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Ankle Joint Osteology
  • Ankle Joint
    • consists of 
      • tibial plafond
      • medial malleolus
      • lateral malleolus
      • talus
    • motion 
      • main motion 
        • plantar flexion
        • dorsiflexion
      • secondary motions
        • inversion/eversion
        • rotation
  • Distal tibiofibular joint
    • consists of
      • distal fibula
      • incisura fibularis 
        • concave surface of distal lateral tibia
    • motion
      • fibular rotates within incisura during gait
      • mortise widens when ankle goes from plantar to dorsiflexion
      • syndesmosis screws limit external rotation
  • Joint reaction force 
    • ankle joint
      • 5 times body weight with walking on level surfaces
Ankle Ligament Introduction
  • Primary ligaments of ankle include (see below for details)
    • medial
      • Deltoid ligament
      • Calcaneonavicular ligament (Spring Ligament) 
    • lateral
      • Syndesmosis (includes AITFL, PITFL, TTFL, IOL, ITL)
      • Anterior talofibular ligament (ATFL)
      • Posterior talofibular ligament (PTFL)
      • Calcaneal fibular ligament (CFL)
      • Lateral talocalcaneal ligament (LTCL)
  •  Function
    • responsible for integrity of ankle mortise
  • Anatomy
    • Syndesmosis components 
      • Anterior-inferior tibiofibular ligament (AITFL)
      • Posterior-inferior tibiofibular ligament (PITFL)
        • deep portion of this ligament sometimes reffered to as the inferior transverse ligament
      • Transverse tibiofibular ligament (TTFL)
      • Interosseous ligament (IOL)
  • Physical Exam
    • test to identify a syndesmosis injury include
      • external rotation test 
      • squeeze test 
  • Imaging
    • AP and mortise ankle radiographs
      • used to evaluate the tibiofibular clear space and tibiofibular overlap
        • tibiofibular clear space should be < 5 mm
        • tibiofibular overlap for AP view > 10 mm
      • weight bearing mortise view is most accurate radiograph for diagnosis
      • CT scan is most accurate for assessment but true normals have not been validated and comparison to the uninjured side are helpful
  • Clinical conditions
    • high ankle sprain & syndesmosis injury 
    • ankle fracture 
Anterior Talofibular Ligament (ATFL)
  • Function
    • primary restraint to inversion in plantar flexion
    • resists anterolateral translation of talus in the mortise
    • weakest of the lateral ligaments
  • Anatomy 
    • extends from the anteroinferior border of the fibula to the neck of the talus
      • origin is 10mm proximal to tip of fibula
      • inserts directly distal to articular cartilage of the talus (18mm distal to joint line)
      • runs 45°-90° to longitudinal axis of the tibia
  • Physical exam
    • anterior drawer in 20° of plantar flexion
      • test competency by anterior drawer in 20° of plantar flexion and compare to uninjured side
      • forward shift of more than 8 mm on a lateral radiograph is considered diagnostic for an ATFL tear
  • Imaging
    • stress radiographs
      • more accurate in chronic injuries
    • MRI 
      • can diagnose injury 
    • arthroscopic findings 
      • can confirm MRI imaging  
    • ultrasound
      • more accurate than radiographs 
  • Clinical Conditions
    • low ankle sprains 
Posterior Talofibular Ligament (PTFL)
  •  Function
    • strongest of the lateral ligaments
    • plays only a supplementary role in ankle stability when the lateral ligament complex is intact
    • under greatest strain in ankle dorsiflexion and acts to limit posterior talar displacement
      within the mortise as well as talar external rotation
    • if ATFL and CFL are incompetent, then
      • short fibers of PTFL restrict internal and external rotation, talar tilt, and dorsiflexion;
      • long fibres inhibit only external rotation, talar tilt, and dorsiflexion
  • Anatomy
    • origin is posterior border of fibula 
    • inserts on posterolateral tubercle of the talus
    • runs perpendicular to longitudinal axis of the tibia
  • Physical exam
