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Standardized femur program

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  • Standardized femur program

    To: BIOMCH-L

    Dear Colleagues,
    here enclosed is an announcement of the "Standardized Femur
    Program" proposed by the Laboratory for Biomaterials Technology of the
    Rizzoli Institute in the frame of the Prometeo project.

    It is available on the market a bone analogue, hereinafter referred as
    "composite femur", made of glass fibre reinforced epoxy and polyurethane
    foam. Differently from many similar products for surgical simulation, this
    bone replica was designed to mimic as close as possible the mechanical
    behaviour of a human femoral bone (Beals, 1987; Szivek, 1990; Szivek, 1991;
    Cristofolini, 1995).

    The advantages of using a standardized artificial analogue for in vitro
    studies are obvious; in fact an increasing number of published experimental
    works report the use of the composite femur in place of cadaver bones
    (Bianco, 1989;McKellop, 1991; Otani, 1993a; Otani, 1993b; Cristofolini,
    1994; Harman, 1995).

    It is here proposed to use the three dimensional geometry of this composite
    femur as a standardized reference for finite element models of the human
    femur. These models are used in orthopaedic Biomechanics to investigate
    the mechanical behaviour of the bone under load. This would allow every
    researcher to use all the published experimental measurements made on the
    composite femur as calibration data. Furthermore, a common reference
    geometry would allow the inter-laboratories replication of numerical
    studies. This cross-calibration approach has already been used in our lab
    with good results (McNamara, 1994; McNamara, 1995).

    We used this particular commercial bone replica as reference geometry
    because in our knowledge it is the only available on the market which was
    designed to replicate the mechanical behaviour of a human bone (Inquiry on
    BIOMCH-L, 15/5/1995). Nevertheless, this program will not endorse in any
    way the company which produce the composite femur; on the contrary the
    diffusion of this reference geometry could create market opportunities for
    other commercial subjects.

    To further support this proposal, we have made available at no cost through
    Internet the solid model of the composite femur, converted in formats which
    should be readable by most commercial CAD/CAE programs. Although already
    useful the available models could be improved; if our initiative will be
    approved by the community, more and better models will be made available.

    - Beals, N. (1987) Evaluation of a composite Sawbones femur model. Research
    Report ML-87-25. Richards Medical Company, Memphis, Tennessee.
    - Bianco, P.T., Bechtold, J.E., Kyle, R.F., Gustilo, R.B. (1989) Synthetic
    composite femurs for use in evaluation of torsional stability of cementless
    femoral prosthesis. Proc. Biomechanics Symposium (Edited by Torzilli, P.A.,
    Friedman, M.H.), pp.297-300 ASME AMD.
    - Cristofolini L., Cappello A., Toni A. (1994) "Experimental errors in the
    application of photoelastic coatings on human femurs with uncemented hip
    stems", Strain 30(3): 95-103.
    - Cristofolini L., Viceconti M., Cappello A., Toni A. (1995) "Structural
    validation of commercially available composite femur models", J.
    Biomechanics, In press.
    - Harman, M.K., Toni, A., Cristofolini, L., Viceconti, M. (1995) Initial
    stability of uncemented hip stems: an in-vitro protocol to measure
    torsional interface motion. Medical Engineering and Physics 17(3):
    - McKellop, H., Ebramzdeh, E., Niederer, P.G., Sarmiento, A. (1991)
    Comparison of the stability of press-fit hip prosthesis femoral stems using
    a synthetic model femur. J. Orthop. Res. 9, 297-305.
    - Mcnamara B.P., Cristofolini L., Toni A., Taylor D. (1994) "Effect of
    bone-prosthesis interface bonding on stress shielding in cementless THA.",
    Advances in Bioengineering 1994, Askew M.J. Ed., ASME-BED, New York publ.:
    vol. 28 201-202
    - Mcnamara B.P., Cristofolini L., Toni A., Taylor D. (1995) "Evaluation of
    experimental and finite element models of synthetic and cadaveric femora
    for pre-clinical design-analysis", J. Clinical Materials, In press.
    - Otani, T., Whiteside, L.A., White, S.E., McCarthy, D.S. (1993b). Effect
    of femoral component material properties on cementless fixation in total
    hip arthroplasty. J. Arthrop. 8, 67-74.
    - Otani, T., Whiteside, L.A., White, S.E.. (1993a) Strain distribution in
    the proximal femur with flexible composite and metallic femoral components
    under axial and torsional loads. J. Biomed. Materials Res. 27, 575-585.
    - Szivek, J.A., Gealer, R.L. (1991) Comparison of the deformation response
    of synthetic and cadaveric femora during simulated one-legged stance. J.
    Appl. Biomaterials 2, 277-280.
    - Szivek, J.A., Weng, M., Karpman, R. (1990) Variability in the torsional
    and bending response of a commercially available composite femur. J. Appl.
    Biomaterials 1, 183-186.

    Marco Viceconti 1
    Massimiliano Casali 1
    Luca Cristofolini 1 4
    Aldo Toni 1 2
    Barbara Massari 3
    Sanzio Bassini 3

    1 Laboratory for Biomaterials Technology, Rizzoli Institute
    2 Orthopaedic Clinic, University of Bologna
    3 C.I.N.E.C.A.
    4 Engineering Faculty, University of Bologna

    **************** THE STANDARDIZED FEMUR PROPOSAL ***************

    - What is the "Standardized Femur"?
    The standardized femur is the 3D computer model of a femoral bone analogue
    produced by Pacific Research Labs (Vashon Island, Washington, USA) which
    is becoming a de facto standard in experimental orthopaedic Biomechanics.

    - Why to use the "Standardized Femur"?
    More and more experimental data based on this bone analogue are becoming
    available in the literature; we propose to adopt this geometry as a
    reference for finite element studies in orthopaedic Biomechanics . This
    will produce two advantages:
    1) because of the common geometry, it will be easier to compare results
    from different FEM studies.
    2) Every researcher building FE models will be able to use data from
    experimental tests available in literature to calibrate his model.

    - Where is the "Standardized Femur"?
    Information on the femoral bone analogue and all of the geometry files are
    available through a link available in the Biomechanics WWW pages or
    directly at the following URL:
    Actually only data referring to the smaller size adult femur are available.
    Together with the CT scan images we used to generate the model (all
    converted in TIFF format), you will find also files containing the inner
    and outer contours of every slice. Lastly, an IGES model of the inner and
    outer surface is available.

    - How to obtain the "Standardized Femur"?
    If you try to download a file, a dialog box will request your
    username-password. The "Standardized Femur" files containing the model are
    publicly available for research purposes to anyone who makes an explicit
    request. However, we would like you to acknowledge the source of the
    geometrical model every time you use it (we are looking for fame!). Thus,
    we devised this mechanism: you download the "Transfer Agreement Form"
    available on-line, fill it out, sign it, and send it to us by regular mail.
    When we receive it, we shall send you the password which allows you to
    download the files. Files download will be possible only after September
    15th, 1995.

    ************ END OF THE STANDARDIZED FEMUR PROPOSAL ************

    Laboratorio di Tecnologia dei Materiali tel. 39-51-6366865
    Istituti Ortopedici Rizzoli fax.
    via di barbiano 1/10, 40136 - Bologna, Italy

    Tiger! Tiger! Burning bright in the forest of the night,
    what immortal hand or eye could frame thy fearful symmetry?
    Opinions expressed here do not necessarly reflect those of my employer