Completed research Projects

The ODFS

The Odstock Dropped Foot Stimulator (ODFS) was originally developed under funding from the Medical Devices Agency in the Department of Health between 1989 - 1995. The Odstock Dropped Foot Stimulator (ODFS) is a single channel neuromuscular stimulator that corrects dropped foot by stimulating the common peroneal nerve using self adhesive skin surface electrodes placed on the side of the leg. The electrical stimulation causes dorsiflexion (lifting of the foot) and when timed to the gait cycle using foot switches placed in the shoe, walking performance can be significantly improved. The device works by causing a contraction of inactive muscles but also may cause a relaxation of the calf muscles. Electrical stimulation feels like pins and needles and is found to be comfortable by most users. The device is designed to allow sufficient flexibility to cope with a range of problems that have been seen over some considerable clinical experience, while remaining simple to use and set up by the physiotherapist.

Between January 1993 and September 1995 a controlled trial was conducted. 32 subjects were randomly allocated to treatment and control groups. Both groups received equal amounts of physiotherapy while the treatment group also used the device. Measurements showed that the treatment group had a statistically significant increase in walking speed of 16% and a reduction in physiological cost index which is a estimate of the amount of effort in walking, of 29%. In addition, a significant reduction in quadriceps spasticity, measured with the Wartenberg Pendulum Test was seen and also an improvement in Quality of Life measured using the Hospital Anxiety and Depression Index. QALY analysis of the results showed a cost per QALY of £10,307 over 5 years. The results were presented to the South and South West Regional Health Authority Development and Evaluation Committee who "recommended" the treatment for use within the NHS. DEC Report

The DEC approval has enabled the department of Medical Physics and Biomedical Engineering to offer a clinical service with patients from all over the UK being referred for treatment as Extra Contractual Referrals. To date over 1000 systems have been fitted in Salisbury including people with multiple sclerosis, cerebral palsy, spinal cord injury and head injury as well as stroke. The department has run many training causes for physiotherapists from other hospitals in the use of the device and more are planed. The course is mandatory before equipment can be purchased. Centres are now fitting the equipment at over 150 centres in he UK and overseas and more centres are being trained. (see the Clinics page ) At lease 1000 systems have been fitted outside Salisbury.

A study based on results from 160 subjects have shown that the main benefit received from use of the device is that it reduces the effort of walking and increases the confidence of the users. Use of the device by people who have had a stroke leads to a therapeutic benefit, increasing their walking speed and reducing their PCI even when the ODFS is not used. The compliance rate at 18 weeks is 92% and 86% at 1 year. Please click on Clinical Results and Research abstracts for more information. Analysis of the cost of falls prevented by use of the ODFS show that its use leads to a significant cost saving to the NHS.

The ODFS is CE marked and can be supplied to clinicians who have completed a training course in its use. In the year 2000 the device was recommended by the Royal College of Physicians in their publication "National clinical guidelines on stroke" www.rcplondon.ac.uk

Clinical Results

How to obtain treatment

What ODFS users think

Flow diagrams showing the set up procedure for the ODFS

What's in a name

Salisbury Contacts:

Paul Taylor p.taylor@mpbe-sdh.demon.co.uk

Geraldine Mann g.mann@mpbe-sdh.demon.co.uk

Improved Dropped Foot Correction - 2 Channel Stimulators.

While the ODFS has been successful at improving the mobility of many neurologically impaired people, problems often still remain with control of the ankle, knee and hip. These can be addressed by the addition of a second channel to stimulate a second muscle. Two devices have been developed to perform this function. The Odstock 2 Channel Stimulator O2CHS was developed from the ODFS and is essentially two dropped foot stimulators in a single box with additional electronics to allow the 2 channels to interrelate. The device can be controlled by a single or two foot switches. Different algorithms can be set up by adjusting switches and trimmer controls. The second device is the Compustim 10B. This is a computer controlled device developed under funding from the MDA and Action Research (October 1994- October 1996) in conjunction with the University of Surrey. Its action is essentially the same as the O2CHS but its parameters are set up on a computer screen allowing greater flexibility.

