Clinical and functional results after implantation of the bonebridge, a semi-implantable, active transcutaneous bone conduction device, in children and adults

Abstract

Purpose: Aim of the study was to evaluate the surgical, clinical and audiological outcome of 32 implantations of the Bonebridge, a semi-implantable transcutaneous active bone conduction implant.

Methods: In a retrospective cohort study, we analyzed data for 32 implantations in 31 patients (one bilateral case; seven age < 16 years) with conductive or mixed hearing loss, malformations, after multiple ear surgery, or with single-sided deafness as contralateral routing of signal (CROS).

Results: Four implantations were done as CROS. Five cases were simultaneously planned with ear prosthesis anchors, and 23 implantations (72%) were planned through three-dimensional (3D) "virtual surgery." In all 3D-planned cases, the implant could be placed as expected. For implant-related complications, rates were 12.5% for minor and 3.1% for major complications. Implantation significantly improved mean sound field thresholds from a preoperative 60 dB HL (SD 12) to 33 dB HL (SD 6) at 3 postoperative months and 34 dB HL (SD 6) at > 11 postoperative months (p < 0.0001). Word recognition score in quiet at 65 dB SPL improved from 11% (SD 20) preoperatively to 74% (SD 19) at 3 months and 83% (SD 15) at > 11 months (p < 0.0001). The speech reception threshold in noise improved from - 1.01 dB unaided to - 2.69 dB best-aided (p = 0.0018).

Conclusion: We found a clinically relevant audiological benefit with Bonebridge. To overcome anatomical challenges, we recommend preoperative 3D planning in small and hypoplastic mastoids, children, ear malformation, and simultaneous implantation of ear prosthesis anchors and after multiple ear surgery.

Keywords: Bone conduction implant; Bone-anchored hearing aid; Conductive hearing loss; Mixed hearing loss; Transcutaneous hearing implant.

Fig. 1

Example of optimal FMT position determined by preoperative 3D planning (“virtual surgery”). a Extracranial view with distances to landmarks for intraoperative transfer. b Intracranial view, where a partial impression of the sigmoid sinus indicates the necessity of the use of lifts. c Verification of the implant position overlying the axial CT scan layer

Fig. 2

Safety. a Scatterplot of pre- and postoperative BC thresholds (THR, 4PTA). CROS patients are indicated within the frame (n = 4; 2 values overlap). b Scatterplot of preoperative BC thresholds and postoperative vibrogram thresholds (4PTA) showing sufficient transfer of vibrational energy to the inner ear and an adequate implant function

Fig. 3

Distribution of preoperative (preop.) and postoperative (postop.) unaided and at 3 months (3 M) and > 11 months (> 11 M) postop. Aided AC thresholds (4PTA) as a boxplot. Significance is indicated with **** (p < 0.0001). Aided condition was measured in the sound field

Fig. 4

Speech recognition in quiet and in noise. a Distribution of preoperative (preop.) unaided, preop. best-aided, at 3 months (3 M) and > 11 months (> 11 M) postoperative (postop.) word recognition scores (WRS₆₅, 4PTA) as a boxplot. Significance is indicated with **** (p < 0.0001) or * (p = 0.019). b Boxplot of speech recognition thresholds in noise (SRT, 50% correct in Oldenburg sentence test) with the frontal presentation of speech signal and noise (S₀N₀). Significance is indicated with ** (p = 0.0018)

Fig. 5

Progressive protrusion of the implant under a preexisting thin retroauricular skin without local signs of irritation or inflammation (patient 14)