Biomedical Engineering Reference
In-Depth Information
bones that are effective to counter soft tissue artifacts, in motion capturing of actual
motion. However, bone-pin marker placement may affect an individual's gait as the
pin insertion is invasive and requires surgery. Hence, obtaining ethical clearance
poses the largest constraint for most countries [
42
]. Because of this, in vitro studies,
to this date, are the preferred method to gain reliable data as the advantages of in
vitro studies, in certain contexts, outweigh the limitations [
43
].
With the advancements of hydraulic motor-controlled test rigs and robotic tech-
nologies that allow six degrees of freedom, in vitro studies are advancing in parallel
to these technologies. Cadaveric studies using robotic technologies allow for the
investigation of kinematics bearing a simulated bodyweight or zero loading. Weight
bearing simulators are more commonly used for clinical research due to the influ-
ence of tendons and muscles in vivo. Simulation of the quadriceps and hamstrings
has shown to influence kinematic output such as flexion-extension of the tibia in
relation to the femur about the knee joint, in addition patella kinematics, contact area
and forces [
44
,
45
]. Additional advantages of in vitro studies include the possibility
to obtain data concerning contact forces and areas as well as investigate the role of
muscles and tendons around joint, where this is normally in conjunction with clinical
studies comparing pre and post operative surgeries [
46
,
47
].
7.5 Software for Human Gait Analysis and Simulation
In the last decade, musculoskeletal modeling software design and development have
flourished. Commercial software packages able to perform kinematic and dynamic
analysis of human musculoskeletal systems have been introduced and made avail-
able to researchers. Some of the first commercial software packages used for muscu-
loskeletal modeling are ADAMS (Mechanical Dynamics Inc., MI, USA), SDFAST
(Symbolic Dynamics Inc., CA, USA), DADS (LMS International, Leuven, Belgium)
and Working Model (MSC Software Corp., CA, USA) among others. These soft-
ware packages are still maintained and frequently used, but were known to have
limitations regarding musculotendinous force production, musculoskeletal moment
arms and the ability to generate realistic animations of the motion in musculoskeletal
systems [
48
]. Delp and coworkers [
49
] indicated that musculoskeletal models cre-
ated by different research groups were generally done with different programming
language and software platforms which constituted an obstacle to facilitate shar-
ing among the research community. Thus, the article suggested the need for more
specialized computer software packages able to shorten the time and simplify the
pipeline to build a musculoskeletal model and run simulations. This situation pro-
pelled the development of commercial software packages with the sole purpose of
musculoskeletal simulation such as SIMM (Software for Interactive Musculoskele-
tal Modeling, MusculoGraphics, Inc., CA, USA), Visual3-D (C-Motion, Inc., TN,
USA), AnyBody (AnyBody Technology, Aalborg, Denmark), VIMS (Virtual Inter-
active Musculoskeletal system, Engineering Animation Inc., IA, USA), LifeMOD
(LifeModeler, Inc., CA, USA) among others.
