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Ankle Sprain

  • Most ankle sprains occur in the 15 - 35 year old athletes and dancers
  • 97% of all ankle ligament ruptures occur on the antero-lateral side
  • Injury to the Anterior Talo-Fibular Ligament (ATFL) is the most common
  • Injury to the Calcaneo-Fibular Ligament (CFL) occurs in more severe injuries
  • Disruption of the Posterior Talo-Fibular Ligament (PTFL) is rare
  • It is almost impossible to injure the CFL alone. ATFL is torn first, then CFL, rarely then PTFL. Finally the ankle dislocates
  • Usually, an inversion injury
  • Important to accurately delineate mechanism; gives clues to structures injured
  • May be associated with
    • Syndesmosis injury
      • Known as 'High ankle sprain'
      • 10% of all ankle sprains
      • Usual mechanism is eversion-dorsiflexion which also puts stress on Deltoid ligament
      • Except the most severe injuries, usually PTFL, transverse tibio-fibular ligament and interosseous membrane remain intact
    • 5th metatarsus base fracture
    • Talus lateral process fracture
    • Osteo-chondral fractures of talus dome
    • Calcaneal anterior process fracture
    • Peroneal tendon injury
  • Beware of distal fibular Salter-Harris type I fractures in adolescents presenting with ankle sprain

Clinically

  • Inspect for swelling, palpate for tenderness over each ligament
  • Anterior drawer test : knee flexed, ankle plantar flexed 10 degrees, slight internal rotation to relax deltoid ligament, compare with other side. Positive test indicates torn anterior talo-fibular ligament (major restraint to anterior shift)
  • Talar tilt test : similar positon; ankle 10 degrees plantar flexed, slight internal rotation, palpate joint line, compare with other side. Positive test indicates torn anterior talo-fibular and calcaneo-fibular ligaments

Investigations

Plain X-Ray

  • AP, Lateral and Mortise views
  • Primarily used to rule out fracture/dislocation
  • Indications for obtaining X-Ray according to Ottawa rules are:
    • Patient is unable to walk on the affected foot
    • Tendernes at the base of 5th metatarsus
    • Lateral/medial malleolus tenderness

Stress views

  • Anterior talar shift stress test : position as above
    • ATFL is the primary restraint to anterior shift
    • A side to side difference of >3 mm = torn ATFL
  • Talar tilt stress test : position as above
    • CFL is the major restraint to "tilt" 
    • A side to side difference of 10 degrees or more = torn ATFL and CFL
  • External rotation stress view
    • Shows syndesmotic injury
    • Widening of >6 mm is abnormal

Ankle arthrography / peroneal tenography

  • ATFL is a capsular ligament; tear will show dye leakage
  • CFL is extracapsular and closely related to the peroneal sheath; tear will show dye leaking into peroneal sheath on ankle arthrography,or leakage of dye into joint on peroneal tenography

Ultrasound

MRI

  • Demonstrates tears, but other tests are less expensive 
  • Limited Indications

Classification

May be graded as unstable/stable,high/low or traditionally as:

  • Grade 1
    • Stretch of the ligament, without macroscopic tearing
    • Little swelling or tenderness
    • Little or no functional loss
  • Grade 2
    • Partial macroscopic tear of the tendon
    • Moderate pain, swelling and tenderness
    • Some loss of motion
    • Mild instability of joint (positive drawer test)
  • Grade 3
    • Complete rupture of the both ATFL and CFL
    • Severe swelling, tenderness, ecchymosis
    • Severe loss of function
    • Major instability (positive drawer and tilt tests)

Treatment

  • Functional treatment for acute injuries
    • NSAIDs
    • RICE
    • Short periods (3 weeks) of immobilisation may be necessary in grades 2 and 3
    • Physiotherapy after pain and swelling subsides and patient is able to bear weight
  • The only indication for operative reconstruction acutely is in the high demand sports person
  • If residual instability remains despite exercise, strapping or use of a splint, reconstruction is indicated
  • The type of procedure used is not critical
  • 85% good / excellent results
  • Options are :
    • Late direct repair of the torn ligaments (Brostrom)
    • Augmented reconstruction; e.g. peroneus brevis (Evans, Watson-Jones)

Prognosis

  • Primary repair of the lateral ligament is rarely indicated 
  • Greater than 85% require no further treatment
  • Most cases are able to return to full activity after 6 weeks
  • Results of early repair no better than delayed
  • Risidual pain after 6 weeks, despite adequate therapy, necessitates work-up

ref: Kannus and Renstrom "Current concepts review: Treatment for acute tears of the lateral ligaments of the ankle" JBJS 73A:305-312, 1991  Marder "Current Methods for evaluation of ankle ligament injuries"JBJS 76A:1103,1994  Colville " Reconstruction of the lateral ankle ligaments" JBJS 76A: 1092, 1994


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