Rockwood & Green’s Fractures in Adults
6th Edition

Chapter 54
Fractures of the Talus
David W. Sanders
Fractures of the talus are difficult injuries. Talus fractures are renowned for the high incidence of unsatisfactory results, owing to the comparatively frequent incidence of serious complications such as osteonecrosis. Since the early descriptions by Anderson and others of the “aviator’s astragalus,” fractures of the talus have earned a reputation as a problematic fracture (1).
Over time, the understanding of talus fractures has evolved such that orthopaedic surgeons are now well aware of the inherent dangers of this injury. Surgical techniques, timing, and instrumentation have changed. Many of the surgical implants in common use to stabilize talus fractures were not available in past years. Similarly, our understanding of the biology of bone
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repair and the vascular supply to the talus has grown. Nonetheless, talus fractures remain one of the most interesting and difficult injuries in foot and ankle trauma.
PRINCIPLES OF MANAGEMENT
Fractures of the talus are generally thought to be relatively uncommon. However, the talus is the second most commonly fractured tarsal bone. Improved recognition has resulted in an increased number of talar process fractures being diagnosed. Coltart reviewed 228 talus fractures and noted that chip and avulsion injuries were most common, followed by fractures of the talar neck (2).
Mechanism of Injury
Most serious fractures of the talus are high-energy injuries. Fractures of the talar neck are commonly the result of a hyperdorsiflexion-type injury. Following World War I, Anderson, the consultant surgeon to the Royal Flying Corps, described the aviators’ astragalus (1). Pilots resting the sole of the foot on the rudder bar at the time of impact commonly sustained a hyperdorsiflexion force such that talar neck fractures were relatively common. Flying accidents were also common in the description by Coltart (2). Currently, motor vehicle collisions and falls from a height are more common mechanisms of serious talus fractures.
The mechanism of progressive hyperdorsiflexion forces was described by Penny and Davis (3), as follows:
With dorsiflexion, initially the posterior capsular ligaments of the subtalar joint rupture, the neck of the talus impacts against the leading anterior edge of the distal tibia, and a fracture line develops at this point and enters the nonarticular portion of the subtalar joint between the middle facet and the posterior facet. With a continuation of the dorsiflexion force the calcaneus with the rest of the foot and including the head of the talus subluxes forward. If there is a concomitant inversion component to the force, the foot may sublux or dislocate medially (if there is a concomitant eversion force, the foot dislocates laterally). If the force subsides at this moment, the foot recoils, the body of the talus tips into equinus and the fracture surface of the neck comes to ride on the upper surface of the os calcis. A continuation of the dorsiflexion force, however, produces further rupture of the posterior ankle capsular ligaments, the strong posterior talofibular ligament, and the superficial and posterior aspects of the deltoid ligament…. The body of the talus is then wedged posteriorly and medially out of the mortise and rotates around a horizontal and transverse axis so that the fracture surface faces upwards and laterally. This is a constant position for the body when there has been dislocation of the body out of the mortise occurring because of the direction of the posterior facet of the subtalar joint, and because the talus pivots around the intact deep fibers of the deltoid ligament and flexor hallucis longus tendon. The body of the talus then comes to lie in the interval between the posterior aspect of the medial malleolus and the anterior aspect of the tendo Achillis. It may be tightly jammed behind the medial malleolus, which is often concomitantly fractured, and the sustentaculum tali. The posterior tibial neurovascular structures almost invariably evade injury by this mechanism, lying anterior to and being protected by the flexor hallucis longus tendon.
In a laboratory study, however, Peterson et al applied a dorsiflexion force to cadaveric specimens and were unable to produce a talar neck fracture. Rather, the typical pattern of talar neck fracture was achieved by the application of an axial load to the plantar surface of the foot when the body of the talus was fixed as a cantilever between the tibia and the calcaneus (4).
Low-energy injuries can also result in talus fractures. Fractures of the lateral and posteromedial processes of the talus can result from inversion and eversion mechanisms such as are commonly seen in sports injuries. Subtalar dislocations are often seen in conjunction with sports injuries and can vary with respect to the severity of the mechanism of injury. In the case of subtalar dislocations, the energy applied at the time of the injury is often predictive of the ultimate result.
On occasion, talus fractures can be associated with neuropathic joints. Although a Charcot foot (5) associated with a talus fracture is relatively uncommon, when it does occur it can be difficult to manage. Typically, the midfoot progressively dorsiflexes relative to the body of the talus, resulting in significant loss of ankle motion and deformity of the hindfoot. As is the case with a Charcot midfoot, the talar body can eventually become prominent medially and even progress towards dislocation.
Fractures of the talar neck and body are often seen in conjunction with one another. In this case the proposed mechanism of injury relates more to axial load than to the specific position of the foot. However, dorsiflexion is usually an associated mechanism. Fractures of the talar body are commonly associated with fractures of the tibial plafond, in particular, involving the medial and lateral malleoli. Virtually all fractures of the talar body as well as combined injuries of the neck and body are high-energy injuries.
Signs and Symptoms
In comparison to other lower extremity injuries, fractures of the talus are relatively uncommon. Perhaps 2% of all lower extremity injuries and 5% to 7% of foot injuries involve fractures of the talus. Missed injuries can occur, especially injuries involving the processes of the talus. Talus fractures frequently occur in a young, active, and mobile population.
A high index of suspicion is required for the detection of talar process fractures, in particular, in conjunction with ankle sprain type mechanisms involving inversion or eversion as these injuries can be difficult to appreciate on routine radiographs. In many cases, more advanced imaging is required for the detection of relatively subtle fractures. Fractures of the talus can occur from relatively low-energy mechanisms or major trauma and in all cases can be a disabling injury if not treated expeditiously.
Injuries to the soft tissue envelope are seen in conjunction with talar fractures on occasion. Open talus fractures are usually associated with high-grade fracture dislocations such as Hawkins
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Type III injuries, in which the talar body can be extruded posteromedially and wrapped around the deltoid ligament (6). In all high-energy talar fractures significant compromise of the soft tissue envelop is common, although the injury does not always penetrate the skin. When the talus fracture is open, the situation can be even more devastating. In some cases the talar body can be completely extruded as all soft tissues can be detached from the bone (7). The talar body may even be left at the scene of the accident. Management of this particular injury, the extruded or absent talus, is indeed challenging.
Because of the frequent association of dislocations with talar neck fractures and because the soft tissue envelope of the hindfoot is at risk, an urgent reduction is mandatory to minimize additional soft tissue injury and skin necrosis. Emergent reduction of the dislocated talus is one of the key principles in the management of fractures of the talus.
Neurovascular injury associated with talus fractures can occur. Frequently, however, even when the talus is dislocated posteromedially relative protection of the neurovascular bundle is afforded by the flexor hallucis longus tendon such that the posterior tibial nerve and vessel are usually intact (8). Vascular injury to the talus itself, however, is frequently noted and is the frequent predisposing factor associated with osteonecrosis of the talus. For example, when the talus is dislocated posteromedially, the arteries of the tarsal sinus and tarsal canal are usually disrupted, as are the dorsal neck branches such that the only remaining vascular supply to the talar body may be through the deltoid ligament.
Although perfusion to the foot is usually seen to be intact in conjunction with talar fractures, it may at times be injured. Talus fractures can be associated with all types of midfoot and forefoot fractures depending on the mechanism of injury, particularly in a fall from a height, or a major motor vehicle collision. In fractures associated with severe soft tissue injury, neurovascular injury may be severe. An accurate assessment of the vascular and neurologic status of the foot is an important principle in the initial management of these injuries.
Associated Injuries
Talus fractures are commonly associated with other musculoskeletal injuries and systemic trauma. Because the fractures occur secondary to high-energy mechanisms, management of the talus fracture in the multiply injured patient can be difficult. An important principle remains emergent reduction of dislocated joints whenever possible. Stabilization of the fractures and dislocations facilitates management of the soft tissues (8,9,10). However, in some cases the multisystem injury is so severe that treatment of the talus fracture is by necessity delayed. Nonetheless a good result for the talus fracture can still be seen, even when appropriate orthopedic intervention is delayed.
In the multiply injured patient, appropriate initial assessment is critical and following the Advanced Trauma Life Support (ATLS) protocols for management is essential. Where possible, an emergent reduction of dislocated joints can be performed followed by application of an external fixator (11,12) or internal fixation (13) if the patient has been adequately resuscitated. Foot injuries are among the most commonly missed injuries in the multiply-injured patient (14) and therefore once again a high index of suspicion is required. In one series of talar fractures from a level I trauma center, 31 out of 70 fractures occurred in multiple trauma patients with an Injury Severity Score greater than 16, and 41 of 70 fractures were associated with other ipsilateral lower extremity injuries suggestive of the common association of multiple trauma and ipsilateral injuries in patients with fractures of the talar neck (15).
Other high-energy foot injuries may be associated with talus fracture-dislocations, particularly in the multiply-injured patients or in patients with a fall from a height or major motor vehicle trauma. High-energy foot injuries should be managed in conjunction with the talus fracture such that early reduction and stabilization of all dislocated joints can be achieved (16,17). In many cases, the management of dislocated joints, as well as management of soft tissue problems, may preclude further definitive fixation or internal fixation of fractures; however, where possible early stabilization of the joints is preferred (18). High-energy foot injuries seem to be increasing in frequency in part related to the increasing use of air bags in motor vehicles. With the improved survival of patients who previously may have died from chest, head, and visceral injuries, serious trauma to the foot, ankle, and lower extremity is more commonly noted. These foot injuries can be devastating in terms of long-term outcome for the patient.
Associated fractures of the foot and ankle are commonly seen with fractures of the talar neck and body. In a recent study by Vallier et al., associated foot and ankle fractures occurred in 44 of 100 patients (19). Talus fractures are frequently associated with tibial plafond and malleolar fractures. The incidence of associated malleolar injury ranged from 19% to 28% in prior studies (20,21). Fractures of the distal tibia and fibula can be addressed in conjunction with the talus fracture and may even afford a means of exposure of the talar body through the malleolar injury. A 10% incidence of calcaneal fractures has been reported in conjunction with talar neck fractures (19). Tibiofibular diastasis has also been found in conjunction with talar neck fractures (22).
Surgical Timing and Principles
Displaced fractures of the talar neck and body are best treated as orthopaedic emergencies. Reduction of dislocated joints is critical to maintain vascularity to the talar body where possible and to reduce tension on the skin, soft tissues, and associated neurovascular structures around the foot and ankle. Delayed treatment is preferably avoided. However, when delayed treatment is an unfortunate necessity due to a deteriorating condition of the patient, a prolonged delay in transfer, or other reasons,
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immediate management should still include reduction of dislocations wherever possible.
Open talus fractures are also surgical emergencies in terms of appropriate debridement of contaminated or devitalized tissue.
The principles of surgery are to obtain an anatomic reduction of the talar neck fracture and associated joints, and to achieve sufficient stabilization such that early motion can be facilitated. A variety of surgical techniques are available to accomplish these principles. Emergent reduction of dislocated joints, urgent anatomic fracture reduction and stabilization, and maintaining an intact vascular supply and soft tissue envelope provide the best probability of regaining an excellent functional result.
Diagnosis and Classification
Plain Radiographic Views
Because of its unique shape and associated processes, a variety of plain radiographic views are important to visualize the talus. Standard anteroposterior (AP), lateral and mortise views of the ankle are essential to assess fractures of the talar body, talar neck, and associated processes. However, in many cases, standard plain radiographic views are inadequate to demonstrate relatively subtle fractures of the talus and to give adequate visualization of comminution and alignment. Canale and Kelly described a view of the talar neck achieved by internal rotation of the foot, achieved by placing the foot plantigrade on an x-ray film and angling the beam at 75 degrees to the perpendicular (20). Pronation of the foot or internal rotation of the limb will achieve rotation of the talus such that the medial aspect of the talar neck can be well visualized. This view is particularly useful intraoperatively to assess the reconstruction of a talar neck fracture with associated medial comminution and to confirm that varus malalignment has been avoided (Fig. 54-1).
Additional useful views include a lateral view of the calcaneus as associated fractures of the posterior facet can often be seen. As well, achieving a true lateral view of the subtalar joint can be beneficial to assess for comminution and subluxation (Fig. 54-2).
FIGURE 54-1 Canale and Kelly view of the foot. The correct position of the foot for x-ray evaluation of the foot is shown.
Computed Tomography and Magnetic Resonance Imaging
Computed tomography (CT) scans are very useful in the assessment of talar fractures and dislocations. CT scans give excellent visualization of the congruity of the subtalar joint reduction, and provide superior detail compared with plain films. Comminuted fractures of the talus as well as fractures involving the inferior aspect of the talus extending into the subtalar joint benefit from the improved detail noted with CT scans as these regions may be especially difficult to visualize on plain films. CT scans, however, are less useful at defining the overall alignment of the talus because of the unusual shape of the bone.
The routine use of computed tomography to assess comminuted talar fractures for congruency of reduction can be very useful similarly to assess subtalar dislocations. Subtalar dislocations are often associated with small but significant fractures of the inferior aspect of the talus, which are better appreciated on CT scans compared to plain films alone.
Magnetic resonance imaging (MRI) has an important role in the assessment of talar fractures (23,24). MRI is a useful measure of osteonecrosis. Previously MRI has been subject to artifact from the placement of significant volume of stainless steel screws. This problem is lessened when titanium implants are used for fracture fixation. Improved MRI technology has lessened the degree of metallic artifact, such that MR imaging may still provide useful information when significant amounts of hardware are in place.
Classification of Talar Neck Fractures
Fractures of the talus are a heterogeneous group of injuries. Varying in severity from devastating to trivial, these injuries necessarily are grouped in several distinct classifications. The most clinically useful general classification separates talus injuries into fractures of the talar neck, the talar body, the talar head and the talar processes. Subtalar dislocations are usually considered separately. Each of these anatomic regions may be subclassified and will be discussed in the appropriate section of this chapter. The most well known classification refers to talar neck fractures.
