I was thinking of using a self-tapping screw rather than tapping the hole first. Gives a whole new meaning to "self-tapping", eh?
I'll get me white coat.
Barakta's hearing aid implant is indeed a chunky titanium self-tapper into the bone, into which a thread is pre-tapped for the external gubbins to bolt into (with a gold plated T.notverymuch torx screw, using a ludicrously expensive torque wrench). The processor itself clips on with a simple quick-release plastic thingy, which is a massive improvement on the previous faffing-about-with-O-rings design. They do this for adults under local anaesthetic. It's a bit like root canal, but with less drooling and a much scarier looking drill.
The clever thing about titanium and living bone is that it osseointegrates over a period of a few months, which means if you don't play rugball, it makes a bond even better than the really strong Loctite. Exactly the opposite of B&M handlebar brackets, where the screw gets looser over time.
You could certainly mount a pair of glasses using the same technology. The downside is that while the implant will bear weight (and transmit sound) admirably well without any pressure on the skin, the skin:abutment interface is effectively a permanent open wound, with cleaning and maintenance issues far greater than a bit of mild dermatitis. Research into solving this problem continues, with a view to bone-anchored prosthetic limbs. Animals with horns and antlers manage it - it's mostly a question of the right materials.
