Re: bone implant

>I've got a couple of questions for you "Hard Tissue" folks.
>A researcher has asked me to paraffin embed a decalcified bone with a
>Tantalum implant.  His words, "It's just a sponge!  It cut on the band saw
>pretty well!"   HAH!  HAH!  HAH!  I told him that I had news for him.  This
>is NOT going to cut on a paraffin embedded block.  Well, he wants to know
>how to do it.  I suggested he look into several different things.  Well, he
>comes back and wants ME to do the looking.  Anyway,  Is this something that
>is even cutable (ie with titanium blade or something) ?  He said maybe he
>needs a diamond blade.  Now, I may be wrong, but this specimen is from a
>dog and is about 1.5 inches X 1.5 inches.  I didn't think that a diamond
>blade would work.  Someone told him it would.  If a titanium blade is a
>possibility, where do you purchase these and how much are they
>approximately.  Maybe the price tag will scare him off.  Then there's
>always grinding the specimen after plastic embedding.  Is this something
>that might be a possibility with this type of implant?
>	This should be a start and then I'm sure I'll have more questions.


I did bone stuff for the Orthopedic Dept. at the U. of Minnesota for 10
years and this kind of thing happened to me all the time.  People, who
should have known better, would plan and execute  an experiment and then
ask "what now? ".   Many times I would have to explain how it was not
possible to make paraffin sections of steel implants in bone.  I would try
to be a part of their planning process as much as possible, in order to
avoid situations just like this.  This is not easy to do when you have 6 or
7 investigators.
	Now for the opinion.  There is no 'blade' that will cut metal in a
paraffin block.  Even if you had a blade that would cut through metal, the
surrounding bone would not tolerate the forces involved.  What you will
need to do is to use a low speed diamond saw, made by Buehler, to cut
through the specimen.  You will also need to remove the paraffin from your
sample and reembed  in methyl methacrylate.  I used a method like this and
would get sections around 50 microns in thickness.  This would be good
enough to show any kind of bone growth around the sponge. You should be
able to find someone at a university that would be able to help you.  This
is also a good skill to pick up if you  are going to be involved ion bone
work.  It really is the only way to treat certain samples.   If you have an
other questions, I would be happy to put in my  2 pennys.

Randy Carpenter
Parker Hughes Institute

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