The following sets of muscles / nerves can be controlled

The Compustim 10B has been the subject of a small trial which showed that when the common peroneal was stimulated with the calf or the hamstrings, there was a much greater training effect than when the ODFS was used alone. i.e., walking was improved even when use of the Compustim 10B was stopped. The device is the subject of a second Action Research Grant which started March 1998.

A recent study showed that when the O2CHS was used for correction of bilateral dropped foot, walking speed and PCI were significantly improved. See Clinical results. The O2CHS is now fully integrated in to the clinical service in Salisbury and is rapidly gaining use in other centres.

As with the ODFS, a training course is mandatory requirement to allow purchase of the device. The O2CHS is CE marked. More information

Clinical results

How to obtain treatment

Salisbury Contacts:

Paul Taylor p.taylor@mpbe-sdh.demon.co.uk

Geraldine Mann g.mann@mpbe-sdh.demon.co.uk

Clinical trial to compare electrical stimulation and the conventional ankle foot orthosis in the correction of dropped foot following stroke.

Funded by Action Research; £80,000 for two years from January 2000

With some hemiplegic patients, gait abnormalities are due not only to an inability to dorsiflex the ankle but also from inappropriate activation of the calf muscles. Conventional correction of dropped foot, using mechanical splinting of the ankle with an ankle foot orthosis (AFO), in our experience, is often rejected by patients because it is either ineffective or uncomfortable and prevents passive movement. It is also thought that using AFOs may lead to further loss of muscle control or increased calf spasticity. Dropped foot may also be corrected by electrical stimulation of the common peroneal nerve to dorsiflex the foot during the swing phase. However, stimulation of the calf muscles to improve push-off has led to further improvements in gait re-education with some patients. A randomised control trial (RCT) is therefore proposed to compare the effect that electrical stimulation and AFOs have on the walking ability in the early stages of rehabilitation following CVA. Both will be compared with a control group of patients who do not use either device but who receive the same amount of therapy contact time and are given a home exercise programme. The efficacy of the three treatment modalities will be assessed by measuring walking parameters, spasticity, functional mobility and quality of life.

Salisbury Contacts:

Philip Wright ..........p.wright@mpbe-sdh.demon.co.uk

Geraldine Mann g.mann@mpbe-sdh.demon.co.uk

Identification of Suitable Candidates for Dropped foot stimulators.

This project aims to identify which candidates respond well to use of the dropped foot stimulator by examination of the spasticity and loss of mechanical contractility of the muscles around the ankle. Measurements are made of EMG and torque in response to passive and voluntary movement and also of EMG while walking. From these measurements the absence of muscle activity and the type and degree of spasticity can be found. The effect of using the stimulator is recorded and the success in using the device related to the outcome measures. This work is funded from within the department (1993 -97) and is subject of a Ph.D. thesis.

Results

Contact:

Jane Burridge ..........jhb1@soton.ac.uk

Pilot study to investigate the combined use of Botulinum Toxin A and Functional Electrical Stimulation with Physiotherapy for spastic dropped foot in stroke

This study has been funded by IPSEN (1999 - 2000) who produce Dysport, one of the commercially available forms of Botulinum Neurotoxin A (BoNTA). The aim is to investigate the combined effect of BoNTA and Functional Electrical Stimulation (FES) in the treatment of spastic dropped foot in stroke. BoNTA is injected into a spastic calf – the medial and lateral heads of gastrocnemius and tibialis posterior as required - weakening the overactive muscles. FES is applied to the common peroneal nerve to reinforce dorsiflexion and eversion using the Odstock Dropped Foot Stimulator (ODFS III).

The study hypothesis is that whilst FES applied to the common peroneal nerve is able to reduce calf tone in many patients, through reciprocal inhibition, this is not always so. The use of the neurotoxin inhibits over activity in the calf and may reduce its braking effect on the agonists. This provides an opportunity for greater active ankle dorsiflexion and forefoot eversion, and may be further reinforced by the use of FES. It is hoped that the combined therapy will facilitate the re-education of a more normal walking pattern and improve function in stroke patients.

