Force recorded at during explant of CWRU and Peterson type
Change in extraction force with duration of implant (Right)
Peak force at dislodgement (PFD) during
explant for each electrode type. Electrodes were explanted
immediately following implant in one group and after periods
of one and four hours, one, three and five days, one week,
ten days, two and four weeks in others.
The dislodgement force at immediate explant represented the
degree of mechanical fixation due to the barb design. The CWRU
type had the most compliant barb and the lowest PFD at this
time. The NEC electrode fabricated from a hard drawn wire matched
the fixation of the Peterson type electrode at immediate explant.
The change in PFD at the later implant periods resulted from
the change in the amount and properties of the tissues around
the electrode coils and barb. In the CWRU, Peterson and Scheiner
type of electrodes, the most rapid increase in peak dislodgement
force was observed between five and seven days.