A bone conduction implant using self-drilling screws : Self-drilling screws as a new fixation method of an active transcutaneous bone conduction hearing implant.

Background: The active transcutaneous bone conduction implant (tBCI; BONEBRIDGE™ BCI 601; MED-EL, Innsbruck, Austria) is fixed to the skull with two self-tapping screws in predrilled screw channels. The aim of this prospective study was to evaluate the safety and effectiveness of fixation with self-drilling screws instead of the self-tapping screws, in order to simplify the surgical procedure.

Materials And Methods: Nine patients (mean age 37 ± 16 years, range 14-57 years) were examined pre- and 12 months postoperatively for word recognition scores (WRS) at 65 dB SPL, sound-field (SF) thresholds, bone conduction thresholds (BC), health-related quality of life (Assessment of Quality of Life, AQOL-8D questionnaire), and adverse events (AE).

Results: Due to avoidance of one surgical step, the surgical technique was simplified. Mean WRS in SF was 11.1 ± 22.2% (range 0-55%) pre- and 77.2 ± 19.9% (range 30-95%) postoperatively; mean SF threshold (pure tone audiometry, PTA) improved from 61.2 ± 14.3 dB HL (range 37.0-75.3 dB HL) to 31.9 ± 7.2 dB HL (range 22.8-45.0 dB HL); mean BC thresholds were constant at 16.7 ± 6.8 dB HL (range 6.3-27.5 dB HL) pre- and 14.2 ± 6.2 dB HL (range 5.8-23.8 dB HL) postoperatively. AQOL-8D mean utility score increased from 0.65 ± 0.18 preoperatively to 0.82 ± 0.17 postoperatively. No device-related adverse events occurred.

Conclusion: Implant fixation by means of self-drilling screws was safe and effective in all nine patients. There was significant audiological benefit 12 months after implantation.