Talus fractures

INTRODUCTION — The talus is composed of dense bone and significant force is required to cause a fracture. Thus, talus fractures are relatively uncommon, comprising less than 1 percent of all fractures [1]. However, when talus fractures do occur they are high risk injuries that often present difficulties in management, and therefore only a limited subset of fractures are amenable to treatment in the primary care setting [2].

The presentation and basic management of talus fractures is reviewed here. Other injuries in the ankle region are discussed separately. (See "Ankle fractures in adults" and "Ankle sprain in adults: Evaluation and diagnosis" and "Achilles tendinopathy and tendon rupture" and "Foot and ankle pain in the active child or skeletally immature adolescent: Evaluation".)

EPIDEMIOLOGY — Talus fractures comprise approximately 0.1 to 0.85 percent of all fractures [1]. Most occur as a result of high-energy trauma, such as motor vehicle accidents [2]. As a result, talus fractures are often accompanied by other injuries, including dislocation of adjacent joints and fracture of neighboring bones [3].

There is an increased incidence of talus fracture among snowboarders due to the unique stress placed on the talus when landing from jumps on a snowboard. In snowboarders, 15 percent of ankle injuries involve fractures of the lateral process of the talus [4]. Snowboarders are therefore 17 times more likely to suffer a talus fracture compared to the general population [5]. (See 'Lateral process (snowboarder) fractures' below.)

CLINICAL ANATOMY — The talus is involved in the transmission of force between the lower leg and the foot and bears the weight of the body, and thus it is composed of dense bone. The superior surface of the talus bears a greater load per unit area than any other bone [6].

The talus is generally divided into the head, neck, and body (figure 1). The superior surface (trochlea) of the body of the talus articulates with the tibia (talocrural joint), while the inferior surface articulates with the calcaneus (subtalar joint), and the anterior surface (head) articulates with the navicular bone (figure 2 and figure 3 and figure 4). The neck is the area between the body and the head. Medial and lateral to the talus lies the medial malleolus (tibia) and the lateral malleolus (fibula) (figure 5 and figure 6 and figure 7). The lateral process of the talus extends beneath the distal fibula and also comprises part of the subtalar joint. It is largely covered with articular cartilage. The posterior process or tubercle of the talus extends from the posterior aspect of the bone. A variation of the posterior process is the os trigonum, a separate bone that originates from a secondary ossification center that fails to unite with the talus and is frequently mistaken for a fracture.

Greater than 60 percent of the surface of the talus is covered in articular cartilage and thus talus fractures are often intra-articular [7]. The abundance of articular cartilage limits the areas of the bone that can be accessed by nutrient arteries. Therefore, the blood supply to the talus is relatively tenuous and fractures are associated with an increased risk of avascular necrosis [8].

Although many ligaments attach to the talus, no muscles insert on or originate from the bone. The posterior talofibular ligament attaches to the lateral aspect of the posterior process of the talus. In addition to the ligaments, a number of surrounding tendons provide structural support to the talus.

MECHANISM OF INJURY — Most talus fractures occur as a result of falling from a significant height or from high energy trauma. Approximately 50 percent of talus fractures occur from automobile or motorcycle accidents [2]. Axial loading of the ankle or impact sustained with the ankle in extreme plantar flexion or dorsiflexion is often involved. The subset of lateral process talus fractures, most often seen in snowboarders, frequently occurs during a hard landing after a jump and involves an uncontrolled axial load, often when the ankle is dorsiflexed and slightly rotated [4]. More detailed explanations of the mechanisms associated with specific types of talus fractures are provided below. (See 'Talus fracture types: Special aspects of presentation and management' below.)

HISTORY AND EXAMINATION FINDINGS — The patient with a talus fracture typically presents with pain and swelling around the ankle and difficulty with weight bearing following trauma. Swelling may obscure the landmarks of the ankle or, if the fracture is displaced or the ankle dislocated, skin contours may be obscured or deformed. Ankle range of motion is often limited. The symptoms and signs associated with lateral process fractures of the talus, which are relatively common among snowboarders, are similar to an ankle sprain and therefore these injuries can be misdiagnosed. A general approach to the athlete with ankle pain following minor trauma is reviewed separately. (See "Foot and ankle pain in the active child or skeletally immature adolescent: Evaluation".)

