This review article provides an overview of talus fractures. Special attention is given to the clinical literature that evaluates the timing of surgical management for displaced talus fractures. Several series support delayed definitive fixation for talus fractures, suggesting displaced fractures do not necessitate emergent surgical fixation.
Key points
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This article gives special attention to the clinical literature that evaluates the timing of surgical management for displaced talus fractures.
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Despite surgical fixation, high complication rates accompany displaced talar fractures, creating significant patient morbidity.
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Contrary to historical recommendations, delayed fixation for displaced talar fractures produces satisfactory outcomes, suggesting displaced fractures do not necessitate emergent surgical treatment.
Introduction
As the osseous link between the foot and leg, the talus is essential for normal gait mechanics. It involves both the ankle and the subtalar joint complexes through multiple articular surfaces with the fibula, tibia, calcaneus, and navicular. The talus consists of 3 main sections (body, head, and neck) and 2 processes (lateral and posterior processes). The posterior process is composed of 2 tubercles (posteromedial and posterolateral tubercles). Articular cartilage covers more than 65% of the talar surface, and no tendon or muscle attachments originate from the talus. With its many articulations, fractures frequently lead to posttraumatic arthrosis, and malunions alter mechanics, creating disability. The exta-articular surface allows for ligamentous and capsular attachments and entrance for the extraosseous blood supply. Traveling through these limited soft tissue attachments, the extraosseous blood supply is at risk for injury, making the talus prone to osteonecrosis. Talar injuries cause significant patient morbidity, highlighting the importance of effective and efficient treatment to minimize resultant complications.
High-energy mechanisms such as falls from a height or motor vehicle accidents account for most fractures, but low-energy mechanisms, such as sports injuries, have also been reported. Because of the distraction of other injuries in critically ill patients or the decreased awareness in unsuspecting sport injuries, talus fractures may be undiagnosed on initial presentation. Clinicians must maintain a high index of suspicion for any patient presenting with hindfoot pain after an acute injury. These patients should have a detailed history and physical examination plus dedicated foot and ankle radiographs, and any radiographic irregularities should prompt a computed tomographic (CT) scan to better identify and characterize talar fractures.
Introduction
As the osseous link between the foot and leg, the talus is essential for normal gait mechanics. It involves both the ankle and the subtalar joint complexes through multiple articular surfaces with the fibula, tibia, calcaneus, and navicular. The talus consists of 3 main sections (body, head, and neck) and 2 processes (lateral and posterior processes). The posterior process is composed of 2 tubercles (posteromedial and posterolateral tubercles). Articular cartilage covers more than 65% of the talar surface, and no tendon or muscle attachments originate from the talus. With its many articulations, fractures frequently lead to posttraumatic arthrosis, and malunions alter mechanics, creating disability. The exta-articular surface allows for ligamentous and capsular attachments and entrance for the extraosseous blood supply. Traveling through these limited soft tissue attachments, the extraosseous blood supply is at risk for injury, making the talus prone to osteonecrosis. Talar injuries cause significant patient morbidity, highlighting the importance of effective and efficient treatment to minimize resultant complications.
High-energy mechanisms such as falls from a height or motor vehicle accidents account for most fractures, but low-energy mechanisms, such as sports injuries, have also been reported. Because of the distraction of other injuries in critically ill patients or the decreased awareness in unsuspecting sport injuries, talus fractures may be undiagnosed on initial presentation. Clinicians must maintain a high index of suspicion for any patient presenting with hindfoot pain after an acute injury. These patients should have a detailed history and physical examination plus dedicated foot and ankle radiographs, and any radiographic irregularities should prompt a computed tomographic (CT) scan to better identify and characterize talar fractures.
Talus blood supply
With osteonecrosis commonly reported as a complication in talar injuries, the blood supply of the talus has been extensively researched. The extraosseous blood supply includes branches from the posterior tibial artery (artery of the tarsal canal, deltoid branches), branches from anterior tibial artery (dorsalis pedis branches), and branches from the peroneal artery (posterior tubercle branches, artery of tarsal sinus). The artery of the tarsal canal (branch of the posterior tibial artery) gives off the deltoid branches supplying the medial talar body. The artery of the tarsal canal continues distally to join the artery of the tarsal sinus (branch of the peroneal artery) forming an important anastomosis inferior to the talar. Branches from this anastomosis enter the inferior neck supplying a significant portion of the talar body. Dorsalis pedis branches (branch of the anterior tibial artery) enter the dorsal neck supplying most of the talar neck and a portion of the talar head. The talar head is further supplied from the artery of the tarsal canal (branch of the peroneal artery). Last, the posterior tubercle branches (branch of the peroneal artery) contribute to the posterior process ( Fig. 1 ).
Fracture classification
The Orthopedic Trauma Association (OTA) has extensively classified talus fractures, in which the fractures are divided into head fractures (81-A), neck fractures (81-B), and body fractures (81-C). Included in the head fracture category, avulsion and process fractures also receive the 81-A designation. Talar neck fractures are further divided into nondisplaced fractures (81-B1), fractures with subtalar joint incongruity (81-B2), and fractures with subtalar and tibiotalar joint incongruity (81-B3). Body fractures are divided into talar dome fractures (81-C1), talar body fractures with subtalar joint involvement (B1-C2), and body fractures with subtalar and tibiotalar joint involvement (81-C3). Fractures of the talar head, neck, and body are further classified according to comminution. Talar neck fractures are also commonly classified according to Hawkins, which is further discussed with talar neck fractures.
