RELIABILITY OF CLOSED DOUBLE HELIX ELECTRODE FOR FUNCTIONAL ELECTRICAL-STIMULATION

The reliability of a closed double helix electrode in the lower limbs was studied, This electrode is an implanted intramuscular electrode an d is used for a totally implantable functional electrical stimulation system, Eighty electrodes were evaluated retrospectively with a mean p eriod of 15 months, The total implant time was 1222 electrode months, The cumulative proportion surviving was 0.934 at 6 months, 0.855 at 1 year, 0.765 at 2 years, and 0.730 after 30 months, Fifteen of 80 elect rodes failed, seven showed increasing electrode impedance, and eight h ad undesirable changes in recruitment, Of the failed electrodes, 2/3 f ailed during the first 10 months, The reliability was 0.91 at 6 months and 0.80 at 1 year after implantation in all muscle groups, The close d double helix electrode displayed an increased reliability when compa red with the open double helix electrode at 6 months, and an equivalen t reliability as compared with the electrodes developed by Handa and c olleagues at 6 months and 1 year, using the chi squared test for indep endence, This study suggests that the closed double helix electrode ha s an acceptable reliability and can be used as a part of a totally imp lantable functional electrical stimulation system.