Figure 1. A conventional bone conduction hearing device.

The main drawbacks with these conventional bone conduction devices consist of:

the transducer is pressed with a constant force causing discomfort and irritation of the skin;

soft tissues between the transducer and the skull bone act like an attenuator giving reduced sensitivity and distortion;

feedback problems due to sound radiation from the vibration transducer to microphone, especially if high amplification is needed.

It was in view of these drawbacks with conventional BC devices that Brånemark and coworkers suggested that a rigid penetration of the soft tissues might improve the condition for these patients. A first group of three patients was thus operated for a BAHA in 1977. One of these is still living and is a successful user of the BAHA. She has to date “consumed” three implants and several devices from the first prototypes to the Devino that she is using today.

In 1977 the author received a position as a PhD student at The Department of Applied Electronics at Chalmers and was offered to look into this project from an engineering point of view.  The PhD project lasted for six years (40% teaching and 60 % research) and the thesis “The Bone Anchored Hearing Aid – engineering aspects” was defended in 1984. Since the start, almost 30 years of exciting technical research in this field has been conducted at Chalmers that has resulted in four PhD exams and three Licentiate of engineering exams and a tenfold of Master thesis exams.

In this multidisciplinary project many people have been involved and contributed significantly to the development. Beside the key role by Prof P-I Brånemark it should be emphasized that the medical and surgical side of the project has been headed from the ENT department at Sahlgrenska sjukhuset under outstanding performance of Prof Anders Tjellström. Also Professors Gösta Granström (at the ENT department at Sahlgrenska Academy, Göteborg) and late Professors Olle Hallén and Gunnar Lidén played an important role in the project. All have shown an exceptional understanding of the importance of the multidisciplinary collaboration that I believe is the single most important key factor for success in the BAHA project.

During the first years, the project frequently faced a reverse wind or reluctance among clinicians, which is not unusual when trying to promote new treatments and procedures. “A plug through your skin - its horrible”, “you are young and have the future in front of you - do something else”, “patients are just kind to you don’t dare to say to you that it doesn’t work” were comments heard during the first 10 years. However, there was a core group of positive and enthusiastic colleagues at Chalmers, at Sahlgrenska, at Brånemark Osseo Integration Center, Industrial partners and above all, important patients that encouraged us to continue and solve the multitude of technical challenges that faced us. It took approximately 10 years before this treatment was clinically accepted (approved 1987 in Sweden) and then it took another 5 years to get it commercially accepted (Nobelpharma started to invest in new employments etc) and finally it took another 10 years before it was a commercial success. This timeframe of 25 years from idea to a commercial success is long but not unusual for projects in the biomedical field. This shows the importance for funding bodies and early investors to have an understanding for that a final success requires endurance and long term engagements.

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