Technology overview

This briefing describes the regulated use of the technology for the indication specified, in the setting described, and with any other specific equipment referred to. It is the responsibility of health care professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

CE marking

Odstock Medical first received a Class IIa medical device CE mark for the Odstock Dropped Foot Stimulator (ODFS) Pace in November 2008. This certification was amended in April 2012 to add the ODFS Pace XL device.


The ODFS is a portable functional electrical stimulation (FES) device that is designed to correct drop foot in people with upper motor neurone conditions (for example, stroke, multiple sclerosis and spinal cord injury). Two versions of the device are available, the ODFS Pace and the ODFS Pace XL. Both devices share a similar design, with the major difference being that the Pace XL device is wirelessly activated.

The device consists of:

  • a battery‑operated stimulator, with dimensions of 72 mm × 62 mm × 26 mm and a weight of 119 g (including the battery)

  • a pair of self‑adhesive electrodes

  • an electrode lead that connects the stimulator to the electrodes

  • a footswitch, that activates the stimulator, and a footswitch lead, which is not needed for the Pace XL.

During use, the electrodes are externally attached to the lower leg; 1 on the outside of the leg below the knee and 1 on the shin. The footswitch is placed inside the user's shoe so that it is under the foot, and is connected to the stimulator using the footswitch lead for the Pace device, or wirelessly in the case of the Pace XL device. The stimulator is commonly attached to the user's belt by a clip or in an accessory pouch, and the electrodes, electrode lead and footswitch lead are worn under clothing.

A change in pressure on the footswitch as the user walks activates the stimulator. The stimulator then sends a small pulse of electricity through the electrodes to the common peroneal nerve in the leg, causing contraction of the inactive muscles. This causes the foot to lift (dorsiflexion) and turn out slightly (eversion), and also stabilises the ankle as the foot is returned to the floor, all of which aid walking. The ODFS Pace and Pace XL include an activity logger that allows the user to view information, such as the total number of steps or total time spent walking since the logger was last reset. These activities are automatically recorded by the stimulator. The ODFS Pace and Pace XL also have an exercise mode to stimulate muscles independent of walking. This can be used to increase muscle strength and control spasticity.

The ODFS devices are powered by 1 standard 9V battery. Two rechargeable lithium polymer batteries and a battery charger are provided with the Pace XL. The battery needs to be recharged every 1 to 2 days depending on usage and should last for 3 to 6 years. The Pace device can be operated with a non‑rechargeable battery, however the manufacturer can provide a rechargeable battery with the device. This must be paid for by the user.

People with 2 drop feet (bilateral drop foot) can also be treated using 2 Pace or Pace XL devices, although Odstock also distribute a 2 channel stimulator which can be used for this purpose. This briefing focuses on using the ODFS Pace devices to manage unilateral drop foot.

FES devices, including the ODFS Pace device, are not indicated for people with lower motor neurone lesions resulting from peripheral nerve injuries or for prolapsed intervertebral discs in the lumbar region of the spine. The ODFS Pace devices should not be used by people with an implanted electronic device, such as a cardiac pacemaker or implanted defibrillator, unless investigations by the NHS clinical team have shown no interactions between the devices.

The manufacturer states that the ODFS Pace device was first developed in 2007. Earlier versions of the Odstock FES were analogue devices (in terms of adjusting the settings of the stimulator). These devices are no longer being produced, and those in use are being replaced by the digital Pace devices as they wear out.

Setting and intended use

Treatment for drop foot is part of an integrated rehabilitation programme, which aims to increase user mobility and to reduce the risk of injury through falling. In current NHS practice, a person is usually referred to a FES clinic by their GP or a consultant in neuro‑rehabilitation. If assessed as suitable for the ODFS Pace, the devices must be provided to the user by a suitably trained healthcare professional, usually a physiotherapist. A detailed user manual explains how the device should be set up and operated.

The main purpose of the ODFS Pace and ODFS Pace XL devices is to have an orthotic effect on users, which is the direct effect on the user's ability to walk while the device is being worn. Additionally, the device may have a training effect, also referred to as a therapeutic effect, which is the impact of the device on mobility when it is not being worn.

The devices are portable so they can be used in several settings, including independent use by people at home and during physiotherapy sessions. The device is suitable for wearing all day, and should be kept dry. The length of time the device is worn each day will depend on several factors, such as the preferences of the wearer and the severity of the condition. Some users will wear the device throughout their waking hours, whilst others may only use it for specific activities.

The devices are approved for use in both children and adults.

