Osseointegrated Bone-Conducting Hearing Protheses

Hearing loss is a common worldwide health concern that increases in both prevalence and severity with age. Individuals suffering from hearing loss often complain of having trouble communicating with poor speech recognition and localization of sounds at the work environment or social gatherings. Elderly patients with hearing loss are at higher risk for social isolation, lack of independence, and early dementia. Treatment for hearing loss often involved sound amplification medical devices called conventional hearing aids. Conventional hearing aids are commonly used as the main auditory rehabilitation tool because they are non-invasive and less expensive treatments available. The medical device consists of a microphone, amplifier, and loudspeaker. Its main function is to raise the volume or magnify the sound in our environment. While its positive impact on patients' quality of life, including communication, social, emotional, and cognitive function, has been proven, most patients are non-compliant because of the non-ideal features. These features include insufficient amplification, acoustic feedback, lack of directionality, occlusion effects. Conventional hearing aids have been forced to evolve since they were first developed to adjust to patient aesthetic and functional demands.

There are two types of conventional hearing aids; air conduction hearing aids and bone conduction hearing aids. Air conductive hearing aids are a medical device that consists of a microphone, amplifier, and transducer that works as a loudspeaker in the external auditory canal. Bone conductive hearing aids consist and function similarly to air conductive hearing aids but differ in how the transducer function and where it is placed. In this type of hearing aids, the transducer work as bone oscillators that transmits vibration to the inner ear from the sound recollected by the external microphone. To effectively transduce the sound into a vibration, a medical device needs to be located near the temporal bone. The hearing aid is often placed near the temporal bone using headband or eyeglasses pieces.

Osseointegrated bone conduction prosthesis is a medical device implanted by an otolaryngologist under local or general anesthesia in a simple single or two-stage procedure. The technique allows for a reversible surgical alternative that does not risk any further hearing loss and avoids non-ideal features of both types of conventional hearing aids. The prosthesis is implanted directly into the temporal bone and merges with the skull in a process is called osseointegration. Direct implantation provides advantages over conventional hearing aids, including the elimination of “in the ear” or “in the canal medical device,” reducing canal moisture and discomfort. Additional advantages include eliminating the pressure exerted by the device over soft tissue and soft tissue impedance in the case of bone conductive hearing aids. It also allowed an alternative treatment for the patient where conventional hearing aids are contraindicated, including patients with congenital/acquired anatomic deformities and chronic ear infections. Finally, the success of the system can be predicted for a patient with conductive hearing loss with a trial of conventional bone conductive hearing aid, a patient who reported improved quality of hearing where more likely to be content with the system due to the absence of interposed soft tissue between the medical device and temporal bone.