dynamic ultrasound for ankle stability cover

Dynamic Ultrasound for Assessing Ankle Stability

Lateral ankle injuries are commonly seen in sports. Isolated fractures of the distal fibula are seen when the ankle experiences a supination and external rotation injury (1)

Supination-external rotation of the ankle (2)

Concurrent injury of the deltoid ligament can lead to the development of ankle instability (1). The deltoid ligament is composed of the superficial deltoid, which prevents talar abduction and hindfoot eversion, and the deep deltoid, which prevents external rotation and lateral talar shift (1).

Deltoid ligament (2)

Providers will typically assess for ankle stability with radiographs (1). Standard weight bearing views and  manual stress views can be used to measure for medial clear space widening (1). However, these views are sometimes difficult to assess due to the patient’s pain level after an acute injury. In-office point-of-care ultrasound has been studied to evaluate for dynamic instability.

A study published in the American Academy of Orthopaedic Surgeons assessed the use of ultrasound to assess for medial clear space widening (1). They used a linear probe and assessed the medical clear space with the patient in lateral decubitus position (1). The measurement was made first with the foot being held in dorsiflexion and then plantarflexion (1). Then, the foot was allowed to fall with gravity and the measurement was made again (1).

Visualization of medial clear space testing (1)

A study published in Foot & Ankle International looked for deltoid ligament disruption as a surrogate for ankle stability with ultrasound (3). A typical deltoid ligament was measured with the patient in the lateral decubitus position and the ankle placed on a soft bump (3). The deltoid ligament in an uninjured ankle measured 4 to mm in diameter (3). Providers evaluated for loss of continuity of the tendon (3). 

Image on the left shows intact deltoid ligament and image on the right is disrupted deltoid ligament (3)

A second study evaluated the deltoid ligament for disruption as well. They discriminated between the superficial and deep deltoid fibers on their ultrasound evaluation (7). They found that the medial clear space widening measured 5.2mm on average in patients with a partial tear of the deltoid ligament (7). In patients who were found to have complete tears, the medial clear space radiographs showed a widening of 9.9mm (7).

Superficial and deep deltoid fibers (7)

A cadaver study evaluated for tearing of the anterior inferior tibiofibular ligament (AITFL) by measuring the tibiofibular clear space to assess for syndesmotic widening. Syndesmosis injury leads to syndesmosis instability (4). They found that the AITFL can maintain ankle stability even if fibers are partially torn (4). A linear probe is typically used and the patient can be placed in the supine position and the ankle neutral (6). The ankle is then measured again with a maximum force externally rotating the ankle (6). The typical anterior tibiofibular clear space distance is 4mm (6).

Ultrasound image of tibiofibular clear space (4)

Ultrasound evaluation can also assess for anterior talofibular ligament tear as another marker of ankle laxity (5). 

Assessing for ankle stability is an important part of the decision making process when deciding upon surgical verse nonsurgical treatment of an ankle fracture (3). Evaluating for ankle stability is performed with standard weight bearing radiographs, manual stress view radiographs, and ultrasound evaluation. This review looked at how to perform an ultrasound evaluation for ankle stability. 

By Gregory Rubin, DO

– More Ankle Pain @ Wiki Sports Medicinehttps://wikism.org/Ankle_Pain_Main

– More Ankle Pain @ Sports Med Review: https://www.sportsmedreview.com/by-joint/ankle/


1)      Saengsin, Jirawat, et al. “Medial Ankle Stability Evaluation With Dynamic Ultrasound: Establishing Natural Variations in the Healthy Cohort.” The Journal of the American Academy of Orthopaedic Surgeons, vol. 29, no. 16, Aug. 2021, pp. 703–13. PubMed, https://doi.org/10.5435/JAAOS-D-20-00597.

2)      Grushky, Alexander D., et al. “Traumatic Injuries of the Foot and Ankle.” Seminars in Roentgenology, vol. 56, no. 1, Jan. 2021, pp. 47–69. PubMed, https://doi.org/10.1053/j.ro.2020.09.003.

3)      Chen, Pei-Yu, et al. “Ultrasonographic Examination of the Deltoid Ligament in Bimalleolar Equivalent Fractures.” Foot & Ankle International, vol. 29, no. 9, Sept. 2008, pp. 883–86. PubMed, https://doi.org/10.3113/FAI.2008.0883.

4)      Fisher, Cara L., et al. “Diagnostic Capability of Dynamic Ultrasound Evaluation of Supination-External Rotation Ankle Injuries: A Cadaveric Study.” BMC Musculoskeletal Disorders, vol. 20, no. 1, Oct. 2019, p. 502. PubMed, https://doi.org/10.1186/s12891-019-2899-z.

5)      Lee, Kyung Tai, et al. “New Method of Diagnosis for Chronic Ankle Instability: Comparison of Manual Anterior Drawer Test, Stress Radiography and Stress Ultrasound.” Knee Surgery, Sports Traumatology, Arthroscopy: Official Journal of the ESSKA, vol. 22, no. 7, July 2014, pp. 1701–07. PubMed, https://doi.org/10.1007/s00167-013-2690-x.

6)      Hagemeijer, N. C., et al. “Diagnosing Syndesmotic Instability with Dynamic Ultrasound – Establishing the Natural Variations in Normal Motion.” Injury, vol. 51, no. 11, Nov. 2020, pp. 2703–09. PubMed, https://doi.org/10.1016/j.injury.2020.07.060.


7)      Rosa, Isabel, et al. “Ultrasonographic Assessment of Deltoid Ligament Integrity in Ankle Fractures.” Foot & Ankle International, vol. 41, no. 2, Feb. 2020, pp. 147–53. PubMed, https://doi.org/10.1177/1071100719882679.