The physical examination should include vital signs and a careful evaluation looking for signs of internal injury, particularly for patients involved in significant trauma or at high risk of injury (eg, elderly patient). Following major trauma, an ankle injury, particularly if there is deformity, may distract the examiner from other more serious problems. If there is any doubt about the nature or extent of injury, it is best that the patient be evaluated in the emergency department. (See "Initial management of trauma in adults".)

Examination of the patient with a foot or ankle injury follows the standard approach, including inspection, palpation, and range of motion testing, if this is tolerated. Neurovascular assessment is required. Look carefully at the skin for abrasions, lacerations, blistering from rapid stretching of the skin, and tenting. Any break in the skin increases the risk of infection and may complicate the application of a splint or cast. Open fractures and fracture-dislocations are considered orthopedic emergencies since delays in treatment lead to worse outcomes, possibly including avascular necrosis [9,10]. Blister formation may suggest more forceful trauma.

Typically, patients with a talus fracture manifest tenderness to palpation at and below the ankle. Tenderness may be focal or generalized. Palpation should include the talar head and neck (just distal and anterior to the ankle joint) (picture 1), the talar body (just anterior, inferior, and posterior to each malleolus) (picture 2 and picture 3 and picture 4), the talar dome (on the anterior joint line with the foot and ankle plantar-flexed) (picture 5), and the posterior talus (deep palpation just anterior to the Achilles tendon from both the medial and lateral aspect).

Nerve integrity can be assessed by confirming sensation in each independently innervated area of the foot (figure 8), and by testing flexion and extension of the great toe, small toes, and ankle. The neurologic examination is described in detail separately. (See "The detailed neurologic examination in adults".)

Assessment of the dorsalis pedis and posterior tibialis pulses and distal capillary refill is required. If the pulses are not palpable due to swelling, a handheld Doppler device can be used to determine if they are present. Immediate surgical consultation is required for any vascular deficit [9].

DIAGNOSTIC IMAGING — A standard three-view ankle series (anterior-posterior (AP), mortise, and lateral views) should be obtained if there is any suspicion of a talus fracture (image 1 and image 2). The Canale–Kennedy view may be useful since it projects the talar head and neck above the calcaneus. This view is obtained if computed tomography (CT) is unavailable. Positioning for a Canale-Kennedy radiograph view involves fully plantar flexing the ankle, pronating the foot 15 degrees and placing the bottom of the foot on the x-ray table (figure 9). The x-ray beam is then angled 75 degrees of from the table [11].

Plain radiographs using special views have largely been supplanted by CT, as a precise assessment of alignment and displacement is critical for proper management (image 3 and image 4 and image 5) [12,13]. CT should be obtained for any confirmed talus fracture or whenever clinical suspicion for a fracture remains high despite negative plain radiographs. According to a retrospective review of 132 talus fractures, a substantial number of injuries are not seen on plain radiograph, including 31 percent of talar dome compression fractures in this series (overall sensitivity for talus fractures was 74 percent) [3]. Failure to recognize even minimal displacement or angulation of a talus fracture is associated with worse outcomes [1].

Magnetic resonance imaging (MRI) is generally not obtained for an acute talus fracture, unless the injury is isolated to the cartilage of the talar dome. CT generally provides more detailed images of bone than MRI [14]; MRI is reserved for the assessment of patients whose symptoms persist for four to six weeks after an ankle injury and whose repeat ankle radiographs do not reveal a fracture. In such cases, MRI can better assess any articular cartilage injury and damage to adjacent ligaments or tendons, and can distinguish between os trigonum fracture and an ossicle [6,15]. MRI may be required if a stress fracture is suspected in the appropriate clinical setting. (See "Overview of stress fractures", section on 'Imaging studies'.)

Musculoskeletal ultrasound has a limited role in the evaluation of most talus fractures. It can be useful for examining the talar dome (image 6).

DIAGNOSIS — The patient with a talus fracture typically presents with pain and swelling around the ankle and difficulty with weight bearing following trauma to the ankle region. The diagnosis of a talus fracture is made by radiographic imaging, with CT scan typically required to make a definitive diagnosis. CT scan should be obtained if clinical suspicion for a fracture remains high despite negative plain radiographs.