Current NHS options

NICE interventional procedures guidance on functional electrical stimulation for drop foot of central neurological origin states that current evidence on the safety and efficacy (in terms of improving gait) appears adequate to support using this procedure provided that normal arrangements are in place for clinical governance, consent and audit. It also notes that other treatment options include physiotherapy to strengthen the affected muscles, or an ankle‑foot orthosis (or brace) device to provide ankle stability and improve gait by aligning the lower leg and controlling motion. Ankle‑foot orthosis devices do not stimulate the muscles in any way (Dale et al. 2010). Less commonly, relaxant drugs or botulinum toxin type A injections may be used. Surgery may be considered for people whose walking is not improved by these approaches, either by transferring tendons to the affected area to pull the ankle upwards (dorsiflexion) or fusing the ankle or foot bones to increase stability (NHS Choices 2014). Treatment for drop foot often includes multiple interventions, provided as part of an integrated rehabilitation system.

NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to the ODFS Pace and ODFS Pace XL devices:

  • L300 Foot Drop System (Bioness)

  • Walkaide (Innovative Neurotronics)

  • MyGait (Ottobock).

Costs and use of the technology

An ODFS Pace kit costs £670 and includes the stimulator, 1 electrode lead, 1 foot switch lead, 2 foot switches and 1 pack (2 pairs) of electrodes. Additional ODFS Pace consumables are the foot switch (£24.98), foot switch lead (£12.57) and rechargeable nickel‑metal hydride batteries with charger (£16).

An ODFS Pace XL kit costs £995 and includes the stimulator, 1 electrode lead, 1 back‑up wired footswitch, 1 wireless footswitch module and wireless insole, 1 pack (2 pairs) of electrodes and rechargeable batteries with charger. Additional ODFS PACE XL consumables are the wireless foot switch module (£130), wireless foot switch insole (£40), rechargeable lithium polymer batteries (£20) and battery charger (£30).

Additional consumables for both the ODFS Pace and Pace XL are the electrodes (£10.25 per pack) and electrode lead (£4.27).

All costs are excluding VAT.

The manufacturer states that there are no maintenance costs for the stimulator, which has an anticipated lifespan of approximately 5 years. The manufacturer estimates that each person will need 6 to 9 packs of electrodes, 1 electrode lead, 1 foot switch, and 1 foot switch lead per year. The manufacturer also notes that people use the device for an average of 5 years, at which point they stop using it. The device stimulator can be reused by another person, if it is in a suitable condition. Over 5 years, the cost of the ODFS Pace and Pace XL is £3,320 and £4,325 respectively, excluding VAT, once consumables have been added.

Likely place in therapy

The ODFS is likely to be used as part of an integrated rehabilitation programme instead of, or in addition to, an ankle‑foot orthosis or other walking aid.

Specialist commentator comments

One commentator noted that people with drop foot are fearful of trips and falls and so often limit their daily activities, including social activities. This can impact on whole families and place a great burden on the carer. Increased mobility can reduce this burden. A second commentator noted that carers often report that they are less concerned over patient safety when the ODFS is being used, and feel the devices result in greater independence.

One commentator stated that, in their experience, both clinicians and users are happy with the results of the ODFS. This is because it leads to clinically meaningful increases in walking speed, which improves functional walking capacity, and has a positive impact on the person's quality of life. Users also report a number of positive outcomes when using the devices, including less effort when walking, the ability to walk further, reduced risk of trips or falls, greater confidence when walking and less pain. A second commentator noted that the ODFS can increase muscle strength, range of movement and memory of movement, reducing spasticity effects. They also stated that the effect of the ODFS can make the leg feel lighter. These factors can allow users to stay in employment for longer as a result of improved mobility.

Two commentators considered the ODFS devices to be suitable for people with long‑term conditions, particularly multiple sclerosis, because they can allow them to keep active for longer. One commentator added that in their experience, using the ODFS can provide about 4 years of extra mobility for people with multiple sclerosis.

One commentator remarked that the ODFS is beneficial compared with orthotic devices because it is not a passive support, but rather stimulates muscle activity. A second commentator added that the ODFS is more appropriate for certain people and whether the device is suitable can be determined by analysing several factors before treatment. These include: pre‑morbid status, co‑morbidities, degree of spasticity, muscle weakness and sensory impairment. One of these commentators also highlighted that some users benefit from a combination of FES and orthotic devices used together. They also noted that the ODFS is lighter than orthotic devices, with users often preferring the freedom of movement associated with its use. The commentator added that the Pace and Pace XL devices have improved comfort and ease of use, compared with the analogue versions of the device. A third commentator noted an advantage of the Pace and Pace XL devices is the exercise mode feature, which may be used to support rehabilitation programmes when the user is at home.

