To begin, prepare for ultrasound imaging. Use B-mode ultrasound with a five centimeter linear array transducer. For a visualization of the tricep 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 proximally along the midline of the Achilles tendon towards the mark at the gastrocnemius 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 proximally along the midline of the Achilles tendon toward the mark at the soleus until the soleus myotendinous is 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 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 hypoechoic 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 retrocalcaneal 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 distending 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.
