PDA

View Full Version : Cancellous bone replacement



Dr. Gamal Baroud
11-04-2000, 11:06 AM
Re: Cancellous bone replacement
Screws fixation


Hello,

I thank all those have answered to my inquiry regardiung cancellous bone
replacement.

The emails I received have suggested either (a) PU or (b) metallic foam.
For metallic foams, see: http://www.ergaerospace.com/al.htm
and/or: http://www.goodfellow.com/static/A/38.HTML
and for PU foams, see: www.sawbones.com .

The PU foams often exhibit accentuated time-dependent properties.
Thus, I feel hesitant using PU foams and favor metallic foams instead
in view of their dominant elastic-plastic behavior.
However, it always depends on the application.

Bye,

Jamal Baroud, Ph.D.
Orthopaedic Research Lab
McGill University



=================================================

Hi

At the European Society of Biomechanics concfereence last August I saw a
paper presented which performed 3D deformation measurement using micro-CT on
an open porous aluminium material (6101-T6, ERG, Oakland,CA, USA). The
reference is:
R.A. Muller and M. Tantillo. Accuracy and reproducibility of image guided
failure assessment In Proc. 12th Conference of the European Society of
Biomechanics, Dublin, pg. 22, 2000.
The proceedings are available online in pdf format at the following address:
http://www.mme.tcd.ie/esb2000/
There are some images of the material in the abstract which give a good idea
of the morphology of the structure. Its supposed to be very repeatable alos.
Hope this is useful. Regards

Alex Lennon
Dept. Mechanical Engineering email: alennon@tcd.ie
Trinity College, Tel: +353-1-608 1976
Dublin 2 Fax: +353-1-679 5554
Ireland
------------------------------------------------------
Dear Jamal:

We have developed a bioactive bone cement which is combined with ceramic
and polymer, therefore is not so brittle. It can be injected into the
cancellous bone or to spine. Cheers,

Dr. William Lu, Ph.D,
Department of Orthopaedic Surgery
The University of Hong Kong
Tel: (852) 2974-0359 or 2974-0332
Fax: (852) 2974-0335
e-mail: wwlu@hkusua.hku.hk
-------------------------------------------------------

Contact Tammy Cleek at NASA Ames Research Center
(tcleek@mail.arc.nasa.gov); for a couple of years now she's been playing
with an open-cell aluminum foam (originally used as baffling in fighter
aircraft fuel tanks) in much the same way that you're proposing.
C Les

Clifford M. Les, DVM, PhD
Bone and Joint Center
2015 Education and Research Building
Henry Ford Hospital
2799 West Grand Boulevard
Detroit, MI 48202 USA
(313) 916-3166
fax (313) 916-8064

plure sunt clunes equorem quam equii
--------------------------------------------------

Sawbones in Vashon Island, OR has prepared several different densities of
foam materials which have been used successfully in some laboratories to
simulate cancellous bone in mechanical testing.
Additionally, the researchers at Harrington Arthritis Research Foundation in
Phoenix, AZ have worked with a foam material to simulate cancellous bone.
Hope this helps.

Kenneth R. St. John Phone: 601-984-6199
Assistant Professor Fax: 601-984-6087
Orthopaedic Surgery and Rehabilitation
University of Mississippi Medical Center
2500 North State Street
Jackson, MS 39216-4505
E-mail: kstjohn@sod.umsmed.edu
------------------------------------------------------
Hello. You may be interested in Coralline hydroxyapatite (HA). It is from
the coral Porites goniopora which has its carbonate skeleton converted into
calcium phosphate. I believe it is currently being tested in humans or may
already be finished human clinical testing. The porosity of HA is quite
similar to human bone but is not necessarily ideal. Different HA samples
are available with different average pore size and pore distribution.
Interpore International (Irvine, California) manufactures HA.
I hope this helps. Any further questions I may be able to answer.
Best wishes,

Jason Leach
Masters Candidate
University of Windsor
Windsor, Ontario, Canada
------------------------------------------------------
Hi Gamal,

check out www.sawbones.com
They are selling some biomechanical testing material.

Karol Galik
PhD student at ME department
University of Pittsburgh, PA
412 624 9776 Phone
kagst34@imap.pitt.edu
----------------------------------------------------
Dr. Baroud,

What about using a metal foam? There are a wide variety of aluminum foams
available, in both open-celled and closed-cell varieties. The open-celled
foam that I'm thinking of is investment cast, and has strut-like cell
walls. Micro-CT images of the foam look remarkably similar to young human
vertebral trabecular bone. One trade name of open-cell foams is Duocel.
The metal foams have some ductility, although the foaming agents used often
make the material more brittle than a "regular" aluminum alloy.

There's a textbook (Cellular solids: structure and properties) by Gibson
and Ashby that discusses various foams. They have examples of open-celled
polyurethane foams, although I don't know where you'd get them from. If
you are interested, I can see about finding the source of that foam. I
work in a cellular solids lab (for Prof. Gibson of Gibson and Ashby), so I
can ask around to see if anyone else has some ideas. I'd be interested in
learning what you decide.

Hope this helps,

Tara Arthur Moore
Ph.D. Candidate
Medical Engineering/Medical Physics
Harvard/MIT Division of Health Sciences and Technology
(617) 253-2076
tarthur@mit.edu
--------------------------------------------
Jamal,

I did some work in the past on constitutive modeling of porous materials and
found that in general, the constitutive behavior of the substrate dominates
the shape of the stress- strain behavior. We tested some aluminum foams and
these may work for you. The loading behavior was elastic plastic.

Ed Wachtel
-------------------------------------------------------------------------

Dear Dr Gamal

It depends what you want to do. If you want mechanical properties to test
screw or fixation methods we have been using Sawbones PU foams and found
them good and reproducible. Sawbones Euriope are bsed in Malmo Sweden but a
re a US company. However, if you want to do some cementing tests then you
must use open celled foams. There is only one I am aware of and that is the
tantanum (?) foam which is being used experimentally in animal trials as the
backing of acetabular cups which allows cancellous bone ingrowth. Sorry I do
not know where you get this.

Yours

Liz Tanner

================================================== ==
Professor Elizabeth Tanner
Professor of Biomedical Materials
IRC in Biomedical Materials and Department of Materials
Queen Mary University of London
Mile End Road
London E1 4NS
Phone +44 (0)20 7882 5318
Fax +44 (0)20 8983 1799
Mobile phone +44 (0) 7803 207292
================================================== ==

---------------------------------------------------------------
To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
---------------------------------------------------------------