Using the Existing Fixture in a Bone Osseointegrated Implant for Switching to a Transcutaneous system: Case Reports with Three Possible Scenarios

Objective: To evaluate revision BAHA surgery in three cases switching to a transcutaneous system using the existing osseointegrated fixture.

Patients: Three adults previously implanted with a tissue preserving technique, a 4 mm fixture and a Dermalock abutment (Cochlear), suffering from skin problems, were revised and implanted with a Cochlear Attract transcutaneous BAHA magnet.

Intervention: The Dermalock abutment was removed permitting the skin to heal. Revision surgery introducing the Attract system implantable BIM 400 magnet was performed lifting a skin flap over the BI300 titanium fixture. No additional soft tissue flap was lifted. Follow up was scheduled at one week, at one to two months for loading and then regularly for six months. Visits with the audiologist included magnet force measurements and clinical controls by the surgeon.

Main outcome measure and results: The first patient had no problems with the healing of the flap or retention force pressure by the magnet and hearing outcome was good. The second patient developed a small central skin break down over the magnet six months after the surgery requiring removal of the implanted magnet. The third patient experienced an insufficient hearing outcome and developed problems with pain when wearing the processor more than one hour. With a weaker magnet the sound processor fell off. She was switched back to a percutaneous solution again.

Conclusion: Revision BAHA surgery switching the existing percutaneous system to a transcutaneous solution without an additional soft tissue flap is feasible but related to risks of complications. Careful selection of candidates is mandatory and preoperative counselling requires information of the different scenarios seen in this report.