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Table 1 The material properties

From: Where should Kirschner wires be placed when fixing patella fracture with modified tension-band wiring? A finite element analysis

Parts

Specification

Element size

Material properties

Patella

40.1 mm in height, 44.5 mm in width, 19.1 mm in thickness, patellar ridge ratio 6:5

C3D4, 0.8 mm (0.4 mm in K-wires tunnels)

Based on the gray value distribution of distal femur*, elastic modulus 5–16.3 GPa, Poisson’s ratio 0.3

K-wire

2 mm in diameter

C3D4, 0.4 mm

Elastic modulus 200 GPa, Poisson’s ratio 0.3

SS-wire

1 mm in diameter

C3D4, 0.2 mm

Femur

Larger than patellofemoral facet

C3D4, 2 mm

Rigid body

Cartilage

3 mm in thickness, cover femur side only

C3D4, 1 mm

Elastic modulus 7 MPa, Poisson’s ratio 0.47

  1. *The empirical expressions: density = − 13.4 + 1017 × HU, elastic modulus = − 388.8 × 5925 × density. We used the expressions for femur because that for patella was not well validated