Understanding the Impact of Muscle and Bony Injury in the Lumbar Spine - How Multifidus Muscle and Facet Joint Damage Impact Muscle Architecture and Joint Degeneration in the Rat

Rodent models that experience a mechanical injury to the facet joint have had contradicting results regarding the degree of osteoarthritis that the injured joint experiences. This thesis sought to answer if this disagreement was caused by surgical injury to the paraspinal multifidus muscle. It was expected that muscle and joint injury would drive changes in the muscle architecture, collagen content, facet joint transverse plane angle and characteristics of osteoarthritis. No consistent changes in any muscle measures were seen outside of the injured multifidus muscle, which had a decrease in mass and fascicle length while the collagen content increased. No changes in the facet joint angles or osteoarthritis statuses were seen. It is suspected that the degree of fibrosis for the injured muscle may have inhibited osteoarthritis processes. Future work should explore the role of paraspinal muscles in facet joint osteoarthritis using nonsurgical models. Ontario Government via the Ontario Graduate Scholarship, The National Science and Engineering Research Committee 2021-12-14