Talus Fractures

The talus is critical to normal function of the ankle, subtalar, & transverse tarsal joints. Talar injuries can interfere with normal coupled motion of these joints & can result in pain, loss of motion, & deformity.

Talus Fracture: Management and Timing of surgery – Presentation by Dr Navid Nazarian

Anatomy

  • talus has no muscle or tendinous attachments + half the surface is articular cartilage
  • Corresponding middle + posterior facets on the talus + calcaneus form the cone shaped tarsal sinus. The tarsal canal posteroinferior to the medial malleolus forms with the tarsal sinus a funnel
  • Blood supply to the talus is derived from 3 arteries & in order of significance are
    1. posterior tibial
    2. anterior tibial
    3. perforating peroneal
  • A posterior tibial artery branch in the tarsal canal supplies most of the talar body
  • A dorsalis paedis artery branch supplies the head & neck (along with tarsal sinus artery)
  • Extensive intraosseous anastomoses are present. Preservation of at least 1 of the 3 main vessels can potentially maintain talar viability

Talar Head Fractures

  • Talar head fractures are rare. ORIF should be considered for articular incongruence
  • Posttraumatic Osteoarthritis may lead to TN arthrodesis (due to coupled motion TN arthrodesis also removes ST + CC motion)

TALAR NECK FRACTURES

Talar neck fractures more often represent high energy injuries & have associated malleolar fractures.

Classification (Hawkins 1970 revised by Canale 1978)

  • Type 1 = undisplaced talar neck fracture
  • Type 2 = talar neck fracture + subtalar dislocation
  • Type 3 = talar neck fracture + displaced body of talus. All 3 blood supplies are usually disrupted

Assessment

  • Sensation + skin integrity + vasculature. Xrays = AP + lateral + oblique
  • Posterior talar body displacement leads to flexor tendon + NV bundle bowstringing = tibial nerve dysaesthesia
  • Prompt reduction mandatory to avoid skin necrosis
  • 50% Hawkins type 3 are compound with 38% subsequent infection rate

Treatment

  • Goal of treatment is anatomical reduction. Malunion of talar neck fractures leads to altered hindfoot mechanics & subsequent posttraumatic Osteoarthritis
  • Surgical approach
    • Medial approach = medial to tibialis anterior tendon starting at navicular tuberosity
    • Anterolateral approach = lateral to common EDL + peroneus tertius sheath
  • Posterior to anterior screw placement provides superior mechanical strength compared with anterior to posterior. Approach = interval between FHL + peroneal tendons. Potential problems are STJ or lateral trochlear screw penetration, FHL injury, screw head impingement limiting ankle plantar flexion
  • Anterior to posterior screws must be countersunk into talar head + potentially can irritate TN function
  • 50% Hawkins type 3 injuries are compound & require urgent debridement & typically are associated with long term functional impairment

Avascular Necrosis

Type 1 <10%

Type 2 30-40%

>90%

Talar Body Fractures

  • Talar process + tubercle fractures → ORIF for displaced fractures + significant articular involvement
  • Displaced cleavage + crush talar body fractures → ORIF

Complications + Salvage

  • AVN presents as a relative opacity of involved bone caused by osteopaenia of adjacent bones secondary to disuse + NWB
  • Hawkins’ sign seen at 6-8 weeks post injury = patchy subchondral osteopaenia on AP + mortise Xrays = evidence of preserved vascularity
  • Presence of Hawkins’ sign is a reliable indicator that AVN is unlikely, however the absence of Hawkins’ sign does not predict AVN
  • MRI is sensitive for detecting AVN + amount of talar involvement. Marrow adipocyte death produces altered signal on T1 weighted image (after 3 weeks)
  • Initial treatment is nonoperative. Fractures can heal despite AVN. Once fracture has united then commence weightbearing. Talar AVN is not always symptomatic
  • No evidence that weightbearing on an avascular talus will contribute to collapse
  • Operative treatment of talar AVN depends on
    • location + extent
    • ankle + ST Osteoarthritis
    • limited AVN → arthrodesis of involved joint
    • total body AVN + collapse → fuse talar head to anterior distal tibia, resect necrotic talar body, tricortical graft (avoids problems related to limb shortening), ± Blair technique of anterior sliding cortical graft

Nonunion + Malunion

  • 2mm talar neck displacement can lead to altered STJ mechanics + Osteoarthritis

Skin Necrosis + Infection

  • Displaced fractures produce skin tension ± necrosis
  • Extensive soft tissue loss requires flap coverage
  • Chronic deep infection requires debridement + metal removal