High Ankle Sprain & Syndesmosis Injury

• high ankle sprain
  • 1-10% of all ankle sprains
  • involves the syndesmosis (primarily anterior inferior tibiofibular lig)  
  • mechanism is external rotation
• low ankle sprain 
  • involving ATFL and CFL
  • mechanism is plantarflexion and inversion

• ankle sprains are the most common reason for missed athletic partcipation
  

• osteochondral defects (15% to 25%)
• peroneal tendon injuries (up to 25%)
• fractures (5th metatarsal base, anterior process of calcaneus, lateral or posterior process of the talus)
• deltoid ligament injury (isolated deltoid ligament injuries are very rare)
• loose bodies (20%)

• single leg hop
  • the inability to single leg hop is considered the best indicator of a syndesmosis ankle sprain without diastasis
• syndesmosis tenderness
  • usually have point tenderness over the AITFL
  • estimation of extent of injury to interosseous ligament is made by proximal extent of tenderness
  • is the best determinant for prediction of return to play. It is measured from the distal fibula up the syndesmosis.
• squeeze test
  • squeezing tibia and fibula together at the midcalf causes pain at the syndesmosis
• external rotation stress test
  • dorsiflexion and external rotation cause pain

• ER rotation stress xray 
  • to diagnosis syndesmosis injury in high ankle sprain
  • look for asymmetric mortise widening
    • medial clear space widening > 4mm
    • tibiofibular clear space widening of 6 mm
  • use contralateral ankle as control
• varus stress xray
  • used to diagnose injury to ATFL or CFL
  • measures ankle instability by looking at talar tilt and anterior talar translation
  • use contralateral ankle as control
• indications for an xray with and ankle injury (Ottawa ankle rules)
  • inability to bear weight
  • posterior tenderness of medial and/or lateral malleolus
  • 5th metatarsal base tenderness
  • navicular tenderness
• views to obtain
  • standard ankle series (AP, lateral, and mortise)
    • calcification of interosseous membrane may be a late finding

• usefull to look for
  • peroneal tendon pathology
  • osteochondral injury

• non-weight bearing CAM boot or cast for 2 to 3 weeks
  • indications
    • first line of treatment
  • technique
    • delay weight bearing until pain free
      
    • a physical therapy program using a brace that limits external rotation
      
  • outcomes
    • typically display a notoriously prolonged and highly variable recovery period 
    • recovery tends to be more prolonged (at least twice that of standard ankle sprain)

• syndesmosis screw fixation
  • indications
    • widening of medial or tibiofibular clear space on plain or stress xrays
    • presenting for first time with symptoms > 3 months from time of injury
    • refractory to conservative treatment
  • technique
    • two 4.5 mm syndesmosis screws through 3 or 4 cortices
    • a recent study challenges the priciple of holding the ankle in maximal dorsiflexion to avoid overtightening
  • postoperative
    • place in a non-weight bearing cast for two weeks
    • continue non-weight bearing for 6 weeks
    • screws often removed at 12 weeks

• return to play depends on, grade of sprain, syndosmosis injury, associated injuries, and compliance with rehab

Average Time to RTP for different ankle sprains
Grade I	1 week
Grade II	2 weeks
Grade III	2-4 weeks
High ankle (immobilization)	4-8 weeks
High ankle (screw fixation)	next season

• semirigid orthosis
• peroneal brevis muscle strengthening
• propioception exercise

• a fasicle of the AITFL becomes trapped in the joint
• treat with arthroscopic removal of the fascicle

• up to 50% continue to experience symptoms following and acute ankle sprain
• most common cause of chronic pain is a missed injury, including
  • injury to the anterior process of calcaneus
  • injury to the lateral or posterior process of the talus
  • injury to the base of the 5th metatarsal
  • osteochondral lesion
  • injuries to the peroneal tendons
  • injury to the syndesmosis

• typically follows an eversion (high) ankle sprain that results in disruption of the interosseous membrane. 
• ossification usually develops within 6 to 12 months after the injury. 
• return to sports is possible despite the lack of normal ankle dorsiflexion and mobility between the tibia and fibula.
• surgical excision is reserved for persistent pain that fails to respond to nonsurgical management once the ossification is “cold” on bone scintigraphy.