ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

each simulation and the position of the most stressed area in the transverse section of
the left rod (distribution of stresses was found to be symmetrical between left and right
rod in each simulation but torsion and lateral bending, position convention is reported
in Figure 3).
S1
S2
M1
M2
M3
only F Moment (10Nm)
F1
(2000N)
F2
(500N)
Flex. Ext.
Lat. Bend.
(Right)
VM 493.8 117 .5
pos. in
transv.
plane
L
A
P
M
L
A
P
VM 2420 .1 593.3 236.0 245.4
pos. in
transv.
plane
L
A
P
M
L
A
P
M
M
L
Torsion
(C-clock)
- - - -
A
P
VM 479 124 70 49 68 95
pos. in
transv.
plane
L
A
P
M
L
A
P
M
L
A
P
VM 2306 576 242.9 380 80 290
pos. in
transv.
plane
L
A
P
M
VM 190 47.5 23.5
pos. in
transv.
plane
5. DISCUSSION
L
A
P
M
L
L
A
P
A
P
M
M
L
L
A
P
A
P
Table 2
M
M
M
L
L
L
A
P
A
P
A
P
M
M
M
L
L
-
A
P
A
P
M
M
L
L
L
265
- - -
The first goal of this work was to compare the ISO and ASTM standards, eventually
finding a load to be applied during procedure according to ASTM configuration that
permits to obtain the same state of stress as ISO configuration (this could be useful for
manufacturers in order to compare the mechanical behavior of different constructs
tested according to different procedures). The second target was to compare the state of
stress in the fixator during the experimental procedure to the one expected when
implanted in a lumbar spine, here represented by a FE model which is less simplified as
concerning both boundary conditions (bone, ligaments and discs are present) and
typologies of load (not only axial load but also other loads representative of daily
activities).
From the analysis of the results (Table 2) some conclusions can be drawn:
M
A
P
A
P
A
P
M
M
M