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Squier, Kip

University of British Columbia

Background: Tendons - essential for skeletal movement and joint articulation - are characterized by high tensile strength and force transmission. Tendon health can be affected by local and systemic factors, which may impact injury risk. The objectives of this thesis were to investigate several under-researched local and systemic factors (i.e. hypercholesterolemia, mechanical stimulation, ovulation cycle) to explore their potential impact on tendons. The overarching hypothesis is that these factors induce functional alterations in tendons. Methods: We examined the effects of hypercholesterolemia on Achilles tendon mechanics and structure with dynamometry, gait analysis, and magnetic resonance imaging; explored the influence of the ovulation cycle on Achilles tendon stiffness with myotonometry; and systematically reviewed the impact of in vitro mechanical stimulation on tendon cell collagen synthesis. Results: No differences were observed in tendon mechanics between patients with hypercholesterolemia and control participants. Patients with hypercholesterolemia had increased tendon size and water content compared to controls. Sub-group analysis showed that patients with hypercholesterolemia and xanthoma had increased tendon dimensions, decreased Young’s modulus, and increased strain, compared to those without xanthoma. We found no change in tendon stiffness over the menstrual cycle in either ovulating or non-ovulating women, which was in contrast with the finding of significant increases in anterior tibial translation in ovulating women. The systematic review revealed an adaptive response of tendon fibroblasts with upregulated collagen in response to mechanical stimulation, with strain intensity and cycle number emerging as important influences on the magnitude of tendon cell adaptive responses. Conclusions: This thesis enhances understanding of tendon health by explaining the impact of several local and systemic factors on tendon mechanics and composition. The findings open new avenues for research – particularly in addressing the tendon alterations in hypercholesterolemia patients that have more severe signs of the disorder, where physical rehabilitation protocols could play a role.

Text

2025-02-11

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90355

Rehabilitation Sciences

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/