Lateral Ankle Ligament Injuries

A lateral ankle ligament injury is a sprain of the lateral ligament complex, usually from an inversion injury, and is the most common injury in sport.

The anterior talofibular ligament (ATFL) is injured most often, with the calcaneofibular ligament (CFL) also torn in more severe sprains. Many patients are left with recurrent sprains or chronic ankle instability, particularly without proper rehabilitation. The priorities are to exclude fracture with the Ottawa Ankle Rules, look for associated injuries and start structured rehabilitation early.

The lateral ligament complex has 3 parts:

• •ATFL: lateral malleolus to talar neck. The weakest, tight in plantarflexion, and the first to fail
• •CFL: malleolar tip to lateral calcaneus. Resists inversion across both the ankle and subtalar joints
• •Posterior talofibular ligament (PTFL): the strongest, rarely injured except in severe injuries or dislocation

The classic mechanism is forced inversion in plantarflexion. As force increases the ATFL fails, then the CFL, then the PTFL.

Grading:

• •Grade I: ligament stretched, stable on stress testing
• •Grade II: partial tear, some laxity with an end-point
• •Grade III: complete tear, laxity with no end-point

Chronic ankle instability has mechanical (laxity) and functional (proprioceptive and peroneal) components.