Biomedical Engineering Reference
In-Depth Information
and complex processes. This section does not intend to elaborate in detail on each
one of these processes but merely to illustrate and explain in general the pipeline
and concepts required to construct a model. Section
7.4
describes the importance of
in-vitro studies for musculoskeletal validation. Section
7.5
briefly overviews widely
used simulation softwares, while Sect.
7.6
provides a short overview describing some
of the most recent work on multi-body simulation with a focus on clinical applica-
tions. This section groups the research according to the modeling software used.
Section
7.7
presents an Illustrative case study of a state of the art multi-body simu-
lation study with focus on clinical application [
3
,
4
] performed at the Laboratory of
Biomechanics and Biomaterial of the Hannover School of Medicine (LBB-MHH,
Germany). Finally a brief conclusion is formulated in Sect.
7.8
.
7.2 Clinical Gait Analysis and 3D Motion Capture
Gait analysis is the study of human motion, more precisely the mechanical quan-
tification and assessment of walking and/or running. The knowledge obtained from
gait analyses provide the foundation to study a wide range of movements from hand
grasping to swallowing. In the case of clinical gait analysis, the aim is not only to
understand movement patterns but also to discern gait abnormalities and to assist
in treatment decision making and rehabilitation. Some of the more prevalent appli-
cations of clinical gait analysis is in studies related to cerebral palsy, orthopaedics,
physiotherapy, prosthetics, orthotics, motor control [
5
] and gait variability in neuro-
logical disorders [
6
-
8
].
Gait is cyclic and thus, divided into phases for better understanding and analysis
(Fig.
7.1
). Acomplete gait cycle is fromheel strike (when the heel touches the ground)
to the next heel strike of the same foot. This cycle is divided into phases known as
the stance phase and the swing phase. Stance phase starts with heel strike and ends
with toe off of the same foot (foot is in contact with the ground) and swing phase
starts with toe off and ends with heel strike (foot is in the air). Stance phase has been
divided into the following sub-phases: contact phase (heel strike until the first sign of
forefoot loading), mid-stance phase (first sign of forefoot loading until heel lift) and
propulsive phase (heel lift until toe off). Several muscles of the leg are responsible
for creating the gait cycle and maintaining balance during walking. Moreover, it is
presently known that foot, ankle and knee interactions, lateral pelvic tilt in the front
plane, pelvic rotation in the transverse plane and knee flexion at mid-stance interact
dynamically to obtain higher walking efficiency by displacing the center of mass
vertically and/or horizontally [
9
]. Consequently, the acquisition of kinematic and
kinetic data is fundamental to analyze walking. Kinematics describe the pattern and
temporal aspects of motion such as positions, angles, velocities, and accelerations of
body segments and joints during motion while kinetics refer to the study of forces
causing the motion of the body.
