Ankle Sprain Definition and Characteristics

Introduction to Ankle Sprains

An ankle sprain is defined as an injury to one or more ligaments in the ankle, typically occurring when the ankle is forced into an abnormal position, most commonly through an inversion injury in the plantar-flexed position 1, 2

The most common type is a lateral ankle inversion sprain, which accounts for the majority of ankle sprains 2
Ankle sprains can be classified into three grades based on severity:
- Grade I: Mild stretching of the ligament without macroscopic tearing, minimal swelling and tenderness, no joint instability 1
- Grade II: Partial tearing of the ligament, moderate pain, swelling and tenderness, mild to moderate joint instability 1
- Grade III: Complete rupture of the ligament, severe swelling and pain, significant joint instability 2, 3

High ankle (syndesmotic) sprains involve injury to the posterior and anterior tibiofibular ligaments, occurring through dorsiflexion and eversion of the ankle with internal rotation of the tibia 2

Key physical examination findings associated with more severe (grade III) sprains include significant swelling 1, hematoma formation 1, pain on palpation 2, and a positive anterior drawer test 3
The presence of all four findings above has been associated with a 96% likelihood of lateral ligament rupture 3
The anterior drawer test detects excessive anterior displacement of the talus onto the tibia, indicating a torn anterior talofibular ligament 3
A crossed-leg test can detect a high ankle sprain, indicated by pain in the syndesmosis area when pressure is applied to the medial side of the knee 3

Diagnosis is primarily clinical, based on history and physical examination 2
The Ottawa Ankle and Foot Rules can help determine the need for radiography, with high sensitivity (99.7%) for ruling out fractures 3
Reexamination 3-5 days after injury, when pain and swelling have improved, is important to distinguish partial tears from complete ligament ruptures 2, 3

Failure to recognize high ankle (syndesmotic) sprains, which require different management 3
Inadequate follow-up assessment after initial swelling has subsided, which is crucial for accurate grading 3