TABLE OF CONTENTS

• What is New?
• What is the Standardized Femur?
• What is the Muscle Standardized Femur?
• Related Publications
• Technical data
• Model history and Accuracy

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What is New?

• New distribution model: the SF Program is now distributed as part of the BEL Repository. The License Agreement is substantially unchanged.

• The Standardized Femur version 2.3:a new model is available which should represent an significant improvement over the previous version. It has been imported in Ansys, Patran and Marc without any problem, closed as a solid and meshed without any additional editing. Additionally the surface patches have been partitioned in a way which should simplify the generation of a solid mapped mesh. Last, but not least, the accuracy of the reconstruction has been improved.

• The Muscle Standardized Femur version 1.0: is a new model, based on the Standardise femur geometry, on which we have identified the most likely location of muscle insertions as separate surface patches.

What is the Standardized Femur?

The standardized femur is the 3D surface model of a femoral bone analogue (mod. #3103) produced by Pacific Research Labs (Vashon Island, Washington, USA) which is becoming de facto a standard in experimental orthopaedic biomechanics.

Much experimental data based on this bone analogue are becoming available in the literature; we propose to adopt this geometry as a reference for orthopaedic Biomecanics finite element studies. This will produce two advantages:

• Being based on a common geometry, it will be easier to compare results from different FEM studies.
• Every researcher building FE models will use data from experimental tests available in literature to calibrate his model.

What is the Muscle Standardized Femur?

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Related Publications

Base Biblio Reference

• Viceconti, M., Casali M., Massari B., Cristofolini, L., Bassini S. and Toni, A., The 'Standardized femur program'. Proposal for a reference geometry to be used for the creation of finite element models of the femur, J. Biomech., 1996a, Vol. 29, 1241.
  
  

Validation works on composite femurs and related material

• Cristofolini L., Viceconti M., Cappello A., Toni A. (1996) Mechanical validation of whole bone composite femur models J. Biomechanics 29(4): 525-535.
• Cristofolini L., Cappello A., Viceconti M., Toni A., Giunti A. (1994) "A validation of synthetic femur models in relation with comparative stress shielding studies of hip stems", 2nd World Congress of Biomechanics, Amsterdam.
• Cristofolini L., Viceconti M., Toni A., Giunti A. (1993) "Can composite femurs replace cadaveric femurs in in-vitro testing?", Transactions of the 19th annual Meeting of the Society for Biomaterials, Birmingham, Alabama: 125.
• Viceconti M., Cristofolini L., Toni A., Giunti A. (1992) "Transversal compliance of synthetic femurs". Biomaterials and Intelligent Materials C.N.R. Meeting, Brindisi.
• Szivek, J.A., Thomas, M., Benjamin, J.B. (1993) Characterisation of a synthetic foam as a model for human cancellous bone. J. Appl. Biomaterials 4, 269-272.
• 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.
• Uta, S. (1992) Development of synthetic bone models for the evaluation of fracture fixation devices. Nippon Seikegeka Gakkai Zasshi 66(11), 1156-1164.
• Beals, N. (1987) Evaluation of a composite Sawbones femur model. Research Report ML-87-25. Richards Medical Company, Memphis, Tennessee.
• Hilado, C.J. (1974) Glass reinforced epoxy systems. Technomic Publ., Westport Connecticut.
  
  

Experimental studies with composite femurs

• Cristofolini, L., Viceconti, M., Toni, A. and Giunti, A. Influence of thigh muscles on the axial strains in a proximal femur during early stance in gait. J Biomechanics 28:5:617-624, 1995.
• Ramer, M., Viceconti, M., Toni, A., Pipino, F. and Giunti, A. Biomechanical validation of a new nail-plate for the repair of stable proximal femoral fractures. Arch Orthop Trauma Surg 116:137-142, 1997.
• 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., Cappello, A., McNamara, B.P. and Viceconti, M. A minimal parametric model of the femur to describe axial elastic strain in response to loads. Med Eng Phys 18(6):502-514, 1996.
• Cristofolini L., Mcnamara B.P., Cappello A., Toni A., Giunti A. (1994) "A new protocol for stress shielding tests of hip prostheses", 2nd World Congress of Biomechanics, Amsterdam.
• Cristofolini L., Mcnamara B.P., Cappello A., Toni A. (1995) "Errors in stress-shielding evaluation of cementless hip stems". 15th I.S.B. Congress, Jyvaskyla, Finland.
• Harman M.K., Cristofolini L., Toni A., Viceconti M., Giunti A. (1994) "A reproducible in-vitro protocol for initial hip stem torsional stability", 2nd World Congress of Biomechanics, Amsterdam.
• 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): 163-171.
• 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.
• 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.