More Information

Contact:

Catherine Johnson ..........calj@mpbe-sdh.demon.co.uk

IMPULSE

(Improved Mobility through imPlanted fUnctional eLectrical Stimulation of nErves)

The purpose of this project is to investigate the safety and efficacy of the Finetech Implanted Dropped Foot Stimulator. This medical device is a 2 channel implanted neuromuscular stimulator intended for the correction of dropped foot following stroke. The device has been developed by the University of Twente and Roessingh Research and Development in Holland in collaboration with the UK based company, Finetech-Medical Ltd who have organised this trial.

The nerve that controls the lifting of the foot in walking is called the common peroneal nerve. At a point, just below the knee, this nerve splits into two branches, the deep branch and the superficial branch. The deep branch goes to the muscles that lift (dorsiflex) and turn inward (inversion) the foot while the superficial branch supplies the muscles that turn the foot outwards (eversion). In normal walking, a combination of these movements is required. Therefore an electrode is surgically inserted in both nerves enabling the movements to be controlled separately. The nerves are stimulated at a frequency of 30Hz, a pulse width of 300ms and at current amplitudes of up to 1mA. This causes nerve impulses to travel down the nerve to the muscle in the same way as naturally occurring nerve impulses. Power to run the stimulator is passed through the skin using radio waves from a small control box strapped to the outside of the leg. To stimulate the muscles at the correct time a foot switch (a small pressure pad placed in the shoe) is use to detect when the foot is lifted from the ground. Stimulation begins when the foot is lifted and ends when the heel is returned to the ground. Sensation from the electrical stimulation should be very slight and it is expected that users will quickly become accustomed to it. Use of the system will be automatic; the user only has to set the stimulation intensity using two control knobs. Once healing has occurred the operation site scars should be negligible. It may be possible to palpate the implant under the skin but it is not expected to be noticeable to the eye.

The five devices have been implanted in The Netherlands and five in Salisbury in stroke subjects. It is expected the device will also be applicable to people with other neurological conditions. This work is funded by Medlink.

NEWS

Salisbury Contacts:

Paul Taylor p.taylor@mpbe-sdh.demon.co.uk

Geraldine Mann g.mann@mpbe-sdh.demon.co.uk

Clinical Results

For more information regarding the planned clinical service for stroke click STIMuSTEP implanted dropped foot stimulator

SAFO - Silicone ankle foot orthosis

For the above techniques to be successful, the peripheral nerve that runs from the spinal cord to the paralysed muscles must be undamaged. This is because when a nerve is damaged, the distal part, that is the part furthest from the spinal cord, degenerates and it is not possible to stimulate it. This would typically be the case where the sciatic nerve is damaged, for example, following hip surgery. The Department of Medical Physics and Biomedical Engineering has recently carried out a trial investigating the use of a new walking aid - the silicone ankle foot orthosis, or SAFO. The SAFO is pulled over the foot like a sock and keeps the foot elevated enabling the leg to 'swing through' more easily during walking. It allows movement of the foot and ankle but also supports and stabilises the leg. The SAFO is ideal for patients who have a dropped foot that cannot be corrected by Functional Electrical Stimulation treatment.

The device is manufactured by Dorset Orthopaedic

Contact:

Philip Wright ..........p.wright@mpbe-sdh.demon.co.uk

Clinical Results

FES for the Upper Limb in Stroke

A trial of the use of electrical stimulation exercise in the upper limb in stroke subjects was funded from within the department. Twenty chronic stroke subjects received electrical stimulation exercises of the hand and wrist muscles. Wrist and finger extensors were stimulated reciprocally with lumbricals, finger flexors or triceps. Subjects exercised twice a day for two periods of up to one hour for a period of three months. Three assessments were made, the Jebsen-Taylor hand function test, static two point discrimination and palmar, pinch and key grip strength measurements. 15 subjects improved their Jebsen test score while 3 reduced their score and 2 were unchanged. There was a significant increase in key grip of 38% (p < 0.01). The mean two point discrimination score increased from 1.80 to 2.44 (p<0.02). There was a significant difference between groups at the start of the trial but no statistical difference at the second static two point discrimination score. While statistically significant differences were found in function, sensation and grip strength, it is not clear if these benefits were carried over into activities of daily living. Some subjects however reported improved function in activities such as fastening trouser buttons using both hands, and writing.

