The talus is unique in lacking muscular and tendon attachments, with 60% of its surface covered by articular cartilage, and a precarious retrograde blood supply primarily from the artery of the tarsal canal (anterior tibial branch via dorsalis pedis), tarsal sinus artery, and posterior tibial artery branches. This makes talus fractures—occurring in 0.85% of all fractures—uniquely prone to avascular necrosis (AVN) with osteonecrosis risk directly correlating with degree of displacement and dislocation. Mechanism is typically high-energy: motor vehicle accidents (most common), falls from height, aviation injuries (the term 'aviator's astragalus' from World War I pilots in crashes). Snowboarder's ankle is a specific lateral process fracture from forced dorsiflexion-inversion.
Anatomic classification by location: talar neck fractures (most common, 50-60%) classified by Hawkins—type I non-displaced, type II displaced with subtalar dislocation, type III displaced with both subtalar and tibiotalar dislocation, type IV (Canale modification) with additional talonavicular dislocation; AVN risk: I <13%, II 20-50%, III 70-90%, IV approaching 100%. Talar body fractures (20-25%) include sagittal, coronal, and shearing fractures, with high articular involvement and AVN risk. Talar dome osteochondral fractures—medial (deeper, posterior) more common than lateral (more superficial, anterior); often missed acutely; cause persistent ankle pain after sprain. Lateral process fractures (snowboarder's ankle, 15-20% of talus fractures in snowboarders)—often missed on plain radiographs, requires CT for confirmation. Posterior process fractures (Shepherd, lateral tubercle; or medial tubercle) often confused with os trigonum (accessory ossicle).
Initial management: prompt reduction of dislocation (closed reduction in ER for displaced types II-IV reduces AVN risk and skin pressure; failure requires urgent OR for open reduction). Imaging: AP, lateral, and Canale view radiographs; CT essential for surgical planning, fracture characterization, and detection of subtle injuries (lateral process, posterior process, dome). MRI for osteochondral injuries and acute AVN assessment. Treatment by type: Hawkins I (non-displaced talar neck)—non-weight-bearing cast 8-12 weeks; Hawkins II/III/IV (displaced)—anatomic open reduction and internal fixation with screws (typically 4.0 mm cannulated through anteromedial and/or anterolateral approaches; some surgeons add plate for comminuted patterns); body fractures with displacement—ORIF; lateral process—non-displaced cast immobilization, displaced or non-union—ORIF with mini-fragment screws; posterior process—conservative if non-displaced, ORIF for displaced with delayed union; talar dome osteochondral—small lesions debridement and microfracture, larger lesions OATS or osteochondral allograft. Postoperative: non-weight-bearing 8-12 weeks, gradual return to weight bearing once union evident, physical therapy for ROM and strengthening, monitoring for AVN with serial radiographs and MRI if suspected. Hawkins sign (subchondral lucency in talar dome on AP at 6-8 weeks indicating preserved subchondral blood supply) is favorable prognostic sign. Complications: AVN (rates as above; managed with extended non-weight bearing if dome partially involved, ankle arthrodesis or talar body replacement for collapse, total ankle arthroplasty selectively); post-traumatic arthritis (subtalar 50-90% within 5 years requiring fusion); persistent stiffness; malunion (varus malalignment); infection.