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Date of Final Oral Examination (Defense)
Type of Culminating Activity
Thesis - Boise State University Access Only
Master of Science in Mechanical Engineering
Mechanical and Biomechanical Engineering
Trevor Lujan, Ph.D.
Gunes Uzer, Ph.D.
Clare K. Fitzpatrick, Ph.D.
Brian J. Jaques, Ph.D.
The knee meniscus is a soft fibrous tissue that is subjected to large and repetitive loading, and is frequently torn. Tears of the meniscus are painful and cause knee instability, which contributes to the development of osteoarthritis, an irreversible and debilitating condition. Meniscus tears commonly occur from single high-magnitude loads that disrupt the highly aligned fibrous network, with a higher incidence of meniscus tears occurring in older populations.
The objective of this study is to determine the effect of age and fiber alignment on the localized failure behavior of the lateral human knee meniscus during tensile loading. Testing consisted of a single quasi-static pull to failure while imaging with a high-speed camera. Digital image correlation was used to calculate the magnitude of the principal strains local to the failure initiation site, and the angle of the failure plane. Tests were performed on specimens from “young” and “aged” donors under 40 and over 65 years old, respectively, and loaded along or perpendicular to the preferred fiber axis.
Results showed that the local first principal strains at failure were two to three-fold greater than the clamp-to-clamp strains. Age of the donor tissue had no significant impact on any of the stresses, strains, or failure planes measured. Testing perpendicular and along the fibers had failure strains of 129% and 34% respectively, and failure plane angles of 20° and 44°, respectively. These results indicate that failures initiate in the ground substance when loaded along the fiber direction, as the failures occur closest to the plane of maximum shearing of the ground substance at 45°, rather than maximum axial elongation of the fibers.
For the first time, this study has measured the failure plane of the meniscus relative to the reinforcing fibers, and has measured the principal strains of the human lateral meniscus using a full field approach. This is also the first study to investigate the effect of age on the failure properties of the human lateral meniscus. Results from this experimental study can be used to develop and validate mathematical models that describe and predict meniscus failure, and thereby give insight into methods to treat and prevent this prevalent injury.
Nesbitt, Derek, "Effect of Age and Fiber Orientation on Localized Tensile Failure Behavior in Human Mensicus" (2018). Boise State University Theses and Dissertations. 1487.