FES and Improving Gait Patterns

Welcome again and thank you for your continued support. In this blog we will be focusing on one of the future benefits of FES, gait patterns in people who are unable to walk unsupported. As we have previously stated FES can be used to produce muscle contractions but with the use of multiple electrodes and channels, FES has the ability to produce gait patterns in people with impairments such as stroke victims. An example of a neuroprosthesis that can be used to help with retraining of walking is the Complex Motion Simulators, as used by Thrasher, Flett and Popovic (2006). This system delivers biphasic asymmetrical pulses to the quadriceps, hamstring, calf muscle groups and the tibialis anterior muscles by 8 self adhesive electrodes. A program was developed to stimulate the gait pattern through an open loop control system. The system functioned so that during the mid and late stance phases, the quadriceps and calf muscles were activated continuously with no stimulation to the other two muscle groups. When the patient began the swing phase they would push a button which would start the predetermined program as shown in the image below. At the end of the sequence, the program would return back to the initial extension stance phase until the button was pushed again to trigger another gait cycle. The results from this paper displayed impressive results with all the subjects improving their walking speed following their gait training with FES.

Preprogramed stimulation settings for FES open loop system for one gait cycle (Thrasher, Flett & Popovic, 2006)

A meta-analysis (Robbins, Houghton, Woodbury & Brown, 2006), which only included 5 FES studies involving gait patterns, concluded that gait training with the use of FES can increase gait speed. However, the increases in gait speed did not always result in an improvement in the patients overall functional capabilities. Even with current research showing that FES can improve gait in people who are paralysed, few patients actually use a FES system in their everyday life (Popovic & Sinkjaer, 2000). This is because FES gait systems generally give the user minimal control of their walking speed and can be very energy demanding (see table below). This increase in effort and energy expenditure is independent of what type of FES gait system is used (Popovic & Sinkjaer, 2000). This increased difficulty in movement means many patients choose to continue using their wheelchair or other preferred methods to move around (Popovic & Sinkjaer, 2000).

The energy costs associated with different FES systems compared to normal walking (Popovic & Sinkjaer, 2000)

FES and its benefits in improving gait are clear, but future developments in FES are required for it to acquire widespread usage and recognition as the best clinical practice. Future developments need to look at reducing the energy cost of walking with FES and increasing the users control of their gait speed. This could help facilitate uptake of the FES systems and help increase the function of patients living with paralysis.

           Example of a pateint undergoing gait retraining using an FES system similar to the one mentioned above

 References:

Popovic, D., & Sinkjaer, T. (2000). Improved control for functional electrical stimulation to restore walking. Hong Kong Physiotherapy Journal, 18, 12-20.

Robbins, S. M., Houghton, P. E., Woodbury, G., & Brown, J. L. (2006). The therapeutic effect of functional and transcutaneous electric stimulation on improving gait speed in stroke patients: A meta-analysis. Archives of Physical Medicine and Rehabilitation, 87, 853-859.

Trasher, T. A., Flett, H. M., & Popovic, M. R. (2006). Gait training regimen for incomplete spinal cord injury using functional electrical stimulation. Spinal Cord, 44, 357-361.