Name: Mechanical Loading Protocol for an In Vivo Model of Overuse-Induced Tendinopathy
Uploaded: 2024-03-01T13:00:00
Description: Watch this Scientific Journal Video about Mechanical Loading Protocol for an In Vivo Model of Overuse-Induced Tendinopathy at JoVE.com

mechanical loading protocol for an in vivo model of overuse-induced tendinopathy

Cyclic Mechanical Loading for Inducing Tendinopathy in Rat Achilles Tendon

As tendons connect muscle to bone and experience daily repetitive motions throughout their lifetime, they are highly prone to overuse injuries that are painful and limiting and result in impaired mechanical function, affecting 30-50% of the population1. Tendinopathies are chronic conditions considered overuse injuries due to repetitive fatigue motions and inadequate healing to pre-injury levels. Both upper and lower extremities are commonly affected, including the rotator cuff, elbow, Achilles tendon, and patellar tendon2,3,4,5. Achilles tendinopathy is common in activities involving running and jumping, especially athletes involved in track and field, middle- and long-distance running, tennis, and other ball sports, affecting 7-9% of runners6,7. Injuries from running and jumping may also cause limited ankle dorsiflexion, which is a risk factor for Achilles and patellar tendinopathies8,9,10. Thus, there is a need for a better assessment and characterization of tendinopathy, which this study can provide as a rat model of passive ankle dorsiflexion for overuse Achilles tendon injuries.
Previous work using small animal models has been aimed at studying the development and markers of tendinopathy. These include treadmill exercise, repetitive reaching, direct tendon loading, collagenase injections, surgery, and in vitro studies11,12,13,14,15,16. Although the literature has benefited from the identification of damage markers from employing these tendinopathy models, limitations include loading the tendon in non-physiologically relevant joint motions, as in the case of direct loading of the tendon, not directly measuring applied loads, such as for treadmill studies, and not using physiological overuse, as in the case for collagenase injections, among others. To that end, this study aimed to develop a system that noninvasively applies quantified loads to the Achilles tendon with the application for overuse-induced tendinopathy studies to fill the gaps in previously developed small animal models for tendinopathy. We performed a pilot study to demonstrate that the system induces reproducible changes in mechanical properties over a range of loading cycles. This system enables physiologically relevant motion and loading to induce overuse while simultaneously quantifying and measuring the forces applied to and experienced by the tendon during the loading regimen.

Author Spotlight: Integrating Mechanical and Biological Analysis in Tendinopathy Research 

A Passive Ankle Dorsiflexion Testing System for an In Vivo Model of Overuse-induced Tendinopathy

Our work addresses the mechano biological factors involved in the initiation and progression of overuse induced tendinopathy. The questions we are trying to answer include what factors of exercise, such as frequency, magnitude, and duration of load affect the tendon's response to injury. Current tools such as mechanical measures, histology, and biological assays to evaluate outcome measures are centered and limited to end stage tissue harvesting.With this model, we can explore in vivo continuous measurements with tools such as ultrasound and MRI In the field, in vivo models load the tendon and physiologically relevant manners, while ex vivo models allow for the measurement of biological responses to injuries. Our protocol combines these two measures for direct measurement of tendon stresses and strains during injuries and the associated biological changes. We've established an adaptive system to induce tendon injuries, which allows for simultaneous exploration of mechanical and biological factors.Having established this model, future directions include assessing different parameters, therapeutic avenues, and rehabilitation measures.

Watch this Scientific Journal Video about Mechanical Loading Protocol for an In Vivo Model of Overuse-Induced Tendinopathy at JoVE.com

Mechanical Loading Protocol for an In Vivo Model of Overuse-Induced Tendinopathy  

Research

JoVE Journal

Bioengineering

Tendinopathy is a chronic tendon condition that results in pain and loss of function and is caused by repeated overload of the tendon and limited recovery ...