Clinical results

Salisbury Contacts:

Paul Taylor p.taylor@mpbe-sdh.demon.co.uk

Geraldine Mann g.mann@mpbe-sdh.demon.co.uk

Paraplegic Standing.

Under funding from the MDA (1986 - 1995) a device was developed to allow standing by paraplegics by means of FES. The quadriceps and gluteus maximus are stimulated using skin surface electrodes causing knee and hip extension. The knee angle is monitored by the system which will increase the stimulation level in response to reduction in knee angle, there by ensuring safe standing. An additional component of the system is a wheel chair mounted standing frame which when folded can be easily carried but provides a balance aid when extended. To stand the user presses a button and is lifted as the quadriceps are stimulated. To sit the button is pressed again. Measurements of muscle bulk and limb blood flow showed that training for standing improved these quantities to normal values, improving skin quality and reducing the chance of pressure sores. To date 41 paraplegics have used the system while 22 have achieved adequate standing for use at home.

Clinical Results


Contact:

Duncan Wood .......... d.wood@mpbe-sdh.demon.co.uk

The LARSI Project

While the standing system has successfully provided standing the user is required to don and doff equipment each day and the function is limited. For this reason it was decided to develop an implanted system. The Lumbar Anterior Root Stimulator Implant (LARSI) was developed by the implanted devises group at University College London. The implant stimulates the anterior nerve roots as they leave the spinal cord, within the spinal dura. This approach has the advantage of a single operative site and a reduction in cable runs which are prone to breakage. Power and control signals for the implanted are passed through the skin by radio telemetry. Root stimulation produces gross patterns of movement which can be combined to produce the desired function. Following funding by the MRC (1992-1997) two systems have been implanted in Salisbury. Measurements are made using a specially designed device known as the multi moment chair. The patient sits in the apparatus which has force measurement transducers to record the force moment about each joint. In this way, combinations of stimulated roots can identified that produce useful movements. The first candidate has achieved standing, basic stepping and tri-cycling. The second subject has stood.

While initial work has been promising, further work is required to perfect the movements produced. This is presently being funded by the Welcome foundation (1998-2001).

More information


Contact

Duncan Wood .......... d.wood@mpbe-sdh.demon.co.uk

Feasibility design of a standing frame for mounting on lightweight wheelchairs

Funded by REMEDI charity; £4000 for six months from April 1999

Maintaining balance whilst standing is an important function - physiologically, functionally to perform activities and as a prerequisite for gait - but it is a difficult one for a large number of patients. These include those with neurological disorders, arthritis and the elderly. At Salisbury, we have concentrated on using functional electrical stimulation (FES) to assist complete lesion paraplegics to stand from their wheelchairs. Integral to our FES-based standing system has been a standing frame which is used for balance, so that one hand can be removed to pick up objects, drink, etc. A variety of such frames have been designed, but from their use with paraplegics we have identified limitations - primarily for the paraplegic, these are the necessity to carry part of the frame not attached to their chair and also time to erect the frame. These have meant that users have not used the system to its full potential. This project will investigate the feasibility of designing a frame which can be mounted on most makes of modern wheelchairs to assist these patients to stand.

