46 Talus Fractures



10.1055/b-0040-176987

46 Talus Fractures

Laura S. Phieffer and Shan Lansing

Introduction


This chapter provides an overview of fractures that occur in the talus with an approach to examine patients with talus fractures, the anatomy of the talus and its blood supply. Treatment options including surgical approaches and fixation techniques are provided.



I. Preoperative




  1. History and physical examination


    Talar neck fractures:




    1. Fractures of the talar neck make up 45 to 50% of all talus fractures.



    2. Talar neck fractures are produced by decelerating forces with axial impaction. This has also been described as a hyperdorsiflexion injury.




      1. Due to dorsiflexion, the posterior capsular ligaments of the subtalar joint are ruptured and the superior aspect of the talar neck is forced against the distal end of the tibia. As the force continues, the posterior ankle capsule, posterior talofibular ligaments, and the deltoid ligament give out and the talar neck sustains a fracture as it impacts the anterior lip of the distal tibia.



      2. Historically, fractures to the talar neck have been called “aviator’s astragalus” because they were seen in pilots after crash landings of airplanes during World War I.



    3. Patients present with swelling and hematoma over the ankle joint, especially near the proximal dorsal foot. Pain and swelling may mask a dislocation or fracture displacement.



    4. Range of motion (ROM) at the talocrural and subtalar joints will likely be limited. Patients will have pain and be unable to bear weight on the injured side.



    5. The foot and ankle should be evaluated for soft-tissue injuries and neurovascular deficits; blood supply can be evaluated through palpation or Doppler ultrasound.



    6. Ecchymosis, abrasions, fracture blisters, and deformity should be noted.



    7. Integrity of the medial malleolus and calcaneus should be evaluated:




      1. Twenty-eight percent of talar neck fractures present with concurrent fractures of the medial malleolus.



      2. Ten percent present with concurrent calcaneus fractures.


    Talus body fractures:




    1. Talar body fractures make up approximately 40% of talus fractures.



    2. Often they involve the articular surface of the trochlea and the posterior facet of the subtalar joint.



    3. Lateral process fractures will present as lateral ankle pain, which can be misdiagnosed as a sprained ankle.


    Talar head fractures:




    1. Fractures of the talar head make up 5 to 10% of all talus fractures.



    2. Talar head fractures generally result from plantar flexion combined with axial compression.



    3. Patients will present on examination with tenderness and swelling of the talonavicular joint.



  2. Anatomy


    Talar neck fractures:




    1. Blood supply to the talus (▶ Fig. 46.1 ).

      Fig. 46.1 Vascular supply to the talus.



      1. The blood supply to the talus comes from the posterior tibial artery, anterior tibial (dorsalis pedis) artery, and peroneal artery, which connect to form an anastomosis.



      2. Medially the posterior tibial artery provides the following:




        • i. Artery of the tarsal canal—entering along the inferior talar neck.



        • ii. Deltoid branch—enters the talar body medially; often is the single source of blood supply to the talar body following talus fracture.



      3. Laterally the anterior tibial artery (becomes the dorsalis pedis artery as it crosses the ankle joint) and peroneal artery provide the following:




        • i. Artery of the tarsal sinus—distal branch of the dorsalis pedis artery; supplies blood to the talar head.



    2. The talus is one of the few bones in the foot that has no muscular attachments. It is held in place by surrounding bones and attached ligaments.



    3. Osteology (▶ Fig. 46.2a–c ):

      Fig. 46.2 (a) Medial view of a saw bone talus (a, body with articular surface for tibia; b, Neck; c, head of the talus articulating with navicular; d, navicular; e, sustentaculum tali of the calcaneus; f, medial process of the talus). (b) Lateral view of a saw bone talus (a, body with articular surface for tibia; b, articular surface for lateral malleolus; c, neck of the talus; d, lateral process of the talus, arrow pointing to the tarsal sinus; e, posterior process of the talus; f, calcaneus; g, cuboid; h, navicular). (c) Anterior view of a saw bone talus (a, body with articular surface for tibia; b, arrow indicating articular surface for lateral malleolus; c, arrow indicating articular surface for the medial malleolus; d, arrow indicating lateral talar process; e, navicular; g, calcaneus).