INDICATIONS FOR SURGICAL REFERRAL — Emergent (ie, immediate) surgical referral is required for open fractures, fractures associated with neurovascular injury, and fractures associated with dislocation (which must be reduced immediately).

Comminuted and displaced fractures should be referred urgently by contacting the surgeon at the time of diagnosis and arranging appropriate follow up. There is little high quality evidence to guide practice, but some fractures require more urgent management (within a few hours) due to the increased risk of avascular necrosis from disruption of the vascular supply to the talus, while others may be safely managed with splinting and surgical evaluation within three to five days. Thus, it is best to discuss the timing for appropriate referral directly with the surgeon who will assume care.

The high-risk fractures associated with specific subtypes of talar fractures are described in the sections below.

DIFFERENTIAL DIAGNOSIS — Talus fractures are usually the result of major trauma and the patient typically has an obvious ankle or rear-foot injury. Appropriate imaging studies, typically computed tomography (CT), enable diagnosis. Other significant bony and soft tissue (eg, tendon) injuries of the lower leg, ankle, hindfoot, and midfoot can present with symptoms and signs similar to a talar fracture but are readily distinguished with diagnostic imaging in the large majority of cases. In most instances, soft tissue injuries around the ankle can be distinguished from talus fracture based upon the history (often low energy with tendon injuries), examination findings (no bony deformity and focal tenderness over tendons rather than talus with soft tissue injuries), and if necessary diagnostic imaging. A potentially difficult diagnosis is distinguishing an os trigonum from an acute fracture of the posterior process of the talus. Should uncertainty persist after radiographs and CT imaging, an MRI showing edema can help to differentiate these conditions.

TALUS FRACTURE TYPES: SPECIAL ASPECTS OF PRESENTATION AND MANAGEMENT

Talar head fractures

Mechanism and overview — Talar head fractures are typically sustained when a forceful axial load is placed on a plantar-flexed foot [1]. Talar head fractures often occur in association with other injuries, and may extend into the neck or body of the talus, or coincide with navicular fractures. Talar head fractures are nearly always intra-articular and may disrupt the stability of the talonavicular joint, leading to subluxation or dislocation of the talus. Small avulsion fractures can also occur. The talar head has a better blood supply than the body, which generally allows for better outcomes, but there remains a 5 to 10 percent risk of avascular necrosis (AVN) in these fractures [2]. Among patients with osteoporosis, insufficiency fractures of the talar head can occur from normal activity without explicit trauma [16].

Clinical features — The patient with a talar head fracture is typically unable to bear weight and has significant swelling around the ankle. Pain is most severe in the anterior ankle or arch of the foot, and there is tenderness over the talonavicular joint. The talonavicular joint can be identified by palpating just proximal to the medial prominence of the navicular bone (picture 1), and the dorsum of the talonavicular joint can then be examined by gradually palpating laterally from this location (picture 6). Smaller avulsion fractures in the area of the talonavicular joint may occur with inversion injuries of the ankle. These injuries can present like an ankle sprain, with pain and swelling in the anterior ankle following a twisting injury.

Imaging — Plain radiographs (three-view ankle series) may reveal a fracture in or around the head of the talus. The degree of displacement, areas of fracture extension, and degree of articular involvement are difficult to appreciate on plain radiographs. In addition, due to the shape of the talar head and other factors, talar head fractures may be missed on plain radiographs [1]. Therefore, a CT scan of the ankle should be obtained if a talar head fracture is confirmed on plain radiograph or suspected clinically despite negative radiographs (image 3) [1,7].

Insufficiency fractures of the talar head may be missed on plain radiographs and are described based upon abnormalities identified with MRI [16]. Therefore, MRI may play a role in the assessment of the osteoporotic patient without trauma that has debilitating pain in the ankle to mid-foot region and normal plain radiographs.

Management — Most talar head fractures are managed by surgeons, and non-operative treatment of talar neck fractures should be performed only by primary care clinicians experienced in caring for patients with musculoskeletal problems, including the use of braces, casts, and foot orthoses. The treatment of talar head fractures is aimed at maintaining and preserving the articular surfaces of the talus and the stability of the talonavicular joint.

