<P> Hearing is of importance for a normal speech development . The skull bone in children is often very thin and softer than in the adult . Surgery is thus often delayed until the age of four to five years . In the meantime, the child with bilateral atresia can be fitted with a band around the head with a coupling for a BAHA . This may be done at the age of one month . Infants at this age may tolerate this well . </P> <P> Patients with chronic ear infection where the drum and / or the small bones in the middle ear are damaged often have hearing loss, but difficulties in using a hearing aid fitted in the ear canal . Direct bone conduction through a vibrator attached to a skin - penetrating implant addresses these disadvantages . </P> <P> In 1977, the first three patients were implanted with a bone - conduction hearing solution by Anders Tjellström at the Ear, Nose, and Throat Department at Sahlgrenska University Hospital in Gothenburg, Sweden . A 4 - mm - long titanium screw with a diameter of 3.75 mm was inserted in the bone behind the ear, and a bone conduction hearing aid was attached . </P> <P> The term osseointegration was coined by Professor Brånemark . During animal studies, he found the bone tissue attached to the titanium implant without any soft tissue in between . He also showed an such an implant could take a heavy load . His definition of osseointegration was "direct contact between living bone and an implant that can take a load". </P>

When was the bone anchored hearing aid invented