MICROSCOPIC CONSTITUENTS AND THEIR MECHANICAL CONTRIBUTIONS IN LIGAMENT by Heath

The knee is a diarthrodial joint whose primary function is to provide a wide range of motion while supporting potentially large loads during locomotion. To perform this task over a lifetime, the joint must be stabilized to prevent abnormal motion. Ligaments within the joint capsule span from bone to bone to limit the amount of relative motion between articulating surfaces. Injuries to these ligaments result in altered gait and may eventually lead to degenerative disorders such as osteoarthritis. Much work has been done to understand the results of injury and the interactive effects of the ligaments in the whole joint structure, but the microscopic organization and molecular constituents within ligaments may also provide insight into how these tissues respond to daily or extreme loading conditions. The goal of this dissertation was to build on existing scientific knowledge and investigate the micro-macro scale interrelationships that occur within the medial collateral ligament (MCL). The MCL is a model tissue in that it is hierarchically organized, amenable to experimental analysis and provides a standard from which more complex ligament structures may be studied. The primary building block of ligament is Type I collagen, but a significant molecular constituent of MCL is the sulfated glycosaminoglycan (GAG). GAGs have been linked to tissue organization and maintenance and have been proposed to directly contribute to the mechanical response of their host tissues, though conflicting reports exist in the literature.