The most commonly used classification for talar neck fractures is that described by Hawkins (6) with the modifications suggested by Canale and Kelly (20). In the Hawkins classification, a Type I fracture refers to a fracture without associated joint dislocation, that is, an undisplaced fracture of the talar neck (Fig. 54-3). As noted by Daniels, “There is no room for the term ‘a minimally displaced Type 1 talar neck fracture’” (25). In equivocal cases, careful attention should be directed to the reduction of the subtalar joint to confirm that there is in
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fact no degree of subtle incongruity; and to the clinical exam, as most slightly displaced talar neck fractures are associated with malalignment. Often the talar head is rotated relative to the talar body, such that supination of the midfoot and forefoot relative to the hindfoot can be noted.
FIGURE 54-2 Intraoperative fluoroscopic evaluation of the talus. A. A Canale and Kelly view and lateral image of the subtalar joint, and (B) shows lateral and anteroposterior views of the ankle in a talar neck fracture with an associated lateral process fracture.
The Hawkins II fracture refers to a talar neck fracture with associated dislocation of the subtalar joint (Fig. 54-4). This is perhaps the most common type of talar neck fracture dislocation and in some cases is amenable to closed reduction. While osteonecrosis of the body of the talus in Hawkins Type I fractures is relatively rare, perhaps 15%, the incidence of osteonecrosis in Type II fractures ranges as high as 40% to 50% (20).
A Hawkins Type III fracture involves a dislocation at the ankle as well as at the subtalar joint (Fig. 54-5). In this case, osteonecrosis is the rule rather than the exception with rates of nearly 100% (20). In the series by Hawkins (6) as well as Canale and Kelly (20), with Hawkins III fractures the body is commonly dislocated posteromedially, although alternate directions can be noted. With the posteromedial dislocation, the fracture can be rotated completely around the deep fibers of the deltoid ligament and may be directed posterior to the long flexors of the foot. These injuries are most commonly irreducible by closed means.
The Hawkins Type IV fracture was described by Canale and Kelly and implies associated subluxation or dislocation of the talonavicular joint (Fig. 54-6). These injuries are relatively uncommon compared to the Hawkins Type II and III fracture dislocations. The quoted rate of osteonecrosis remains close to
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100%. Some authors have grouped comminuted fractures of the talus associated with high-energy foot injuries into the Hawkins IV classification to imply a worse prognosis and because these injuries are difficult to fit into the classification elsewhere. Pantazopoulos et al described an interesting case in which the talar neck fracture was associated with a dislocation of the talar head, but the body remained reduced. This injury was classified as a Hawkins type 4 talar neck fracture (26).
FIGURE 54-3 Nondisplaced vertical fracture of the talar neck, Hawkins type 1.
The AO/OTA classification of talus fractures is comprehensive, although somewhat more complicated and difficult to use. According to the Orthopedic Trauma Association, Fracture and Dislocation compendium, talus fractures are divided into extra-articular (72-A), partial articular (72-B), and articular (72-C) injuries (Fig. 54-7). Extra-articular injuries include neck fractures and avulsion fractures. Neck fractures are subdivided into simple fractures, multifragmentary fractures, and fractures associated
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with dislocations. Avulsion fractures include fractures of the lateral and posterior processes. Partial articular fractures include split and/or depressed fractures of the lateral, medial, or posterior segments of the talar body. Articular fractures include fractures of the talar neck with extension into the body, and multi-fragmentary fractures of the talar body with fracture lines in multiple planes, including both displaced and undisplaced fractures (27).
FIGURE 54-4 Displaced Hawkins Type II fracture of the talar neck with subluxation (left) and dislocation (right) of the subtalar joint.
FIGURE 54-5 Displaced fracture of the talar neck with dislocation of both the subtalar and tibiotalar joints (Hawkins Type III).
FIGURE 54-6 Type IV fracture of the talar neck with subluxation of the subtalar joint and dislocation of the talonavicular joint.
Although the Hawkins classification is commonly applied to talar neck fractures and is predictive of rates of osteonecrosis, other important prognostic factors include fracture comminution. Like the Hawkins classification, comminution may be reflective of the energy absorbed at the time of injury. In two recent large series of talar neck fractures, comminution was predictive of outcome independent of Hawkins classification (15,19). Although there is no universally applied grading system for comminution, the presence of severe comminution implies more energy imparted to the fracture, and may suggest a worse prognosis and outcome.
FIGURE 54-7 The AO/OTA classification of talus fractures. (Orthopaedic Trauma Association. Fracture and Dislocation Compendium [27].
SURGICAL AND APPLIED ANATOMY
Osteology and Articular Surfaces
The talus is unique in that the majority of its surface is covered in articular cartilage (28). Although there are multiple capsular and ligamentous sites of attachment no muscles attach to the talus itself (29). Therefore, blood vessels penetrating the talus traverse regions of articular capsule and synovial membrane in which they are vulnerable to trauma. Because of the lack of muscular soft tissue attachments, and due to the limited space available for vascular foramina, the talus is particularly predisposed to difficulties with blood supply. Trauma associated with capsular or ligamentous disruption may be complicated by osteonecrosis of the body of the talus.
The trochlea, or superior surface, supports the body weight and transmits loads to the inferior aspect of the tibial plafond. The surface is wider anteriorly compared to posteriorly such that the medial and lateral sides of the trochlea converge in a posterior direction. Medially and laterally the articular cartilage extends plantarward to articulate with the medial and lateral malleoli. The inferior side of the talus is also predominantly covered by cartilage to form the articulation with the posterior facet of the calcaneus. Swanson described an increase in bone density in the lateral aspect of the talar head and inferolateral aspect of the talar body compared with the medial bone support (Fig. 54-8) (30).
The neck of the talus has less cartilaginous coverage than the remainder of the talus (Fig. 54-9). Multiple vascular foramina exist, particularly on the dorsal neck where capsular and ligamentous attachments originate. The neck of the talus deviates medially by about 15 to 20 degrees. This part of the bone is more susceptible to fracture compared to the body of the talus. The head of the talus has rounded cartilaginous facets to articulate with the navicular anteriorly. The spring ligament
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wraps around the inferior aspect of the talar head and the deltoid ligament attaches to the medial aspect of the talar body. There is a wide area of attachment for the deltoid ligament extending from the talar body onto the medial aspect of the neck.
FIGURE 54-8 Superior and inferior views of the talus (stippling indicates the posterior and lateral processes).
The lateral process of the talus is wedge shaped. Its inferior medial surface forms the lateral third of the talar articulation with the posterior facet of the calcaneus. Its superior lateral surface forms the articulation with the distal end of the fibula. It is vulnerable to fracture as an isolated injury or associated with fractures of the talar body. The posterior process of the talus is derived from two tubercles. The medial tubercle and the lateral tubercle are separated by a groove, within which courses the flexor hallus longus tendon. The os trigonum may exist as a separate ossicle or be fused with the lateral tubercle of the posterior process. The os trigonum is present in 50% of normal feet (31). This small ossicle arises from a separate ossification center just posterior to the lateral tubercle.
FIGURE 54-9 Superior view of the right talus demonstrating the convergence of the sides of the trochlear surface and the vascular foramina on the neck. (After Giannestras NJ. Foot disorders: Medical and surgical management, 2nd ed. Philadelphia: Lea and Febiger; 1973.)
Blood Supply of the Talus
The blood supply of the talus has been extensively investigated (7,28,29,32,33,34,35,36,37,38,39). The talus is 60% covered by articular cartilage (28). As a result, a very limited surface area is available to provide adequate vascular perforation. Blood vessels enter the talus via capsular and ligamentous attachments and are therefore vulnerable to injury such that osteonecrosis can be a complication of many fractures and dislocations of the talus.
Understanding of the talar circulation is ascribed to Wildenauer (39) who described the critical anastomotic sling of vessels in the tarsal sinus and tarsal canal, lying inferior to the neck of the talus. Within the tarsal canal and the tarsal sinus, the critical anastomosis perforates the inferior neck to form the primary source of blood supply to the body of the talus. The tarsal sinus is bounded by the calcaneus inferiorly, the body of the talus posteriorly and the talar head and neck anteriorly. The tarsal canal lies between the talus and calcaneus just behind and below the tip of the medial malleolus. The tarsal sinus and tarsal canal can be likened to a funnel. Kelly and Sullivan compare the tarsal sinus to the cone of the funnel and the tarsal canal the tube of the funnel (Fig. 54-10) (28). The
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artery to the sinus tarsi and the artery of the tarsal canal form an anastomotic sling inferior to the talus from which branches arise to enter the talar neck area.
FIGURE 54-10 The anastomotic sling of vessels that provides the blood supply to the body of the talus. Laterally, the artery of the tarsal sinus (a); medially, the artery of the tarsal canal (b). Additional arteries enter dorsally through the neck and on the medial surface of the body (c). (Kelly PJ, Sullivan CR. Blood supply of the talus. Clin Orthop 1963;30:38.)
The artery of the tarsal canal arises from the posterior tibial artery. This branch arises just proximal to the origin of the medial and lateral plantar arteries (36). The deltoid branches arise from the artery of the tarsal canal and supply the medial third of the talar body (32). From the anterior tibial, or dorsalis pedis artery, come multiple branches to the dorsal aspect of the talar neck. An additional branch may form a significant contribution to the artery of the sinus tarsi. From the peroneal artery come branches to the posterior process and a branch to form the artery of the sinus tarsi. Peterson and colleagues emphasized the important contribution of additional capsular and ligamentous vessels adjoining the talus with the navicular, the calcaneus and even the tibia through capsular and ligamentous attachments (38). Interosseus communications between the major arterial supplies to the talus have also been demonstrated (32).
The talar body therefore receives most of its blood supply from the anastomotic sling in the tarsal canal and sinus. Many branches of the sling enter the neck and course posterolaterally. Additional blood supply originates from the deltoid branches of the posterior tibial artery and contributes significantly to the medial third of the talus. Branches of the peroneal artery may make a minor contribution posteriorly, around the posterior process.
The talar head is nursed by branches of the dorsalis pedis arising from the dorsal neck vessels and also from the artery of the tarsal sinus. Peterson and Goldie demonstrated that undisplaced fractures of the talar neck are associated with intraosseus disruption of the branches of the arteries of the tarsal sinus and tarsal canal (37). However, the major vascular sling should remain intact. With increasing displacement, branches from the dorsalis pedis artery as well as the artery of the tarsal canal and artery of the tarsal sinus can be disrupted. These findings confirm the clinical observation that the rate of osteonecrosis depends upon the degree of fracture displacement (6,20).
TALAR NECK FRACTURES
Current Treatment Options
Outcome following talar neck fracture is most dependent on the development of complications. These include, in particular, osteonecrosis of the talar body, osteoarthritis of the subtalar joint and the ankle joint, delayed union, nonunion, malunion, and infection. Treatment should be directed to an early anatomic reduction of the talar neck fracture and, where possible, avoidance of complications.
Nonoperative Management
Nonoperative management has a limited role in fractures of the talar neck. Only those fractures in which there is no displacement of the fracture line and no incongruity of the subtalar joint can potentially be treated nonoperatively. According to the Hawkins classification system, only type 1 fractures can be treated nonoperatively. When nonoperative treatment is selected as the treatment modality, confirmation of the anatomically maintained reduction should be obtained with a CT scan or other advanced imaging technique. As stated by Daniels and Smith, “There is no room for the term ‘a minimally displaced Type I talar neck fracture’” (25). In other words, fractures which appear to be even slightly displaced are also associated with incongruity of the subtalar joint and therefore should be classified as Type II fractures and require anatomic reduction.
Nonoperative management of the undisplaced talar neck fracture includes nonweight-bearing short leg cast immobilization, for 8 to 12 weeks or until clinical and x-ray signs of fracture healing are present. Nonweight-bearing is required for the first 4 to 6 weeks of treatment (2,6,20,25,40,41,42,43,44,45,46,47).
Closed Reduction
Closed reduction can be performed for fractures of the talar neck; however, closed reduction can be very difficult to achieve such that it is often preferable to proceed directly to open reduction and internal fixation. However, when operative intervention will be delayed, and in some cases of Type II fractures in particular, closed reduction can be a successful technique of initial treatment (Fig. 54-11).
Obtaining a successful closed reduction requires adequate analgesia and frequently general anesthesia. The essential technique involves bringing the foot, including the talar head, to the residual talar body fragment. This requires the talar body to be reduced within the ankle mortise. In the Type II fracture with subluxation or dislocation of the subtalar joint a reduction is most likely to be successful with the knee flexed and the foot flexed plantarward. This relaxes the gastrocsoleus complex and brings the talar head fragment into proper relation to the body. At that point any varus or valgus malalignment can be corrected as well. Excessive dorsiflexion will cause the head fragment to become malreduced and therefore x-rays to confirm reduction should usually be performed with the foot in a comfortable position of equinus.
In the case of a Type III fracture, in rare cases it may be possible to replace the talar body fragment back into the ankle mortise. This requires plantar flexion and varus positioning of the foot. In some cases, closed reduction is aided by the use of a transverse Steinman pin placed through the calcaneus to apply traction. However, this also increases the soft tissue tension around the ankle including the flexor tendons, posterior tibial tendon and even the deltoid ligament and can render a closed reduction more difficult. Direct pressure on the talar body fragment is often required to reduce it relative to the medial malleolus. Because of the degree of direct pressure which is often required, closed reduction can in some cases increase the risk of complications particularly related to skin necrosis. Therefore this maneuver should be reserved for situations in which an open reduction will not be feasible in a reasonable time frame.