Clinical Evaluation of the Free Hand System

The Free Hand System is an implanted neuromuscular device for the restoration of hand function in C5 - C6 tetraplegics. These subjects typically have no voluntary movement of the hand and at best a little wrist extension. The device, developed at the Case Western Reserve University in Cleveland, Ohio, USA, stimulates up to eight muscles in the hand and arm. Power and control signals are passed to the implant by radio telemetry and hand movements are controlled by movements of the opposite shoulder. For example, to open the hand the shoulder may be moved back and then forward to close the hand. If the user wishes to hold an object for an extended time, a quick jerking movement of the shoulder is made which tells the system to lock the hand in that position. The movement is repeated to release the hand. Users are assessed using a range of functional, activities of daily living and quality of life measures. Users of the device have been able to perform such functions as writing with a pen, using a knife or fork, preparing meals, drinking from a glass etc. To date seventeen subjects have received the implant in Salisbury. This work is funded by the charity INSPIRE (1994 - ) and was the first clinical use of the implant in Europe.

The Freehand project is currently on hold. This is due to financial difficulty at the company who supply the device. We are currently exploring new avenues to continue this work.

Clinical Experience

More information

Salisbury contacts:

Paul Taylor p.taylor@mpbe-sdh.demon.co.uk

Julie Esnouf j.esnouf@mpbe-sdh.demon.co.uk

Long pulse stimulation for denervated muscle

Electrical stimulation is now used quite extensively for the toning of muscles to enhance cosmetic appearance and strength. It can also be used to restore muscle function, such as raising the foot during walking, grasping of the hand, control of breathing and internal organs. This treatment involves stimulation of the nerve controlling the muscle with an electric field from electrodes applied to the skin surface or implanted around the nerve and is used by people who have sustained damage to their brain or middle to high level spinal cord (typically T12 and above).

In conditions where the nerve to the muscle is no longer functional the muscle is said to be denervated. Typically muscle wasting occurs and there is a reduction in blood flow. Recent studies have shown that these effects can be at least partially restored by electrical stimulation of the muscle fibres themselves, known as 'direct stimulation'. However this requires greater intensities and pulse widths than stimulation via the nerve and careful application of the stimulation current to ensure there is no skin damage

The purpose of this study (commencing April 1998) is to quantify the effects of using Long Impulse duration Biphasic electrical stimulation (LIB) with surface electrodes on the tissue quality (blood flow, muscle bulk, muscle strength, sensory discrimination) of long term denervated muscle. We will also evaluate the effectiveness of variation of stimulation pulse shape at minimising the sensation of stimulation and later, investigate the possibility of producing functional muscle use. The initial trial will be conducted on 5 volunteer subjects over 6-12 months, progressing with an additional 10-15 volunteers if results appear beneficial. Volunteers must have lower motor neurone nerve damage due to peripheral nerve lesion, low level spinal cord lesion or a brachial plexus lesion and be at least 1 year post injury.

More information

Clinical Results and Further Work

Contact:

Philip Wright ..........p.wright@mpbe-sdh.demon.co.uk

EFFECTIVENESS OF F.E.S. FOLLOWING KNEE ARTHROPLASTY

Thirty (30) patients undergoing elective total knee arthroplasty in the Department of Orthopaedics of the Salisbury District Hospital will participate in this study. They will be assigned to a Control group or a FES/treatment group (15 subjects in each), using randomised allocation codes. The control group will receive the ordinary course of physiotherapy, while the FES group will be using the Stimulator to exercise the medial part of their Quadriceps muscle (Vastus Medialis), for the first 6 weeks following the total knee replacement operation. Measurements of the patient's walking distance over 3 minutes and their Functional Knee Score according to the Hospital for Special Surgery rating system, will take place prior to surgery and then 6 weeks and 12 weeks following the procedure. The aim of the study is to exploit the effects of FES of the Vastus Medialis muscle in the course of rehabilitation of patients following Total Knee Arthroplasty. It will establish estimates of walking speed variability and possible effect size as a prelude to power calculations for a subsequent RCT.

To start on the 1st of June 2001.

Mr. K. Avramidis SpR in Orthopaedics, Professor I.D. Swain Consultant Biomedical Engineer, Paul Taylor Principal Clinical Engineer.

Clinical Results

Contact : Kerk Avramidis e-mail: kavramidis@lineone.net

Who can use FES? Contraindication and precautions.

How to get to Salisbury District Hospital

News Letters For more information on FES, check the back issues of our news letters.

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