Studies with models of the composite femur

• 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 17, 131-140.
• 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., Viceconti M., Cristofolini L., Toni A., Taylor D. (in press) "Experimental and numerical pre-clinical evaluation relating to total hip arthroplasty", Recent Advances in Computer Methods in Biomechanics and Biomedical Engineering, Middleton J., Pande G.N., Williams K.R. Eds., Books & Journals International publ., Swansea.
• Mcnamara B.P., Cristofolini L., Toni A., Taylor D., Giunti A. (1994) "Stress shielding predicted using a composite material femur", 2nd World Congress of Biomechanics, Amsterdam.
• Mcnamara B.P., Cristofolini L., Toni A., Taylor D. (1994) "Effect of bone-prosthesis interface bonding on stress shielding in cementless THA", ASME Winter Annual Meeting, Chicago.
• McNamara B. P., Cristofolini L., Toni A. and Taylor D. Relationship between bone-prosthesis bonding and load transfer in total hip reconstruction. J.Biomechanics vol.30 N. 6, 1997, pp. 621-630.
• Viceconti, M., L. Bellingeri, et al. (1998). A comparative study on different methods of automatic mesh generation of human femur. Medical Engineering & Physics 20: 1-10.

Methodology studies used to create the New Standardized Femur

• Viceconti, M., C. Zannoni, et al. (1999). CT data sets surface extraction for biomechanical modelling of long bones. Computer Methods and Programs in Biomedicine 59: 159-166.
  
  
• Viceconti, M., C. Zannoni, et al. (1998). TRI2SOLID: an application of reverse engineering methods to the creation of CAD models of bone segments. Computer Methods and Programs in Biomedicine 56: 211-220.
  
  
• Viceconti, M., C. Zannoni, et al. (1998). CT-scan data acquisition to generate biomechanical models of bone structures. Computer Methods in Biomechanics & Biomedical Engineering - 2. J. Middleton, M. J. Jones and G. N. Pande. Amsterdam, Gordon & Breach: 279-288.

• Zannoni, C., A. Cappello, et al. (1998). Optimal CT scanning plan for long bone 3D reconstruction. IEEE Transactions on Medical Imaging 17(4): 663-666.

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Technical data

The following are some information on the physical object from which the standardized femur model has been derived. This is composite material femoral bone analogue designed to mimic the mechanical behaviour of a human femur under the action of external loads.


Manufacturer

Pacific Research Laboratories, Inc. (under the brand Sawbones)
P.O. Box 589
Vashon Island, WA 98070
Phone: **-1-206-463-5551
Fax: **-1-206-463-2526

Dealer in Europe

Sawbones Europe AB
Krossvergatan 3
S-21616 Malmo, Sweden
Phone: **-46-40-163040
Fax: **-46-40-164842

Materials

"Cortical bone": glass fibre reinforced epoxy
"Spongy bone": polyurethane foam.

Anatomies

There are two sizes available, both normally "left" femurs:

TYPE	Length (mm)	Canal Diameter (mm)	Model
Adult composite Femur	480	15.5	3106
Adolescent composite Femur	420	13.0	3103

Material properties (as reported by the manufacturer):

	Glass fibre/epoxy	Polyurethane foam
Compressive strength	not indicated	4.83 -13.8 MPa
Compressive modulus	not indicated	103 - 413 MPa
Tensile strength	172.2 MPa	3.44 - 10.3 MPa
Tensile modulus	18600 MPa	55.1 - 413 MPa
Flexural strength	275.6 MPa	5.51 - 17.2 MPa
Flexural modulus	14200 MPa	13.8 - 68.9 MPa
Poisson's ratio	0.3	not indicated
Hardness	Shore D 80	Shore D 45-55

Model history and Accuracy

std v1.0	This is the original SF model; it was based on parallel contours and had some major problems at the bifrucations which made it very difficult to manage.
fs329	This is the first version created by non-parallel contours; poor accuracy in the export function of our CAD made most of the surfaces unstitched.
std v2.0	This is the last public version; it has minor modifications toward a simplification of the surface patches (but with a larger error).
std v2.1	We finally got our new CAD: Unigraphics. This is the first SF model obtained under this program. Not distributed.
std v2.2	Re-partitioning of the solid to simplify mapped meshing
std v2.3	Currently available model; a few driving curves have been added to achive a better accuracy.

Each SF model is verified against a second set of 20 CT contours which has not been used to generate the model (off-plane accuracy); in a previous study we found these contours to be accurate to the pixel size (0.3 mm in this case). For each contour the solid model is sliced at the same level and the max. distance between the two contours is recorded. These are the results,, expressed in millimetres, for the mentioned models: