ESSENTIALS OF DIAGNOSIS
Localized pain and swelling.
The majority of ankle injuries involve inversion injuries affecting the lateral ligaments.
Consider chronic ankle instability or associated injuries if pain persists for longer than 3 months following an ankle sprain.
Ankle sprains are the most common sports injuries seen in outpatient clinics. Patients usually report “turning the ankle” during a fall or after landing on an irregular surface such as a hole or an opponent’s foot. The most common mechanism of injury is an inversion and plantar flexion sprain, which injures the anterior talofibular (ATF) ligament rather than the calcaneofibular (CF) ligament. Other injuries that can occur with inversion ankle injuries are listed in Table 41–8. Women appear to sustain an inversion injury more frequently than men. Chronic ankle instability is defined as persistent complaints of pain, swelling, and “giving way” in combination with recurrent sprains for at least 12 months after the initial ankle sprain. Chronic ankle instability can occur in up to 43% of ankle sprains despite physical therapy, which makes appropriate attention to acute ankle sprains important.
Table 41–8.Injuries associated with ankle sprains. ||Download (.pdf) Table 41–8. Injuries associated with ankle sprains.
Subtalar joint sprain
Sinus tarsi syndrome (ongoing anterolateral post-traumatic ankle pain)
Syndesmotic (distal tibiofibular ligamentous) sprain
Lisfranc (tarsometatarsal bony or ligamentous) injury
Posterior tibial tendon strain
Peroneal tendon subluxation
Osteochondral talus injury
Lateral talar process fracture
Posterior impingement (os trigonum)
Fracture at the base of the fifth metatarsal
Jones fracture (between base and middle of fifth metatarsal)
Salter (growth plate) fracture (fibula)
The usual symptoms following a sprain include localized pain and swelling over the lateral aspect of the ankle, difficulty weight bearing, and limping. The patient’s ankle may feel unstable. On examination, there may be swelling or bruising over the lateral aspect of the ankle. The anterior, inferior aspect below the lateral malleolus is most often the point of maximal tenderness consistent with ATF and CF ligament injuries. The swelling may limit motion of the ankle.
Special stress tests for the ankle include the anterior drawer test (eTable 41–4); the clinician keeps the foot and ankle in the neutral position with the patient sitting, then uses one hand to fix the tibia and the other to hold the patient’s heel and draw the ankle forward. Normally, there may be approximately 3 mm of translation until an endpoint is felt. A positive test includes increased translation of one foot compared to the other with loss of the endpoint of the ATF ligament.
eTable 41–4.Ankle examination. ||Download (.pdf) eTable 41–4. Ankle examination.
Examine for the alignment of the ankle (SEADS).
Include important landmarks: Ottawa Ankle Rules (medial and lateral malleolus, base of fifth metatarsal and navicular area), anterior tibiofibular ligament, posterior talus; tendons (Achilles, peroneals, posterior tibialis, flexor hallucis longus).
Range of motion testing
Check range of motion actively (patient performs) and passively (clinician performs), especially with flexion and extension of the spine. Rotation and lateral bending are also helpful to assess symmetric motion or any restrictions.
Ankle strength testing
Test resisted ankle dorsiflexion, plantarflexion, inversion and eversion strength manually.
Ankle anterior drawer
The clinician keeps the foot and ankle in the neutral position with the patient sitting, then uses one hand to fix the tibia and the other to hold the patient's heel and draw the ankle forward. Normally, there may be approximately 3 mm of translation until an endpoint is felt. A positive test includes increased translation of one foot compared to the other with loss of the endpoint of the anterior talofibular ligament.
Subtalar tilt test
Performed with the foot in the neutral position with the patient sitting. The clinician uses one hand to fix the tibia and the other to hold and invert the calcaneus. Normal inversion at the subtalar joint is approximately 30 degrees. A positive test consists of increased subtalar joint inversion greater than 10 degrees on the affected side with loss of endpoint for the calcaneofibular ligament.
External rotation stress test
Performed when the clinician fixes the tibia with one hand and grasps the foot in the other with the ankle in the neutral position and then dorsiflexes and externally rotates the ankle, reproducing the patient's pain.
Another stress test is the subtalar tilt test, which is performed with the foot in the neutral position with the patient sitting. The clinician uses one hand to fix the tibia and the other to hold and invert the calcaneus. Normal inversion at the subtalar joint is approximately 30 degrees. A positive test consists of increased subtalar joint inversion by greater than 10 degrees on the affected side with loss of endpoint for the CF ligament (eTable 41–4). In order to grade the severity of ankle sprains, no laxity on stress tests is considered a grade 1 injury, laxity of the ATF ligament on anterior drawer testing but a negative tilt test is a grade 2 injury, and both positive drawer and tilt tests signify a grade 3 injury. Difficulty jumping and landing within 2 weeks from the acute ankle sprain, abnormal postural or hip muscle control, or ligamentous laxity noted 8 weeks after injury are poor prognostic signs.
Routine ankle radiographic views include the AP, lateral, and oblique (mortise) views. Less common views requested include the calcaneal view and subtalar view. The Ottawa Ankle Rules remain the best clinical prediction rules to guide the need for radiographs and have an 86–99% sensitivity and a 97–99% negative predictive value. If the patient is unable to bear weight immediately in the office setting or emergency department for four steps, then the clinician should check for (1) bony tenderness at the posterior edge of the medial or lateral malleolus and (2) bony tenderness over the navicular (medial midfoot) or at the base of the fifth metatarsal. If either malleolus demonstrates pain or deformity, then ankle radiographs should be obtained. If the foot has bony tenderness, obtain foot radiographs. An MRI is helpful when considering the associated injuries.
Immediate treatment of an ankle sprain follows the MICE mnemonic: modified activities, ice, compression, and elevation. NSAIDs are useful in reducing pain and swelling in the first 72 hours following the ankle sprain. Subsequent treatment involves protected weight bearing with crutches and use of an ankle stabilizer brace, especially for grade 2 and 3 injuries. Early motion is essential, and patients should be encouraged to do a program of exercises or physical therapy. Proprioception and balance exercises (eg, “wobble board”) are useful to restore function to the ankle and prevent future ankle sprains. There is strong evidence for bracing and moderate evidence for neuromuscular training in preventing recurrence of an ankle sprain. Chronic instability can develop after acute ankle sprain in 10–20% of people and may require surgical stabilization with ligament reconstruction surgery.
Recurrent ankle sprains or signs of chronic ligamentous ankle instability.
No response after more than 3 months of conservative treatment.
Suspicion of associated injuries.
et al. Risk factors for lateral ankle sprains and chronic ankle instability. J Athl Train. 2019 Jun;54(6):611–6.
et al. Treatment and prevention of acute and recurrent ankle sprain: an overview of systematic reviews with meta-analysis. Br J Sports Med. 2017 Jan;51(2):113–25.
et al. Prevention of lateral ankle sprains. J Athl Train. 2019 Jun;54(6):650–61.
et al. Beyond the bones and joints: a review of ligamentous injuries of the foot and ankle on (99m)Tc-MDP-SPECT/CT. Br J Radiol. 2019 Dec;92(1104):20190506.
et al. The ankle-joint complex: a kinesiologic approach to lateral ankle sprains. J Athl Train. 2019 Jun;54(6):589–602.
et al. Criteria-based return to sport decision-making following lateral ankle sprain injury: a systematic review and narrative synthesis. Sports Med. 2019 Apr;49(4):601–19.
et al. Diagnosis, treatment and prevention of ankle sprains: update of an evidence-based clinical guideline. Br J Sports Med. 2018 Aug;52(15):956.