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Summary: Spinal Implant

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  • Summary: Spinal Implant

    Question: I would appreciate if anyone can suggest useful equipment and
    procedure
    for the testing of spinal implants.
    Thank you for all your replies. I believe my query has been fully
    answered.
    Replies are:
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    I believe there is an ASTM standard for fatigue/ static testing of
    spinal fixation systems, although I haven't got the number to hand.
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    You should have a look to the ASTM Standards (American Society fot
    Testing and Materials). They have a whole set of standards about spinal
    implants testing. (Which are currently proposed as ISO standards).
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    You have to make various fixtures to hold the parts, which are
    defined in the standards. Depending on your material and the parts
    you are testing, you may need a temperature controlled water bath and
    circulating system to immerse the components in Ringer's solution or
    similar while you test them. For polymers or composites, you will
    need to soak them before testing.
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    have you looked at the protocols being developed by ASTM Committee F04
    on
    Medical Devices? ASTM is in West Conshohocken, PA and you can reach
    their
    WEB page to get names and e-mail addresses by accessing www.astm.org.
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    I just realized that I only answered half of your question in my first
    message. We test spinal implants using test machines from MTS Systems
    Corporation and I know that they have developed some special fixturing
    for
    theit Mini-Bionix machine to assist in spinal testing.
    They can be reached by e-mail at lito.mejia@mts.com (Lito Mejia,
    Biomaterails Testing Systems) or:
    MTS Systems Corporation
    14000 Technology Drive
    Eden Prairie, MN 55344-2290
    612-937-4000
    FAX: 612-937-4515
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
    I have tested spinal implants in porcine spinal segments in torsion,
    compression and fatigue. Basically the spinal segment consists of two
    vertebrae and one intervertebral disc. A discetomy is performed to
    remove
    the disc nucleus, and the replacment disc inserted. The spinal segment
    is
    then mounted inbetween two holding jigs using both screws and a medical
    cement (dental or bone cement) set around the cut ends of the two
    vertebrae
    A compressive load is applied, using typically a MTS or Instron testing
    machine, and if you have the capability, a rotation can be applied for
    several cycles to simulate fatigue loading. The magnitude of loads
    depends
    on your model (animal or human cadaver), which values can readily be
    found
    in the literature.
    If you want to test the implant on its own, that depends on what your
    artificial disc is made of.
    ++++++++++++++++++++++++++++++++++++++++++++++++++ +++++
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