DOI
https://doi.org/10.25772/F36H-6W51
Author ORCID Identifier
https://orcid.org/0000-0002-0005-8734
Defense Date
2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Physical Therapy
First Advisor
Benjamin Darter
Abstract
Individuals with unilateral lower limb amputation (LLA) frequently experience intact limb knee pain, dysfunction, and osteoarthritis. These problems can worsen pre-existing reductions in mobility and quality of life that this population regularly experiences. It is widely accepted that knee joint loading is implicated in the development of knee joint issues, and intact limb knee joint load alterations are thought to be widespread in individuals with LLA. Prior work suggests that gait deviations frequently present in this population may be a contributory cause of these altered forces. These deviations can take many forms, but individuals with LLA commonly demonstrate alterations in step lengths and step length symmetry. Previous research has linked changes in these variables to knee joint loading in other populations, but this relationship has not been evaluated in this group. Step length and step length symmetry changes are frequently targets of rehabilitation for this population and therefore clinicians may be altering the intact limb knee joint dysfunction risk in patients unknowingly. Additionally, if this relationship does exist, it may present an accessible intervention to reduce the risk of knee dysfunction development and improve quality of life for individuals with LLA.
This dissertation aimed to understand the relationship between step lengths and step length symmetry with intact limb knee joint loading forces in individuals with a transtibial amputation. Prior to doing so, we performed an analysis to determine the number of gait cycles necessary to capture a representative measure of medial compartment tibiofemoral joint contact forces derived from muscle-driven musculoskeletal modeling and simulation (Chapter 2). These findings suggested at least 3 gait cycles were necessary to obtain a representative measure, and informed the procedures performed for the subsequent studies in Chapters 3 and 4. These results also have a broader application, as most studies examining joint contact forces do not provide a rationale for the number of movement cycles analyzed. This study provides a basis for future researchers to create experimental designs that assure enough data is captured to draw accurate conclusions.
Additionally, we examined the relationship between step lengths (Chapter 3) and step length symmetry (Chapter 4) on intact limb medial knee joint contact forces. We found that shortening and lengthening step lengths by approximately 15% during in vivo treadmill walking did have an impact on the force conducted by the knee joint, but the overall changes were relatively small (Chapter 3). It is currently unknown if these changes comprise a clinically meaningful difference in knee dysfunction risk and future research is required. Lastly, our results from Chapter 4 suggest that step length symmetry changes imposed by predictive simulations do not cause substantial changes in intact limb knee joint loading forces. While these results do represent conceivable strategies to change step lengths in individuals with LLA, it is unknown if individuals would pursue the same strategies when required to change step length symmetry in vivo. Future in vivo work is necessary to confirm these results. Taken together, these studies provide information to future researchers investigating knee joint contact forces in individuals with LLA and other populations, as well as highlight the potential impact that spatial gait parameters may have on the development of intact limb knee joint disorders in individuals with LLA.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-8-2024