Definition
Injury to the lateral ligament complex of the ankle from inversion and plantarflexion, the most frequent musculoskeletal injury in physically active people.
Anatomy
- Anterior talofibular ligament is the weakest, taut in plantarflexion and torn first
- Calcaneofibular ligament is extra-articular, deep to the peroneal tendons, taut in dorsiflexion
- Posterior talofibular ligament is the strongest and rarely torn
Classification
- Grade 1, ligament stretch without laxity
- Grade 2, partial tear with some laxity
- Grade 3, complete rupture with gross instability
Clinical Features
- Lateral swelling, bruising and tenderness over the anterior talofibular ligament
- Anterior drawer test for the anterior talofibular ligament
- Talar tilt test for the calcaneofibular ligament
- Delayed examination at 4 to 5 days is more reliable than acute assessment
- Squeeze and external rotation tests for syndesmosis injury
- Palpate the fifth metatarsal base, navicular and both malleoli
Investigations
- Ottawa ankle rules guide radiography, with sensitivity close to 100%
- Bone tenderness at the posterior edge or tip of either malleolus
- Bone tenderness at the navicular or fifth metatarsal base
- Inability to bear weight for four steps
- MRI for pain persisting beyond 6 weeks or a suspected osteochondral lesion
Differential Diagnosis
- Syndesmosis injury
- Osteochondral lesion of the talus
- Peroneal tendon injury
- Fifth metatarsal base fracture
- Lateral process of talus fracture
- Anterior process of calcaneus fracture
Management
- Functional treatment. Tape or brace with an exercise programme, preferred to prolonged immobilisation
- Short immobilisation. Below knee cast for 10 days in severe sprains gave faster recovery in the CAST trial
- Supervised exercise. Balance and neuromuscular training restore function and reduce recurrence
- Bracing. Prevents recurrent sprains in athletes
- NSAIDs. Short term pain relief, with possible suppression of ligament healing
- Surgical repair. Reserved for chronic instability after failed rehabilitation, see ankle instability
Prognosis
- High recurrence rate
- A large proportion develop chronic ankle instability
- Associated with post-traumatic ankle osteoarthritis
References
- Gribble PA, Bleakley CM, Caulfield BM, Docherty CL, Fourchet F, Fong DT, Hertel J, Hiller CE, Kaminski TW, McKeon PO, Refshauge KM, Verhagen EA, Vicenzino BT, Wikstrom EA, Delahunt E. Evidence review for the 2016 International Ankle Consortium consensus statement on the prevalence, impact and long-term consequences of lateral ankle sprains. Br J Sports Med. 2016, 50(24), 1496-505. PubMed
- Vuurberg G, Hoorntje A, Wink LM, van der Doelen BFW, van den Bekerom MP, Dekker R, van Dijk CN, Krips R, Loogman MCM, Ridderikhof ML, Smithuis FF, Stufkens SAS, Verhagen EALM, de Bie RA, Kerkhoffs GMMJ. Diagnosis, treatment and prevention of ankle sprains. Update of an evidence-based clinical guideline. Br J Sports Med. 2018, 52(15), 956. PubMed
- Lamb SE, Marsh JL, Hutton JL, Nakash R, Cooke MW, Collaborative Ankle Support Trial (CAST Group). Mechanical supports for acute, severe ankle sprain. A pragmatic, multicentre, randomised controlled trial. Lancet. 2009, 373(9663), 575-81. PubMed
- Bachmann LM, Kolb E, Koller MT, Steurer J, ter Riet G. Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot. Systematic review. BMJ. 2003, 326(7386), 417. PubMed
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.