Achilles Tendinopathy: Factors Affecting Recovery and Gait Biomechanics

Abstract

Achilles tendinopathy is a painful, debilitating injury causing afflicted individuals to reduce their activity level with substantial negative impacts on mobility, overall health, and quality of life. Despite being previously considered an athletic injury, up to 65% of the prevalence is not sports related. Progressive tendon loading exercise treatment is the standard first-line intervention for Achilles tendinopathy. However, even with the most effective exercise treatment, outcomes vary across individuals, with many experiencing lingering pain and functional impairments years after treatment. The purpose of this dissertation was to evaluate factors contributing to variability in recovery in patients with Achilles tendinopathy. Specifically, we aimed to evaluate the influence of metabolic risk factors on recovery of tendon health in patients with midportion Achilles tendinopathy and evaluate gait in patients with insertional Achilles tendinopathy. Metabolic risk factors, such as obesity and hypertension, increase the risk for developing tendinopathy and affect tendon structure, mechanical properties, and homeostasis. While older age and sedentary lifestyles have been shown to relate to negative outcomes with standard exercise treatment for Achilles tendinopathy, little is known about how metabolic risk factors affect tendon health recovery with traditional exercise treatment in patients with midportion Achilles tendinopathy. Given the relationship between metabolic risk factors and Achilles tendinopathy, this dissertation aimed to evaluate the effect of metabolic risk factors on recovery from Achilles tendinopathy with exercise treatment. Insertional Achilles tendinopathy is associated with worse outcomes when compared to midportion Achilles tendinopathy, perhaps related in part to mechanical compression of the Achilles tendon insertion in positions of dorsiflexion. Repetitive detrimental compression of the Achilles tendon insertion during walking may result in pain in those with insertional Achilles tendinopathy and affect the efficacy of traditional exercise treatment. In those that do not recover with exercise treatment, surgical management is next proposed to address the pathologic Achilles tendon structure and compression. Despite lingering pain with walking being a key factor in pursuing surgical treatment, little is known about how surgical treatment affects gait and comprehensive tendon health. This dissertation aimed to investigate ankle kinetic and kinematic gait patterns in individuals with insertional Achilles tendinopathy. Additionally, aim 3 of this dissertation aimed to explore structural, functional, and symptomatic recovery with insertional Achilles tendinopathy operative treatment. In aim 1, we found no differences in 1 year recovery trajectory with exercise treatment of any tendon health domain in individuals with midportion Achilles tendinopathy with and without the presence of metabolic risk factors. Individuals with multiple metabolic risk factors demonstrated worse symptoms, function, and physical activity than those with no metabolic risk factors which persisted across exercise treatment. However, significant improvements in symptoms and function were observed over time regardless of metabolic risk factor presence. Therefore, while exercise treatment appears to effectively improve tendon health regardless of presence of metabolic risk factors, additional treatment duration or adjuncts to treatment may be needed in those with multiple metabolic risk factors to facilitate complete symptomatic and functional recovery. In aim 2, we found that individuals with insertional Achilles tendinopathy did not walk with asymmetrical gait. However, worse symptom severity and worse Achilles tendon structure was associated with gait biomechanics. Further, changes in symptom severity were related to changes in gait biomechanics. These findings suggest gait plays an important role in individuals with insertional Achilles tendinopathy and consideration of strategies to address gait in this population may be warranted. In aim 3, we found that individuals with insertional Achilles tendinopathy recover from surgical management with increased Achilles tendon cross sectional area in addition to improved symptom severity and ability to participate in activities of daily living. Reduced plantarflexor performance was observed with changes in ankle kinetics and plantarflexor strength but no differences in gait speed or kinematics were observed from pre to post-surgery. Collectively, the results from this dissertation demonstrate that targeted adjunctive treatment strategies may be needed to address metabolic risk factors and gait in those with insertional Achilles tendinopathy, to facilitate complete tendon health recovery in all individuals with Achilles tendinopathy.