Precise bonebridge implantation in challenging cases: a novel approach using virtual planning and electromagnetic navigation.

backgroundThe second generation of the Bonebridge (BB) bone conduction implant was shown to be a viable option even for younger children with conductive or mixed hearing loss. However, preoperative imaging often shows only small areas where the FMT (4.5 mm) or screws (4.0 mm) can be fully and safely inserted without the need to use lifts. Navigation systems allow precise placement of the device and prevent potential complications such as dural or vascular injuries. The latest version of the preoperative planning software Otoplan® allows to assess bone thickness and perform virtual implantation. MATERIALS &

methodsSix children between 3 and 12 years of age underwent BB implantation using Otoplan® with export of the planned BB position to a navigation system. Prior to an intraoperative cone beam CT (CBCT), 3 marker screws were placed in the temporal bone. Images were loaded into Otoplan® to virtually define the optimal BB position and export the corresponding model. CBCT scan and model were then loaded into an electromagnetic navigation system. The screws were used to accurately register the system, and the planned BB placement was projected onto the patient. BB implantation was performed accordingly and finally the marker screws were removed. Possible complications were monitored and the audiological success was measured using an age-appropriate speech test.

resultsBone thickness at the screw location was over 4.0 mm in every case, documenting the accuracy of the procedure. No medical complications occurred intraoperatively, during the immediate hospital stay, or up to and including the initial fitting 4-6 weeks after implantation. Speech test results were greater than or equal to 90% in all measurable patients.

conclusionVirtual implantation with Otoplan® can be loaded into a navigation system to mark the safe position of the screws on the temporal bone. Projecting the planned position onto the patient using navigation is a practical tool that can make implantation more reliable and safer for patients.