Biomedical Engineering Reference
In-Depth Information
Fig. 8.4 a
Normal joint,
b
pincer joint,
c
dysplastic joint,
d
cam type joint [
13
,
15
,
23
]; (Image
courtesy of Salman Chegini, ARTORG, University of Bern) (With kind permission from Wiley:
Journal of Orthopaedic Research, Penetration depthmethod—novel real-time strategy for evaluating
femoroacetabular impingement, Vol. 28, 2010, pp. 880-886, Arbabi E, Chegini S, Boulic R, Tannast
M, Ferguson S J, Thalmann D, Figs. 3 and 6)
8.3.2 Hip Models
The morphology of the human hip can be described by various selected anatomical
and radiographical parameters [
27
]. For simplicity and comparability, only two
important parameters were chosen to quantify acetabular and femoral pathomor-
phologies: the lateral center-edge (CE) angle of Wiberg [
28
], and the
α
angle of Nöt-
zli [
29
], respectively. The hip models were prepared by Salman Chegini at ARTORG,
University of Bern, by using CAD software.
1
These models included acetabular and
femoral bone, articular cartilage, the labrum and the chondrolabral transition zone. In
order to create a wide range of hip geometries, a consecutive series of
and CE angles
were chosen for evaluation, covering normal and pathological joint morphologies.
The CE angle values ranged from 0
◦
to 40
◦
,α
α
angles ranged from 40
◦
to 80
◦
. Incre-
mentsof10
◦
were selected for both parameters, resulting in a total of 25 different
joints for evaluation, e.g. normal (CE
20
◦
,α
=
40
◦
), cam (CE
20
◦
,α
=
80
◦
),
=
=
40
◦
,α
=
40
◦
), combined FAI (CE
40
◦
,α
=
80
◦
), dysplas-
pincer (CE
=
=
0
◦
,α
=
40
◦
), or combined dysplastic and impinging morphologies
tic (CE
=
0
◦
,α
=
80
◦
) (Fig.
8.4
)[
23
].
(CE
=
8.3.3 Simulation
The hipmodels were simulated during standing-to-sittingmovement. Known average
in-vivo load and motion data for standing-to-sitting were used for evaluation [
30
].
The total motion for standing-to-sitting was divided into 30 equal and consecutive
sub-motions. All of the penetrating vertices were found, and both curvilinear and
radial penetration depths as well as the von Mises stresses were calculated in each
sub-motion.
1
Solidworks 2005, Solidworks Corp., Boston, MA, USA.
