Epidemiology/Importance: Suspect this injury with mechanisms including dorsiflexion and external rotation (eg. football, basketball, rugby, hockey, skiing, etc.) . This injury is much more likely to create long term instability .
Symptoms: Patient may have inability to walk or have anterior ankle pain.
Physical Exam: External rotation test: pain with slight dorsiflexion and external rotation. Positive tib/fib “Squeeze Test.” Talar Tilt Test: > 3 mm on Talar Tilt. Ability to hop on affected foot, lack of pain at syndesmosis, and negative external rotation tests are highly sensitive for ruling out syndesmosis injury .
Diagnostic Imaging: Look for > 5 mm increase in medial clear space or > 6 mm widening of tibiofibular space. Of note, plain films may only detect up 50% on AP and 66% on Mortise Views .
Treatment: Boot immobilization and non weight-bearing until follow up with orthopedics or sports medicine in 1 week.
Figure 2: High ankle sprain. Note the widened tibiofibular clear space. Case courtesy of RMH Core Conditions, Radiopaedia.org