    • no specific clinical test for isolated PTFL injury
  • Imaging
    • MRI can indicate structural injury, rarely indicated
  • Clinical Conditions
    • rarely injured, except in association with a complete dislocation of the talus
Calcaneal Fibular Ligament (CFL)
  • Function
    • primary restrain to inversion in neutral or dorsiflexed position
    • restrains subtalar inversion, thereby limiting talar tilt within mortise
  • Anatomy 
    • origin is anterior border of fibula, 9mm proximal to distal tip
    • inserts on calcaneus 13mm distal to subtalar joint and deep to peroneal tendon sheaths
  • Physical exam
    • inversion (supination) test 
      • perform with ankle in slight dorsiflexion
    • talar tilt test
      • angle formed by tibial plafond & talar dome is measured as inversion force is applied to hindfoot (<5 deg is normal for most ankles)
      • useful for evaluation of combined injury of both ATFL and CFL ligament
  • Imaging
    • talar tilt radiographs 
    • ankle arthrograms
      • CFL rupture can lead to extra-articular dye leakage into the peroneal tendon sheath
    • MRI
  • Clinical Conditions
    • injury occurs with ankle inversion with the foot in the neutral position
    • low ankle sprain 
Lateral Talocalcaneal Ligament (LTCL)
  • Function
    • thought to stabilize the talocalcaneal joint
  • Anatomy
    • short narrow ligamentous band that connects the lateral process of the talus to the lateral surface of the calcaneus
    • located anterior and medial to calcaneofibular ligament
  • Physical Exam
    • no specific test for this ligament
  • Imaging
    • LTCL ligament (red arrows) identified distinctly from the calcaneofibular ligament 
    • relationship of the calcaneofibular ligament (green arrow) and the LTCL (red arrow) 
  • Clinical conditions
    • often injured in conjunction with ATFL injuries
    • low ankle sprain 
Deltoid Ligament
  • Function
    • primary restraint to valgus tilting of the talus
    • both the superficial and deep layers individually resist eversion of the hindfoot
    • stabilizes ankle against plantar flexion, external rotation and pronation
  • Anatomy
    • superficial layer
      • crosses both ankle and subtalar joints
      • originates from anterior colliculus and fans out to insert into the navicular neck of the talus, sustenaculum tali, and posteromedial talar tubercle
      • the tibiocalcaneal (sustenaculum tali) portion is the strongest component in the superficial layer and resists calcaneal eversion
    • deep layer
      • crosses only ankle joint
      • functions as the primary stabilizer of the medial ankle
        • prevents lateral displacement and external rotation of the talus 
      • originates from inferior & posterior aspects of medial malleolus and inserts on medial and posteromedial aspects of the talus
  • Physical exam 
    • eversion test
      • with ankle in neutral, evaluates superficial layer
      • external rotation stress test evaluates syndesmosis and deep layer
  • Imaging
    • radiographs
      • mortise radiograph with medial clear space widening can suggest injury 
      • gravity stress view can identify medial clear space widening 
    • MRI
      • normal deltoid ligament 
      • ruptured deltoid ligament 
  • Clinical conditions
    • ankle fracture 
      • injury occurs with pronation (eversion) trauma leading to forced external rotation and abduction of ankle
      • may occur with fracture of the medial malleolus
    • high ankle sprain & syndesmosis injury 
Calcaneonavicular Ligament (Spring Ligament)

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(OBQ08.33) A 35-year-old man is referred to you for left foot pain after falling from a bicycle. A recent MRI shown in Figure A. The injured structure demonstrated in the MRI will most likely lead to which of the following deformities if left untreated? Review Topic

QID: 419

Syndesmotic widening




Flatfoot deformity




Widening of the 1st and 2nd tarsometatarsal joints




Hallux valgus deformity




Talar tilt deformity



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