Episode 172.0 – Ankle Sprains

We dissect one of the most common injuries we see in the ER -- ankle sprains

Hosts:
Brian Gilberti, MD
Audrey Bree Tse, MD

November 4th, 2019 Download Leave a Comment Tags:

Show Notes

Background

  • Among most common injuries evaluated in ED
  • A sprain is an injury to 1 or more ligaments about the ankle joint
  • Highest rate among teenagers and young adults
    • Higher incidence among women than men
  • Almost a half are sustained during sports
  • Greatest risk factor is a history of prior ankle sprain

Anatomy

  • Bone: Distal tibia and fibula over the talus → constitutes the ankle mortise
  • Aside from malleoli, ligament complexes hold joint together
    • Medial deltoid ligament
    • Lateral ligament complex
      • Anterior talofibular ligament
        • Most commonly injured
        • Weakest
        • 85% of all ankle sprains 
      • Posterior talofibular ligament
      • Calcaneofibular ligament
    • Syndesmosis

Mechanism of Injury

  • Lateral ankle sprains 
    • Most common among athletes
    • ATFL most commonly injured
      • Combined with CFL in 20% of injuries
    • 2/2 inversion injuries
  • Medial ankle sprains
    • Less common than lateral because ligaments stronger and mechanism less frequent
      • More likely to suffer avulsion fracture of medial malleolus than injure medial ligament
    • 2/2 eversion +/- forced external rotation
    • Typically landing on pronated foot -> external rotation
  • High Ankle sprains
    • Syndesmotic injury
    • More common in collision sports (football, soccer, etc)
  • Grade I
    • Mild
    • Stretch without “macroscopic” tearing
    • Minimal swelling / tenderness
    • No instability
    • No disability associated with injury
  •     Grade II
    • Moderate
    • Partial tear of ligament
    • Moderate swelling / tenderness
    • Some instability and loss of ROM
    • Difficulty ambulating / bearing weight
  •     Grade III
    • Severe
    • Complete rupture of ligaments
    • Extensive swelling / ecchymosis / tenderness
    • Mechanical instability on exam
    • Inability to bear weight

Examination

  •     Beyond visual inspection for swelling, ecchymoses, abrasions, or lacerations
    • Palpation 
    • Pain when palpating ligament is poorly specific but may indicate injury to structure
    • Check sites for Ottawa ankle rules to evaluate if there may be an associated fracture with injury
      • Posterior edge or tip of lateral malleolus (6 cm)
      • Posterior edger or tip of medial malleolus (6 cm)
      • Base of fifth metatarsal
      • Navicular bone
    • Acute ATFL rupture / Grade III Sprain
      • 90% chance of this injury if hematoma and localized tenderness with palpation present on exam over this ligament 
      • Anterior drawer test
        • Assess for anterior subluxation of talus from the tibia
          • Ankle in relaxed position, distal extremity is stabilized with one hand while the other cups the heel to apply anterior force
        • Compare to contralateral side
        • Difficult to determine if there is an acute rupture at this point and may be more easily diagnosed in subacute phase (4-5 days after injury)
        • Ability to perform exam adequately limited by pain, swelling and potential muscle spasm
      • Talar tilt test
        • If applying inversion force to ankle and there is excessive mobility → calcaneofibular ligament
      • Thompson test
        • Can be performed if there is concern for concomitant Achilles tendon injury 
    • Do not miss a Maisonneuve fracture by palpating proximally about the fibular ahead as forces may be transmitted through the syndesmosis 
      • Squeeze test – pressure just proximal to ankle
        • If elicits pain → concern for syndesmotic injury

Diagnostics

  •     X-rays indicated if unable to rule out using Ottawa Ankle Rules
    • Sn (Up to 99.6) (one of the best validated tools we use in the ER)
    • May have trouble applying rule if there is question of patients ability to sense pain (diabetic neuropathy), in which case obtain radiographs

Treatments

  •     RICE
    • Crutch train so they can be weight bearing a tolerated
    • Ideally initiate within first 24 hours of injury
    • Ice 15-20 minutes q2-3h over the first 48 hours or until swelling improves
  •     NSAIDs
    • Topical and PO are better than placebo 
    • We do not know if PO is superior to topical NSAIDs
  •     Early mobilization / Functional Rehab (sample patient instructions here)
    • Work to restore range of motion, strength, proprioception
    • For Grade I and II, can begin as soon as the patient can tolerate and ideally within 1 week of the injury
    • Patients return to work sooner, decreased chronic instability, less recurrent injuries
    • Dorsiflexion, plantarflexion, and perform foot circles as well as toe curls, inversion and eversion as tolerated
    • Proprioception
      • Balancing on wobble board
    • Continue exercises until patient is able to return to activities at full capacity, without pain
  • Immobilization
    • High re-injury rates and important to protect against this
    • Grade I
      • No immobilization required
      • +/- Ace wrap
    • Grade II
      • Aircast brace
      • Ensure patient understands that they should still partake in rehabilitation exercises
    • Grade III
      • Data conflicts
      • RCT, multicenter study comparing aircast brace, compression bandage, Bledsoe immobilization boot and below-knee cast for 10 days
        • Ankle function at 3 months
          • Cast group had most improvement
          • No difference at 9 months in function or complications
      • May be institution-dependent and a cast can be offered initially

Prognosis

  • Acute inflammation → reduction in swelling → development of new tissue → strengthening of tissue 
  • Return of basic function, though limited, occurs over 4-6 weeks depending on severity of sprain
  • Try to limit strain put on joint (no heavy lifting, walking on uneven surfaces, try to limit standing while at work)
  • Follow up:
    • If pain or instability does not improve over 4-6 weeks
    • Grade III sprains
    • Medial ankle sprains (may have underlying fracture that was undetected in ED on XR)
    • Syndesmosis injuries (protracted recovery course)
    • Injuries associated with fractures or dislocation / subluxation

 

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