Ankle Sprain

Aka: Ankle Sprain, Lateral Ankle Sprain, Calcaneofibular Ligament Ankle Sprain, Talofibular Ligament Ankle Sprain

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II. Epidemiology

  1. Lateral sprains represent 80-85% of Ankle Sprains
  2. Sports with highest rate of Ankle Sprain
    1. Basketball
    2. Ice skating
    3. Soccer

III. Mechanism

  1. Ankle Inversion with Plantar Flexion

IV. Pathophysiology

  1. Anatomy
    1. See Ankle Anatomy
  2. Lateral ankle ligaments (In order of injury)
    1. Anterior talofibular ligament (ATF): Easily injured
    2. Calcaneofibular ligament (CF)
    3. Posterior Talofibular ligament (PTF): Rarely injured (third degree sprain)
  3. TibioFibular Ligaments
    1. See High Ankle Sprain
    2. Anterior tibiofibular ligament
    3. Posterior tibiofibular ligament
  4. Medial ankle ligament
    1. See Medial Ankle Sprain
    2. Ankle Deltoid Ligament (rarely injured, but associated with serious ankle injury)

V. Associated Conditions: Other associated Injuries

  1. Peroneal Tendon Injury
    1. Peroneal tendon avulsion Fracture
      1. Distinguish from Jones Fracture
      2. Everts foot and prevents inversion
      3. Palpate lateral foot at its insertion
    2. Hemorrhage at Peroneal Muscle
    3. Peroneal Nerve damage may occur
  2. Bone Injury: Foot
    1. Jones Fracture at fifth Metatarsal metaphysis
      1. Peroneal brevis tendon avulsion Fracture
      2. May require surgery for non-union
    2. Tarsal Navicular Fracture (or Stress Fracture)
    3. Lisfranc Fracture-Dislocation (uncommon, but high morbidity)
  3. Bone Injury: Fibula
    1. Pott's Fracture-Subluxation
    2. Maisonneuve Injury (Proximal Fibula Fracture related to Syndesmotic Sprain)
  4. Bone Injury: Talus
    1. Talar Dome Fracture (occurs in 6 to 22% of cases)
    2. Posterior Talus Fracture (Medial or Lateral Tubercle)
    3. Lateral process of Talus Fracture (most commonly missed Ankle Fracture)
  5. Bone Injury: Calcaneus
    1. Calcaneus Anterior Process Fracture

VI. Differential Diagnosis: Delayed healing

  1. Unrecognized associated injury as listed above
  2. Talar Dome Fracture
  3. Reflex Sympathetic Dystrophy
  4. Chronic Tendonitis
  5. Peroneal tendon subluxation
  6. Syndesmotic Sprain (High Ankle Sprain)
  7. Occult Fracture
    1. Anterior Superior Calcaneus Fracture
    2. Lateral Talus Fracture

VII. Symptoms

  1. "Pop" heard with injury
  2. Ankle swelling and decreased function
  3. Inability to walk four feet after Ankle Sprain is higher risk of Fracture
    1. See Ottawa Ankle Rules

VIII. Signs

  1. See Ankle Exam
  2. See Ankle Anatomy
  3. Distal neurovascular exam (always assess in every Musculoskeletal Injury)
    1. Ankle Motor Function and distal Sensation
    2. Distal pulses (dorsalis pedis, posterior tibial)
  4. Evaluate for Syndesmotic Sprain (High Ankle Sprain)
    1. Crossed-Leg Test
      1. Patient sits in a chair
      2. Cross the affected leg over the opposite knee
      3. Pressure applied to the proximal fibula of affected leg
      4. Positive if reproduces pain at the syndesmosis
    2. Squeeze Test
      1. Patient dorsiflexes foot
      2. Examiner squeezes tibia and fibula together
      3. Pain between tibia and fibula suggests tibiofibular syndesmosis injury
    3. Dorsiflexion External rotation stress test (Kleiger Test)
      1. Patient seated with knee flexed to 90 degrees
      2. Examiner stabilizes distal tibia and fibula with one hand
      3. Examiner's other hand exerts external rotation stress on the slightly dorsiflexed foot
      4. Positive if external rotation stress reproduces pain at the syndesmosis
  5. Evaluate ankle stability
    1. Efficacy
      1. Improved accuracy at 4-7 days post-injury
      2. Most useful at follow-up at 4-6 weeks after Ankle Sprain
        1. Used in grading Ankle Sprain (see below)
        2. Does not typically modify initial management after acute injury
    2. Ankle Anterior Drawer Test
      1. Tests anterior talofibular ligament integrity
    3. Ankle Talar Tilt (Inversion stress Test)
      1. Tests calcaneofibular ligament integrity
  6. Evaluate for associated Fracture
    1. See Ottawa Ankle Rules
    2. Ankle bony tenderness
      1. Medial malleolus or distal tibia tenderness within last 2.4 inches (6 cm)
        1. May also indicate Growth Plate Fracture in adolescent
      2. Lateral malleolus or distal fibula tenderness within last 2.4 inches (6 cm)
      3. Talocrural joint line (anterior talar dome) tenderness or swelling
        1. May indicate osteochondral Talar Dome Fracture
        2. Not part of Ottawa Ankle Rules
    3. Foot bony tenderness (midfoot)
      1. Fifth Metatarsal tenderness or pain at base or metaphysis (e.g. Jones Fracture)
      2. Tarsal Navicular tenderness or pain at medial, proximal foot (Tarsal Navicular Fracture)
      3. Lisfranc Joint tenderness, swelling or deformity at midfoot region (Lisfranc Fracture Dislocation)