One commentator highlighted the benefits of the ODFS in rehabilitation for children with cerebral palsy, because new learning is encouraged by activating muscles using electrical impulses. They added that re‑learning can happen in people after stroke, who may also benefit from maintaining muscle physiology, which can enhance rehabilitation because muscle activity reduces muscle wasting.

Two commentators noted that implanted FES devices are significantly more expensive than external devices, but may be recommended for people who would struggle to consistently fit external electrodes, such as those with poor upper limb dexterity, those with cognitive difficulties, and people with skin conditions. (Please note, ODFS devices are external only, and implanted devices are outside the scope of this briefing.) A third commentator added that although implanted devices remove the risk of electrodes being incorrectly placed, they can cause local infection and bleeding.

Two commentators stated that in their experience maintenance is needed for the device, particularly if it is used daily, and there is a cost associated with these repairs. One of them added that a 5‑year lifespan for the stimulator is realistic, if repairs are carried out. One commentator also noted that in their experience at least 12 pairs of electrodes (6 packs) are needed annually, and more than 1 electrode lead and footswitch lead is sometimes needed.

One commentator remarked that in their experience, appointment frequency and the overall cost of care will vary depending on the local population, and may be significantly different from the National FES Clinical Centre standard.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance and advice, NICE aims to comply fully with all legal obligations to:

  • Promote race and disability equality and equality of opportunity between men and women.

  • Eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief (these are protected characteristics under the Equality Act 2010).

The ODFS may help people with a disability to improve their mobility and so carry out more everyday activities. Disability is a protected characteristic under the Equality Act 2010.

Drop foot is a common secondary outcome for people with neurological conditions, in particular stroke and multiple sclerosis. The risk of stroke is greater in men and people of African and Caribbean family origin, and also increases with age (Wang et al. 2013). Women are at a greater risk of multiple sclerosis, with the condition most likely to affect people aged 40 to 60 years (Mackenzie et al. 2014). Age, sex and race are protected characteristics under the Equality Act 2010.

Patient and carer perspective

The Multiple Sclerosis (MS) Trust gave the following patient perspectives:

  • People with MS typically have many other symptoms that they are dealing with and, because of the progressive nature of the disease, have different needs to people who have had a stroke.

  • The ODFS Pace is a practical addition to physiotherapy, it is simple and easy to use, and can generally be managed independently by the person with MS.

  • Although the effects of a FES are unlikely to be permanent, it can allow people with MS to stay active, independent, in work, engaged in leisure activities, and with reduced dependence on either formal or informal carers. A FES can make the difference between a person being mobile, and the need for permanent use of a wheelchair. They stated that independence and mobility is crucial in helping people to stay in control of their condition and their life.

  • A FES can reduce the risk of trips and falls, which can result in injury, time off work, loss of income and increased healthcare costs. It can increase both walking speed and distance, which helps people do important daily tasks. It can reduce effort when walking, which in turn reduces fatigue, 1 of the major factors contributing to people leaving employment. Further advantages include improvements in breathing, muscle tone, balance, posture and gut motility, all of which happen because users can keep standing and walking.

  • They regularly hear from people with MS about the critical importance that a FES makes to their walking, and about the frustration felt by those who have been unable to get a FES, and now face loss of independent mobility as a consequence.

  • They noted that there is a therapeutic window in which a FES can be used in people with MS, and that the Expanded Disability Scale Score can be used to determine this. A score in the range of 4–6 would mean that the device could be considered for the person; a score below this indicates a sufficient level of mobility and a score above means that the person is too severely disabled. They estimated that a FES would be suitable for and benefit about 5% people with MS.

The Stroke Association gave the following patient perspectives:

  • Drop foot can be a very life‑limiting condition that affects people's confidence and makes it difficult to return to work. Also, people with drop foot often report feeling that it is something that they just have to put up with.

  • Stroke survivors have described how FES devices can have a positive impact on their lives, helping them to overcome the consequences of the condition and recover.

  • Problems with the ODFS devices have been reported, but they are usually minor, and often relate to cosmetic concerns with the devices.

  • They remarked that people of African, Caribbean and South Asian family origin tend to have strokes at a younger age and, so they may have a greater need for FES devices to aid rehabilitation at a younger age. Also, people in economically deprived areas are twice as likely to have a stroke, making them more likely to benefit from a FES device.

  • FES clinics do not exist in all areas and, so people in these areas must be referred to a clinic in a neighbouring area or to the National Clinical FES Centre in Salisbury.