Biomedical Engineering Reference
In-Depth Information
accurately for different kinds of joints whose movement can be modeled as rotation
(ball-and-socket joints such as hip joint and shoulder). In case the joint movement
contains some non-negligible translations (e.g. knee), the radial segmenting collision
detection method can still be used to return accurately the radial penetration depths
[
13
,
14
].
8.3 Using Virtual Penetration Depth for Hip Medical Diagnosis
8.3.1 Overview
In the past few years, femoroacetabular impingement (FAI) was recognized as the
leading pathomechanism leading to a significant number of so-called 'primary' hip
osteoarthritis [
19
,
20
]. It is defined by an early pathological contact between pri-
mary osseous prominences of the acetabulum and/or the femoral head-neck junction.
Depending on the underlying pathomorphology and its related pathomechanism, two
different types of FAI are distinguished: 'pincer' and 'cam' impingement. The pincer
type of FAI describes a linear contact between the acetabular rim and the femoral
head-neck junction. A cam impingement occurs when the femoral head-neck junc-
tion has an abnormally large radius. Diagnosis of FAI can prove to be difficult,
particularly in cases with subtle pathomorphologies and/or combined hip dysplasia
and FAI occurring in the same hip [
21
]. Several computer aided simulations for
three-dimensional analysis of hip pathologies have been presented before [
2
,
3
,
7
,
22
-
25
]. Most of these methods imply substantial drawbacks for use in daily clinical
practice or for research purposes. These limitations include mainly the neglect of
soft tissue structures (labrum, cartilage) or the inability to achieve a real-time sim-
ulation. Approaches based on finite element (FE) analysis can provide an excellent
evaluation of static hip problems such as developmental dysplasia of the hip [
23
-
26
].
However, having a better estimation of stresses for a dynamic pathomechanism such
as FAI is very time-consuming and not applicable for real time medical hip simula-
tions [
23
]. Finally, there is a lack of a fast method evaluating penetration depth of the
colliding soft and bony tissues in FAI, and which has been correlated with available
biomechanical simulation data [
13
,
15
].
Arbabi et al. introduced a computer-assisted method for real-time evaluation of
FAI based on virtual penetration depth for the colliding tissues including soft tissue
structures [
15
]. Analogous to the pincer type of FAI, the 'curvilinear' penetration
occurs in the angular direction, which is tangential to the rotational trajectory. By
applying cylindrical segmenting collision detection method proposed Arbabi et al.
[
14
] (see Sect.
8.2.2
),the curvilinear penetration depth during hip movement can be
calculated. Also, analogous to the cam type of FAI, the 'radial' penetration takes place
in the radial direction. By using the radial partitioning collision detection method
proposed by Arbabi et al. (see Sect.
8.2.3
), the radial penetration depth during hip
movement can be calculated too [
14
].