IX. Evaluation: Red Flags suggestive of more complicated injury

  1. See Ottawa Ankle Rules
  2. Mechanism different than classic inversion injury
    1. Eversion injury (see Medial Ankle Sprain)
    2. Forced severe plantar flexion (see Fifth Metatarsal Fracture)
    3. Dorsiflexion
  3. Atypical signs on acute evaluation immediately after injury
    1. See signs above (under evaluate for associated Fracture)
    2. Immediate swelling or Bruising over the forefoot or toes
  4. Children with tenderness over Physis
    1. Suspect Salter-Harris Fracture I (Physis is weaker than ligaments)
    2. Safest to apply splint despite negative XRay
    3. Low risk of Salter Harris I Fractures on MRI in these patients
      1. Boutis (2016) JAMA Pediatr 170(1): e154114 +PMID: 26747077 [PubMed]

X. Imaging: Initial

  1. Ankle XRay
    1. Indications
      1. See Ottawa Ankle Rules (adults and children over age 5 years old)
      2. See Low Risk Ankle Rule (children over age 3 years old)
      3. See ankle bony tenderness above
      4. Inability to walk four feet at injury site (e.g. sideline) or at acute evaluation by medical provider
    2. Views: Ankle AP, Lateral and Mortise
      1. Weight bearing XRays are preferred if possible
  2. Foot XRay Indications
    1. See foot bony tenderness above

XI. Imaging: Delayed healing (suspected Talar Dome OCD)

  1. Indications
    1. Symptomatic beyond 6 weeks
    2. Persistent crepitus
    3. Locking or catching Sensation
  2. Imaging
    1. Repeat Ankle XRay and foot XRay
    2. Ankle CT or Ankle MRI

XII. Imaging: Instability or Syndesmotic Sprain

  1. See High Ankle Sprain (Syndesmotic Sprain)
  2. MRI Ankle indications
    1. Syndesmotic Sprain suspected (nondiagnostic xrays)
    2. Acute or chronic ankle instability

XIII. Grading

  1. Indications
    1. Ankle stability at 4-6 weeks after Ankle Sprain
      1. Instability directs additional management with rehabilitation (or possibly surgery for third degree Ankle Sprain)
    2. Inaccurate and not useful on initial Ankle Sprain evaluation
      1. Does not modify initial management
  2. First degree Lateral Ankle Sprain
    1. Mild pain and swelling (able to ambulate)
    2. No mechanical instability
    3. Anterior talofibular ligament stretched
    4. Localized tenderness anteriorly
  3. Second degree Lateral Ankle Sprain
    1. Moderate pain and swelling with Ecchymosis present
    2. Pain with ambulation
    3. Moderate lateral ankle instability
    4. Partial tear of anterior talofibular ligament
  4. Third degree Lateral Ankle Sprain
    1. Severe Ecchymosis and swelling (>4 cm at fibula)
    2. Unable to bear weight
    3. Severe lateral ankle instability
    4. Total disruption of lateral ligaments
      1. Anterior talofibular ligament
      2. Calcaneofibular ligament
    5. Heard "Pop" with immediate pain and swelling

XIV. Management

  1. See Ankle Sprain Management

XV. Prognosis

  1. Outcomes generally good
  2. Full recovery may require months
    1. Severe Lateral Ankle Sprains
    2. Syndesmotic Sprains (High Ankle Sprains)

XVI. Complications (uncommon)

  1. Late Traumatic Arthritis of the ankle or foot
  2. Chronic ankle instability

XVII. References

  1. Orman and Ramadorai in Herbert (2016) EM:Rap 16(3): 8-9
  2. Rifat (1996) Am Fam Physician 53(8):2491-8 [PubMed]
  3. Rubin (1996) Am Fam Physician 54(5):1609-18 [PubMed]
  4. Sitler (1995) Sports Med 20(1):53-7 [PubMed]
  5. Swain (1993) Postgrad Med 90(3):91-100 [PubMed]
  6. Tiemstra (2012) Am Fam Physician 85(12): 1170-6 [PubMed]
  7. Wolfe (2001) Am Fam Physician 63(1):93-104 [PubMed]
  8. Wu (2025) Am Fam Physician 112(6): 609-17 [PubMed]

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