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, who will provide a valuable insight into relationship between structure, function, symptoms, recovery of structure of after injury, and structural characteristics of healthy 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.

To begin, prepare for ultrasound imaging. Use B-mode ultrasound with a 5-centimeter linear array transducer. For visualization of the triceps surae, set the frequency to 10 megahertz and the depth of the measurement to 3.5 centimeters.

Adjust the foci between 0.75 and 1.75 centimeters with gain adjusted to 49 for optimal visualization of tissue. Place ultrasound gel on the posterior calcaneus. Holding the probe in the long axis, visualize the proximal calcaneal notch.

After aligning the notch with the midpoint of the ultrasound probe, mark this location on the skin. To determine the position for measurement of Achilles tendon thickness in healthy individuals, measure two centimeters proximal from the proximal calcaneal notch and mark this location on the skin. For individuals with Achilles Tendinopathy, visualize the thickest portion of the achilles tendon with the ultrasound probe on the long axis, and mark this location on the skin.

For individuals with Achilles Tendinopathy without visible fusiform thickening, palpate the tendon and locate the position of most pain. Mark the skin at this location. For individuals with Achilles tendon rupture, visualize the location of rupture with the ultrasound probe in the long axis and mark this location on the skin.

For the other limb, make the skin marking at the same distance from the proximal calcaneal notch as the involved limb. To measure gastrocnemius tendon length, hold the probe on the long axis. Using an extended field of view, begin the image at the calcaneus by visualizing the achilles tendon insertion.

Glide the probe approximately along the midline of the achilles tendon towards the mark at the gastrocnemius tendon midpoint until the myotendinous junction is seen. End the image here and take three images. Then measure the soleus tendon length using an extended field of view, beginning the image at the calcaneus by visualizing the Achilles tendon insertion.

Glide the probe approximately along the midline of the achilles tendon toward the mark at the soleus until the soleus myotendinous junction is visualized. Take three images of the Achilles free tendon length. Next, to measure achilles tendon thickness, place the probe on the long axis on the skin marking.

Use the B-mode view and take three images of Achilles tendon thickness. Measure Achilles tendon cross-sectional area. Place a gel standoff pad on the skin marking.

Holding the probe on the short axis, take three images of the achilles tendon cross-section. Further measure the soleus thickness by placing the probe on the long axis on the skin marking made for the soleus. Using B-mode view, visualize the anterior border of the soleus muscle and take three images for soleus thickness.

To distinguish between the soleus and flexor hallucis longus, ask the participant to actively flex and extend the great toe. Observe the movement of the fibers of the flexor hallucis longus and no movement in the soleus fibers. To measure the gastrocnemius cross-sectional area, hold the ultrasound probe on the short axis and in line with the mark for the gastrocnemius.

Visualize the medial border of the medial gastrocnemius and begin the image by gliding the probe from medial to lateral until the lateral border of the lateral gastrocnemius is visualized. To capture the most medial aspect of the medial gastrocnemius, ask the participant to abduct their legs and internally rotate the hip slightly. Using the B-mode view, observe the calcifications within the achilles tendon.

Calcifications are unattached from the calcaneus, and appear as hyperechoic areas with a shadow below present in multiple planes of view. Next, determine the presence of bursitis visualized by a hypoechoic area deep to the achilles tendon at the proximal calcaneus for retro calcaneal bursitis. To assess neovascularization within the achilles tendon, use the doppler setting on the ultrasound.

Position the doppler box on the tendon and hold the ultrasound probe still, avoiding pressing or descending the tissue. Scan the length of the Achilles free tendon being sure to assess each portion of the tendon without movement of the probe to prevent artifact. If there is vasculature visible within or in contact with the tendon, take three videos each for three seconds in the region with maximal blood flow.

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 squares.

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.