Outcomes with transcutaneous bone conduction implants in patients with mixed hearing loss.

Objective: To evaluate audiological outcomes of transcutaneous devices among individuals with mixed hearing loss (MHL) who underwent implantation with the Cochlear™ Osia® and Med-El Bonebridge™ devices.

Methods: Adults with MHL in at least one ear, including a best bone conduction (BBC) threshold of 30 dB HL or poorer, and air-bone gaps of 15 dB HL or more at one or more frequencies were implanted with the Cochlear™ Osia® or Med-El Bonebridge™ devices for MHL. Four-frequency pure tone average (PTA) was calculated for aided thresholds and compared to preoperative PTAs for BBC thresholds.

Results: Among the study participants, 11 were implanted with Osia, and 11 were implanted with Bonebridge. In the Osia group, the BBC PTA averaged 23.6 dB, which was not significantly different from the aided PTA of 27.0 dB (P = 0.2). In the Bonebridge group, the BBC PTA averaged 23.3 dB while the aided PTA was significantly poorer at 32.9 dB (P = 0.03). In both groups, aided sound field thresholds were worse than BBC thresholds overall except for a 7 dB improvement at 2000 Hz in the Osia group (P < 0.05).

Conclusion: We highlight important limitations of current transcutaneous bone conduction systems for rehabilitation of MHL. Sound field outcomes for Osia and Bonebridge devices are limited by the BBC thresholds of either ear; these devices do not provide significant gain or "overclosure" beyond BBC thresholds. While both groups generally experienced declines in aided thresholds compared to best conduction thresholds, the Osia implant exhibited an exception of a 7 dB improvement at 2000 Hz.