Talar head fractures
Talar head fractures are very uncommon, accounting for less than 10% of all talus fractures, and there is limited clinical research that assessed these fractures. Compression and shear forces have been described as mechanisms for injury. Forefoot impaction forces along the medial column create compression fractures, and navicular shear forces resultant from midfoot adduction create shear fractures to the medial talar head. Radiographic evaluation should routinely involve anterior-to-posterior (AP), oblique, and lateral foot radiographs. These fractures may be difficult to see on radiographs, particularly the plantar portion of the talar head. Any irregularities on radiographs should elicit advanced imaging.
The principles of treatment include maintenance of the medial column length and height, and restoring talonavicular joint congruity, stability, and motion. Nondisplaced fractures with a stable joint may be treated conservatively with immobilization and non-weight-bearing for 4 to 6 weeks, but displaced fractures or joint instability requires operative treatment. Small comminuted fractures may be excised to restore talonavicular motion, but larger fragments are stabilized with headless screws, mini-fragment screws, or bioabsorbable implants ( Fig. 2 ). Minimizing dorsal dissection, dorsal, or medial approaches are used depending on the fracture location. Unlike neck and body fractures, osteonecrosis is uncommon in talar head fractures, but posttraumatic arthritis is a likely complication following intra-articular fractures.
Talar neck fractures
The area designated as the talar neck lies between the talar head and body (lateral process). This area is commonly injured, accounting for nearly half of all significant injuries to the talus. Unlike most of the talus, the neck is void of articular cartilage, providing a site for soft tissue attachments and vascular foramen. Adjacent to the inferior talar neck, the artery of the tarsal canal joins the artery of the tarsal sinus forming an important anastomosis. The close proximity of this anastomosis to the talar neck makes it vulnerable to injury with neck fractures, explaining the common complication of osteonecrosis.
As aforementioned, the OTA categorizes talar neck fractures according displacement and subtalar joint congruity, but before the OTA classification, Hawkins classified talar neck fractures in 1970. The Hawkins classification is still the most commonly used nomenclature to describe talar neck fractures. A Hawkins type I refers to a nondisplaced fracture of the talar neck. In a Hawkins type II, the neck fracture is accompanied by subtalar joint subluxation or dislocation. Type II fractures are the most common. Talar neck fractures with tibiotalar and subtalar incongruity represent Hawkins type III fractures. Last, Canale and Kelly added the type IV modification, in which neck fractures are accompanied with complete talar dislocations (ie, tibiotalar, talonavicular, and subtalar joint incongruity) ( Fig. 3 ). Osteonecrosis has been reported in type II fractures as high as 40% to 50%, and in type III and IV fractures as high as 100%. Recently, Vallier and colleagues suggested a modification of the Hawkins type II fracture, adding types IIA and IIB. In type IIA, the subtalar joint is mildly subluxated, and in type IIB, the subtalar joint is dislocated. Of 19 Hawkins type IIA fractures, none developed osteonecrosis, but 25% (4/16) of IIB fractures developed avascular necrosis (AVN).
For completely nondisplaced fractures (Hawkins type I), treatment consists of immobilization and non-weight-bearing for 6 weeks or until radiographic union. If the fracture line is easily visible on radiographs, then the fracture should be appropriately classified as a Hawkins type II, and conservative treatment is not recommended. For any displaced neck fractures, anatomic reduction and rigid fixation are recommended. Complete joint dislocations require immediate closed reductions, but, as discussed separately, definitive fixation can be delayed. Surgical approaches typically include dual incisions medially and laterally, but in simple, noncomminuted fractures, a percutaneous or single approach may be used. In addition, a posterolateral approach (open or percutaneous) may be added for posterior-to-anterior (PA) screw fixation ( Fig. 4 ).
Fixation techniques include the use of small and mini-fragment lag screws (headed and headless) for noncomminuted fractures. With comminuted fractures, the surgeon should avoid fracture compression (ie, shortening malunion) by using length-preserving screw techniques or small plates. Screws can be used in an AP or PA direction. PA screws generally provide fixation at an angle more perpendicular to the fracture line, but PA screws also require additional exposure posterolaterally, adding increased dissection and difficulty in the supine position. With distal neck fractures, AP screws commonly require entrance through the talar head articular surface. By way of countersink techniques or headless implants, the talonavicular joint must remain free of hardware impingement ( Fig. 5 ). Even with surgical treatment, complications include osteonecrosis, malunion, nonunion, and posttraumatic arthritis. Open injuries, displacement, and comminution negatively impact outcomes.
Talar body fractures
Talar body fractures are defined as any fracture line at or posterior to the lateral tubercle of the talus. Talar body fractures account for 7% to 38% of all talar injuries. The mechanism of injury typically involves high-energy compression between the tibial plafond and the calcaneus, but low-energy shearing forces can also generate body fractures. Corresponding with the high-energy mechanisms, open injuries are common, occurring in roughly 20% of body fractures. Talar body fractures include lateral and posterior process fractures, which are discussed separately.
Treatment goals include restoration of stability and congruity for the tibiotalar and subtalar joints. For displaced fractures, anatomic reduction and internal fixation are indicated. The reduction can be achieved through percutaneous, arthroscopic, or open approaches. A variety of approaches (lateral, medial, posterolateral, or posteromedial) may be used to achieve optimal visualization and reduction. Furthermore, medial or lateral malleoli osteotomies may be needed to visualize the talar dome reduction ( Fig. 6 ). Despite surgical treatment, osteonecrosis, posttraumatic arthritis, and malunion are common sequelae.