Non-surgical treatment is indicated for isolated, non-displaced impaction or avulsion fractures involving a small portion (<5 mm) of the talonavicular surface without extension into the anterior subtalar joint, as determined by CT [1,7]. All other talar head fractures are referred for surgical consultation. (See 'Indications for surgical referral' above.)

Non-displaced talar head fractures involving less than 5 mm of the talonavicular joint surface and not involving the subtalar joint are treated in a short-leg walking cast with a molded arch or in a removable cast boot with arch support for six to eight weeks [1,7]. Repeat radiographs are obtained every two to three weeks to monitor healing. Casting is continued for six to eight weeks or until signs of healing are present. These signs include the absence of tenderness over the fracture site and radiographic evidence of healing (eg, filling of the fracture line). The patient is then transitioned to a longitudinal arch support for two to three months. There are no long term outcome studies of talar head fractures but these injuries are associated with an increased risk of talonavicular osteoarthritis [2,7].

Talar neck fractures

Mechanism and overview — The talar neck is the most common site for talus fractures, accounting for up to 50 percent of these injuries [17]. These fractures typically occur during high-energy trauma and involve forceful dorsiflexion of the foot, as might occur during a motor vehicle crash when the driver’s foot is pushing the brake pedal during impact [17]. Talar neck fractures may also occur with falls from a height. With either mechanism, the anterior tibia striking the talus may cause a fracture at the talar neck while simultaneously distracting the posterior ankle, possibly leading to disruption of the posterior ankle or subtalar joint.

Talar neck fractures are classically described as extra-articular fractures, since the talar neck is defined as the area between the joint surfaces of the ankle and the talonavicular joint. However, these fractures often extend into the head or body of the talus, possibly involving the articular surfaces. Talar neck fractures are at relatively high risk of developing complications, including ligament rupture, posterior ankle joint disruption, dislocation of the talar body, and subtalar injuries [7]. Open fractures and neurovascular injury occur in greater than 20 percent of talar neck fractures [2]. In addition, a large minority of patients with talar neck fractures sustains additional injuries (eg, fractures of the medial malleolus, calcaneus, tibia, fibula, and spine).

A small number of talar neck fractures are isolated, non-displaced fractures with perfect congruency of the ankle and subtalar joint on CT scan. Nevertheless, even these fractures carry a risk of subtle angulation or displacement and up to 15 percent develop avascular necrosis [7]. Thus, even apparently straightforward talar neck fractures must be managed with caution.

Clinical features — Patients with talar fractures are often victims of high-energy trauma and such patients usually warrant evaluation in the emergency department. Talar neck fractures are usually painful, which may distract the patient and examiner from other injuries. There is typically significant swelling and possible deformity of the ankle, and the patient is unable to bear weight. There may be diffuse tenderness to palpation, with the point of maximal tenderness typically one to three cm distal to the anteromedial ankle joint, provided extensive swelling does not preclude discreet palpation. (See 'Indications for surgical referral' above and "Initial management of trauma in adults".)

Imaging — Plain radiographs may reveal a talar neck fracture (image 7 and image 8), even if it is non-displaced (image 9). However, although data on their frequency is limited, false negative studies can occur and plain radiographs cannot be used to rule out a fracture. Do not rely on plain radiographs to confirm that a fracture is nondisplaced. A CT scan is indicated if occult fracture is suspected and is required if a talar neck fracture is present on plain radiographs to define the extent and morphology of the fracture (image 10) [13].

Management — The treatment of talar neck fractures is surgical in all but the most select cases. In a few instances, isolated, non-displaced talar neck fractures may be managed by non-surgical clinicians with expertise in such care. Up to 15 percent of non-displaced talar neck fractures go on to develop avascular necrosis, with a significantly higher rate for displaced fractures [11].

Studies comparing non-surgical treatment with percutaneous pinning for non-displaced talar neck fractures have yet to be performed. Surgical fixation may provide some advantages as it allows for earlier motion and weight bearing, and less risk of avascular necrosis [11,17].

Isolated, non-displaced talar neck fractures may be treated using a non-weight bearing splint, with the ankle kept at 90 degrees, for the first five to seven days. The patient is then placed in a short-leg, non-weight bearing cast until radiographic healing is apparent (usually 6 to 12 weeks). Radiographs are obtained weekly to confirm proper alignment [1]. Once healing is apparent, the patient may bear weight as tolerated in a short-leg walking cast with arch support for four weeks until pain-free [7]. Once this four week period is completed, the patient should begin a rehabilitation program, while continuing to use arch support, to regain motion, strength, and proprioception. If no healing is evident by eight weeks, the patient should be referred to a surgeon.

