A 75-year-old male presented after injury involving the right ankle and midfoot. The patient reported pain on the dorsal foot in the navicular area, swelling, and difficulty walking for 10 minutes.
Ultrasound examination of the lateral ankle demonstrates a partial rupture of the anterior talofibular ligament. Part of the ligament is elongated and thickened, while another portion shows focal discontinuity of the normal fibrillar architecture, consistent with a partial tear.
The distal tibiofibular syndesmosis and calcaneofibular ligament are intact. The peroneus brevis tendon demonstrates normal continuity without evidence of tearing.
At the talonavicular joint, there is marked thickening and hypoechogenicity of the dorsal capsuloligamentous complex. These findings are consistent with a post-traumatic sprain and reactive capsuloligamentous change.
The individual ligamentous component primarily involved within the talonavicular complex cannot be identified with certainty on ultrasound. The pronounced talonavicular abnormality may represent the most clinically relevant finding, depending on the location of maximal pain and functional impairment.
1. Final diagnosis
Partial rupture of the anterior talofibular ligament, with elongation and reactive thickening of the remaining ligament fibres. Marked post-traumatic sprain of the dorsal capsuloligamentous complex of the talonavicular joint. The distal tibiofibular syndesmosis, calcaneofibular ligament and peroneus brevis tendon are intact.
2. Differential diagnosis
The talonavicular abnormality primarily represents a post-traumatic capsuloligamentous sprain. Differential considerations include a partial tear of an individual talonavicular ligament, reactive capsulitis or a small associated avulsion injury that is not reliably visible on ultrasound.
3. Teaching points
An ankle inversion injury may involve both the lateral ankle ligaments and the dorsal midfoot capsuloligamentous structures. Examination should therefore not be limited to the anterior talofibular ligament when pain or swelling extends towards the midfoot. Ultrasound can demonstrate capsuloligamentous thickening and fibre disruption, but it may not reliably distinguish every individual component of the talonavicular ligament complex or exclude a small osseous avulsion.
4. Injury/disease information
Initial management is generally functional and conservative, with temporary reduction of loading, bracing or taping, followed by progressive rehabilitation focusing on mobility, strength, proprioception and ankle stability. Clinical correlation should assess focal tenderness, swelling, weight-bearing ability and mechanical instability at both the lateral ankle and midfoot. Persistent midfoot pain, inability to bear weight, focal bony tenderness or inadequate recovery may warrant radiography. MRI may be considered when a more extensive capsuloligamentous injury, occult avulsion injury or osteochondral lesion is suspected.
Marc is founder of, and trainer at, SonoSkills. SonoSkills is an organization dedicated to MSK ultrasound education. He's also an MSK Sonographer at EchoConsult in Roermond, the Netherlands.
More Cases from Marc Schmitz
