Walk the walk: Ottobock creates unique innovation for Functional Electrical Stimulaton
Recent innovations in Functional Electrical Stimulation (FES), Dr Salim Ghoussayni, Ottobock
Dorsiflexor weakness or drop foot are not commonly known terms but the symptoms they describe are familiar to many. These terms refer to the inability to raise the foot due to a weakness in, or paralysis of, the dorsiflexor muscles in the leg and the foot. This condition is a frequent result of damage to the central nervous system which could be a result of stroke, cranio-cerebral injury, multiple sclerosis, incomplete spinal cord Injury and infantile cerebral palsy.
For those suffering with the condition it means that walking becomes a daily challenge and a slow inefficient process with the foot often dragging along the floor. This in turn leads to a reduction in mobility and independence as well as the increased risk of falls. Individuals with drop foot often become fatigued easily when walking; they sometimes avoid long distances and can gradually withdraw from social life. As such, it can have a sizeable impact both physically and mentally.
Conventional treatment options for drop foot are mainly physiotherapy and the use of an Ankle Foot Orthoses (AFO) as a supportive device. However, due to the passive nature of the AFO, it does not stimulate the user's own muscles to enhance walking. Medical therapy can also be used in the form of muscle relaxant drugs or botulinum toxin type A injections. Functional Electrical Stimulation is another therapy used for drop foot. While FES was originally introduced in 1961, the technology has developed significantly since its beginning.
The technology works by stimulating the surface of the leg, acting on nerves via electrodes placed on the skin to lift the foot. During the swing phase of the gait cycle, it assumes the function of the damaged central nervous system and gives the intact peripheral common peroneal nerve the signal to lift the foot. The signal is then transmitted to the muscles responsible for foot lift.
The most recent development is the introduction of the first double channel wireless surface stimulator. The MyGait system by Ottobock, launched in 2013, has a unique second channel aspect which is something that had not been previously explored on other devices. The first channel is used for the dorsiflexor muscle and the other can be used for a variety of other purposes such as supporting knee flexion and extension or providing hip stability. This improves stabilisation and gait function.
The MyGait system is made up of various components that can easily be fitted by patients independently, without the help of others. The stimulator is secured to the lower leg with a cuff where the electrodes for transfer of the pulses are already correctly positioned; therefore the patient does not have to reposition the electrodes every time the device is put on again. It is important that the electrodes are accurately placed each time the FES is used so the correct movement can be produced.
The MyGait system also includes a heel switch housed in a special sock. It is used for wireless transmission of information about heel lift (start of stimulation) and heel/foot strike (end of stimulation) to the stimulator. A remote control is then used for calling individual functions and for making stimulator settings. Software is then used which allows data to be transferred from the device to a computer, so it can be evaluated.
Following use of the MyGait system, a patient's gait pattern is improved and in many cases, an increase in walking speed and distance can be gained. This is an important aspect in regards to everyday safety when walking on uneven surfaces and on stairs and ramps and active participation in a social life outside of the home. The patient no longer has to look at the ground at every step, is able to walk longer distances and in many cases can regain a more active lifestyle, having postive physiological benefits.