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Graduate Defense: Derek Nesbitt

May 1 @ 9:00 am - 11:00 am MDT

square graphic which says "Dissertation Defense"Dissertation Information

Title: Effect of Age on the Mechanical Behavior and Molecular Structure of Human Meniscus

Program: Doctor of Philosophy in Biomedical Engineering

Advisor: Dr. Trevor Lujan, Mechanical and Biomedical Engineering

Committee Members: Dr. Clare Fitzpatrick, Mechanical and Biomedical Engineering; Dr. Gunes Uzer, Mechanical and Biomedical Engineering; Dr. Julia Oxford, Biological Sciences; and Dr. Tracye Lawyer, Biomedical Engineering


The meniscus becomes more susceptible to injury in older populations, and how the mechanical properties change with age are poorly understood. In order to quantify changes with age, we performed uniaxial tensile tests on human menisci under 40 and over 65 years old, showing older donor groups had reduced strength and toughness. We refined the data analysis into a fast, free web application to standardize data analysis in soft tissue tensile testing. We then used the mechanical testing data to build and validate a finite element model of tissue failures with continuum damage mechanics. This work fit experimental data well, and mimicked failure behavior. Finally, we performed biochemical analysis to evaluate structure-function relationships with age, showing changes to collagen crosslinks correlated to changes in tissue strength. Collectively, this work detailed why aging meniscus becomes more susceptible to tears, and provided tools to further analyze failures in soft tissues.