Talar body fractures

Mechanism and overview — Fractures of the talar body are high-risk injuries involving the articular cartilage of the ankle joint and possibly the subtalar joint. Fractures isolated to the lateral and posterior processes of the talar body are discussed separately. (See 'Lateral process (snowboarder) fractures' below and 'Posterior process (trigonum) fractures' below.)

High-energy injuries involving a direct axial load placed on the leg and ankle can cause a distal tibia fracture or transmit force through the ankle joint causing a fracture of the body of the talus [18]. Talar body fractures frequently involve disruption of the vascular supply to the talus, resulting in a high rate of avascular necrosis (AVN), particularly for comminuted and open fractures. The incidence of AVN is reported to be as high as 25 percent for talar body fractures and 50 percent for fracture dislocations [2,9]. Post-traumatic osteoarthritis is common in talar body fractures due to involvement of one or both joint surfaces (ankle and subtalar joints). Approximately 15 to 100 percent of patients eventually develop osteoarthritis, with higher rates among those with more extensive injury [2,10,19,20].

Clinical features — Patients with talar body fractures are usually victims of high-energy trauma, typically motor vehicle accidents or falls from a height. The presentation is generally similar to that of talar neck fractures. (See 'Clinical features' above.)

Imaging — Plain radiographs may reveal a talar body fracture. A CT scan to assess alignment and displacement is indicated if an occult fracture is suspected on clinical grounds or if a fracture is identified on plain radiographs (image 5) [1].

Management — The treatment of talar body fractures is reserved for surgeons in all but the most select cases [13]. Non-displaced fractures without associated injury may be treated with casting if CT imaging shows that the fracture is perfectly aligned and without any step-off at the joint surface. Non-surgical management should only be performed by clinicians experienced in fracture management due to the high likelihood of complications [13]. Clinicians must inform patients of the increased risk of avascular necrosis and osteoarthritis associated with this injury, even in the most compliant and healthy patients [21].

Treatment of non-displaced fractures begins with a non-weight bearing cast for six to eight weeks, until there is radiographic evidence of healing, followed by a gradual resumption of weight bearing as tolerated in a walking cast [10]. Radiographs are repeated every two weeks to confirm that alignment has been maintained. Once immobilization is no longer needed, patients begin a rehabilitation program to help restore motion, strength, and proprioception. If no healing is evident by eight weeks, the patient should be referred to a surgeon.

Lateral process (snowboarder) fractures

Mechanism and overview — Fractures of the lateral process of the talus are uncommon outside of snowboarding, comprising less than 10 percent of all talus fractures. However, such fractures may account for as many as 15 percent of ankle injuries that require medical care in snowboarders and the injury is 17 times more likely to occur in snowboarders than the general population [5,22].

The mechanism of lateral process talus fractures is thought to involve a substantial axial load on the ankle joint while the ankle is dorsiflexed and rotated, typically externally rotated [4,23]. There are reports of such fractures occurring with both ankle inversion and eversion [23]. The primary mechanism described can occur in snowboarding during a "hard landing" after a jump. In such a landing, the snowboard itself may act as a lever arm increasing ankle dorsiflexion and exerting additional torque on the ankle.

Lateral process fractures are commonly misdiagnosed due to the difficulty visualizing the injury on plain radiographs and because the presentation is similar to a moderate to severe ankle sprain [5,22]. Up to 40 percent of these fractures are missed on initial ankle radiographs [12]. The lateral process of the talus extends beneath the distal fibula and comprises part of the subtalar joint. It is largely covered with articular cartilage. Approximately 5 to 25 percent of patients with lateral process fractures develop osteoarthritis of the subtalar joint. Pain and disability from osteoarthritis are more likely to occur if there is a delay in diagnosis [12].

Clinical features — The presentation of patients with a lateral process fracture of the talus is similar to that of a moderate to severe ankle sprain, which can lead to misdiagnosis. Patients typically experience diffuse pain that increases with weightbearing and swelling along the lateral ankle. There is usually tenderness at the lateral process just anterior and inferior to the lateral malleolus between the anterior talofibular and calcaneofibular ligaments (picture 3).

