Tendon tension increases during gait following Achilles tendon injuries.

Abstract

Patients with Achilles tendinopathy and Achilles tendon rupture experience functional challenges during and beyond rehabilitation. The objective of this study was to combine advanced methods including shear wave tensiometry and ultrasound imaging to assess symptoms and tendon loading during gait to better understand the root cause of these injury-specific impacts. 15 individuals (five with Achilles tendinopathy, five with a previous Achilles tendon rupture, five uninjured) participated. Patient reported outcome measures were used to assess injury severity, pain, function, and activity level. Ultrasound imaging was performed to measure tendon thickness and length. Shear wave tensiometry was used to assess dynamic tendon loading during treadmill walking at a self-selected and 20% increased speed. Participants in both injury groups exhibited significantly increased tendon loading during gait, with 1.25-fold to 2-fold greater tendon load in the affected limb in rupture and tendinopathy groups, respectively. These changes were paired with increased pain in the tendinopathy group, increased tendon thickness in the rupture group, and worse patient reported metrics in both. The results of this study show long term gait asymmetries in individuals with Achilles tendinopathy and Achilles tendon rupture. In tendinopathy, the increased shear wave speeds may not be due to an increased muscle load but rather increased passive dorsiflexion (and as such, increased tendon stretch) with a calf-avoidance gait. In the rupture group, tendon lengthening likely has been associated with increased calf muscle activation which can result in increased tendon shear wave speeds.