If a closed reduction is successful and an anatomic reduction
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is achieved, one can consider the use of cast treatment or percutaneous screw fixation to stabilize the talar neck fracture. If cast treatment is selected, the reduction will be most easily maintained with the foot casted in equinus for up to one month. Subsequent casting can be performed to gradually bring the foot out of equinus as long as the reduction is maintained. Nonweight-bearing immobilization is usually required until union is achieved.
FIGURE 54-11 Closed reduction of a talar neck fracture. Lateral radiograph demonstrating alignment pre-reduction (A) and postreduction (B) of a Hawkins Type II fracture.
Open Reduction and Internal Fixation
Operative reduction and internal fixation is the standard treatment for most displaced talar neck fractures. Operative treatment is indicated to achieve an anatomic reduction of the talar neck fracture. Multiple attempts at closed reduction can increase the risk of complications and therefore prolonged and repeated attempts at closed reduction should be avoided as an open reduction will be safer and more effective.
Open reduction is performed to anatomically reduce the talar neck fracture. Displacement of the talar neck is associated with subluxation or dislocation of the posterior facet of the subtalar joint. As noted by Adelaar (41), subluxation of the posterior facet of the subtalar joint results from disruption of the interosseous talocalcaneal ligament. The talar body assumes a plantar flexed, malaligned position usually also associated with varus deformity. Sangeorzan et al demonstrated the importance of slight deformity of the talar neck. In their biomechanical study, residual displacements of as little as 2 mm altered the contact characteristics of the subtalar joint (48). Daniels et al performed a biomechanical study using cadaveric specimens and demonstrated that varus malalignment of the talar neck is associated with forefoot adduction, calcaneal internal rotation, and loss of subtalar motion (49). As well, displacement of the fracture fragments can cause skin tenting and necrosis and therefore prompt reduction of any malaligment is critical to lessen skin complications and infection. Reduction may similarly reduce the risk and severity of osteonecrosis by facilitating vascular ingrowth.
Surgical Approaches
Various options exist to approach the talar neck fracture. Considerations for which approach to use include the degree and location of any comminution; potential need for malleolar osteotomy, for reduction and visualization purposes; and preservation of the remaining vascular supply.
The anteromedial approach is perhaps the most commonly used. The incision is made directly over the talar neck and medial to the anterior tibial tendon. For fractures which extend more posteriorly into the talar body, the incision can be sited slightly posterior in between the anterior and posterior tibial tendons to facilitate medial malleolar osteotomy if necessary. As well, fractures of the talar neck are commonly associated with malleolar fractures in which case the use of a medial incision will facilitate reduction and fixation of the medial malleolar fragment. In some cases, open reduction is difficult and the talar body is wrapped around the deltoid ligament. In such instances, osteotomy of the malleolus is preferable to cutting the deltoid ligament to achieve a reduction. Osteotomy of the malleolus may preserve the deltoid ligament and thereby protect what may be the only remaining source of vascularity for the talar body (3). For the more distal talar neck fracture, an incision just medial to the anterior tibial tendon is sufficient to provide direct access to the fracture site to visualize and manipulate
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both fragments. The anteromedial incision can be performed without exposing the anterior tibial tendon and leaving it within its sheath. Subsequently an incision down to bone can be performed elevating full thickness flaps from the anteromedial aspect of the tibia to facilitate exposure of the talar neck.
The anterolateral approach is recommended by some authors. It has been suggested that this may lessen the chance of damage to the blood supply of the talus and it provides adequate exposure of the fracture (3). In many cases a cortical fragment is visible at the anterolateral corner of the talar neck fracture, adjacent to or within the lateral process, upon which one may base an anatomical reduction. Exposure of the lateral aspect of the talus and the subtalar joint requires extra caution to avoid injury to the blood vessels of the sinus tarsi.
The direct lateral approach can be performed as an additional option for reduction. This approach is often performed in conjunction with an anteromedial incision to facilitate exposure of the subtalar joint. This approach requires elevation of the extensor digitorum brevis muscle. Caution is exercised around the sinus tarsi to protect the vessels therein. However, the direct lateral approach facilitates good visualization of the subtalar joint especially in the case of comminuted fractures with extension into the subtalar joint. Like the anterolateral approach, visualization of the lateral process facilitates placement of a “shoulder screw” across the fracture.
A posterior approach can be useful to facilitate screw fixation of the talar neck fracture. The use of screws directed from posterior to anterior may facilitate placement of screws perpendicular to the fracture line, thereby achieving compressive lag screw fixation. In some cases, a posteromedial approach is performed to facilitate reduction of a Type III talar neck fracture. Malleolar osteotomy can be performed through this approach in cases where the deltoid ligament is intact and the talar body has been reflected posteriorly between the posterior tibial tendon and the medial malleolus. Reduction can be very difficult and is facilitated through the use of a calcaneal traction pin in addition to the malleolar osteotomy.
In other cases a posterolateral approach can be used to facilitate lag screw fixation. Use of the posterior approach, however, and posterior screw fixation does involve some damage to the posterior articular cartilage of the talus as well as risking neurovascular compromise, and therefore, when posterior screw fixation or the posterior approaches are used, care should be taken to minimize surgical complications.
Combined Approaches
Combined approaches can be useful for talar neck fractures, especially those associated with extensive comminution (50). Often in these cases, judgment of an anatomic reduction can be difficult. The use of an anteromedial approach combined with a direct lateral approach affords a slightly larger skin bridge between the two incisions compared to the combined anteromedial and anterolateral approach. However, it is nonetheless rare to achieve a bridge greater than 5 or 6 cm across the midfoot. Combined approaches should be performed with caution to protect the tenuous blood supply to the talar body such that, in particular, the arteries of the tarsal sinus and tarsal canal are protected. The use of a combined approach may facilitate maintaining a blood supply through any remaining dorsal neck vessels by avoiding excessive retraction on the anterior skin bridge.
The utility of combined approaches has been demonstrated in recent large series of talar neck fractures. From one center 38 out of 70 talar neck fracture-dislocations were treated with dual approaches (15); four patients from the group of 70 developed an early infection requiring reoperation. In another series of 102 talar neck fractures from a large trauma center, dual anteromedial and anterolateral approaches were used for 91 fractures; of 60 fractures which were evaluated for complications, only 5 had development of wound dehiscence, superficial or deep infections (19).
Percutaneous Fixation
Percutaneous internal fixation can be used when a closed reduction has been successful at achieving an anatomic result (Fig. 54-12). Similarly when a truly undisplaced talar neck fracture presents with an anatomic reduction visualized on imaging, percutaneous fixation can be used to facilitate early range of motion as opposed to cast treatment. Fixation can be inserted from posteromedial, posterolateral, or a percutaneous anterior approach and used to lag the fracture fragments together with screws placed perpendicular to the fracture line or in opposite directions. Due to the proximity of the sural nerve posterolaterally and the neurovascular bundle posteromedially it is worthwhile to perform careful blunt subcutaneous dissection to avoid injury to the neurovascular structures (51,52).
Fixation Options
Once reduction of the fracture is achieved and temporary stabilization has been accomplished, appropriate internal fixation can be employed for definitive stabilization. Swanson et al, using mathematical modeling, calculated that the theoretical maximum shear force across the talar neck during active motion was 1129 Newtons (53). Internal fixation of the talus should ideally be sufficient to withstand the theoretical forces involved with active motion until healing has occurred.
Screws are commonly employed for fixation of talar neck fractures. They can be inserted from anterior to posterior or posterior to anterior. Posterior screw insertion provides the advantage of allowing screw placement perpendicular to the fracture line and therefore perhaps improving compressive rigidity while avoiding shear with screw placement. In the mechanical study of Swanson et al, posterior screw fixation was sufficient to withstand the theoretical shear forces of active motion (53). Cannulated screws are useful as the direction of screw travel requires careful fluoroscopic visualization and frequent redirecting to achieve an anatomic screw position. Only a limited window is available for correct screw insertion (54). Multiple cannulated screw sizes are available and frequently a smaller screw is preferable. Thordarson et al recommended the use of titanium
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screws to facilitate the later use of magnetic resonance imaging scans in the assessment of osteonecrosis of the talus (55).
FIGURE 54-12 Closed reduction followed by posterior-to-anterior screw fixation of a noncomminuted Type II fracture. A. Initial injury films are difficult to interpret but demonstrate a subtalar dislocation. B. An attempt at closed reduction partially reduced the subtalar joint but left residual subluxation. C. Formal closed reduction was accomplished in the operating room and stability achieved with 2 posterior to anterior screws.
A number of anterior screw fixation options exist. In many cases it is not possible to insert anterior screws perpendicular to the fracture site. Removal of a small amount of cortical bone using a rongeur or a countersink adjacent to the screw head may allow improved screw direction. Stabilization of comminuted fractures may be performed with the use of noncompressive or “buttress” screw techniques. Lag screw techniques can be employed for noncomminuted fractures. On the anterolateral side, a shoulder of bone often exists when the talar neck fracture extends into the lateral process directly adjacent to the subtalar joint. At this point a reduction can often be visualized and a compressive screw inserted. This shoulder screw can be useful in addressing a complex talar neck fracture in particular. This screw runs from anterolateral to posteromedial in areas of the talus where the bone is denser and compression along this axis does not cause varus malalignment (Fig. 54-13) (56).
Recently, the development and improvement of small plates has facilitated improved fixation of talar neck fractures. These can be particularly useful for comminuted talar neck fractures in which bridging of comminuted zones on the medial or lateral columns may be required (Fig. 54-14). Use of plates around the talar neck fracture often requires some caution as the hardware can easily be prominent and potentially cause damage to malleolar cartilage. In some cases counter-sinking of the plates is required, but in general careful placement of the hardware on the nonarticular regions of the talus facilitates plate use. Fleuriau Chateau et al described a series of 23 patients with comminuted talar neck fractures treated with medial, lateral, or combined medial and lateral plate fixation. Four patients required hardware removal, but only two patients developed a malunion (57). The development of appropriate sized implants has been critical to effective plate fixation in talar neck fractures.
External fixation as definitive treatment is rarely indicated for talar neck fractures. The healing of the talar neck occurs generally by creeping substitution and primary bone healing as opposed to callus formation. As such, absolute stability with plate and screw fixation is preferred. However, external fixation may have a role in situations in which talar neck fracture fixation is delayed, as a means of maintaining the reduction of the ankle and subtalar joints (Fig. 54-14). As well, external fixation can have a role in the case of highly contaminated open fractures to facilitate soft tissue management. Finally, external fixation has a role following talectomy as a temporary means to maintain length and alignment while further surgical intervention is being determined.
Delayed reduction is a treatment strategy which is again not commonly employed for talar neck fractures. As a rule, prompt reduction and stabilization is preferred. However, it is sometimes a requirement due to multisystem injury, or severe soft tissue compromise, to delay reduction. In those cases in which
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reduction must be delayed, open reduction and internal fixation can still be accomplished with a reasonable expectation of an acceptable outcome. In particular, fracture healing can still be anticipated even when surgery is delayed (58). Whether complications are more frequent following delayed surgery is unknown. Osteonecrosis may be more likely when surgery is delayed; however, most studies in which early versus late surgery were compared have been unable to detect a difference (15,19,58,59).
FIGURE 54-13 Intraoperative and postoperative views of a Type II talus fracture treated with anterior-to-posterior screw fixation including a lateral shoulder screw. Anteroposterior (AP) (A), lateral (B), and Canale views (C) are shown following open reduction and internal fixation. Postoperative AP (D) and lateral (E) views 6 weeks later clearly demonstrate subchondral resorption of bone indicating vascularity of the talar body (Hawkins sign).
FIGURE 54-14 Hawkins Type III fracture treated with temporary spanning external fixation followed by definitive plate fixation. Anteroposterior (AP) (A) and lateral (B) images with the external fixator in place demonstrate residual displacement of the talar neck fracture. C. Clinical photo 10 days post-injury demonstrates resolution of soft tissue swelling with persistent deformity. AP (D) and lateral (E) radiographs 8 weeks following definitive open reduction, plate fixation, and an intercalary tricortical iliac crest bone graft demonstrate maintenance of alignment but sclerosis of the talar body, suggesting avascularity.
Talectomy again is another treatment which is generally reserved for situations of necessity. In some cases of open talus fracture-dislocation, the talus is lost at the scene of the injury in which case there is no possibility of talar repair. In other situations, the bone is so comminuted such that replacement of the talus within the ankle mortise is considered impossible or unlikely to result in successful outcome. The principles of talectomy include maintenance of length and alignment with the use of spanning external fixation, followed by tibiocalcaneal fusion. Gunal et al described a technique of talectomy in four patients including lateral translation of the medial malleolus, and reported good results in 3 out of 4 patients (60). In general, however, results of talectomy are probably worse than results of talus reduction and stabilization. Therefore, in the case of a dislocated extruded talus, it is generally preferred to attempt to replace the talus within the mortise, provided it is possible to achieve a clean surgical bed. Irrigation and debridement of the bone and the soft tissue is performed, followed by re-implantation of the clean talus. External fixation is helpful to stabilize the fractures and associated soft tissues followed by appropriate wound care. Union can be obtained, even through a completely avascular talar neck fracture, by creeping substitution although this may occur very slowly. It is not uncommon to see evidence of complete sclerosis of the talus even 4 to 6 months after reimplantation, suggesting complete osteonecrosis. Ultimately, however, revascularization may occur. Although osteonecrosis with collapse might be expected in most, if not all, patients with a reimplanted talus, it appears that some patients can successfully revascularize without collapse. Brewster and Maffulli reported on two cases of re-implanted extruded taluses which revascularized without collapse (61). As such, wherever possible, treatment of the completely dislocated talus will include replacement of the talus within the ankle mortise, followed by appropriate fixation, wound care, and rehabilitation.
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Pearls and Pitfalls
Treatment of talar neck fractures requires meticulous attention to achieving an anatomic reduction (Table 54-1). In many cases this is complicated by comminution, particularly when the talar neck fracture is combined with a talar body fracture. In these cases, the use of multiple surgical approaches is valuable; one approach directed to the noncomminuted side (if one exists), to evaluate the reduction; and the second to strut the comminuted side with a plate. The development of appropriate sized plates has definitely facilitated talus fracture surgery and they should be available whenever possible.
Reduction of the dislocated talus can be surprisingly difficult. The simplest means of addressing this usually involves a malleolar osteotomy. A medial malleolar osteotomy for the posteromedial talar body is very helpful. An extensile incision is similarly beneficial, because the soft tissues that normally lie posterior to the medial malleolus are often displaced around the fracture trapping the talar body in a dislocated position.
TABLE 54-1 Fixation Options for Talar Neck Fractures
  Advantages Disadvantages
Anterior-to-posterior screw fixation 1. Direct visualization of fracture reduction 1. Difficult to insert perpendicular to fracture line
2. Avoidance of articular cartilage damage 2. Less strong compared to posterior-to-anterior screws and plate fixation
3. Use of compression screws where indicated 3. Inappropriate use of compression may cause malalignment
Posterior-to-anterior screw fixation 1. Stronger fixation compared with anterior screw fixation 1. Indirect visualization of reduction; may require change in positioning
2. Easily inserted perpendicular to fracture line 2. Some cartilage damage to posterior talus
3. May cause less soft tissue disruption 3. Risk of iatrogenic nerve damage
Direct plate fixation 1. Strong fixation 1. Extensive soft tissue dissection
2. Useful to buttress comminuted columns 2. Risk of hardware prominence
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Complications
Despite advances in surgical timing, techniques and devices, complications following talar neck fractures remain common (3,6,15,19,20,25,47,59,62,63,64). The frequency of complications seems to be particularly dependent on the severity of the initial injury, such that the Hawkins classification continues to be very relevant. Recent reports (15,19) have also highlighted the importance of fracture comminution as a predictor of complications. Also notable is the comparatively good function which can be achieved in the absence of osteonecrosis and other complications (15).
Infection and Skin Necrosis
The skin of the ankle and foot is fragile and easily injured. Infection can be a problem in both closed and open fractures of the talus. Deep infection is, without question, a devastating complication.
The older literature notes the severity of this complication. Syme, in 1848, described a series of 11 deaths in 13 patients with open fracture-dislocations of the talus, all resulting from infection (65). He recommended a trans-tibial amputation as appropriate treatment. Other more recent reports have also noted the dangers of deep infection (18,66,67).
Once a deep infection is established, treatment becomes extremely challenging. The avascular body of the talus acts as a large necrotic sequestrum. Surgical debridement, including talectomy may be necessary to achieve control of the infection. Excision of the necrotic talus combined with delayed tibiocalcaneal fusion provide the best results in terms of hindfoot alignment and stability (18,46,67,68).
Osteonecrosis
Overall, osteonecrosis occurs rarely in Type I fractures with a risk of 0% to 13%. In fracture dislocations, the risk of osteonecrosis increases to 20% to 50% of Type II fractures and over 80% of Type III fractures. The incidence of osteonecrosis varies between published reports, and diagnostic criteria used; but, in general, the incidence correlates with the Hawkins classification (69). The overall incidence of osteonecrosis is between 21% and 58%, making it a common complication of talar neck fractures (6,20). Radiographic diagnosis of osteonecrosis is made when the talar body demonstrates increased density compared with the surrounding bone which is vascularized and undergoing disuse atrophy. Later as revascularization occurs there is partial or complete collapse of the subchondral bone, narrowing of the joint space and occasionally fragmentation of the talar body.
The “Hawkins sign” is a well-described radiographic indication of viability of the talar body (Fig. 54-13). As noted by Hawkins, “The time to recognize the presence of avascular necrosis [osteonecrosis] is between the sixth and the eighth week after the fracture-dislocation. By this time, if the patient has been nonweight-bearing, diffuse atrophy is evident by roentgenogram in the bones of the foot in the distal part of the tibia. An anteroposterior roentgenogram of the ankle made with the foot out of the plaster cast, reveals the presence or absence of subchondral atrophy in the dome of the talus. Subchondral atrophy excludes the diagnosis of avascular necrosis [osteonecrosis]” (70).
Daniels and Smith have pointed out that the Hawkins sign has a high degree of sensitivity but only moderate specificity (25). The extent of involvement of the talar body is variable (34). In some cases partial osteonecrosis is noted, particularly in Type II fractures. In many Type III injuries the entire talar body blood supply is disrupted, resulting in osteonecrosis of the entire talar body. Tehranzadeh et al describe three cases of a partial Hawkins sign following fractures of the talus and suggested the partial Hawkins sign may correlate with disruption of end arteries within the body of the talus. Recognition of a partial Hawkins sign should lead to further evaluation with additional diagnostic studies (71).
Other diagnostic tools used to evaluate osteonecrosis include technetium bone scan and magnetic resonance imaging. The use of bone scanning with a pin-hole collimator (3) can be effective but has largely been replaced with MRI. MRI can be used as early as 3 weeks postinjury, and defines not only the presence but also the extent of osteonecrosis, as well as the condition of the articular cartilage (Fig. 54-15) (41,55,72).
Once osteonecrosis is diagnosed, the prognosis and best treatment remain a source of controversy. Even osteonecrosis of the entire talar body may result in a reasonable outcome. Union can occur in the presence of osteonecrosis, provided the fixation is stable. Prolonged periods of nonweight-bearing have been recommended, because the talus is revascularized slowly via creeping substitution of necrotic bone with vascularized bone. This process may require up to 36 months (35). The duration of nonweight-bearing required is unpredictable, relatively
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impractical, and difficult to adhere to for patients. An alternative solution is the use of a patellar tendon bearing orthosis. Saltzman et al evaluated the effect of patellar tendon bracing in Charcot arthropathy and determined that force transmission to the hindfoot was reduced by 37% (73). The brace also reduces varus and valgus stresses to the hindfoot.
FIGURE 54-15 This T1-weighted MRI was obtained 6 months after talar fracture-dislocation and demonstrates osteonecrosis of the talar body. The region of osteonecrosis corresponds to the distribution of the artery of the tarsal canal. The MRI also demonstrates arthritis of the talonavicular and subtalar joints, subluxation of the subtalar joints, and extensive fluid accumulation around the talus in keeping with infection.
Operative options to deal with the osteonecrotic talus are numerous. Some authors have recommended immediate surgical treatment. Options have included primary triple arthrodesis (68), total talectomy with tibial calcaneal fusion (74), talectomy alone (42), subtalar fusion (75,76), pantalar fusion (77), and primary tibiotalar fusion. In most cases, however, the recommendation is for a relatively conservative approach in which osteonecrosis of the talus can be treated expectantly with preservation of the talar body fragment. Anatomic reduction and fixation are maintained, and primary arthrodesis is not indicated.
Selected case reports and small series in the literature describe successful efforts to revascularize the necrotic talus. Hussl et al describe a technique using vascularized corticocancellous iliac crest bone graft to prevent collapse (78). Mont et al performed a variation of core decompression of the talus in 17 ankles with symptomatic nontraumatic osteonecrosis without collapse (79). Often, however, the patient with osteonecrosis will present with associated collapse, in which the treatment is directed toward relief of pain symptoms and restoration of alignment.
Not all cases of collapse are symptomatic. In unusual instances, collapse of the entire talar body can occur while leaving a relatively congruent ankle joint. Function of these ankles is not normal, but may be acceptable to the patient. Partial collapse of large segments of the talar body is often associated with severe hindfoot malalignment and irregularities in the articular cartilage such that further treatment is necessary to relieve symptoms.
Unfortunately, osteonecrosis is often associated with collapse of the talar dome and the development of symptomatic arthritis of the ankle joint. For these patients, ankle arthrodesis is indicated. Tibiocalcaneal arthrodesis and the Blair or modified Blair fusion have both been found effective. Blair described the technique of ankle fusion in 1943 specifically designed to treat osteonecrosis of the talus (80). He recommended excision of the avascular talar body and placement of a sliding corticocancellous graft from the anterior distal tibia into the residual, viable talar head and neck (Fig. 54-16). Modifications of this technique include screw fixation of the sliding anterior distal tibial graft, suggested by Lionberger et al (81), and retention of the talar
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body. Authors such as Morris et al (82) and Dennis and Tullos (83) have reviewed case series and recommend the modified Blair fusion as a satisfactory reconstructive treatment after severe talar injuries. Benefits of the Blair fusion include a normal appearance of the foot, minimal shortening, and potential retention of some subtalar function.
FIGURE 54-16 Blair fusion. Schematic drawing showing the anterolateral incision (A), the sliding graft from the distal tibia (B), and the sliding graft embedded into the talar neck and head fragment (C). Note the space left by removal of the talar body. (Blair HC. Comminuted fractures and fracture-dislocations of the body of the astragalus: Operative treatment. Am J Surg 1943;59:38.) D,E. Radiographs demonstrate a healed modified Blair fusion 2 years following a Type III talar neck fracture with the sliding graft incorporated. The talar body has been retained and remains sclerotic, but appears to be healed to the distal tibia.
Tibiocalcaneal arthrodesis is an alternative option in which fusion of the entirety of the calcaneus to the distal tibia in some cases with the use of intercalary graft material can be used to facilitate a hindfoot arthrodesis (74). Results have been noted to be superior to talectomy or ankle fusion by Canale and Kelly (20). Proponents of this procedure note that the fusion of the tibia to the calcaneus may provide more stability compared to the sliding graft technique. The use of intercalary material is required if the appearance and length of the hindfoot is to be maintained.
In summary, osteonecrosis of the talus is a significant complication. In many cases, however, the radiographic appearance of osteonecrosis may not correlate with permanent disability. Current recommendations are to reconstruct the talus at the time of injury with an anatomic reduction and stable fixation. Weight-bearing in the presence of osteonecrosis can be facilitated with the use of a patellar tendon bearing orthosis. Further surgical intervention should be directed to the patient’s symptoms as many patients with osteonecrosis do not require further surgery once healing is complete and revascularization has proceeded. Treatment should be directed to improve symptoms where necessary, and in these patients a Blair fusion or tibiocalcaneal arthrodesis is most commonly indicated.
Malunion
Anatomic reduction is essential to achieve a good result following talar neck fractures. In one series of 46 patients, Peterson et al achieved better results in Type III fractures compared to Type II fractures. The critical variable was the adequacy of initial reduction, with an exact reduction achieved more frequently in patients with Type III fractures (47). Miller felt that “the ability to obtain and maintain an anatomical reduction (closed or open) is the most important factor in predicting good results” (84). Hawkins noted that a good to excellent result is the expected outcome following anatomical reduction of a talus fracture dislocation not complicated by osteonecrosis (6).
The development of malunion can occur in several ways. Obtaining an anatomic reduction can be difficult to assess, particularly by closed means. The use of lateral radiographs and a Canale view are helpful to avoid an inadequate closed reduction. The fixation devices used should be carefully selected to avoid creating a malreduction, and to achieve adequate stability. For example, in fractures with medial comminution, the use of compression screw fixation on the medial aspect of the talar neck will inevitably result in a varus malunion. As well, in patients in whom union is slow to occur, the progressive development of a malunion is sometimes noted. Patients should therefore not progress to full weight-bearing until union is solid.
Malunion can occur with dorsal displacement of the distal fragment, resulting in limitation of dorsiflexion and a painful gait (20). Commonly, malunion in varus occurs, often accompanied by a malrotation resulting in a supination deformity of the foot. Canale and Kelly noted that 14 of 30 patients with Type II fractures treated in a cast developed a varus malunion (20).
More recent reports have also documented a high incidence of varus malunion. In one study of patients with high-energy fractures treated with screw fixation, a varus malunion developed in 40% of patients (15). The use of plate fixation may be associated with a lower incidence of malunion (19,57), although there are currently no studies comparing the techniques.
Treatment of malunion varies. In the case of a dorsal malunion, resection of the dorsal beak may be satisfactory (20,43). Often, however, reconstruction of the malunion is more complicated. Options include calcaneal osteotomy, calcaneal osteotomy combined with midfoot osteotomy, direct osteotomy of the talar neck (85), and triple arthrodesis for severe malalignment associated with degenerative changes. Daniels et al, in a cadaveric study, noted that removal of a medially based wedge of bone from the talar neck resulted in varus deformity, internal rotation of the hindfoot, adduction of the forefoot, and loss of subtalar motion (49).
Malunion after talar neck fracture is a vexing problem. It is likely generally underdiagnosed, but clinically important. Malunion results in subtalar stiffness, and excessive weight bearing on the lateral side of the foot and it is frequently painful. Over time, associated soft tissue structures become contracted such that these contractures may need to be attended to at the time of reconstructive osteotomy surgery (Fig. 54-17) Subtalar or triple arthrodesis is often required to achieve alignment and deal with secondary degenerative changes. In the absence of degenerative changes, the hindfoot should be evaluated carefully for bone and soft tissue pathology to facilitate reconstruction.
Post-traumatic Arthritis
Posttraumatic arthritis of the ankle, subtalar joint or both can occur after fractures of the talar neck. The development of subtalar arthrosis is particularly common (15). Osteoarthritis may be noted in the presence or absence of osteonecrosis. The causes of osteoarthritis, in addition to osteonecrosis, include cartilage damage, immobilization, and malalignment. In many cases substantial damage to the inferior articular margin of the talus articulating with the posterior facet of the subtalar joint is noted at the time of talar fracture-dislocation. This may be a contributing factor to subtalar arthrosis. In addition to cartilage damage from the injury, the prolonged period of nonweight-bearing and cast immobilization can lead to arthrofibrosis, impaired nutrition of the articular cartilage and secondary osteoarthritis. As such, the combination of injury, osteonecrosis, and immobilization ensure a high incidence of arthritis in the peritalar joints. Even relatively undisplaced talar neck fractures have been noted to have decreased motion in both the ankle and subtalar joints,
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require a prolonged time off work with a high incidence of unsatisfactory results (25).
FIGURE 54-17 Reconstruction of talar neck malunion. A. Preoperative clinical photo demonstrates varus deformity. B,C. Postoperative clinical photos following tendo-Achilles lengthening and calcaneal osteotomy demonstrate restoration of neutral alignment.
The development of post-traumatic degenerative changes is very common radiographically, occurring in the subtalar joint in 46% to 69% of patients (15,21,43,59,62,86). Hindfoot symptoms may also be common, but are not always due solely to the development of arthritis. It is frequently necessary to localize the source of symptoms to the arthritic joint prior to proceeding to surgical intervention. Selective joint infiltration with local anesthetic can be useful as an assistive diagnostic modality. This may require fluoroscopic localization to determine the exact needle placement. Preoperative injection of a local anesthetic into the symptomatic joint or presumed symptomatic joint which provides complete pain relief can be a useful indication for arthrodesis.
Once the arthritic joints have been localized, treatment can begin. The use of anti-inflammatory medications, protected weight-bearing, and bracing may be helpful. Failure of these conservative measures leads to surgical intervention, usually arthrodesis of the involved joints. Subtalar fusion in the presence of a talar neck fracture can be performed using standard techniques. Ankle arthrodesis can similarly be performed, although it is often useful to confirm that the talar body is perfused prior to proceeding to arthrodesis.
Ankle arthroplasty in the presence of post-traumatic degenerative changes may be contraindicated after talar neck fracture if osteonecrosis is present. However, if the talar body is well perfused ankle arthroplasty may be an alternative treatment for selected cases of post-traumatic arthrosis. However, the use of ankle replacement as a treatment option for post-traumatic arthritis in young, active patients is a source of considerable controversy (87).
Controversies and Future Directions
Talar neck fractures are difficult and relatively uncommon injuries. Although a substantial body of literature exists regarding treatment options, results, and outcomes, there are no randomized trials comparing variations in treatment strategies.
Several controversies emerge from a review of the literature. One of these frequently discussed in the literature relates to surgical timing. Since the classic articles of Hawkins (6), Canale and Kelly (20), Penny and Davis (3), and others (21,35,40,41,42,43,44,45,46,47), emergent treatment of talar neck fractures has been recommended. The rationale for emergent treatment includes a reduction of osteonecrosis rates related to earlier reduction and decreasing secondary soft tissue injury. Recently, however, other authors have compared the results of early and delayed treatment and found no difference. Lindvall et al compared the results of surgery within 6 hours to delayed surgery in a group of 26 isolated fractures of the talar neck and body, and found no difference in rates of union, osteonecrosis, or arthrosis and no difference in functional outcome (58). Other authors have similar findings (15,19). One should, however, consider that the power of a retrospective review to detect differences in outcome related to surgical timing is very limited by small numbers, differences in treatment techniques, and variables in patient comorbidities.
Other areas of controversy include the use of small plates as compared to screws for fixation, and the use of biologically active bone substitutes for grafting. These controversies are related
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to the availability of new and better technology. For example, the use of small plates for stabilization has been a comparatively recent phenomenon but seems to be evolving (19,57). Promising future considerations for talus fracture surgery include improved technology in bone graft substitutes to potentially improve union rates and perhaps eventually enhance revascularization.
An additional area of controversy relates to the use of minimally invasive techniques to reduce and stabilize talus fractures and dislocations. The advantages of less invasive surgery include improved maintenance of the soft tissue envelope around the fracture, and a more rapid, less painful recovery. However, the goals of surgery must be respected, most importantly, including obtaining an anatomic reduction. With respect to the talus, the irregular shape of the bone and its articulations limits the ability to assess a reduction using closed techniques in complex fractures. However, with improvements in intraoperative imaging and percutaneous reduction techniques, it may be possible to treat more talus fractures with less invasive techniques in the future.
FRACTURES OF THE BODY OF THE TALUS
Fractures of the body of the talus are difficult injuries. Complications following talar body fractures are similar to those following talar neck fractures, including osteonecrosis, arthritis of the ankle and subtalar joints, and prolonged disability. Fewer reports in the literature exist related to fractures of the body of the talus compared to talar neck fractures. Previously this was thought to be related to a much lower incidence of these type of fractures compared to talar neck fractures. However, with the increase in survival following high-energy motor vehicle collisions and the severe foot and ankle injuries that commonly result, talar body fractures seem to be increasing in frequency. Several recent reports in the literature have provided important information related to fractures of the body of the talus.
Mechanism of Injury
Fractures of the talar body result from an axial compression of the talus between the tibial plafond and calcaneus. Common mechanisms of injury resulting in these fractures include motor vehicle collisions and falls from a height. Depending on whether the force is more posterior or anterior, and the relative plantar or dorsiflexion position of the ankle, the force may be directed through the posterior or anterior aspect of the talar body. In many cases, fractures of the talar body are associated with other fractures of the foot and ankle, including talar neck and malleolar fractures (58). Combined talar neck and body fractures were noted in 40% of talar body fractures in a recent study by Vallier et al (88). Although falls were the most common mechanism of talar body fractures overall, vehicular trauma was more common in combined fractures of the talar neck and body (88). Other associated injuries include fractures of the posterior and lateral talar processes. Because of the severe mechanism of injury, other associated injuries to the lower extremities are very commonly noted in conjunction with fractures of the talar body. Open talar body fractures are not uncommon as well, occurring in approximately 20% of cases (88).
Classification
By definition, fractures of the talar body are intra-articular injuries in which the articular surface of the tibiotalar and the subtalar joints are involved. Inokuchi et al distinguished talar neck fractures from talar body fractures based on the location of the inferior fracture line relative to the lateral process of the talus (89). Based on the lateral radiograph, fractures extending into or posterior to the lateral process of the talus are defined as talar body fractures, whereas fractures anterior to the lateral process are defined as talar neck fractures.
Talar body fractures present in a variety of fracture patterns and configurations such that classification can be difficult (Fig. 54-18). Fractures of the talar processes are considered separate from talar body fractures; talar body fractures involve the articular surfaces of the tibiotalar and subtalar joints. In general, the fractures can be defined as shearing type fractures or compression type fractures. The shearing type fractures may occur either in the sagittal or coronal plane. The Orthopedic Trauma Association classification considers talar body fractures according to the location and direction of the primary fracture line. Fractures may be located laterally in the sagittal plane (72-B1), medially in the sagittal plane (72-B2), or in the coronal plane (72-B3). Fractures may also present as markedly comminuted injuries without evidence of a primary fracture line (72-C) (27). The location of the primary fracture line is important, particularly when considering the surgical approach or a malleolar osteotomy for exposure of the talar body.
Treatment
Because fractures of the talar body are often associated with other life and limb threatening injuries, initial attention should be directed to assessment and resuscitation according to the ATLS guidelines. Obvious dislocations can be reduced and open wounds treated appropriately. Once stabilization has occurred, the appropriate diagnostic investigations can be performed, usually including radiographs of the foot and ankle as well as CT scanning.
Treatment of talar body fractures has evolved. Historically, closed treatment and cast immobilization was preferred. Sneppen et al reported on a series of 31 patients with fractures of the talar body. Most patients in that series were treated with closed reduction and casting, and complications were common with high rates of malunion, osteonecrosis, and arthritis. Ninety-five percent of their patients had moderate or severe complaints. They concluded that more aggressive treatment is indicated for displaced fractures and recommended “exact reduction and stable fixation whenever possible” (90).
Open reduction and internal fixation is the current standard
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treatment for displaced fractures of the talar body (41,58,59,88,91). In some cases, percutaneous techniques or arthroscopic techniques may be employed, with the potential benefit of preserving blood supply (92,93). However, the goals of treatment should be respected, including an anatomic restoration of alignment and congruity of both the tibiotalar and subtalar joints.
FIGURE 54-18 Talar body fracture with associated subtalar dislocation and comminution. A. Preoperative anteroposterior film demonstrates dislocation and fracture comminution. B. Combined lateral and anteromedial surgical approaches were used. Intraoperatively, Kirschner wires achieved provisional fixation (C) followed by definitive screw fixation (D,E).
As with fractures of the talar neck, urgent treatment of talar body fractures is preferred. In open fractures, or irreducible dislocations, treatment is by necessity emergently performed. However, in many talar body fractures, definitive treatment can be delayed to facilitate improvement in the patient’s overall condition, and to permit resolution of severe soft tissue swelling.
Surgical approaches available include medial, lateral, and combined approaches. Debridement of the subtalar joint and fragment fixation can also be accomplished using a direct lateral approach. The anteromedial approach is perhaps the most commonly used. It is generally wise to site the incision more posteriorly than usual, particularly if a medial malleolar osteotomy is contemplated, to facilitate the osteotomy. As well, one should avoid disrupting the blood supply to the talus in the region of the tarsal canal by limiting plantar dissection. Finally, it is often not necessary to dissect into the talar head region and the talonavicular joint capsule can often be preserved in its entirety.
The anterolateral approach can be combined with the anteromedial exposure. Again, fibular osteotomy is occasionally necessary such that the incision may need to be redirected. The use of combined anterolateral and anteromedial approaches is often required, especially in comminuted fractures and those fractures with displacement of the coronal fracture line. Isolated, noncomminuted sagittal plane fractures can often be treated with a single incision either medial or lateral, depending on the location of the primary fracture line (94).
In some cases, osteotomy of the medial or lateral malleolus is required to facilitate exposure. Vallier et al utilized a medial malleolar osteotomy in 16 patients and a fibular osteotomy in 3 of their 57 fractures of the talar body (88). Osteotomy is particularly required for fractures of the posterior aspect of the talar body. Anterior fractures can frequently be visualized well without osteotomy. When osteotomy of the malleoli is required, predrilling and tapping may be beneficial to facilate reduction and fixation of the osteotomy once the talar body has been reduced and stabilized (95). Care should be taken to ensure that the osteotomy is of sufficient size to facilitate visualization and implant placement. Furthermore, when a medial malleolar osteotomy is performed, reflecting the malleolus inferiorly may allow preservation of the blood supply to the talar body via the deltoid ligament branches.
Open reduction and internal fixation can be performed for fragments of bone and cartilage large enough to stabilize. Depending on the size of the fragment, cortical screws ranging from 2.0 to 4.0 mm in diameter can be used (Fig. 54-19). The availability of screws of sufficient length is also valuable, as displaced fragments can range in size up to the width of the talar body, usually approximately 35 to 40 mm across. Care should be taken to avoid prominent hardware and for that reason, countersinking of screws or the use of headless screws is advantageous. Compression screw fixation may be used in
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noncomminuted fractures. Alternative fixation devices include Herbert screws (96), Kirschner wires (K-wires) and threaded wires, all of which may be useful depending on the size of the fragments to be stabilized. Small plates can also be used to span comminuted segments medially or laterally; in some cases, a portion of the plate can be countersunk to lessen the risk of hardware impingement.
FIGURE 54-19 Talar body and associated tibial plafond fracture treated with open reduction and internal fixation in an 82-year-old farmer. Coronal and reconstructed computed tomography views demonstrate talar body fracture with subtalar subluxation (A), plafond impaction and malleolar fracture (B), and talar body comminution (C). D–F. Three-month postoperative images demonstrate restoration of alignment with multiple screw fixation. Evidence of sclerosis of the talus can be noted.
Excision can be performed for small fragments, especially those which do not contribute to ankle or subtalar stability. Although no criteria exist for which fragments to stabilize or excise, the removal of small osteochondral fragments which do not contribute to joint stability seems to be well tolerated.
In highly selected cases, primary arthrodesis may be the appropriate treatment for fractures of the talar body with associated dislocations. Limited case reports are available in the literature, describing various techniques of arthrodesis. Length and alignment of the ankle and hindfoot should be retained (Fig. 54-20). The technique of primary arthrodesis offers the potential advantage of earlier return to function compared to unsuccessful attempts at open reduction internal fixation (2,46,87,97). However, most talar body fractures can be successfully treated with retention of intact ankle and subtalar joints, such that primary arthrodesis is only rarely required. Experimental studies also exist with talar body replacement in the setting of severe crush fractures of the talus (98).
As with fractures of the talar neck, rehabilitation following talar body fractures requires a prolonged period of nonweight bearing. When stable fixation has been achieved, early motion may help to prevent joint stiffness. However, weight bearing is usually restricted until union has occurred, often 3 months after the initial injury and surgery.
Prognosis and Complications
Talar body fractures are often accompanied by the development of complications, including osteonecrosis, malunion, and arthritis (2,45,68,99). Although it is thought that improvements in surgical techniques and fixation implants may decrease the incidence of complications, recent reports continue to demonstrate very high rates of osteonecrosis and arthritis. In one study, 88% of patients had radiographic evidence of osteonecrosis and/or post-traumatic arthritis at a follow-up period of 33 months (88). Other complications include flexor tendon entrapment in scar tissue (100), superficial and deep wound infections, and skin necrosis. Lindvall et al reported that in their series, complication rates and outcomes were equivalent between talar neck and talar body fractures (58).
Osteonecrosis of the talar body is a common problem. Treatment is similar to that noted above, following fractures of the talar neck. The combined fractures of the talar neck and body may be more predisposed to osteonecrosis (88), while talar body fractures with associated fractures of the malleoli may have a lower risk of osteonecrosis. The combination of talar body fracture with malleolar fracture is thought to preserve the soft tissue attachments to the body fragments (101).
The development of degenerative changes is common. Radiographic findings suggesting tibiotalar arthritis were noted in 65% and subtalar changes in 35% at the time of follow-up in the study of Vallier et al (88). Vallier et al also noted that functional outcomes were worse in patients with radiographic signs of osteoarthritis compared to patients without arthritis in their series.
Unfortunately, disability, chronic pain, and impairment are common sequelae of talar body fractures. Functional outcome scores demonstrate significant disability and are substantially higher compared to patients with other hindfoot injuries (88,102).
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Pearls and Pitfalls
Talar body fractures are relatively rare, so understanding the tricks inherent in surgical treatment can be helpful. The first pearl is to not rush into surgery without adequate preparation. CT scanning can give valuable information regarding the appropriate surgical approach, and whether malleolar osteotomy is required. It is reasonable to delay surgery until soft tissue swelling has settled, provided the tibiotalar joint is not dislocated.
Appropriate care should be taken to avoid “iatrogenic osteonecrosis.” Avoid stripping the medial and plantar aspects of the talus, where the primary blood supply enters; and avoid stripping any more of the dorsal neck than is necessary. Consider a malleolar osteotomy as a better option compared to any violation of the deltoid ligament. In general, the osteotomy is only required when the fracture line extends posterior to the midpoint of the talus. Visualization in more anterior fractures can usually be achieved with plantar flexion of the ankle.
With respect to implants, the availability of appropriate sized screws is essential. I generally use 2.0, 2.7, and 3.5 mm cortical screws. The screw length varies, but lengths upwards of 40 mm may be required. Placing the implants on the medial side is somewhat easier and less likely to be irritating to the patient. There is a bare area at the superior margin of the deltoid ligament insertion on the talus which is well suited to accept three or four small screws. Otherwise, countersinking of the hardware is a necessity. Intraoperative fluoroscopy is similarly an important necessity and the surgeon should be familiar with obtaining a Canale view to assist with the determination of alignment.
FRACTURES OF THE HEAD OF THE TALUS
Fracture of the head of the talus is a very uncommon injury with a lower incidence than talar neck or body fractures. Fractures of the head of the talus may be seen in conjunction with neck and body fractures, as well as fractures elsewhere in the foot. In most cases, the fracture line involves the articular surface of the talar head such that the talonavicular joint is involved. The injury is often associated with talonavicular subluxation and may be complicated by talonavicular arthritis.
Mechanism of Injury
Talar head fractures result from an axial load applied to the talar head through the navicular bone. The fracture is often described as a compression fracture and may result in significant impaction to the articular surfaces of the navicular and talar head. Coltart described six cases of which four occurred as a result of flying accidents. He believed this was another “rudder bar” injury. He theorized the force of impact was transmitted along the longitudinal axis of the foot through the metatarsals and navicular, with the foot held in extreme plantarflexion, such that a compression force was applied to the talar head (2). The navicular may also fracture as a result of the compressive force (42).
Fractures of the talar head are associated with varying degrees of comminution. In some cases, the fractures are associated with midfoot injuries; particularly divergent tarsometatarsal injuries. An abduction force to the midfoot appears to be associated with the longitudinal compressive force in these cases.
Clinical and Radiographic Findings
The clinical presentation of these injuries ranges from extremely subtle, commonly missed injuries to a markedly swollen midfoot with apparent major injury. Tenderness to palpation is usually noted at the talonavicular joint region. Careful examination is useful to demonstrate the findings of an associated midfoot injury.
Anteroposterior, lateral, and oblique radiographs of the foot demonstrate the fracture. Often the displaced fractures are associated with varying degrees of talonavicular joint subluxation. Fractures of the talar head are associated with other hindfoot injuries, including talar neck and body fractures and peritalar dislocation (103). Careful inspection of the radiographs may demonstrate shortening of the medial column of the foot due to the displaced fracture. Usually the primary fracture fragment involves the medial or dorsomedial aspect of the talar head, such that subluxation of the talonavicular joint occurs in a similar dorsomedial direction.
Treatment
The principles of treatment include maintenance of the alignment of the dorsomedial arch of the foot, preventing talonavicular joint incongruity and instability, and achieving a reduction of the displaced talar head fragment. Occasionally, a talar head fracture may present without displacement. In these cases a well-molded, short-leg cast may be used. In most cases weight bearing can be instituted at approximately the 6-week mark provided a well-fitting shoe with appropriate arch support is used.
Displaced fractures and those associated with joint subluxation or dislocation require open reduction and internal fixation (Fig. 54-21). Small comminuted segments can be excised but larger fragments can usually be reduced and stabilized with small or mini fragment screws or K-wires. I use a dorsomedial approach, taking care to protect the tibialis anterior tendon, and make an effort to preserve portions of the talonavicular capsular and ligamentous supports which are intact. Displaced fragments are reduced and stabilized, usually with screws ranging from 2.0 to 3.5 mm in diameter. Bone grafting is rarely necessary. Following surgery, patients are placed in a short leg
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nonweight-bearing splint until wound healing occurs, at which time early motion may be instituted depending upon the stability of the fixation.
FIGURE 54-21 Talar head fracture treated with primary open reduction and internal fixation. Axial and coronal computed tomography images demonstrate the fracture (A) and associated subtalar subluxation (B) better than plain radiographs (C). D. Open reduction and internal fixation was performed with compression screws.
Prognosis and Complications
Fractures of the talar head are prone to the development of talonavicular arthritis (Fig. 54-22) (104). Nonunion of talar head fractures is relatively uncommon. The treatment options for symptomatic talonavicular arthritis include the use of longitudinal arch supports with increased arch rigidity or a long steel shank in the shoe. If conservative measures fail, arthrodesis of the talonavicular joint may relieve symptoms. Because isolated talonavicular arthrodesis substantially alters hindfoot and midfoot mechanics, triple arthrodesis may also be considered (44).
FIGURE 54-22 Missed talar head fracture with talonavicular subluxation. Lateral radiograph demonstrates the talonavicular subluxation (A) confirmed by computed tomography scan (B) and intraoperative visualization. C. Following osteotomy and reduction, the talonavicular joint is congruent.
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Malunion may also occur. In particular, dorsomedial fragments which remain displaced may result in residual talonavicular joint subluxation. Verhaar reported on a case of late talonavicular subluxation secondary to malunion. Anatomic restoration of alignment of the talar head fragment eliminated the subluxation (105).
FRACTURES OF THE LATERAL PROCESS OF THE TALUS
Fractures of the lateral process of the talus are relatively common, but frequently overlooked. The orthopedic literature includes little information regarding fractures of the talar processes in general. The injury was described by Dimon in 1961 (106), but few case series exist regarding lateral process fractures. Nonetheless, these fractures are controversial. Most surgeons recognize that nonunion of displaced lateral process fractures is relatively common. Similarly, large lateral process fractures with extension into the subtalar joint may develop subtalar pain, arthrosis, and loss of motion. Most reports of lateral process fractures emphasize two key points: firstly that the injuries are commonly misdiagnosed; and secondly, early treatment may improve the ultimate results.
Anatomy
The lateral process of the talus is a large, broad-based, wedge-shaped prominence of the talar body. The lateral process includes two articular surfaces. Dorsolaterally, it articulates with the fibula, and inferomedially, the lateral process articulates with the anterior portion of the posterior facet of the calcaneus. The lateral talocalcaneal ligament originates from the tip of the lateral process (107).
Mechanism of Injury and Classification
Fractures of the lateral process of the talus have received increasing attention in recent years, due to the association between this fracture and snowboarding (108). Kirkpatrick et al reviewed over 3000 snowboarding injuries form 12 Colorado ski resorts and noted 74 lateral process fractures (109). It has been suggested that the fracture results from a combination of ankle inversion and dorsiflexion. However, in a recent cadaveric study, Funk et al noted that eversion of a dorsiflexed and axially loaded ankle was more likely to result in a lateral process fracture (110). Similarly, Boon et al combined external rotation with dorsiflexion, inversion, and axial loading and reproduced lateral process fractures in 75% of specimens (111). It may be
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that both avulsive and axial loading mechanisms may occur, resulting in different variants of lateral process fracture. Stress fractures of the lateral process may also occur particularly in running athletes (112,113).
Hawkins divided fractures of the lateral process into three groups: a nonarticular chip fracture, a single large fragment involving the talofibular and subtalar articulations, and a comminuted fracture involving both articulations (114). In some cases the fracture may be associated with subtalar joint incongruity or marked displacement.
Clinical and Radiographic Findings
Fractures of the lateral process of the talus are easily misinterpreted as a severe ankle sprain. The mechanism of injury, location of symptoms, and physical findings may mimic those of an inversion ankle sprain. Swelling and ecchymosis are commonly localized to the lateral aspect of the ankle. Point tenderness is localized to the lateral process, and most patients retain the ability to bear weight. As a result, the injuries may be commonly overlooked or misinterpreted as a lateral ankle sprain (115). Mukherjee et al reviewed 1500 sprains and fractures of the ankle region, and found 13 cases of lateral process fracture (116). Because the injury is frequently overlooked, the diagnosis of lateral process fracture should be considered in patients who present acutely with findings similar to an ankle sprain, as well as those who present with chronic lateral ankle pain.
Standard AP, lateral, and mortise radiographs are often insufficient to detect and fully diagnose a lateral process fracture. On the lateral view, overlap of the malleoli and the sustentaculum tali may make detection of the injury difficult. However, the fracture can usually be seen on careful inspection of the mortise view because the fracture line is most commonly in the frontal plane. Because of the difficulty in detecting and defining the extent of a lateral process fracture, a CT scan is frequently necessary to fully understand the injury. CT will accurately assess the size, degree of displacement, and comminution of the fractured process as well as joint involvement, tendon pathology, and any associated injuries (117,118). MR imaging will similarly detect and define fractures of the lateral process and associated injuries (119).
Treatment
Critical factors in determining appropriate treatment include size of the fracture fragment, displacement of the fragment, degree of comminution, associated injuries, and joint congruity. Decision making is, however, based more on general principles as opposed to any fixed guidelines. In general, small fracture fragments and undisplaced fractures are appropriately treated without surgery, with a period of immobilization followed by progressive weight-bearing and motion exercises. In contrast, large fractures associated with significant displacement and involving substantial portions of the subtalar joint are treated with open reduction and internal fixation (107,120).
Undisplaced or reduced fractures may be treated with immobilization in a short leg cast or cast brace (114). Weight bearing is usually avoided for a period of approximately 4 to 6 weeks. Following mobilization, physical therapy is often required to assist with rehabilitation of both the ankle and subtalar joints.
Displaced fractures with large fragments may be treated with open reduction and internal fixation (Fig. 54-23). Pre-operative tomograms or CT scanning is helpful in determining if fragments are large enough to consider fixation. Although the lateral process can be a large fragment, the amount of comminution and the small size of fragments are often worse than is apparent on plain radiographs. For comminuted fractures, primary excision of fragments is indicated to avoid the later development of arthritic changes in the subtalar joint (120). Open reduction or fragment excision may be performed through a direct lateral approach using an incision over the sinus tarsi. When open reduction is performed, screw fixation can often be accomplished with the screw inserted from the tip of the process and extending posteriorly and superiorly into the talar body. The increased availability of small screws ranging from 2.0 to 4.0 mm in diameter has made fixation a reasonable option for an increased number of lateral process fractures.
Prognosis and Complications
The literature with respect to outcome of lateral process fractures following treatment is limited to small case series (2,76,106,107,114,116,121,122,123). As noted by several authors, late pain in the region of the subtalar joint seems to be surprisingly common following fractures of the lateral process. Nonunion of unreduced fractures and residual malalignment of the subtalar joint cause persistent symptoms (106,114,116). Several authors have noted that earlier treatment may be associated with better results. In one review of the literature it was noted that earlier treatment resulted in a low rate of nonunion and generally good outcome (115). Heckman and McLean, in a review of nine patients, found best results when patients were diagnosed and treated early compared to a high proportion of patients with pain when treatment was delayed (120). Therefore, whether casting, fragment excision, or open reduction internal fixation is necessary, it seems that the proposed treatment is best performed early.
Nonunion of lateral process fractures probably occurs more frequently than is commonly recognized. Treatment of nonunions is usually restricted to excision of ununited fragments. Attempts at obtaining union of established nonunions are unlikely to succeed. Nonunions associated with subtalar joint subluxation frequently develop subtalar arthrosis, often requiring arthrodesis (124).
POSTERIOR PROCESS FRACTURES
Anatomy
Fractures of the posterior process of the talus are interesting injuries. The anatomy is deceptively complex. Together, the
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medial and lateral tubercles comprise the posterior talar process (Fig. 54-24). The lateral tubercle is larger and projects more posteriorly. The posterior talofibular ligament is attached to the lateral tubercle. The lateral tubercle can be seen on a lateral radiograph of the ankle. Between the lateral and medial tubercles is the groove for the flexor hallucis longus tendon. The medial tubercle projects medially and inferiorly from the groove for the flexor hallucis longus. The posterior third of the deltoid ligament is attached to the medial tubercle.
FIGURE 54-23 Lateral process fracture demonstrated on anteroposterior radiograph of the ankle (A) and confirmed by tomography (B). C,D. Open reduction and internal fixation was performed with a cancellous screw and Kirschner wire.
The inferior aspect of the posterior process is covered by articular cartilage. The posterior 25% of the posterior articular facet of the subtalar joint is formed by the posterior process. McDougall described the development of the posterior process of the talus. It is thought that the posterior process arises from a secondary ossification center that fuses with the body of the talus around age 12 (125).
Diagnosis of fractures of the posterior process of the talus can be difficult, in part relating to the presence of an os trigonum. The os trigonum is an accessory bone of the foot located just posterior to the lateral tubercle of the posterior process. Burman and Lapidus found a separate os trigonum in 64 of 1000 feet examined by x-ray, and noted a fused os trigonum in 429 of 1000 feet (126). These authors defined the fused os trigonum as an elongated lateral tubercle. While Burman and Lapidus described a significant degree of symmetry in the anatomy of the posterior talus between the two feet of any person, McDougall described the os trigonum as a possible unilateral occurrence (125). The os trigonum is usually distinguished from
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a fracture of the lateral tubercle based upon its radiographic appearance. The shape of the os trigonum varies, including round, oval, and triangular shapes. The edges are well corticated and smooth, unlike an acute fracture. A high index of suspicion is necessary to rule out an acute fracture. Giuffrida et al describe a series of six patients with posteromedial talus facet fractures, in whom four were misdiagnosed as having an os trigonum (127). Kim et al described three of five patients in whom fractures of the medial tubercle of the posterior process were misdiagnosed as an os trigonum or an ankle sprain (128). In both series, patients with delayed diagnoses presented with chronic posteromedial ankle pain.
FIGURE 54-24 Posterior view of the talus demonstrating that the posterior process has two tubercles, separated by the groove for the flexor hallucis longus tendon. The posterior fibers of the deltoid insert into the medial tubercle, and the posterior talofibular ligament inserts into the lateral tubercle.
Fractures of the Lateral Tubercle of the Posterior Process
Fracture of the lateral tubercle of the posterior process of the talus was described in 1844 by Cloquet. In 1882, Shepherd described the fracture in the English literature (129). The fracture is often referred to as Shepherd’s fracture (130,131).
Mechanism of Injury
Fractures of the lateral tubercle of the posterior process may occur as a result of avulsion mechanisms, or as a direct compression injury. Inversion of the ankle may create an avulsion fracture as the posterior talofibular ligament avulses the tubercle (76). Direct compression injuries are perhaps a more common mechanism. Extreme equinus of the ankle compresses the lateral tubercle between the calcaneus and the posterior lip of the tibia (76,125,132,133,134,135). Repetitive trauma may occur in kicking athletes such as football or rugby players, in whom subacute pain may develop related to the forced equinus position of the foot on impact (125,136). A stress fracture may result in a similar presentation. Alternatively, pain may result from a failure of fusion of the secondary ossification center of the posterior process with the body of the talus. Repetitive stress in the adolescent may predispose to the development of a painful pseudarthrosis in this manner (136).
Clinical and Radiographic Findings
Patients with a fracture of the lateral tubercle frequently present with symptoms comparable to an ankle sprain. Tenderness can be elicited over the posterolateral ankle and motion of the ankle and subtalar joints is painful. Active flexion of the great toe may produce pain, as the flexor hallucis longus tendon moves over the fracture site. The fracture can be difficult to see on plain radiographs. Often the lateral xray provides the best demonstration of the lateral tubercle (Fig. 54-25). Comparison views of the contralateral foot are useful to identify and contrast the appearance of an os trigonum. Any rough or irregular surfaces visible should be interpreted as potentially indicative of a fracture of the lateral tubercle of the posterior process, in contrast to smooth and well-corticated surfaces usually indicative of the os trigonum. The variability of the anatomy of the posterior process should be considered. CT scanning may be useful when the diagnosis is not apparent on plain radiographs.
Treatment and Prognosis
Treatment of fractures of the lateral tubercle of the posterior process of the talus should be directed toward achieving union. Multiple reports in the literature exist describing ununited and symptomatic fractures requiring surgical intervention. Patients should be prevented from inversion of the ankle and plantarflexed positioning of the hindfoot to avoid displacement. Protection from full weight bearing and the use of a short leg cast or ankle brace is continued for 4 to 6 weeks or until some signs of union are present.
FIGURE 54-25 Lateral x-ray of the ankle showing a fresh fracture of the lateral tubercle of the posterior process of the talus.
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Nonunion of lateral tubercle injuries often requires excision of the fragment. Patients complain of pain with plantarflexion, pain with physical activity, and often restriction of ankle and subtalar joint motion. Making the diagnosis can be difficult; if the fragment has developed a rounded appearance on radiographs, distinguishing an ununited fragment from an os trigonum can be challenging. In addition to the fragment, x-rays may show degenerative changes adjacent to the fragment and in the subtalar joint. As well, a bone scan will demonstrate increased uptake in the area of the fragment.
In addition to nonunion, symptoms referable to the flexor hallucis longus tendon may develop. Partial rupture or tenosynovitis of the tendon may occur without fracture, and is usually noted in athletes such as soccer players or ballet dancers. Inokuchi et al reported a case of complete rupture of the flexor hallucis longus tendon following a nonunion of a Shepherd’s fracture, requiring tendon grafting to restore tendon function (137).
Treatment of an ununited lateral tubercle is usually accomplished by excision of the fragment. Excision may be accomplished via a posterolateral (138) or posteromedial approach (1391), and usually achieves relief of pain and improved motion (125,128,136).
Fractures of the Medial Tubercle of the Posterior Process
Fracture of the medial tubercle of the posterior process is an uncommon injury. The injury was described in 1974 by Cedell (140) and is sometimes referred to as Cedell’s fracture. Although limited case series exist regarding this injury, the existing literature repeatedly notes the problems with this fracture related to delayed diagnosis and the subsequent development of ankle pain.
Various mechanisms have been proposed. Most commonly, fracture of the medial tubercle occurs via an avulsion injury of the posteromedial talar facet. The foot is suddenly forced into combined pronation and dorsiflexion, and the posterior deltoid ligament avulses the medial tubercle of the posterior process (129,140,141,142,143). Alternate mechanisms include direct trauma to the posteromedial talar facet (144), impingement of the sustentaculum tali in supination (145), and forced dorsiflexion in high-energy trauma (146).
Fracture of the medial tubercle is difficult to visualize on plain films. Accordingly, injuries are often missed and patients frequently present late. Common presenting symptoms are posteromedial ankle pain and tenderness. Dougall and Ashcroft described an interesting patient with entrapment of the flexor hallucis longus tendon in the fracture. In this instance, the patient presented with inability to extend the great toe as well as posteromedial ankle symptoms (146). On occasion the fragment can be seen in the lateral projection of plain x-rays, or may be visualized as a small flake fragment off the medial wall of the talus in the anteroposterior projection (Fig. 54-26). However, plain radiographs often do not demonstrate the fracture well. CT is perhaps most helpful at documenting the extent and severity of these fractures (Fig. 54-27).
Kanbe and colleagues treated two patients with these fractures
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with open reduction and internal fixation. In both cases, the fragment was found to be much larger than initially suspected (142). Cedell surgically excised three persistenly symptomatic ununited fragments (140). Stefko et al excised a malunited fragment to relieve a secondary tarsal tunnel syndrome (143). Kim et al reported on two patients diagnosed early who were successfully managed with cast immobilization, and three patients who presented late who were successfully managed with fragment excision (128). In general, excision of ununited or malunited fragments seems to successfully relieve local irritative symptoms in patients who present with posteromedial ankle pain secondary to a posterior medial tubercle avulsion.
FIGURE 54-26 Anteroposterior (A) and lateral (B) radiographs of an acute fracture of the medial tubercle of the posterior process of the talus. The arrows identify the fracture line.
FIGURE 54-27 Coronal computed tomography (CT) scan (A) and CT reconstruction (B) demonstrating the medial process fracture depicted in x-rays in Figure 54-26.
Fracture of the Entire Posterior Process
Fracture of the entire posterior process of the talus is an uncommon injury. Foster described a case in a 20-year-old woman who sustained a displaced fracture of the posterior process as a result of an inversion injury (Fig. 54-28). The process was displaced and was compressing the posterior tibial neurovascular bundle. Open reduction and internal fixation was performed. Nasser and Manoli also described a case which required open reduction and internal fixation to restore congruity of the ankle and subtalar joints (147).
DISLOCATIONS OF AND AROUND THE TALUS
Subluxation and dislocation of the talus can occur in conjunction with major talus fractures, as described above. However, dislocations can also occur with no associated bony injury or with relatively minimal appearing fractures. These injuries can be considered in two broad categories, subtalar dislocation and total talar dislocation.
Subtalar Dislocation
Subtalar dislocation, also known as peritalar dislocation (148), refers to the simultaneous dislocation of the distal articulations of the talus at the talocalcaneal and talonavicular joints. First
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described by Judcy (149) and Dufaurets (150) in 1811, clinical reviews of subtalar dislocations are relatively infrequent and generally limited to small numbers of patients. Smith (151) noted only seven dislocations in a review of 535 dislocations of all types. Leitner noted only 42 among 4215 dislocations (152). Fifteen percent of all talar injuries in Pennal’s series were subtalar dislocations (46). Therefore, subtalar dislocations are uncommon. Most commonly, the injuries occur in young adult males, although Bibbo et al noted 36% of subtalar dislocations in their series of 25 patients occurred in patients over 40 years of age (153).
FIGURE 54-28 Oblique view of the ankle mortise demonstrating fracture of the entire posterior process of the talus. (Courtesy of Robert R. Foster, MD)
Anatomy and Classification
Subtalar dislocation can occur in any direction. Significant deformity is always present. Up to 85% of dislocations are medial (Fig. 54-29) (154,155,156,157,158). The calcaneus, with the rest of the foot is displaced medially while the talar head is prominent in the dorsolateral aspect of the foot. The navicular is medial and sometimes dorsal to the talar head and neck. Lateral dislocation occurs less often. In a lateral dislocation, the calcaneus is displaced lateral to the talus and the talar head is prominent medially (Fig. 54-30). The navicular lies lateral to the talar neck. Rarely, a subtalar dislocation is reported to occur in a direct anterior or posterior direction, but these are usually associated with medial or lateral displacement as well (158,159). The direction of subtalar dislocation has important effects with respect to management and outcome. The method of reduction is different for each type of injury. As well, lateral dislocations are often associated with a higher energy mechanism and a worse long-term prognosis compared to medial subtalar dislocations.
FIGURE 54-29 A. In this medial subtalar dislocation, the head of the talus is palpable on the dorsum of the foot. B. The heel is displaced medially. (From Buckingham WW Jr. Subtalar dislocation of the foot. J Trauma 1973;13:754.)
FIGURE 54-30 In this lateral subtalar dislocation, the head of the talus is prominent medially while the rest of the foot is dislocated laterally. (From Buckingham WW Jr. Subtalar dislocation of the foot. J Trauma 1973;13:757.)
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Mechanism of Injury
Inversion of the foot results in a medial subtalar dislocation, while eversion produces a lateral subtalar dislocation. The calcaneonavicular ligament resists disruption (160), while the inversion or eversion force is dissipated through the weaker talonavicular and talocalcaneal ligaments such that the calcaneus, navicular, and all distal bones of the foot are displaced as a unit either medially or laterally. With a medial subtalar dislocation, the sustentaculum tali acts as a fulcrum about which the foot rotates to lever apart the talus and calcaneus; and in the lateral dislocation the foot pivots about the anterior process of the calcaneus, again causing the talus and calcaneus to separate (161).
High versus Low-Energy Injuries
Subtalar dislocations can result from either high-energy or low-energy mechanisms. The distinction is important because outcome has been correlated with the severity of the initial injury. In the series of Bibbo et al, high-energy mechanisms such as motor vehicle trauma, and falls from height accounted for 68% of subtalar dislocations (153). Other common mechanisms include sports injuries, usually related to a fall from jumping height. Grantham coined the term basketball foot to describe a medial subtalar dislocation because four of the five patients in his series sustained the injury on the hardwood (155). Usually the basketball foot occurs when landing from a rebound. Open subtalar dislocations and lateral subtalar dislocations are more common with a high-energy mechanism. Medial injuries are more common, suggesting that the forces required to produce it are less than those required to produce a lateral dislocation.
High-energy subtalar dislocations may be associated with other injuries, either regional or involving other body systems. One series described associated foot and ankle injuries in 88% of patients with subtalar dislocations (153). Regional fractures include talus, ankle, calcaneus, navicular, cuboid, cuneiform, and metatarsal fractures (162). Osteochondral shearing injuries to the articular surface of the talus, the calcaneus, or the navicular are common. These injuries occurred in 45% of patients in one large series, and were difficult to detect on plain radiographs (154,155,156). Injuries remote from the foot and ankle may occur as well. In a series of subtalar dislocations from a major level 1 trauma center, other musculoskeletal injuries occurred in 48% of patients and 12% of patients had injuries to the head, abdomen, or chest (153).
Signs and Symptoms
Subtalar dislocations present with an impressive amount of deformity. The medial dislocation has been referred to as an “acquired clubfoot” (Fig. 54-31), while the lateral has previously been described as an “acquired flatfoot” (Fig. 54-32) (161). As well, many of the injuries are open, particularly when associated with a high-energy mechanism. Up to 40% of subtalar dislocations may present with an open wound (163). The head of the talus may protrude through the open wound in a lateral dislocation. In closed dislocations, the skin is usually distorted and markedly tented over the prominent head of the talus. Swelling occurs rapidly and may mask the bone deformity. Prompt evaluation for impairment of the neurovascular function is imperative prior to and following reduction of the dislocation.
FIGURE 54-31 Medial subtalar dislocation. The head of the talus is directed inferior to the navicular.
Radiographic Findings
Radiographs of a subtalar dislocation may be difficult to interpret. The severity of the deformity makes it difficult to obtain true anteroposterior and lateral images of the foot, and standard ankle x-rays do not reveal the foot pathology (164). It is important to note that the relationship between the talus and tibia and fibula is normal in a peritalar dislocation because the point of injury is distal to the ankle joint. The anteroposterior view of the foot demonstrates the talonavicular dislocation.
The absence of the talar head within the “cup” of the navicular is an important diagnostic key. On the lateral projection, the head of the talus usually lies superior to the navicular and cuboid for a medial dislocation, and appears to be displaced inferior in a lateral dislocation (Figs. 54-31 and 54-32). Usually interpretation of the plain radiographs provides enough information to determine the direction of the dislocation, such that the physician can proceed with an attempt at reduction. However, plain radiographs should be interpreted with caution. Associated fractures can be missed on plain radiographs, and post-reduction films may not be adequate in all cases to determine whether residual subluxation is present.
CT scanning may be very useful to determine whether associated fractures are present and to rule out talo-calcaneal subluxation. Bohay and Manoli described four cases of subtalar dislocation with associated fractures or residual subluxation not documented on plain radiographs (165). Merchan reported associated fractures in 64% of his series of 39 cases (163), and Bibbo et al reported associated injuries to the foot and ankle in 88% of patients in one series (153). In another study, in which a CT scan was performed in all cases, CT identified additional
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injuries missed on initial plain radiographs on all patients and in 44% of patients, new information gathered by CT dictated a change in treatment (166).
FIGURE 54-32 X-rays of a lateral subtalar dislocation. (From Buckingham WW Jr. Subtalar dislocation of the foot. J Trauma 1973;13:758.)
Treatment
Closed Reduction
All subtalar dislocations require a gentle and timely reduction. In most cases, reduction can be accomplished closed. Often the injury presents with skin tenting such that a prompt reduction will reduce the possibility of skin necrosis. Open peritalar dislocations require a formal irrigation and debridement in addition to the reduction followed by wound closure (167).
The principles of closed reduction include first, the provision of adequate relaxation and sedation. A forceful manipulation may be necessary to accomplish the reduction, and patients are often disturbed by the sight of their markedly deformed extremity, such that general anesthesia may be required to achieve sufficient relaxation. Second, the tension on the Achilles tendon should be relaxed by flexing the knee. Next, longitudinal traction on the foot is applied with counter traction on the leg.
Accentuation of the deformity is often necessary to “unlock” the calcaneus. Inversion is therefore applied for a medial dislocation, and eversion for a lateral dislocation. Once the calcaneus is unlocked, reversal of the deformity can be applied. Reduction is usually accompanied by a satisfying clunk.
Digital pressure over the head of the talus can also by applied to aid in reduction. However, it should be applied with caution. The calcaneus is ideally unlocked with inline traction and accentuation of the deformity before digital pressure is applied. Although digital pressure over the talar head can successfully aid in the reduction, it may also cause further skin necrosis and potentially displace an osteochondral fracture.
Once the reduction is accomplished, it should be confirmed by clinical examination and radiographs. On clinical examination, the foot should demonstrate a restoration of normal alignment and range of motion of the subtalar and midtarsal joints. Plain radiographs confirm the reduction and should be closely inspected for associated fractures that may have been missed on the radiographs of the distorted foot. In many cases, a subtalar dislocation is stable following closed reduction. This is particularly the case when there are no associated osteochondral or other fractures. Clinical assessment of stability can be performed following closed reduction. If the dislocation is clinically stable, no internal fixation is necessary. The foot can then be immobilized in a short-leg posterior splint.
Following a short period of immobilization, physical therapy is instituted to regain subtalar and midtarsal mobility. The outcome following simple dislocations treated with closed reduction seems to be favorable (154). Although recurrent dislocations are reported, they are uncommon (168,169,170). Therefore early mobilization is preferred to avoid potential problems related to joint stiffness.
Closed reduction is unsuccessful in some patients. Garofalo et al reviewed a series of 18 patients with peritalar dislocations in whom no open reductions were required (171). In most series, the need for open reduction seems to be associated with
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higher energy subtalar dislocations. In some series as few as 10% of patients with medial dislocations and 15% to 20% of lateral subtalar dislocations required open reduction (152,156,172,173). Recent series, particularly from trauma centers, have noted the need for open reduction to be more common, with 32% of patients requiring open reduction in one series (153).
A variety of bone and soft tissue structures may become entrapped, resulting in a block to closed reduction. These impediments require open manipulation or release to facilitate reduction. With medial dislocations, the talar head can become trapped by the capsule of the talonavicular joint, the extensor retinaculum or extensor tendons, or the extensor digitorum brevis muscle. Heck et al studied the irreducible medial subtalar dislocation in a cadaver model. Entrapment of the talar head in the extensor retinaculum, talonavicular impaction, and impingement of the deep peroneal nerve and dorsalis pedis branches between the talus and navicular were implicated as causes of irreducible subtalar dislocation (174). Talonavicular impaction is often implicated as an obstruction to closed reduction (Fig. 54-33). The extreme medial displacement of the foot at the moment of injury is followed by a recoil toward the normal position, causing the lateral edge of the navicular to impinge on the medial talus. An impaction fracture is produced and the articular surfaces become interlocked.
Articular surface impaction may also block the reduction of a lateral subtalar dislocation. The posterior tibial tendon is also implicated as a barrier to closed reduction, which can be displaced and wrapped around the head of the talus (Fig. 54-34). Woodruff et al presented a case in which the musculotendinous junction of the tibialis posterior muscle allowed the extreme tendon excursion required to displace the tendon around the talar head. Alternatively, the flexor retinaculum may be torn such that the talar head can buttonhole between the flexor tendons (175).
FIGURE 54-33 Line drawing of a medial subtalar dislocation, irreducible by closed means, due to impaction of the talus and navicular with interlocking of the articular surfaces. (From Buckingham WW Jr. Subtalar dislocation of the foot. J Trauma 1973;13:757.)
FIGURE 54-34 Lateral subtalar dislocation with interposed posterior tibial tendon preventing closed reduction. (From Leitner B. Obstacles to reduction in subtalar dislocations. J Bone Joint Surg 1954;36A:299.)
Open Reduction
Open reduction, when necessary, is performed through a longitudinal anteromedial incision. This approach allows access to the structures that may be incarcerating the head of the talus and allows visualization of an interlocked impaction fracture of the talus and navicular. With a lateral peritalar dislocation, the incision may be sited more medially to facilitate manipulation of the posterior tibial tendon.
It is usually possible to gently displace the offending bone or soft tissue which is preventing closed reduction. In the case of impaction fractures, care should be taken to avoid displacing fracture fragments. Osteochondral shear fractures may also block reduction and should be removed if small and nonstructural (176). It is often possible to repair displaced bone fragments with small screws or wires. When a large impaction fracture is found, it may be possible to elevate and bone graft the fragment to support the reduction. Entrapped soft tissue can usually be gently distracted and the reduction achieved (Fig. 54-35). However, the extensor retinaculum in particular may require transection to facilitate a reduction.
With a lateral dislocation, the posterior tibial tendon when entrapped may present a substantial barrier even to open reduction. The posterior tibial tendon becomes very firmly entrapped. Extreme varus and plantar flexion of the hindfoot is necessary to relax the tendon, along with extending the incision through
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the flexor retinaculum. Even so, in some cases it has been necessary to transect the posterior tibial tendon to achieve a reduction (169). This should be done as a last resort only and it should be repaired and protected following reduction.
FIGURE 54-35 Clinical photograph of a complex lateral peritalar dislocation with entrapment of the peroneal tendons between the calcaneus and cuboid. Removal of the peroneal tendons was required to facilitate reduction.
Following reduction, the peritalar dislocation should be assessed for congruency radiographically and for stability. If an open reduction was required because of soft tissue interposition, the reduction is usually stable. However, if large or multiple bone fragments required removal, stability may be less than ideal. Internal fixation with smooth wires across the subtalar and talonavicular joints may be necessary to maintain the reduction (171). Following 4 to 6 weeks of immobilization, internal fixation can be removed and weight bearing and active physiotherapy instituted.
Prognosis and Complications
Subtalar dislocations have a wide variance in terms of their prognosis. Uncomplicated subtalar dislocations, stable following a closed reduction, have an excellent prognosis with minimal symptoms at long term follow up. Limitation of subtalar joint motion is a consistent abnormal finding and may be associated with pain when walking on uneven ground or pain with weather changes (151,155,160,169). Perugia et al reported on 45 patients with subtalar dislocations followed for a mean of 7.5 years in whom the mean ankle and hindfoot functional outcome score was in the good to excellent range. Only one patient in their study required a subtalar arthrodesis (177).
Most reviews, however, report a mixture of outcomes following subtalar dislocation. Garofalo et al followed 18 patients for 10 years and reported 44% had fair or poor results (171). Ruiz Valdivieso et al followed 17 patients for a mean of 7.9 years. Their results were good in only 6 of 17, and fair or poor in the remaining 11 (178). Bibbo et al studied 25 patients from a level 1 trauma center. Of the 18 patients who were available for review at a mean of 5 years, 89% demonstrated radiographic changes of ankle arthritis; 89% demonstrated subtalar arthritis; and 72% demonstrated midfoot arthritis. Functional outcome scores were much lower than in the study of Perugia et al and eight patients required arthrodesis of the ankle or subtalar joints (153).
Certain subtalar dislocations are clearly associated with a worse prognosis. Lancaster et al, in a review of the literature,
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noted that associated injuries and complications were associated with a worse result. In particular, soft tissue injury, extra-articular fracture, intra-articular fracture, and osteonecrosis were associated with a worse outcome (179). Open fractures are undoubtedly associated with the poorest results. Goldner et al reviewed 15 patients at a mean of 18 years following open subtalar dislocations. Associated injuries were noted to the tibial nerve in 10 patients; to the posterior tibial tendon in 5; and to the posterior tibial artery in 5. Seven patients ultimately required arthrodesis due to osteonecrosis or post traumatic arthritis. They concluded that only fair functional, and poor anatomical, results can be expected following these severe injuries (180).
The mechanism of injury is an important factor in predicting long-term outcome. Inversion dislocations resulting from a low-energy mechanism, such as the “basketball foot,” rarely result in long-term morbidity. Violent mechanisms such as a fall from a height or a motor vehicle collision are much more likely to cause long-term problems. Lateral subtalar dislocations may have a worse outcome compared to medial dislocations, but it is likely that the energy of the mechanism is more important than the direction (154). Associated fractures and articular cartilage damage may also be more common with lateral dislocations.
Osteonecrosis of the talus may develop following peritalar dislocations. Overall, osteonecrosis is uncommon and generally only noted with high-energy and open injuries. Theoretically, the talus is not displaced from the ankle mortise and therefore at least some of the blood supply should be preserved. However, Goldner et al noted osteonecrosis in 5 of 15 patients with grade 3 open subtalar dislocations (180), and Bibbo et al noted osteonecrosis in three patients (153).
Persistent instability is fortunately uncommon (168,169). The subtalar and talonavicular joints have a substantial degree of intrinsic stability such that early mobilization can usually be undertaken safely and effectively. However, repeat subluxation has been noted when immobilization was discontinued early (170) and in patients with generalized joint laxity (168). Subluxation which occurs early may be treated with repeat closed reduction with good results (156).
Post-traumatic arthritis is common after a peritalar dislocation. The causes of arthritis include associated fractures, cartilage damage, and potentially unrecognized instability. Arthritis can be noted in the ankle or the midfoot, but is most common in the subtalar joint itself. Reports on the incidence of subtalar arthritis range from as low as 25% to as high as 89% (153,154,156,163,170). While the radiographically apparent subtalar changes are not always symptomatic, progression to severe and painful arthritis can only be treated with an arthrodesis.
Total Dislocation of the Talus
Mechanism of Injury
Total dislocation of the talus is a rare injury, resulting from an extension of the forces causing a subtalar dislocation. An extension of the supination force causing medial subtalar dislocation will result in a total lateral talar dislocation; and an extension of the pronation force causing a lateral subtalar dislocation will result in a total medial talar dislocation (Fig. 54-36) (181). The injury is usually associated with some degree of associated fracture in the hindfoot but has been reported without fracture in a rare case of posterior dislocation (158,159,160).
Treatment and Prognosis
As with most severe talus fractures and dislocations, complete dislocation of the talus is a devastating injury. Results are complicated by infection, osteonecrosis, and post-traumatic arthritis. Most of the injuries are open. Detenbeck and Kelly reported a series of nine cases of complete dislocation of the talus. Eight of nine eventually required talectomy for control of persistent infection (182).
FIGURE 54-36 More extreme application of the same forces that produced subtalar dislocation can result in total talar dislocation. Supination produces medial subtalar dislocation (A) followed by subluxation and finally complete lateral dislocation of the talus (B). Pronation initially produces lateral subtalar dislocation (C), followed by talar subluxation and eventually total medial dislocation of the talus (D). (Leitner B. The mechanism of total dislocation of the talus. J Bone Joint Surg 1955;37A:93.)
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Initial treatment is directed to the soft tissues. An early and thorough debridement of contaminated and nonviable tissue is performed, as well as an urgent reduction of the talus to reduce skin tension. As would be expected with the rarity of this injury, the literature is limited to small case reports. Most authors recommend reduction and preservation of the native talus, with arthrodesis and talectomy reserved for treatment of complications (183,184,185,186,187,188). Based on their results, Detenbeck and Kelly recommended excision of the talus and primary tibiocalcaneal arthrodesis (182).
In general an open reduction of the completely dislocated talus is required. Aids to reduction include a calcaneal traction pin or distractor. An anteromedial or anterolateral arthrotomy can be used. Blocks to reduction include the extrinsic tendons, associated fracture fragments and capsular soft tissues (189). The reduction is frequently unstable, requiring transfixion of the subtalar or talonavicular joints. Immobilization should be continued until soft tissue healing has achieved stability, at least 6 weeks. Osteonecrosis can be anticipated such that early treatment with a patellar tendon bearing orthosis may be considered. Due to the anticipated development of complications, including osteonecrosis and arthrosis, patients should be counseled that reconstructive surgery is likely to be required in the future in the form of arthrodesis of involved and symptomatic joints.
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