Research on drilling of bones

[Mr C.g. Law#]

Hi all out there,

I am starting a final year project on the subject of drilling bones in
Imperial College Biomechanics section(London). The problem is that screws
which secure fractured bones sometimes come loose (in time). It was proposed
that the drilling process in surgery might thermally damage the bone cells
(thermal necrosis) which subsequently impairs the cells to grow around the
screw to secure it.

My colleague has done substantial work of measuring the peak temperature
rise at the vicinity(2mm away) of the drilled hole in bones(cadeveric) in
controlled conditions which simulate real operating conditions, but has
found that for proper orthopaedic drill bits, the maximum temperature rise
was about 4 degrees C above body temperature which is still below the
critical temperature of 50 deg C at which permanent damage of the bone cells
occur.

So I am now wondering if there are any other ways of looking at this
problem. Is there anyone who have experienced such problems? Surgeons
themselves perhaps?

Cheok Law
Dept of Mechanical Engineering
Imperial College of London