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

Episode 172.0 – Ankle Sprains

Core EM - Emergency Medicine Podcast