ultrasound measurements of achilles tendon in healthy and injured individuals

Ultrasound Evaluation of Achilles Tendon Morphology

The Achilles tendon originates at the myotendinous junctions of the gastrocnemius and soleus muscles and inserts on the posterior calcaneus. The Achilles tendon consists primarily of densely packed, organized collagen tissue arranged in a hierarchical fashion to maximize tensile strength1. Despite its ability to withstand heavy forces, the Achilles tendon is susceptible to several types of injuries throughout one&#39;s lifespan. These injuries, such as Achilles tendinopathy and Achilles tendon ruptures, are often accompanied by changes in the structure of the triceps surae and surrounding tissues. In Achilles tendinopathy, patients often exhibit fusiform tendon thickening, tendinosis, collagen disorganization, and neovascularization, a process of proliferation of vascular and neural tissue into the tendon2. Additionally, pathological changes associated with Achilles tendinopathy include paratendinitis, intratendinous, and/or entheseal calcifications, and bursitis2,3. After Achilles tendon ruptures, structural changes are common occurrences, irrespective of treatment, and include Achilles tendon thickening and increased tendon length4,5. Furthermore, muscular changes, such as triceps surae muscular atrophy, are also commonly associated with Achilles tendon injuries5,6.
The ability to assess triceps surae and surrounding tissue structures provides valuable insight into structural integrity, tissue quality, and size, which are known to relate to symptoms, function, and prognosis4,7,8,9. Ultrasound imaging is a reliable and valid assessment tool of these structures, including, but not limited to, Achilles tendon length10, thickness10,11, cross-sectional area (CSA)12, gastrocnemius anatomical CSA13, and neovascularization14,15. Assessment of these measures provides valuable insight into the understanding of healthy triceps surae tissue, as well as quantification of structural alterations to evaluate injury risk, severity, and recovery, as well as understanding healthy tissue qualities16.
Despite the clinical and research utility of ultrasound imaging in assessing triceps surae structure, there are often differences in imaging techniques and measurement parameters among clinical and research studies17,18. As a result, comparisons between studies are difficult. Therefore, the purpose of this methods paper is to describe a valid and reliable protocol for efficiently evaluating triceps surae muscle and tendon structure using musculoskeletal ultrasound imaging. This protocol aims to demonstrate the feasibility of incorporating this tool into research and clinical settings through its entirety or as specific parts in healthy and injured individuals. In addition, representative values for healthy and injured triceps surae are provided.

Author Spotlight: Exploring the Complexities of Achilles Tendon Injuries &#8212; Research and Future Directions

Measurement of Healthy and Injured Triceps Surae Morphology

Our research focuses on trying to understand the complexities of Achilles tendon injuries, specifically Achilles tendinopathy and achilles tendon ruptures. So we evaluate various domains of tendon health, such as pain and symptoms function, tendon structure, and psychological factors to kind of comprehensively identify individual differences in injured presentation and recovery. There is a current disconnect between those assessing structure and those assessing other measure of tendon health, such as symptoms and function.So with this protocol, in conjunction with additional evaluation methods to assess other tendon health domains, we'll provide a valuable insight into relationship between structure, function, symptoms, recovery of structure of after injury, and structural characteristics of health individuals and those with different injuries or comorbidities. The results from our lab and the use of ultrasound imaging methodology has really paved the way in recognizing the impacts of tendon elongation, the tendon healing longer after an achilles tendon rupture, and the important of minimizing this lengthening to optimize recovery. Additionally, the results have helped us really understand new scientific questions in the differences in recovery amongst patients with Achilles tendinopathy.

Ultrasound Measurements of Achilles Tendon in Healthy and Injured Individuals

Begin by performing ultrasound recordings before measurement. To measure gastrocnemius tendon length, open the longer extended field of view tendon image. Measure from the most proximal point of the tendon insertion.That is, the proximal calcaneal notch to the gastrocnemius myotendinous junction. Next, open the shorter extended field of view tendon image to measure the soleus tendon length. Measure from the proximal calcaneal notch to the soleus myotendinous junction.Then, measure from the proximal calcaneal notch to two centimeters, with the end of the measurement on the deep border of the tendon. Measure from this point to the direct superficial aspect of the tendon to get the two centimeter tendon thickness. In the case of achilles tendinopathy, if the tendon is thickened at this two centimeter distance, locate a healthy area in the free tendon and take this measurement from the proximal calcaneal notch.Next, visually identify the borders of the achilles tendon and outline the circumference of the tendon to measure the tendon cross-sectional area. At the center of the image, measure the achilles tendon from the superficial border to the deep border of the tendon to get the tendon thickness. Also, measure from the superficial border to the deep border of the soleus muscle to get the soleus thickness.Further, to measure the gastrocnemius cross-sectional area, visualize the borders of both the medial and lateral heads of the gastrocnemius and outline them. Demographics of the dataset showed that the individuals post achilles tendon rupture had a lesser proportion of females, whereas the individuals with achilles tendinopathy had an even distribution of males and females. Further, the age of healthy participants was lesser than those with achilles tendinopathy and achilles tendon rupture.Healthy participants showed an achilles tendon mean thickness of 0.47 centimeters and CSA of 0.58 centimeter squared. There were no significant differences between the limbs and achilles tendon length measures for healthy individuals. However, for individuals with achilles tendinopathy, thicker tendons with larger CSA were observed compared to asymptomatic limbs.Also, individuals post achilles tendon rupture showed achilles tendon elongation and larger achilles tendon CSA in the involved limb compared to the uninvolved limb.

Research

JoVE Journal

Medicine

Achilles tendon injuries occur throughout the lifespan and can negatively affect quality of life and overall health. Achilles tendinopathy is generally ...