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Ozan Akkus
07-31-1996, 03:39 PM
Dear Netters,

Below are the responses to our question related to using Araldite or
alternatives for molding biomechanical test models of long bones:

1. There is a company called Pacific Research in the state of Washington,
USA. They make a product called "Sawbones" that sounds to me to be exactly
what you are looking for. I'm sorry that I can't find the address at the
moment, but I'm sure that many people will reply with this suggestion. If
not, email me back, and I'll find the address and phone number for you.

__________________________________________________ _______________________

M. James (Jim) Rudert
Allegheny Singer Research Institute
Biomechanics Laboratory
320 East North Avenue Phone: (412) 359-3389


2. If you have some money, Pacific Research Labs of Vashon Island, Washington
sells a composite femur for about $80. I think people are starting to use
these to standardized testing. The drawback is that the femur only comes in
one adult size so the robustness of your stabilizers cannot easily be tested.
They plan to come out with more sizes in the future.
Paul Chang
chang@pelvis.mae.cornell.edu

3. I have used Araldite and had good success with molding, though I never
tried
to cast a femur. A caution is that the curing process is exothermic.
Increasing the quantity also increases the temperature and the speed with
which it cures. If it becomes too hot, the thermal stress can fracture the
casting and / or mold. If this is a problem, alternatives are to pour small
batches (if this does not compromise the mechanical integrity of the
finished femur) or reduce the amount of hardener (catalyst) to slow the
reaction. Too little hardener will result in a slow or incomplete cure.
Ciba may be able to provide assistance or you can experiment.

Dale
----------
Dale R. Knochenmuss Dale.Knochenmuss@UC.Edu
University of Cincinnati

4. Have you considered producing femurs out of polyurethane foam, such as
Daro
Products' RF-100 (Butler, Wisconsin, USA)? I refer you to papers such as
Szivek et al. (1995) Characterization of Three Formulations of a Synthetic
Foam as Models for a Range of Human Cancellous Bone Types. J. Applied
Biomaterials 6:125-128.

Chris Schroeder (schroede@ansel.eng.uab.edu)
Biomechanics Laboratory
University of Alabama at Birmingham, USA

5. If it is just the geometry and not the mechanical properties of the
bone that
you are desiring, why not use Saw Bones, or some other pre-fabricated
experimental orthopaedic simulant. We have used Saw Bones to examine testing
protocols before running cadaveric specimens, so as to work out as many
problems as possible without sacrificing valuable human bones.

Steven A. Caruso, M.Eng.
Director, Biomechanical Engineering Research
Saint Vincents Hospital and Medical Center of New York
(212) 604-2504
Fax (212) 604-2503



THANK YOU ALL.