Bonebridge Implantation with Image Guidance Localization

Abstract

Objectives: The Bonebridge implant (BBI) is a bone-conduction hearing implant with a relatively large floating mass transducer (FMT), which is seated within a bony well. This well is drilled in the mastoid process and the FMT is anchored onto the bony cortex with screws on the side of the well. The location of the well has to avoid vital structures, such as the posterior canal wall, the dura mater of the middle cranial fossa, and the sigmoid sinus. The size of the well must be sufficient to accommodate the size of the FMT. This becomes more important in patients with contracted mastoids. Methods: This case series aims to review the use of image guidance localization (IGL) in planning the site of the well. Under general anaesthesia, the patient was positioned supine, with the head turned away from the site of the BBI. Local anaesthetic was administered and a postauricular incision was made and deepened down to bone. The subperiosteal flap was elevated and the surgeon determined the location of the FMT, with the help of the IGL. A conservative cortical mastoidectomy was performed to create a well for the FMT to sit in. A subperiosteal pocket for the receiver coil was created posterior-superior to the well. Results: Five patients underwent BBI surgery with IGL. Rapid and accurate localization of the site of the well for the FMT was possible in each case. Conclusions: The authors recommend IGL as a safe, rapid, and reproducible technique in localization of the site for the well of the BBI.