Inversion injury to the lateral ligaments (ATFL most common); Ottawa rules guide imaging; functional rehabilitation outperforms immobilization.
Also known as: ankle sprain, lateral ankle sprain, ATFL sprain, high ankle sprain, syndesmosis injury
Overview
Stretch or tear of the ankle ligaments, most commonly the lateral ligament complex (anterior talofibular ligament — ATFL, calcaneofibular ligament — CFL, posterior talofibular ligament — PTFL) from inversion injury. Less common are medial (deltoid ligament) sprains from eversion and 'high ankle' syndesmotic sprains.
Epidemiology
One of the most common musculoskeletal injuries in athletes and the general population. Incidence highest in court and field sports. Recurrent sprains common — up to 30% develop chronic ankle instability.
Try two board-style Ankle Sprain questions
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Question 1MusculoskeletalEasy
A 22-year-old dancer has acute right ankle pain and swelling immediately after landing from a jump and inverting the foot. There is no prior ankle injury. Examination shows tenderness over the anterior talofibular ligament and an inability to bear weight. Using the Ottawa Ankle Rules, radiographs are obtained and show no fracture. Which of the following is the most likely diagnosis?
ASinus tarsi syndrome
BPeroneal tendon dislocation
CLateral ankle sprain
DHigh ankle sprain
Reveal answer & full explanation
Correct answer: C — Lateral ankle sprain
ASinus tarsi syndrome
BPeroneal tendon dislocation
CLateral ankle sprain✓
DHigh ankle sprain
Why Lateral ankle sprain is correct
An inversion injury with point tenderness over the anterior talofibular ligament (ATFL) and no fracture on radiographs is a lateral ankle sprain, the most common ankle injury, with the ATFL the most frequently torn ligament.
The Ottawa Ankle Rules appropriately excluded fracture; inability to bear weight here reflects pain rather than bone injury.
Management is functional: protection, relative rest, ice, compression, elevation, and early protected mobilization.
Why the others are wrong
Sinus tarsi syndrome — develops weeks to months after repeated inversion injuries as deep pain and tenderness in the sinus tarsi, not immediate ATFL point tenderness after a single event in a patient with no prior ankle injury.
Peroneal tendon dislocation — causes snapping or instability behind the lateral malleolus with posterolateral tenderness, not ATFL tenderness; buzzword-match to a lateral ankle injury.
High ankle sprain — follows forced external rotation or dorsiflexion and produces syndesmotic tenderness above the joint line with a positive squeeze test, not the inversion mechanism and ATFL tenderness described.
Question 2MusculoskeletalMedium
A 28-year-old male basketball player has right ankle pain and swelling after landing awkwardly. He has tenderness over the lateral malleolus and anterior talofibular ligament region. He can bear weight with pain. Ottawa Ankle Rules are negative. Which of the following is the most appropriate management?
ACast immobilization for 6 weeks
BShort-leg walking boot for 3 weeks
CStrict non-weight-bearing for 2 weeks
DFunctional rehabilitation with PRICE protocol
Reveal answer & full explanation
Correct answer: D — Functional rehabilitation with PRICE protocol
ACast immobilization for 6 weeks
BShort-leg walking boot for 3 weeks
CStrict non-weight-bearing for 2 weeks
DFunctional rehabilitation with PRICE protocol✓
Why Functional rehabilitation with PRICE protocol is correct
Lateral ankle sprain is the most common musculoskeletal injury; the anterior talofibular ligament (ATFL) is most commonly injured (85% of cases).
Ottawa Ankle Rules are negative (no X-ray needed): X-ray is indicated only if pain near the malleolus AND inability to bear weight for 4 steps AND bony tenderness at the posterior edge/tip of the malleolus.
Early functional mobilization is superior to immobilization for lateral ankle sprains.
Treatment: protection, rest, ice, compression, elevation (PRICE) acutely; early functional mobilization; nonsteroidal anti-inflammatory drugs (NSAIDs); physical therapy for proprioception and peroneal strengthening.
Why the others are wrong
A) Cast immobilization for 6 weeks — prolonged immobilization is inferior to early functional rehabilitation for ankle sprains without fracture.
B) Short-leg walking boot for 3 weeks — may be appropriate for higher-grade sprains but is not the first-line approach when Ottawa Rules are negative and the patient can bear weight.
C) Strict non-weight-bearing for 2 weeks — not indicated; early weight-bearing and mobilization improve outcomes.
Additional high-yield points
Grading: Grade I (stretch, mild swelling), Grade II (partial tear, moderate instability), Grade III (complete tear, significant instability).
Surgery (Brostrom procedure): only for Grade III with chronic instability after conservative management fails.
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Sports — basketball, soccer, volleyball, running on uneven terrain
Prior ankle sprain (strongest single risk factor)
Inadequate rehabilitation after prior injury
Female sex (sport-controlled)
Ligamentous laxity
High-arched feet (cavus foot)
Improper footwear
Pathophysiology
Plantarflexion and inversion stress (rolled ankle) loads the lateral ligaments. The ATFL fails first (most common isolated injury), then the CFL with more severe injury; PTFL rarely torn except in dislocation. Eversion injuries can sprain the deltoid ligament. External rotation force with dorsiflexed foot can tear the tibiofibular syndesmosis (high ankle sprain).
Clinical presentation
Symptoms
Acute inversion injury with immediate lateral ankle pain
Swelling and bruising over the lateral malleolus
Difficulty bearing weight (variable)
Sense of giving way
High ankle sprain: pain is more proximal and anterior, longer recovery
Signs / physical exam
Tenderness over ATFL (anterolateral to lateral malleolus, between fibula and talar neck) and CFL (inferior to lateral malleolus)
Swelling and ecchymosis
Anterior drawer test (sensitive for ATFL)
Talar tilt test (CFL)
Squeeze test of mid-calf and external rotation stress test — positive in syndesmotic injury
Apply Ottawa ankle rules to decide imaging
Check medial malleolus, base of 5th metatarsal, and navicular for tenderness
Differential diagnosis
Lateral malleolus fracture (Weber A/B/C) — Bony tenderness at malleolus, inability to bear weight; Ottawa rules guide imaging
Fifth metatarsal base fracture (Jones, avulsion) — Tenderness at base of 5th MT after inversion; X-ray
Maisonneuve fracture — Proximal fibula fracture with syndesmotic injury; tender along entire fibula
Talar dome osteochondral lesion — Persistent pain after sprain, mechanical symptoms; MRI
Peroneal tendon subluxation or tear — Lateral retromalleolar pain, snapping with eversion
Achilles tendon rupture — Posterior calf pain, palpable defect, positive Thompson test; older adult or athlete jumping/pushing off
Syndesmotic (high ankle) sprain — Pain anterolateral above the joint line; positive squeeze and external rotation tests; slower recovery
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