Modulation of Insertional Achilles Tendinopathy by Multiaxial Mechanical Strains
Collaborators: A. Samuel Flemister, M.D., Jeff Houck, P.T., Ph.D., John Ketz, M.D., Alayna Loiselle, Ph.D., Michael Richards, Ph.D., Tongtong Wu, M.D.
Insertional Achilles tendinopathy (IAT) is a debilitating disorder that responds poorly to conservative (non-surgical) therapies. An effective conservative treatment for this disease must target the fundamental causes of pathological tissue alterations and induce deformations that promote their reversal. Thus, the objective of this study is to elucidate the patterns of mechanical strain (i.e., deformation) that cause and reverse IAT in vitro, and determine how to induce these strain patterns in vivo during exercise-based physical therapy. This collaborative project brings together expertise in biomechanics (Buckley), ultrasound elastography (Richards), tendon molecular biology (Loiselle), surgical/clinical care for foot and ankle disorders (Flemister and Ketz) and physical therapy (Houck).
In our studies to date, we have used ex vivo materials testing to characterize IAT-associated mechanical changes (Bah et al., 2016) and ultrasound elastography to demonstrate that these changes are greatest in the deep tendon, where transverse compressive strain (compressive strain along the short-axis of the tendon) is highest due to contact with the heel bone (Chimenti et al., 2016; Chimenti et al., 2017). These findings motivate our central hypothesis that deformations with high ratios of transverse compressive strain to axial tensile strain (tensile strain along the long axis of the tendon) cause/sustain IAT while deformations with low strain ratios can reverse this disease. To test this hypothesis, our current studies are aimed at elucidating the patterns of mechanical strain that cause and reverse IAT in vitro and determining how to induce these strain patterns in vivo during exercise-based physical therapy. The results of this study will motivate effective, targeted non-surgical therapies for IAT.