Imaging — Plain radiographs of the ankle may show an irregular appearance of the lateral talus on the anteroposterior and mortise views (image 11). The lateral view may reveal the fracture more clearly, as the lateral process projects above the subtalar joint in this perspective. However, lateral process fracture may be hidden on plain radiographs in up to 40 percent of cases [5]. Therefore, CT scan is required in cases of confirmed or suspected cases of lateral process fractures [4,12,22].

Management — High-quality evidence to determine the best management of lateral process fractures is lacking. An observational study of these fractures reported outcomes at 3.5 years and found that patients treated surgically had less osteoarthritis. Among patients with milder injuries treated non-operatively, 10 percent developed osteoarthritis, while among patients with more severe injuries treated surgically 5 percent developed osteoarthritis [4]. It remains unclear which fractures are amenable to non-operative treatment, and further studies comparing treatments are needed.

Treatment of lateral process fractures is based upon fragment size, the degree of displacement, and the extent of articular surface involvement. Given the close approximation of the subtalar and talofibular joints to the lateral process, perfect anatomic alignment is required to achieve good results [12]. However, osteoarthritis can develop even in cases of perfect alignment, and patients should be warned of this risk.

Management guidelines for lateral process fractures are based upon the McRory-Bladin classification, which consists of the following [23]:

●Type I fracture is a small chip fracture on the tip of the process that does not involve the articular surfaces, or may involve a small portion of the subtalar joint.

●Type II fracture consists of a larger fracture fragment that involves the joint surface of the ankle and subtalar joints.

●Type III fracture is a comminuted fracture.

Small chip fractures (Type I) of the lateral process that are non-displaced can be treated by non-surgical clinicians experienced in the management of lower extremity fractures. These fractures are treated with a short-leg cast and non-weightbearing or limited weightbearing for four weeks, followed by a weight-bearing cast for two weeks [12]. Thereafter, patients can be weaned from the cast boot as their symptoms improve. Once the patient is pain-free, the patient should begin an appropriate rehabilitation program [23]. If pain persists, a CT scan should be obtained to assess the fracture for possible nonunion. If the CT demonstrates healing, the patient continues with weight bearing as tolerated in the cast boot. If signs of healing are not evident or pain persists at three months, the patient should be referred to an appropriate surgeon.

Type I fractures that are displaced more than 1 to 2 mm, Type II, and Type III fractures should be referred to an appropriate surgeon because most are treated with open reduction and internal fixation. Observational data suggests that outcomes for more severe lateral process fractures are better with surgical management than with casting [4,23].

Posterior process (trigonum) fractures

Mechanism — Fractures of the posterior process of the talus may occur from one of two mechanisms. Forceful plantar flexion may drive the posterior process against the posterior tibia or cause it to become caught between the calcaneus and the posterior tibia. Alternatively, the posterior process may be avulsed by the pull of the posterior talofibular ligament during extreme dorsiflexion of the ankle [9,24].

Clinical features — Patients with a fracture of the posterior process of the talus typically present with posterior ankle pain and swelling with ecchymosis. They may be able to bear weight, but typically have an antalgic gait. Tenderness with deep palpation of the posterior ankle is present either medially (picture 4) or laterally (picture 2), or both.

Imaging — Plain ankle radiographs, particularly the lateral view, may show a posterior process fracture (image 12 and image 13). These fractures may occur at the medial or lateral tubercle of the posterior process. However, plain radiographs may suggest the presence of an os trigonum, and it can be difficult to distinguish between a fracture and an ossicle. The borders of an acute fracture are typically more irregular or “ragged,” while an ossicle generally has a smoother and more rounded appearance [24]. Comparison with the other ankle using plain radiographs, or a CT scan, may be needed to make the diagnosis.

Management — Treatment of non-displaced fractures of the posterior process that do not extend into the body of the talus consists of a non-weightbearing short-leg cast for four to six weeks [12,24]. At that point, if the patient is pain-free, a gradual return to normal activity is allowed. If there is continued pain or tenderness, the patient continues treatment in a weight-bearing cast with reassessment every two weeks until symptom free. If the fracture is displaced, comminuted, or extends into the body of the talus, the patient should be referred to an appropriate surgeon for management.

