Biomedical subjects

D J Ewins

Publications and source records attributed to D J Ewins.

7 recordsLinked to original sources

PubMed2004

The incidence and occupational outcome of overuse anterior knee pain during army recruit training.

OBJECTIVES: To determine the incidence and occupational outcome of overuse anterior knee pain (AKP) in Army recruits undergoing basic training. METHODS: A prospective cohort study of 1008 Army recruits. Recruits underwent the 12-week phase 1 training program. Cases of AKP were captured through self-presentation of pain at a primary care medical centre. All recruits medical records were reviewed on leaving training and any other lower limb injuries were recorded for comparison with the AKP group. Training outcomes in terms of medical discharges (MD) and discharges as of right (DAOR) i.e, voluntary discharge, were recorded along with training days lost (TDL) and whether a recruit had been held back in training (BS). RESULTS: 8.75% (95% CI: 6.93-10.57) of recruits reported to the medical centre with AKP. Of these more than half were referred to see a GP and the majority were from patients with no previous history of AKP (91%, 95% CI: 85.2-97.5). The median TDL per AKP case was 3 days (IQR: 3-5 days). The AKP group had a significantly higher (p < 0.01) MD rate (12.5%) than the lower limb injury group (3.3%; 95% CI diff: 1.1-17.2%) and the baseline rate of all other recruits (2.5%; 95% CI diff: 2.3-17.7%). The majority of AKP cases occurred by week 4 (median) of training (IQR: 2.2-64). CONCLUSIONS: There was a high incidence of AKP, and while the short term prognosis appears relatively good in the majority of cases as reflected in the median TDL, a large minority were medically discharged and held back in training. Further work should examine methods of reducing the disease burden of AKP in the Army, addressing areas such as aetiology, prevention and treatment.

Adolescent↗

PubMed2000

Silicon-based microelectrodes for neurophysiology, micromachined from silicon-on-insulator wafers.

A process is described for the fabrication of silicon-based microelectrodes for neurophysiology using bonded and etched-back silicon-on-insulator (BESOI) wafers. The probe shapes are defined without high levels of boron doping in the silicon; this is considered as a step towards producing probes with active electronics integrated directly beneath the electrodes. Gold electrodes, of 4 microns by 4 microns to 50 microns by 50 microns are fabricated on shanks (cantilever beams) 6 microns thick and which taper to an area approximately 100 microns wide and 200 microns long, which are inserted into the tissue under investigation. The passive probes fabricated have been successfully employed to make acute recordings from locust peripheral nerve.

Animals↗

PubMed2000

The development of a long, dual-platform triaxial walkway for the measurement of forces and temporal-spatial data in the clinical assessment of gait.

Force-plate measurement of the ground reaction force (GRF) has, for many years, been considered a vital component of the comprehensive assessment of human gait in the clinical context. For example, the data can be used in the adjustment of prostheses and orthoses and in identifying the mechanisms underlying a gait dysfunction. However, commercial force plates are usually only capable of measuring GRF data from one step in a single traverse. That can lead to problems of 'targeting' and, with less able subjects, fatigue before the necessary data have been collected. Previous work at the University of Surrey resulted in a prototype dual-platform force walkway capable of measuring the vertical component of the GRF and estimating the position of application of that force for multiple foot contacts in a single traverse. In addition, temporal-spatial information, e.g. speed and step length, could also be determined. This paper describes the development of a longer walkway that can measure the three orthogonal components of the GRF and provide and a more accurate estimate of the position of application of that force. Software to allow the rapid reduction of gait data to useful clinical information has also been developed.

Calibration↗

PubMed1999

Long pulse biphasic electrical stimulation of denervated muscle.

In recent years a number of studies have employed long pulse biphasic stimulation as a treatment for denervated muscle to improve tissue quality and in some cases to improve contractile capability sufficient to restore function. However, in the U.K., this treatment is yet to be widely adopted clinically. A 5 subject, case based pilot study of long pulse biphasic direct stimulation of peripheral limb denervated muscle is being conducted and its effect on the tissue evaluated by measurement of muscle bulk, limb blood flow, and skin temperature. In cases of partial denervation. trapezoidal shaped pulses are used to minimize sensory and motor nerve fiber recruitment.

Arm↗

PubMed1995

Comparative analysis of power-line interference between two- or three-electrode biopotential amplifiers.

Differential input amplifiers are commonly used in the measurement of biopotential signals. This is because of their ability to reject common-mode signals, for example power-line interference. Rejection is further enhanced by referencing the subject to the instrumentation system. One such referencing technique uses a third subject electrode connected either to circuit common or to ground. However, these techniques are rarely explained or quantified in the literature. Four recording configurations are examined, isolated and non-isolated amplifiers with two and with three electrodes, and existing models are extended. From a brief assessment of power-line interference sources, it is concluded that only displacement currents induced into the leads and the body need be considered. The effect of these on the four configurations is analysed using SPICE. Results show that interference from displacement currents induced into the leads and into the body is dependent upon the recording configuration used and is significantly lower in three-electrode than in two-electrode amplifiers. Isolation also reduces levels of interference. It is concluded that the choice of referencing may affect interference levels on the biopotential signal significantly. Experimental and further analytical work is planned to confirm this.

Amplifiers, Electronic↗

PubMed1993

Limb blood flow, cardiac output and quadriceps muscle bulk following spinal cord injury and the effect of training for the Odstock functional electrical stimulation standing system.

As part of the assessment of the Odstock functional electrical stimulation (FES) standing system for mid to low thoracic lesion spinal cord injured (SCI) subjects, cardiac output, high blood flow and quadriceps muscle thickness were measured before and following an electrical stimulation muscle retraining programme. The same parameters were also measured in a group of uninjured subjects and in SCI subjects. It was found that there was no difference in cardiac output between the groups. However thigh blood flow was found to be around 65% of normal values in the spinally injured group. This returned to normal values following the retraining programme. The quadriceps muscle wasted to approximately 50% of its original thickness in the first 3 weeks following spinal cord injury. The retraining programme increased the muscle thickness to near normal values.

Adult↗

PubMed1988

Practical low cost stand/sit system for mid-thoracic paraplegics.

The use of functional electrical stimulation (FES) to enable paraplegics to stand is not new or indeed difficult to undertake under laboratory conditions. However, there are substantial problems to overcome before such systems can be used routinely by patients without professional supervision. The overriding consideration has to be one of safety, i.e. the system must be 'fail safe'. Secondly, the system must be quick and easy to use in a wide variety of locations, otherwise it will not provide any increase in function. Finally, it must be inexpensive enough to be available to a large number of paraplegics. The primary aim of our work was to provide such a system to enable mid-thoracic lesion paraplegics to stand wherever they wish. This involved the development of a microprocessor-based stimulator to enable the stimulating envelope to be individually tailored to a given patient's requirements and the provision of closed loop control to minimize fatigue. A folding standing frame was also designed which replaces the arm rests on a standard wheelchair. Using this system, the user is able to stand within 30 s of stopping and can remain standing for up to 10 min. Cosmetic calipers (knee-ankle-foot orthoses) are also being used for paraplegics who require to stand for longer periods. It is hoped that such a system will provide stable standing for a large number of paraplegics at a unit cost of approximately 750 pound.

Electric Stimulation↗