      1. The talus neck is short and broad with relatively weak cortex.


    Talus body fractures:




    1. For blood supply to the talar body, see above section on talar neck fractures: anatomy, blood supply.



    2. Talar body fractures primarily affect the articular surface and posterior facet of the subtalar joint, but include the lateral and posterior process as well:




      1. The lateral process articulates with the distal fibula superiorly and the calcaneus inferiorly:




        • i. The lateral process fractures are often called “snowboarder’s fractures.”



      2. The posterior process has two tubercles (medial and lateral) through which the flexor hallucis longus runs.


    Talar head fractures:




    1. For blood supply of the talar head, see above section on talar neck fractures: anatomy, blood supply.



    2. Bone density is highest in the proximal portion of the talus and decreases distally in the talar neck and head.




      1. The densest portion of bone of the talar head is the lateral aspect.



  3. Imaging


    Talar neck fractures:




    1. Standard radiographs include anteroposterior (AP), lateral, and oblique views of the foot and ankle. Modified AP radiographs may also be useful in assessing, but typically CT scan has replaced these specialty views:




      1. Varus/valgus displacement—place ankle in maximum dorsiflexion, pronate foot 15 degrees and position the radiograph beam at 75-degree angle cephalad.



      2. Axial deviation of talar neck: Canale view; pronate foot 15 degrees and position the radiograph beam at 45-degree angle caudally.



      3. Talonavicular joint assessment—dorsoplantar view of the foot with the radiograph beam angled 20 degrees caudally.



    2. Copious X-rays can be exchanged for a CT scan with coronal, axial, and sagittal reconstruction.



    3. MRI scans are not helpful in preoperative planning.


    Talus body fractures:




    1. Standard radiographs include AP, lateral, and oblique views of the foot and ankle.



    2. Lateral process fractures can be viewed with standard radiography, including the mortise view (AP view with 10-degree internal rotation of the foot).



    3. CT scans with coronal, axial, and sagittal reconstruction are needed to confirm degree of displacement and fracture planes.


    Talar head fractures:




    1. The clearest view of the talar head can be seen with the foot positioned in maximum equinus and pronated 15 degrees with the radiograph beam angled 70 degrees cephalad.



    2. A CT scan will be able to confirm a suspected talar head fracture.



  4. Classification


    Talar neck fractures:




    1. The most frequently used classification of talar neck fractures was proposed by Hawkins, and later modified by Canale and Kelly. The Hawkins classification has been shown to be prognostic with respect to final outcome, but only includes talar neck fractures.




      1. Type I: nondisplaced.



      2. Type II: dislocation at the subtalar joint (▶ Fig. 46.3 ).

        Fig. 46.3 Lateral ankle radiograph demonstrating a Hawkins type II talar neck fracture with subtalar dislocation.


      3. Type III: dislocation at the subtalar joint and tibiotalar joint.



      4. Type IV: dislocation at the subtalar joint, tibiotalar joint, and talonavicular joint.



    2. The Orthopaedic Trauma Association (OTA) has additional classifications based on the number of joints involved. The OTA classification system can also be used for all talus fractures.




      1. Type A: extra-articular fractures—includes talar process fractures.



      2. Type B: partial intra-articular fractures—includes small osteochondral fractures.



      3. Type C: complete intra-articular fractures—includes crush fractures.


    Talus body fractures:




    1. For classification of talar body fractures and the OTA system, see above section on talus neck fractures: classification.

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Jun 26, 2020 | Posted by in ORTHOPEDIC | Comments Off on 46 Talus Fractures
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