What is the diagnosis?

Lateral ankle sprain. Sometimes referred to as a “low ankle sprain” as opposed to a “high ankle sprain”. 

• Pearl: X-ray is negative for any fractures or dislocations. 

• Pearl: There are three ligaments in the lateral ankle ATFL (anterior talo-fibular ligament), CFL (calcaneo-fibular ligament), and PTFL (posterior talo-fibular ligament), these are injured in a reliable pattern of increasing severity of the injury ATFL > CFL > PTFL. 

What physical exam maneuvers can assist in your diagnosis?

Anterior Drawer: Evaluates for ATFL injury. Video of exam maneuver here. Remember to compare to the contralateral side as some people may have some minor laxity that is normal for them. Sensitivity: 0.36, Specificity: 0.43, LR+ 0.63, LR-: 1.5 [1]

Talar Tilt: Evaluates for CFL injury. Video of exam maneuver here.  Compare to the contralateral side and if there is increased pain or laxity this is a positive test. 

Squeeze test: Evaluates for syndesmotic injury (“high ankle sprain”). Video of exam maneuver here. Sens: 0.57, Spec: 0.14, LR+: 0.67, LR-: 3.0 [1]. 

What is the common injury mechanism?

For lateral ankle sprains the common mechanism is an inversion injury. Syndesmotic or high ankle sprains typically involve dorsiflexion and eversion. 

What is your management in the ED?

Management is dependent on the type and severity of sprain. See Pearl below for grading of ligamentous injuries.

For grade I and II: Ice, compression, relative rest. Early mobilization is important and will aid in recovery. In the ED you should counsel patients on this and recommend early mobilization with drawing the alphabet at least 3-4 times daily with their big toe. If patient’s are having difficulty ambulating, an ankle support and crutches are preferred though some patients may require a walking boot for a short period of time to function. 

For grade III: A short period of immobilization with walking boot, cast, crutches or combination (10 days or less) can improve outcomes in the short term [3]. 

• Pearl: Grading of ligamentous injuries or as follows: 

• I: No instability, able to weight bear with minimal pain

• II: Mild - moderate instability, painful to weight bear, some range of motion restriction and loss of function

• III: Significant instability, unable to weight bear, significant loss of range of motion and function

When does this patient need orthopedics?

Most patients with a lateral ankle sprain can be managed as an outpatient with their primary care provider or sports medicine physician. However, If there is concern for a “high ankle sprain” and there is laxity on exam, these patients could be considered to send to orthopedics for possible surgical intervention. 

• Pearl: Patients with an eversion injury need special attention taken to the proximal fibula as the force transmission can result in a Maisonneuve fracture.