Ankle sprains are the most common musculoskeletal injury. After an ankle sprain, about 40% of individuals develop Chronic Ankle Instability (CAI), resulting in recurrent sprains, the ankle giving way, or feelings of instability. Most sprains occur due to excess inversion of the ankle. Frontal-plane ankle stiffness quantifies the ankle’s ability to resist an imposed motion. My thesis explores frontal-plane ankle stiffness under conditions that allow me to isolate the contributions of axial loads on the joint, a mechanism typically overlooked during clinical examinations of the ankle, but relevant as sprains tend to occur under high axial loading, such as while running or landing. First, I first demonstrate that loading significantly affects ankle stiffness and that this effect is independent from muscle activation. Not only do sprains happen under loaded conditions, but they are thought to be more common in specific postures. I then demonstrate that plantarflexed and inverted postures have significantly smaller effects of load compared to other postures, but only when loading occurs with an increase in muscle activity. The overall load-dependency of stiffness is consistent with cadaver studies, which suggest this to arise from the ankle’s articular surfaces. CAI is associated with articular surface abnormalities. I demonstrate that individuals with CAI do not have an altered effect of load on stiffness. Additionally, I found no differences in articular surface morphology. The effect of load on stiffness is not associated with characteristics of articular surface morphology, suggesting that altered articular surface morphology is not a deficit in CAI and does not affect their ability to resist a sprain under passive load. Together, this work provides an in-depth investigation on how axial loading can alter the ankle’s ability to resist a sprain, providing insight on a possible impairment in CAI.

Creator

• Villamar, Zoe Dahlia

DOI

• https://doi.org/10.21985/n2-ttm5-v762

Subject

• Biomedical engineering
• Biomechanics

Language

• en

Alternate Identifier

• http://dissertations.umi.com/northwestern:16668
• etdadmin_upload_1002685

Date created

• 2023-01-01

Resource type

• Dissertation

Rights statement

• In Copyright