Orthonotes
by the.bonestories
Menu
I: no dislocation; II: subtalar dislocation; III: subtalar + tibiotalar; IV: plus talonavicular. AVN risk escalates I→IV; displaced types require urgent reduction and fixation.
10 AI-generated high-yield questions by our AI engine
Fractures of the talar neck are among the most serious foot injuries, carrying a high risk of avascular necrosis (AVN) of the talar body — the devastating complication that distinguishes talar neck fractures from most other foot fractures. The talus is unique in that approximately 60% of its surface is covered by articular cartilage, leaving very little space for periosteal or direct vascular penetration. The blood supply to the talus is therefore precarious, entering primarily through the sinus tarsi and the tarsal canal, and is highly vulnerable to disruption by neck fractures with displacement. The Hawkins classification (1970), developed by H. Bradley Hawkins, grades talar neck fractures by the degree of displacement and the number of articular relationships disrupted — directly predicting AVN risk and guiding management urgency.
| Hawkins Type | Fracture Description | Joints Disrupted | AVN Rate | Treatment |
|---|---|---|---|---|
| Type I — Undisplaced | A non-displaced fracture of the talar neck; no subluxation or dislocation of any joint; the fracture fragments remain in anatomical alignment; the fracture line is visible on X-ray or CT but there is no displacement | NO joint disruption — all three articular relationships of the talus are intact (tibiotalar, subtalar, talonavicular) | ~0–13% AVN rate — the blood supply is largely intact because no displacement has torn the peritalar vascular structures; excellent prognosis for avoidance of AVN | Non-weight-bearing cast for 8–12 weeks; some centres recommend ORIF even for Type I to provide stable fixation and prevent late displacement (particularly for athletes); conservative management is appropriate for truly undisplaced fractures; follow-up CT at 6–8 weeks to confirm position; the Hawkins sign (see below) assessed at 6–8 weeks |
| Type II — Subtalar subluxation/dislocation | The talar neck is fractured with SUBLUXATION or DISLOCATION of the SUBTALAR JOINT; the talar body remains in the ankle mortise (tibiotalar joint is maintained); the fracture causes the posterior talar fragment (the body) to tilt or displace at the subtalar joint level; the subtalar joint may be subluxed (partial malalignment) or frankly dislocated (the talar body is displaced from the calcaneus) | Subtalar joint disrupted; tibiotalar (ankle) joint maintained; talonavicular joint maintained | ~20–50% AVN rate — the subtalar dislocation has torn the vessels in the tarsal canal (the dominant blood supply to the talar body); the risk increases with the degree of subtalar displacement; prompt reduction and fixation reduces AVN risk | URGENT closed reduction (within 6 hours if possible); if closed reduction fails or fracture is displaced → ORIF; surgical fixation through the sinus tarsi (screw fixation from anterolateral or posteromedial); anatomical reduction of the neck fracture is the primary surgical goal; residual neck malunion causes secondary subtalar arthritis and impingement |
| Type III — Subtalar + ankle dislocation | The talar neck is fractured with dislocation of BOTH the subtalar joint AND the tibiotalar (ankle) joint; the talar body is dislocated from BOTH the calcaneus AND the ankle mortise; the talar body typically rotates 90° medially into the medial soft tissues of the ankle (the `medial malleolus dislocation`); the soft tissue attachments to the body are almost completely disrupted | Subtalar AND tibiotalar (ankle) joints disrupted; the talar body is dislocated from both joints; most peritalar vessels are torn; skin compromise is common (the displaced talar body tents the medial ankle skin) | ~80–100% AVN rate — virtually all vessels supplying the talar body have been torn by the dislocation; AVN is expected in the vast majority of Type III injuries; the question is not IF AVN will occur but how severe it will be and what the functional consequence will be | EMERGENCY — urgent open reduction; the displaced talar body frequently tents the medial ankle skin, creating a risk of skin necrosis and open injury; reduction must be performed urgently even if only to decompress the skin; ORIF with screws; despite the near-universal AVN rate, outcomes are better with anatomical reduction than with non-operative management; total talar collapse and subtalar/tibiotalar arthritis are expected long-term outcomes; tibiotalocalcaneal fusion is the salvage procedure |
| Type IV (Canale-Kelly addition, 1978) — + Talonavicular dislocation | All of Type III PLUS dislocation of the TALONAVICULAR joint; the talar head is also dislocated; ALL three joints of the talus (tibiotalar, subtalar, talonavicular) are disrupted; the talus has essentially `dropped out` of all its articulations; this is the most severe talar fracture | ALL three talar articular relationships disrupted — the talus has lost all ligamentous and vascular attachments | ~90–100% AVN rate — complete vascular avulsion of the talus; essentially certain AVN; the talar body is an isolated devascularised fragment | URGENT open reduction; skin necrosis risk; total talar collapse expected; primary tibiotalar + talonavicular arthrodesis (pantalar fusion) may be considered in elderly patients at the time of fixation; for young patients — attempt ORIF despite AVN certainty (osteonecrotic talus can remain functional for years before collapse requires fusion); Blair fusion (tibiocalcaneal fusion with anterior tibial graft strut) for salvage after total talar AVN collapse |
10 AI-generated high-yield questions by our AI engine