The neuroprosthesis for dorsiflexor weakness after a stroke
A Big Step Forward
Dorsiflexor weakness can make walking very difficult after a stroke. With functional electrostimulation (FES), the ActiGait causes the foot to actively lift again – at each and every step.
The media often refer to the neuroprosthesis as a muscle stimulator. The ActiGait is unique in the world: it is partially inserted under the skin in an operation.
The control unit is worn on the hip. It is programmed according to your needs and can be adjusted by you according to your daily condition. The control unit receives the signal from the heel switch and transfers it to the antenna which is connected directly to it.
You wear the heel switch in the heel sock. It registers when your heel lifts off the floor and when you step down again. It transmits this information directly to the control unit – so the tip of your foot always lifts at the right moment. You do not need a shoe and can also walk barefoot.
The stimulator body of the implant transmits an impulse to the cuff electrode which is also implanted.
The cuff electrode is positioned directly at the fibular nerve and controls the muscles of the lower leg.
The signals from the control unit are sent by the antenna through the skin to the stimulator body of the implant. You attach the antenna to the thigh over the implant with an adhesive fastener.
Benefits at a glance
Benefits at a glance
Functional electrical stimulation (FES) has been proven to improve safety while walking. With the ActiGait, many users move more safely even when climbing stairs or walking on uneven surfaces. Specialists observe that the risk of falling decreases and compensating movements such as raising the hip are reduced or disappear entirely, so that new malpositions are prevented. Many users walk more naturally, faster and are able to cover longer distances.
Focus on something new
With the ActiGait, you will notice that you often have to concentrate less on your steps. Numerous users of the ActiGait report that they are now able to look ahead and no longer just at their foot. Enjoy your surroundings! Physiotherapist Jürgen Kaus has already supported more than 80 patients in the fitting process. "The great benefit of the ActiGait is that the patient has far more confidence while walking," he says.
Since components of the ActiGait are implanted, the need to fasten adhesive electrodes to your leg is eliminated. The parts you wear on the outside of your body are easy to put on. Just switch on the stimulator – and the ActiGait takes care of lifting your foot.
Experiences of the specialists
More than 200 fittings with the ActiGait have shown that it can significantly improve the quality of life for stroke patients. ActiGait specialists are on site during the operation and can be reached by you at any time afterwards as well.
Functional electrical stimulation: the signal for your foot
Specific nerves and therefore also muscles in a body region can be activated by electrical impulses. Known as functional electrical stimulation (FES), this principle is used by the ActiGait – in a highly advanced form, since the ActiGait is partly implanted. The stimulator body of the implant receives a signal through an antenna attached to the skin, and transfers it to the fibular nerve (peroneus nerve) as an electrical impulse. The nerve activates the lower leg musculature so that the tip of the foot lifts up. But the ActiGait can do even more: it also corrects lateral malpositions of the foot. This results in balanced lifting of the foot which is as natural as possible.
The electrical impulse is triggered by stepping down on the heel. You wear a heel switch that triggers the foot lifting signal through the control unit – always at the right moment. The control unit in turn allows you to turn the ActiGait on and off, charge it and regulate the stimulation intensity within a certain range determined by your orthopaedic technician.
The approval trial
The ActiGait was studied in a clinical approval trial with 15 stroke patients. The results show that ActiGait users walk 20 percent faster on average and cover longer distances (plus 14 percent in four minutes).
Approval trial with 15 patients fitted with the ActiGait in three centres.
Burridge J, Haugland M, Larsen B, Pickering RM, Svaneborg N, Iversen HK, Christensen PB,
Haase J, Brennum J, Sinkjaer T; 2007; Phase II trial to evaluate the ActiGait implanted drop-foot stimulator in established hemiplegia; J Rehabil Med, 39: 212-218.
From the examination to the fitting
Certain physical requirements have to be met to use the ActiGait. In three steps, you can find out whether ActiGait can help you:
1. Call the Europe-wide toll-free number 00800/63876111 or contact a clinic familiar with fitting the ActiGait. A few questions clarify whether a fitting with the ActiGait is suitable for you in principle. A neurologist will then test whether you react to electrical impulses. Other requirements are verified in the clinic as well.
2. If the ActiGait is suitable for you, a specialised surgeon inserts the implant. The operation takes about an hour.
3. About three weeks after surgery, the skin is completely healed. Now the ActiGait is activated so you can use it.
Stroke patients with dorsiflexor weakness are potential ActiGait users. It is typical for patients who can benefit from the ActiGait that they do not achieve normal heel contact while walking. It has to be possible to achieve this by electrical stimulation of the fibular nerve (peroneus nerve).
- Patients have to meet the following criteria:
- Suffering from one-sided hemiparesis due to a cerebrovascular insult, which has lasted for at least six months
- Fully finished growing
- Able to walk 20 metres in less than 2 minutes with or without a walking aid, but without the help of another person
- Reduced walking speed
- Able to stand upright with both heels touching the floor, while the hip and knee are in a neutral position
- Able to move the affected upper ankle in a passive range of motion of at least 30°
- Positive response to electrical surface stimulation of the fibular nerve, i.e. the muscle contraction has to lead to dorsiflexion of the ankle joint and an improvement in the gait