Do distal fibula fracture ankle X-rays (X-radiographs) require a gravity stress view?

Gravity Stress Views for Distal Fibula Fractures

Gravity stress views should be obtained for isolated distal fibula fractures when standard radiographs show a medial clear space <6 mm, as they reliably identify deltoid ligament disruption and ankle instability that would require surgical intervention. 1

When to Order Gravity Stress Views

Gravity stress radiographs are specifically indicated for supination-external rotation injuries of the ankle where there is concern for deltoid ligament disruption 2. These views are:

• More reliable and easier to perform than manual stress views for evaluating supination-external rotation injuries 2, 1
• Particularly useful when standard mortise views show a medial clear space <6 mm but clinical suspicion for instability remains 3
• Equivalent to manual stress radiographs in detecting deltoid ligament injury (no statistical difference in medial clear space measurements between the two methods) 4

Interpreting Gravity Stress Views

A difference of >2 mm between standard mortise and gravity stress views indicates instability requiring surgical consideration 1. More specifically:

• Medial clear space ≥6 mm on gravity stress view has 100% positive predictive value and 100% negative predictive value for deep deltoid ligament rupture 5
• A medial clear space ≥ superior clear space + 3 mm on gravity stress shows 100% specificity for deltoid ligament injury 3
• Ankle position (neutral vs plantarflexion) does not affect the clinical effectiveness of gravity stress radiographs 5

Clinical Decision Algorithm

For isolated distal fibula fractures, proceed as follows:

1. Obtain standard three-view radiographs (AP, lateral, mortise) initially 2
2. Assess for high-risk features: medial tenderness, bruising or swelling, fibular fracture above the syndesmosis, or high-energy mechanism 2, 1
3. If medial clear space <6 mm on standard views AND clinical concern for instability exists, obtain gravity stress views 3
4. Weight-bearing radiographs (if patient can tolerate) provide additional stability information, though gravity stress views are easier to perform 2, 1

Key Clinical Pitfalls

• Do not rely solely on standard radiographs in supination-external rotation injuries, as up to 28% may have occult deltoid ligament tears despite normal-appearing medial clear space 3
• Gravity stress views can exclude deltoid injury with high specificity (100%) but have low sensitivity (6%), meaning a negative test reliably rules out instability 3
• All isolated fibular fractures with widened medial clear space on stress views have at least two major ligament group injuries, most commonly involving the anterior inferior tibiofibular ligament and deltoid complex 6