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High Ankle Sprain & Syndesmosis Injury

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Topic updated on 07/03/16 3:41pm
Introduction
  • Also known as a "high ankle sprain"
  • Epidemiology
    • incidence
      • 0.5% of all ankle sprains without fracture
      • 13% of all ankle fractures
  • Pathophysiology
    • mechanism of injury
      • most commonly associated with external rotation injuries  
    • pathoanatomy
      • external rotation forces the talus to rotate laterally and push the fibula away from tibia
      • may lead to
        • increased compressive stresses seen by the tibia
        • increased likelihood of lateral subluxation of the distal fibula
        • incongruence of the ankle joint articulation
  • Associated injuries
    • osteochondral defects (15% to 25%)
    • peroneal tendon injuries (up to 25%)
    • fractures
      • ankle
        • Weber C
        • Weber B
      • other
        • 5th metatarsal base
        • anterior process of calcaneus
        • lateral or posterior process of talus
    • deltoid ligament injury
    • loose bodies
  • Prognosis
    • missed injuries may result in end-stage ankle arthritis
    • excellent functional outcomes if syndesmosis is anatomically reduced
Anatomy
  • See complete ligament of ankle 
  • Ligaments
    • distal tibiofibular syndesmosis includes
      • anterior-inferior tibiofibular ligaments (AITFL)
        • originates from anterolateral tubercle of tibia (Chaput's)
        • inserts on anterior tubercle of fibula (Wagstaffe's)
      • posterior-inferior tibiofibular ligament (PITFL)
        • originates from posterior tubercle of tibia (Volkmann's)
        • inserts on posterior part of lateral malleolus
        • strongest component of syndesmosis
      • transverse tibiofibular ligament
      • interosseous membrane
      • interosseous ligament (IOL)
        • distal continuation of the interosseous membrane
        • main restraint to proximal migration of the talus
      • inferior transverse ligament (ITL)
  • Syndesmosis Biomechanics
    • function
      • maintains integrity between tibia and fibula
      • resists axial, rotational, and translational forces
    • normal gait
      • syndesmosis widens 1mm during gait
    • deltoid ligament
      • indirectly stabilizes the medial ankle mortise
Presentation
  • Symptoms
    • anterolateral ankle pain proximal to AITFL
    • may have medial sided ankle tenderness/swelling
    • difficulty bearing weight
      • lateral ankle sprains are often able to bear weight
  • Physical exam
    • palpation
      • syndesmosis tenderness
        • single best predictor for return to play
    • provocative tests
      • squeeze test (Hopkin's)
        • compression of tibia and fibula at midcalf level causes pain at syndesmosis
      • external rotation stress test
        • pain over syndesmosis is elicited with external rotation/dorsiflexion of the foot with knee and hip flexed to 90 degrees
      • Cotton
        • widening of the syndesmosis with lateral pull on the fibula
      • fibular translation
        • anterior and posterior drawer force to the fibula with the tibia stabilized causes increased translation of the fibula and pain
Imaging
  • Radiographs
    • recommended views
      • AP, lateral, mortise view of ankle
      • AP, lateral of entire tibia
        • may show fracture of proximal fibula
    • optional views
      • external rotation stress radiograph
      • gravity stress view
        • will help determine competence of deltoid ligament
      • contralateral ankle radiographs
        • may help clarify syndesmosis widening versus normal anatomic variant
    • findings
      • decreased tibiofibular overlap
        • normal >6 mm on AP view
        • normal >1 mm on mortise view
      • increased medial clear space
        • normal less than or equal to 4 mm
      • increased tibiofibular clear space
        • normal <6 mm on both AP and mortise views
  • CT 
    • indications
      • clinical suspicion of syndesmotic injury with normal radiographs 
      • useful post-operatively to assess reduction of syndesmosis after fixation
    • sensitivity and specificity
      • more sensitive than radiographs for detecting minor degrees of syndesmotic injury
  • MRI
    • indications
      • clinical suspicion of syndesmotic injury with normal radiographs 
    • sensitivity and specificity
      • highly sensitive and specific for detecting syndesmotic injury 
Treatment of High Ankle Sprains
  • Nonoperative
    • non-weight-bearing CAM boot or cast for 2 to 3 weeks
      • indications
        • syndesmotic sprain without diastasis or ankle instability
      • technique
        • delayed weight-bearing until pain free
        • physical therapy program using a brace that limits external rotation
      • outcomes
        • typically display a notoriously prolonged and highly variable recovery period 
        • recovery may extend to twice that of standard ankle sprain
  • Operative
    • syndesmosis screw fixation
      • indications
        • syndesmotic sprain (without fracture) with instability on stress radiographs
        • syndesmotic sprain refractory to conservative treatment
        • syndesmotic injury with associated fracture that remains unstable after fixation of fracture
      • outcomes
        • excellent functional outcomes if syndesmosis is accurately reduced
        • requires removal
    • syndesmosis fixation with suture button 
      • indications
        • same as for screw fixation
      • technique
        • fiberwire suture with two buttons tensioned around the syndesmosis
        • may be performed in addition to a screw
      • outcomes
        • early results promising with some showing earlier return to activity when compared to screw fixation
        • does not require removal
Surgical Techniques
  • Syndesmotic screw fixation
    • technique
      • two 3.5 or 4.5 mm syndesmotic screws through 3 or 4 cortices placed 2-5 cm above the plafond
        • screw material
          • no difference between stainless-steel and titanium screws
          • bioabsorbable screws with similar outcomes
        • number of cortices
          • no difference between 3 or 4 cortices
        • number of screws
          • fixation with two screws is preferable
        • position of foot during fixation
          • a recent study challenges the principle of holding the ankle in maximal dorsiflexion to avoid overtightening
    • postoperative
      • typically non-weight-bearing for 6-12 weeks
        • may prolong if screw breakage is a concern
Complications
  • Posttraumatic tibiofibular synostosis
    • incidence
      • ~10% after Weber C ankle fractures
    • treatment
      • surgical excision
        • reserved for persistent pain that fails to respond to nonsurgical management
        • ossification must be "cold" on bone scintigraphy prior to removal

