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  • Cancellous bone replacement

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

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