces in intrinsic muscles. These apparent biomechanical advantages may be a result of the extensor mechanism's distinctive interconnected fibrous structure, through which the contraction of the intrinsic muscles as flexors of the MCP joint can generate extensions at the DIP and PIP joints.
24 citations
TL;DR: This study demonstrates that an array-based automated setup FES system for foot- drop can be successfully used unsupervised, and it would appear as effective, if not better, at addressing the foot-drop impairment.
23 citations
TL;DR: A novel method for in vivo force estimation for the finger tendon network is proposed by combining a three-dimensional motion analysis technique and a novel biomechanical tendon network model by calculating the forces and deformations throughout the tendon network of the extensor mechanism when subjected to an external load.
Abstract: The complexities of the function and structure of human fingers have long been recognised. The in vivo forces in the human finger tendon network during different activities are critical information for clinical diagnosis, surgical treatment, prosthetic finger design, and biomimetic hand development. In this study, we propose a novel method for in vivo force estimation for the finger tendon network by combining a three-dimensional motion analysis technique and a novel biomechanical tendon network model. The extensor mechanism of a human index finger is represented by an interconnected tendinous network moving around the phalanx’s dorsum. A novel analytical approach based on the “Principle of Minimum Total Potential Energy” is used to calculate the forces and deformations throughout the tendon network of the extensor mechanism when subjected to an external load and with the finger posture defined by measurement data. The predicted deformations and forces in the tendon network are in broad agreement with the results obtained by previous experimental in vitro studies. The proposed methodology provides a promising tool for investigating the biomechanical function of complex interconnected tendon networks in vivo.
16 citations
TL;DR: This research provides a possible explanation to mammography image blurring caused by extra patient movement and proposes a theoretical model to analyse the movement.
Abstract: Objective:To determine if movement external to the patient occurring during mammography may be a source of image blur.Methods:Four mammography machines with eight flexible and eight fixed paddles were evaluated. In the first stage, movement at the paddle was measured mechanically using two calibrated linear potentiometers. A deformable breast phantom was used to mimic a female breast. For each paddle, the movement in millimetres and change in compression force in Newton was recorded at 0.5- and 1-s intervals, respectively, for 40 s with the phantom in an initially compressed state under a load of 80 N. In the second stage, clinical audit on 28 females was conducted on one mammography machine with the 18 × 24- and 24 × 29-cm flexible paddles.Results:Movement at the paddle followed an exponential decay with a settling period of approximately 40 s. The compression force readings for both fixed and flexible paddles decreased exponentially with time, while fixed paddles had a larger drop in compression force t...
13 citations
TL;DR: Images of suitable quality for laterally assessing spinal conditions using Cobb or superimposition measurements were produced from an effective dose of 0.05 mSv, which is 83% less than the average effective dose used in the UK for lateral thoracic/lumbar exposures.
Abstract: BACKGROUND: Patients with vertebral column deformations are exposed to high risks associated with ionising radiation exposure. Risks are further increased due to the serial X-ray images that are needed to measure and asses their spinal deformation using Cobb or superimposition methods. Therefore, optimising such X-ray practice, via reducing dose whilst maintaining image quality, is a necessity. OBJECTIVES: With a specific focus on lateral thoraco-lumbar images for Cobb and superimposition measurements, this paper outlines a systematic procedure to the optimisation of X-ray practice. METHODS: Optimisation was conducted based on suitable image quality from minimal dose. Image quality was appraised using a visual-analogue-rating-scale, and Monte-Carlo modelling was used for dose estimation. The optimised X-ray practice was identified by imaging healthy normal-weight male adult living human volunteers. RESULTS: The optimised practice consisted of: anode towards the head, broad focus, no OID or grid, 80 kVp, 32 mAs and 130 cm SID. CONCLUSION: Images of suitable quality for laterally assessing spinal conditions using Cobb or superimposition measurements were produced from an effective dose of 0.05 mSv, which is 83% less than the average effective dose used in the UK for lateral thoracic/lumbar exposures. This optimisation procedure can be adopted and use for optimisation of other radiographic techniques.
12 citations
TL;DR: An automated algorithm for detection of lift-off and touch-down events of a pick-up walker and for the 88-year-old walking frame user, 96% of LO events and 93% of TD events were detected, demonstrating the potential of the approach.
1 citations
12 May 2014
TL;DR: In this paper, the authors developed a software system for complex control of the stimulation system, which is integrated with the feedback from motion sensors to produce an automated system for exercising movements in the paralyzed upper arm.
Abstract: Functional electrical stimulation is a considerably new technology for stroke rehabilitation therapy of paralyzed limbs by actively stimulating the muscular nerve endings using controlled electrical impulses to produce meaning movements. This project involves development of a software system for complex control of the stimulation system. It is integrated with the feedback from motion sensors to produce an automated system for exercising movements in the paralyzed upper arm.