 

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Qbank (4 Questions)

TAG
(SBQ07.2) A football player develops a synostosis between the distal tibia and fibula 8 months following treatment for a high ankle sprain. What is the most appropriate indication and timing for surgical excision? Topic Review Topic

1. Chronic lateral ankle instability at any time
2. Progressive loss of plantar-flexion at any time
3. Progressive loss of plantar-flexion and increased uptake on bone scan
4. Persistent pain despite non-operative treatment and no uptake on bone scan
5. Persistent pain despite non-operative treatment and "hot" on bone scan

PREFERRED RESPONSE ▶
TAG
(OBQ06.74) A 21-year-old male collegiate basketball player presents with 1 year of left lower leg pain. The pain is worse with activity and the leg is tender to palpation. He denies constitutional symptoms, and conservative treatment has failed to provide relief. He denies recent trauma, but did sustain a severe ankle sprain 7 years ago. Radiograph, bone scan, and CT scans are shown in Figures A-D. What is the next most appropriate step in management? Topic Review Topic
FIGURES: A   B   C   D    

1. External beam irradiation with 60Gray to lesion
2. Neoadjuvant multiagent chemotherapy followed by surgical resection of lesion followed by adjuvant multiagent chemotherapy
3. Observation and repeat bone scans to plan external beam irradiation of 700cGray to lesion
4. Indomethacin 25 mg PO tid for 6 weeks
5. Observation and repeat bone scan followed by surgical resection if no increased uptake

PREFERRED RESPONSE ▶
TAG
(OBQ05.88) Which test for acute syndesmotic injury of the ankle has the fewest false-positive results and smallest inter-observer variance when used intraoperatively? Topic Review Topic

1. Squeeze test
2. Fibular translation
3. Cotton test
4. External rotation stress test
5. Anterior drawer

PREFERRED RESPONSE ▶
TAG
(OBQ04.189) A 38-year-old competitive slalom skier is making a turn to the left around a pole. The right ski sticks in the snow as shown in Figure A, causing external rotation of the right ski and boot. Which of the following ankle ligaments is most likely to be the initial structure injured?

Topic Review Topic
FIGURES: A          

1. Calcaneofibular ligament
2. Anterior inferior tibiofibular ligament
3. Deep deltoid ligament
4. Superficial deltoid ligament
5. Anterior talofibular ligament

PREFERRED RESPONSE ▶



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