Talus Fracture 825.21

synonyms: Astragalus fracture, talus fracture, talar neck fracture,

Talus Fracture ICD-9

• 825.21(closed)
• 825.31(open)

Talus Fracture Etiology / Epidemiology / Natural History

• Talar neck fractures result from forced dorsiflexion.

Talus Fracture Anatomy

• Blood supply: the artery of the tarsal canal(posterior tibial artery) is the main blood supply to the body of the talus.  It forms an anastomotic sling with the artery of the tarsal sinus (peroneal).  Others=superior neck vessels from anterior tibial artery, Deltoid artery(post tibial) (Mulfinger JBJS 1970;52B:160), (Gelberman RH, Foot Ankle 1983;4:64).
• 60% covered with articular cartilage, no muscle originate from or insert into talus.
• Lateral process: a wide, wedge-shaped prominence extending from the lateral aspect of the body of the talus; consists of two distinct articular facets: the dorsolateral and the inferomedial. The dorsolateral facet articulates with the distal fibula; the inferomedial facet forms the anterolateral portion of the subtalar joint. The lateral process is the site of insertion of the lateral talocalcaneal ligament.
• Posterior process: composed of a medial and a lateral tubercle(Stieda’s process) which are separated by a groove within which lies the flexor hallucis longus tendon. The Y-shaped, bifurcate talocalcaneal ligament forms a roof over this grooveand inserts onto each tubercle. The posterior talofibular ligament inserts onto the lateral tubercle of the talus. The posterior talotibial portion of the deltoid ligament inserts onto the medial tubercle.
• Os trigonum: located directly posterior to the lateral tubercle(Stieda's process). It is an accessory bone that arises from a secondary ossification center between the ages of 8 and 11 years. Generally fuses to the lateral tubercle within 1 year of its appearance. May persist as a separate ossicle, attached to the talus by a cartilaginous synchondrosis. (Grogan DP, JPO 1990;10:618)

Talus Fracture Clinical Evaluation

Talus Fracture Xray

• A/P Ankle, Lateral Ankle, Mortise Ankle
• Canale view-visualizes talar neck; taken with ankle in maximum plantar flexion and foot pronated 15 degrees. Radiograph directed at 75 degree angle from horizontal plane in the A/P plane. (Canale, JBJS 60A:143;1978).
• Hawkins Sign=prognostic indicator following displaced neck fx’s. Subchondral radiolucency presnt 6-8 wks after fx suggests blood supply to this region.
• MRI helpful to determing AVN post-operatively, but may be limited by metal from ORIF

Talus Fracture Classification / Treatment

• Talar Neck fx most common
• Talar head
• Lateral process (snowboarder's fx)
• posteromedial tuberosity fx
• Posterior process fx

Talar Neck Fracture Classification

• Type I:  Undisplaced; NWB SLC 6-8 wks: AVN 0-13%
• Type II:  Displaced with subtalar subluxation/dislocation, intact ankle mortise (anatomic reduction, ?closed vs. open); AVN 20%-50%, post-traumatic arthritis 40-90%
• Type III:  Dislocation of tibiotalar and subtalar joints. (ORIF); AVN 69-100%, arthritis 40-90%, nonunion 13%, malunion 27%
• Type IV(rare):  Type III + disruption of talonavicular joint (ORIF); 90-100% AVN, arthritis 40-90%, nonunion 13%, malunion 27%

goal is to minimize posttraumatic arthrosis of ankle and subtalar joint and maintain vascularity

The most stable biomechanical fixation for talar neck fractures has been found to be two parallel screws placed in an antegrade fashion from the posterolateral talar body into the anteromedial talar head, crossing the talar neck fracture. Histologically, this area of the talus has the most dense bone, allowing for improved screw purchase. Threaded Steinmann pins do not provide stable fixation for this fracture.  Swanson TV, Bray TJ: Talar neck fractures: A mechanical and histomorphometric study of fixation, in Greene WB (ed): Instructional Course Lectures 39.  Park Ridge, IL, American Academy of Orthopaedic Surgeons, 1990, pp 147-156.

Lemaire RG, Bustin W: Screw fixation of fractures of the neck of the talus using a posterior approach.  J Trauma 1980;20:669-673.

talar body fx’s: high risk of AVN; >2mm displacement =ORIF via medial malleolar osteotomy and limitied anterolateral arthrotomy.  Grob CORR 199:88;1985

Talus Fracture Associated Injuries

• Fracture-dislocation of the subtalar joint
• Fracture-disloaction of the ankle
• Ankle fracture
• Metatarsal fracture

Talus Fracture Complications

• ON, dx made by absence of Hawkins sign (lucency deep to the subchondral surface of the talar dome on an AP radiograph of the ankle 6-8 wks after injury which denotes revascularization.) ON does not always lead to collapse.  Pts should be cautioned of potential collapse and followed closely.

• Rockwood and Greens
• Grob D, Simpson LA, Weber BG, Bray T: Operative treatment of displaced talus fractures.  Clin Orthop 1985;199:88-96