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CHA PTE R

9

Computational Musculoskeletal Biomechanics

of the Knee Joint

Hafedh Marouane, Aboulfazl Shirazi-Adl, Masoud Sharifi
Division of Applied Mechanics, Department of Mechanical Engineering, Polytechnique, Montr eal, QC, Canada

9.1 INTRODUCTION

Due to large relative movements and a distal location in the body, human knee joints experience loads and move-
ments of substantial magnitude during various occupational, recreational, and regular daily living activities [1]. This
demanding mechanical environment exposes knee joints to a host of painful deformities, injuries, and degenerations
involving patellofemoral (PF) and/or tibiofemoral (TF) structures. With osteoarthritis (OA) as a painful and debilitat-
ing disease (present in 10% of the general population and >70% of those over age 65) that affects the knee more than
any other weight-bearing joint in the human body, total knee replacements approaching 1 million per year in the
United States alone, anterior cruciate ligament (ACL) damage as the most common sports injury with 100k new inci-
dents per year in the United States and 50% reconstruction rate, >500k per year arthroscopic partial meniscectomy in
the United States, and finally also millions of corrective/preventive osteotomy surgeries and biological repairs (tissue
engineering), the knee joint is in the spotlight in immediate need for more effective preventive and treatment programs
[2–7]. The situation is alarming due both to the dramatic increase in these interventions, especially in younger and
more active age groups that expect to remain active even after surgery, and to the ever-growing portion of the pop-
ulation with obesity and aging that are common OA risk factors.
An improved in-depth understanding of the biomechanics of the knee joint is therefore necessary for more efficient
design and management of preventive and treatment programs of these injuries. Due to inherent challenges in exper-
imental studies (in vivo and ex vivo) and the associated limitations, invasiveness, and burdens in time, effort, and cost,
computational approaches have long been recognized as reliable, important, and complementary methods in various
areas of biomechanics and biomedical engineering. The primary advantage of these numerical tools lies in robust con-
trol over boundary conditions, loading, geometry, and material properties allowing for the sensitivity and statistical
analyses in output measures as input parameters vary. Moreover, temporal and spatial variations in internal forces,
contact stresses/areas/centers, and tissue stresses/strains are invaluable outputs that are difficult, if not impossible, to
quantify in experimental investigations. In response, several finite element (FE) models with different degrees of pre-
cision and refinement have been developed [8–14]. Likewise, various musculoskeletal (MS) models of the lower
extremity have been constructed with the objective to further existing understanding of the knee joint functional bio-
mechanics in normal and disturbed conditions under more physiological load and movement conditions [15–24].
While former FE models provide valuable detailed information (i.e., tissue stresses and strains) in joint constituent
materials, latter MS models offer crucial results on activation patterns in musculature and resulting global joint loads
in complex physiological activities such as gait [25–27].
Following a simplified two-dimensional planar model of the knee by Yamaguchi et al. [28] that accounted for the
kinematics of both TF and PF joints in the sagittal plane, numerous models at different complexities have been intro-
duced toward more realistic and accurate simulations and results. Such developments have often involved complex
three-dimensional finite element models. In MS simulations, however, no such detailed knee joints are usually used.
Instead, the most common knee joint description is an idealized planar one that constrains the knee motion and kinetics

Advances in Biomechanics and Tissue Regeneration 181 © 2019 Elsevier Inc. All rights reserved.
https://doi.org/10.1016/B978-0-12-816390-0.00009-1