Review Question - QID 215612

The patient, as shown in figures A and B, has a displaced talar neck fracture. Acute treatment of this injury is associated with high rates of infection, skin necrosis, and wound dehiscence (Answer 1). The other answer choices are not associated with acute fixation of talar neck fractures.

Talar neck fractures are high-energy injuries that have a high incidence of associated fractures and subsequent talus avascular necrosis. The typical mechanism of injury is a high-energy axial load delivered through a dorsiflexed foot. The talus is one of two hindfoot bones and is covered almost entirely with cartilage. The blood supply to the talus is tenuous, easily disrupted with injury, and comes from three sources: the posterior tibial artery via the artery of the tarsal canal (dominant supply), the anterior tibial artery, and the perforating peroneal artery via the artery of the tarsal sinus. Talar neck fractures are classified according to the Hawkins classification (Illustration A). Higher classification injuries are associated with a higher rate of avascular necrosis. Treatment for displaced fractures (Hawkins II-IV injuries) is open reduction and internal fixation. Unfortunately, owing to the high-energy nature of the injury and the tenuous blood supply to the talus, these injuries are fraught with complications. Almost all patients go on to develop subtalar arthritis, and AVN develops in 20 - 100% of patients with Hawkins III and IV fracture patterns. Intact vascularity can be assessed with a mortise radiograph 6-8 weeks after injury. The presence of a subchondral lucency indicates active resorption of subchondral bone and thus, intact vascularity (Illustration B).

Valier et al. retrospectively reviewed surgical outcomes of patients with talar neck and/or body fractures. They report on 56 patients, 23 of which had a talar neck fracture. The average follow-up was 33 months. 88% of patients with complete postoperative radiographs had evidence of osteonecrosis and/or posttraumatic arthritis. Patients with combined talar body and neck fractures or with open fractures had higher rates of osteonecrosis or advanced arthritis when compared to talar body fractures alone.

Canale and Kelly Jr. retrospectively reviewed patients who underwent open reduction and internal fixation of talar neck fractures. They report on 71 patients with a mean follow-up of 12.7 years. Good or excellent outcomes were achieved in 59% of patients. They note that anatomic reduction is a critical component of operative management of these injuries. Overall, they observed AVN in 52% of fractures and noted increasing rates of AVN as displacement increased.

Whitaker et al. present a current concepts review surrounding the operative treatment of talar neck fractures. They assert that definitive fixation should be delayed until the soft tissue envelope is favorable, as fixation too soon can lead to unacceptable rates of infection and wound dehiscence. Even with appropriate soft tissue handling and surgical timing, wound healing complication rates still approach 10%.

Vallier performed a comprehensive review of the literature on the treatment and outcomes of talus fractures. She notes that the rates of wound healing complications, to include dehiscence, skin necrosis and infection, approaches 77% in acutely treated fractures. Delayed definitive fixation has a marked effect on these complications, with wound healing and infection rates dropping to 2-10% in definitively treated fractures. As a result, she asserts that delayed definitive fixation is preferred for most talar neck and body fractures.

Figure A demonstrates a Hawkins III talar neck fracture, with associated subtalar and tibiotalar dislocation.

Illustration A is an outline of the Hawkins classification. Illustration B is a labeled radiograph demonstrating the Hawkins sign, which is an indication of intact vascularity.

Incorrect Answers:
Answer 2: Varus malunion occurs in fractures that are malreduced intraoperatively and fixed in nonanatomic alignment. There is no association between acute fixation and rates of varus malunion.
Answer 3: Rates of osteonecrosis are dependent on the original amount of displacement. A higher Hawkins classification portends a higher rate of subsequent AVN.
Answer 4: Rates of subsequent subtalar osteoarthritis are not correlated with surgical timing.
Answer 5: Acute treatment of talar neck fractures is associated with higher, not lower, rates of wound dehiscence.