Ultrasound techniques for ankle joints

When performing an ultrasound examination of the ankle joint, a certain sequence of actions should be followed and standard positions should be sought. According to the anatomical regions, four standard approaches are used to examine all elements of the joint: anterior, medial, lateral and posterior.

Anterior approach.

This approach provides visualization of the tendons of the anterior tibialis muscle, the long extensor of the thumb and the long extensor of the fingers, as well as the synovial sheaths of the tendons of the anterior group. The patient is in a supine position, the limb is flexed, the sensor is installed in the lower third of the shin.

The examination begins with an assessment of the condition of the tendons of the anterior tibial muscle and the long extensor of the thumb. Proximally upward, the structure of the muscle tissue is studied, and longitudinal and transverse sections of these muscles of the lower leg are obtained.

Continuing further distally, an image is obtained of the tendon of the long extensor of the fingers, which is fan-shaped and divided into four parts and attached to the tendon extension on the back of the II-V fingers.

Medial approach.

This approach allows visualization of the posterior tibial, flexor digitorum longus, and flexor pollicis longus tendons, as well as the synovial sheaths of the medial group tendons, the deltoid ligament, and the posterior tibial nerve.

The patient is in a supine position with the limb straightened. The sensor is placed on the medial surface of the joint, immediately behind the medial malleolus. First in a transverse position for orientation, and then in a longitudinal position. All the described tendons lie side by side in the same plane. The diameter of the tendon of the long flexor of the fingers is two-thirds smaller than the diameter of the tendon of the posterior tibial muscle, which is located anteriorly. During scanning, the structure of the tendons, thickness, contours, condition of the hyaline cartilage, and the presence of effusion in the joint cavity are assessed. The tendons of the posterior tibial muscle, long flexor of the fingers, long flexor of the hallucis longus, and the tibial nerve located between the last two tendons are covered from above by a broad ligament - the flexor tendon retinaculum. The posterior tibial nerve is pinched in the tarsal tunnel on the medial surface of the malleolus. The transducer is then positioned over the medial malleolus to assess the medial ligament group of the ankle joint. The shin is rotated outward to improve visualization of the ligament. The fibers of the tibionavicular portion of the deltoid ligament are visible over the medial malleolus, attaching to the dorsal surface of the navicular bone.

Lateral approach.

This approach allows visualization of the peroneus longus tendon, the peroneus brevis tendon and their synovial sheaths, the anterior talofibular ligament, the calcaneofibular ligament, the anterior tibiofibular ligament and the lateral compartment of the joint.

The patient is in a supine position, the limb is straightened, rotated inwards. The sensor is installed on the lateral surface of the joint, behind the lateral malleolus. The tendons of the long and short peroneus muscles are clearly visualized. The tendon of the short peroneus muscle is located in front of the others. Normally, a small amount of fluid, up to 3 mm thick, may be present in the tendon sheath. When the sensor is rotated downwards, fibers of the calcaneofibular ligament are determined, which starts from the outer surface of the lateral malleolus and is directed downwards to the lateral surface of the calcaneus. When the lower edge of the sensor is rotated, fibers of the anterior talofibular ligament are determined. To visualize the anterior tibiofibular ligament, the sensor is installed on the lateral surface of the joint in a transverse position - between the distal parts of the tibia and fibula.

Rear access.

With this approach, the Achilles tendon fibers and retrocalcaneal bursa are visualized, the cortical layer of the calcaneus and the condition of the plantar aponeurosis are assessed. The patient is in a prone position with the foot hanging freely. The sensor is positioned longitudinally to the long axis of the Achilles tendon fibers. Scanning begins from the point where the soleus and gastrocnemius muscles transition into the tendon and gradually moves to the point of attachment of the tendon on the calcaneus. At this point, the retrocalcaneal bursa is usually visualized; its diameter should not exceed 2.5 mm. The Achilles tendon does not have a synovial membrane and hyperechoic lines - paratenon - are visible along its edges during ultrasound scanning. It is necessary to obtain both longitudinal and transverse sections.

The average anteroposterior diameter of the tendon during transverse scanning is 5-6 mm. It is important to remember that in case of Achilles tendon ruptures, it is necessary to conduct a functional test, which consists of assessing the condition of the rupture site during flexion and extension of the foot. If in both of these positions there is a divergence of torn fibers (diastasis), then surgical treatment is necessary, if not, then conservative.

According to the indications, the plantar region of the foot is examined. The structure and attachment area of the plantar tendon are assessed. The sensor is installed in the area of the calcaneal tubercle and scanned longitudinally along the course of the tendon fibers. Longitudinal and transverse sections of the tendon are obtained.

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