Tendinopathy is a localized tendon injury characterized by loss of normal collagen architecture, increased glycosaminoglycans, hypercellularity, neovascularization, and nerve ingrowth. Overuse (excessive loading) is considered the major causation factor. The Achilles tendon is the strongest tendon in the body but still often injured. In the adult population the incidence rate for Achilles tendinopathy is 2.5 per 1000. Mid-portion tendinopathy is the most common pathological condition in the Achilles tendon and represents between 55% and 65% of the Achilles tendon overuse injuries. The preferred treatment for tendinopathy is therapeutic exercise, which is believed to promote remodeling of the collagenous structure of the tendon. Tendon healing is highly affected by exercise dosage. The two extremes in exercise dosage (immobilization and overuse) have shown to be detrimental for tendon healing. This suggests there is an optimum exercise dosage to maximize function and tendon properties. However, quantifying the effect of treatment (i.e., exercise) is difficult due to the lack non-invasive cost-effective methods to quantify tendon composition, structure and remodeling. Currently, treatments are evaluated using clinical, functional and patient-reported outcomes which evaluate the range of motion of the foot, strength of the lower leg, and symptoms. However, a limitation of these outcomes is the lack of evaluation of tendon structure and mechanical properties. To overcome this limitation, we propose non- invasive measurements of viscoelastic properties, via ultrasound elastography, as an equivalent measurement of changes in composition, structure, and ultimately function of the tendon. We recently developed an ultrasound technique, named Continuous Shear Wave Elastography (cSWE), to measure local viscoelastic properties of tendons. This novel technique is safe, non-invasive, inexpensive, and offer two main advantages over commercially available methods: 1) the parameters can be tune to measure tissue with high stiffness such as the Achilles tendon, 2) the technique can be used to measure spatial variations (i.e. a map) of tendon viscoelastic properties. Therefore, this technique is suitable to evaluate localized lesions caused by tendinopathy, tears or ruptures. The objectives of the study are to quantify the effect of mid-portion tendinopathy on the viscoelastic properties of the Achilles tendon at the moment of diagnosis and during treatment and to explore possible correlations between viscoelastic properties and clinical/functional outcomes. This study will help establishing cSWE as a clinical technique that can potentially play an important role in optimizing a therapeutic exercise program and/or other treatments for tendinopathy to achieve faster return of function, preventing long-term deficits and re-injury, and minimizing the burden and cost to the health care system.
There is a lack of non-invasive cost-effective methods to quantify the effect of tendon injuries on their structural and mechanical properties. This study will evaluate the feasibility of using our novel ultrasound elastography technique to evaluate changes of tendon structural and mechanical properties due to tendinopathy. This technique can potentially play an important role in optimizing a therapeutic exercise program and/or other treatments for tendinopathy to achieve faster return of function, preventing long-term deficits and re-injury, and minimizing the burden and cost to the health care system.
