Robustness and lifetime of the bone conduction implant – a pilot study

Abstract

Objectives

The objective of this study was to develop methods for evaluating the mechanical robustness and estimating the lifetime of the novel bone conduction implant (BCI) that is used in a clinical study. The methods are intended to be applicable to any similar device.

Materials and methods

The robustness was evaluated using tests originally developed for cochlear implants comprising a random vibration test, a shock test, a pendulum test, and an impact test. Furthermore, magnetically induced torque and demagnetization during magnetic resonance imaging at 1.5 T were investigated using a dipole electromagnet. To estimate the lifetime of the implant, a long-term age-accelerated test was performed.

Results

Out of all the tests, the pendulum and the impact tests had the largest effect on the electro-acoustic performance of the BCI implant, even if the change in performance was within acceptable limits (<20%). In comparison with baseline data, the lower and higher resonance peaks shifted down in frequency by 13% and 18%, respectively, and with a loss in magnitude of 1.1 and 2.0 dB, respectively, in these tests.

Conclusion

A complete series of tests were developed, and the BCI passed all the tests; its lifetime was estimated to be at least 26 years for patients who are using the implant for 12 hours on a daily basis.

Keywords:

• audiology
• bone conduction audiometry
• electromagnetic transducer
• electro-acoustics

Acknowledgments

The authors would like to thank R Dumas for his contribution of laboratory access and support. Also great thanks to master’s thesis student HJ Harðardóttir for her laboratory support.

Disclosure

The authors Bo Håkansson, Sabine Reinfeldt, and Måns Eeg-Olofsson have been part-time consultants for Oticon Medical during the clinical study of the BCI. The authors report no other conflicts of interest in this work.