image of the old Vs the new

THE
STANDARDIZED FEMUR PROGRAM
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What is New?

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:

What is the Muscle Standardized Femur?





Related Publications


Base Biblio Reference

Validation works on composite femurs and related material

Experimental studies with composite femurs

Studies with models of the composite femur


Methodology studies used to create the New Standardized Femur





Technical data

composite femur (from sawbones catalog)

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:

 

std v1.0

fs329

std v2.0

std v2.1

std v2.2

std v2.3

RMSE

2.18

1.08

1.22

1.92

1.13

1.09

e90%

3.18

1.41

1.55

1.47

1.41

1.47

max error

5.14

3.21

3.85

3.58

3.41

2.73