Although the risk of non-union exists even for small fractures, most patients become pain free with or without bony union. If pain persists beyond three to four months, a painful non-union may exist. In such cases, an MRI is indicated to assess for additional pathology such as an injury to the articular cartilage of the talar dome. Clinical experience suggests that most symptomatic non-unions respond well to excision of the fragment [24].

Osteochondral fractures

Mechanisms and overview — Osteochondral disorders of the talus include acute injuries and chronic lesions. Acute injuries, including impaction injuries of the articular cartilage and talar dome fractures, can occur as a result of several traumatic mechanisms [6]. One mechanism involves direct compression of the talar dome from an axial load, such as when a patient lands on their feet after falling from a height. Another mechanism involves forceful rotation of the ankle, most commonly an inversion injury. Such inversion injuries can damage the medial ankle from direct impact on the medial joint surfaces or the lateral ankle through direct compression and shear forces [6]. Inversion ankle sprains may be associated with injury to the articular cartilage of the medial talar dome in up to 6 percent of cases.

Although osteochondral fractures can occur in isolation, a substantial number are accompanied by other injuries, including ankle sprains and concomitant fractures [6]. As an example, in one small case series 28 percent of talar dome osteochondral injuries occurred with other fractures, usually malleolar fractures [25]. Treatment of the ankle fracture itself often overshadows the talar dome injury, but it may become apparent later [6].

Chronic lesions, such as osteochondritis dissecans (OCD), osteonecrosis, and bone cysts, can develop in the talar dome. These diagnoses, including osteochondritis dissecans in the young athlete, are discussed separately. (See "Osteochondritis dissecans (OCD): Clinical manifestations, evaluation, and diagnosis" and "Management of osteochondritis dissecans (OCD)" and "Treatment of nontraumatic hip osteonecrosis (avascular necrosis of the femoral head) in adults" and "Nonmalignant bone lesions in children and adolescents", section on 'Cystic tumors'.)

Clinical features — Patients with an osteochondral lesion of the talus generally present with persistent ankle pain, stiffness, or other mechanical symptoms or signs during recovery from an ankle injury in which earlier plain radiographs were negative [6]. Pain lasting greater than six weeks after an ankle sprain suggests the need for further imaging, as discussed below.

Examination generally reveals tenderness of the medial and lateral aspects of the talar dome, which can be palpated by placing the ankle in full plantar flexion. In addition, clinicians may sense a loss of smooth ankle movement when testing passive ankle motion or performing an ankle anterior drawer test (picture 7). (See "Ankle sprain in adults: Evaluation and diagnosis", section on 'Anterior drawer test'.)

Imaging — Clinicians should suspect osteochondral injury when plain radiographs of the ankle taken at the time of injury reveal abnormalities of the talar dome (image 14). However, initial radiographs are negative in approximately one third of patients ultimately diagnosed with osteochondral fractures, according to retrospective studies [26]. In patients with persistent pain following an ankle injury, plain radiographs should be repeated at the time of reassessment to look for occult fracture, bone cyst formation, or signs of fracture healing [26]. If an injury is suspected but plain radiographs do not show a talar dome lesion, further imaging of the ankle, ideally with magnetic resonance imaging (MRI), is indicated (image 15). Observational studies suggest that MRI is the most accurate method for evaluating the integrity of the articular cartilage and underlying bone in talar dome lesions [6,15,26,27].

Management — There is no high quality evidence to guide the management of osteochondral injuries of the talus. Thus, treatment is based upon small case series and clinical experience [28].

Many surgeons treat osteochondral injuries of the talus based upon the type of injury, as defined by the Berndt-Hardy system, first described in 1959 [6,14]. This system describes the fracture or compression of the underlying bone and the stability of the overlying articular cartilage and includes the following stages:

●Stage I lesions – A small area of subchondral bone compression or fracture is present with intact overlying cartilage.

●Stage II lesions – An osteochondral fragment is partially detached.

●Stage III lesions – An osteochondral fragment is completely detached but still in place.

●Stage IV lesions – An osteochondral fragment is completely detached and displaced into the ankle joint.

Acute Stage I and II lesions that involve less than one-third of the articular surface are treated with casting [6,7]. In acute, non-displaced lesions, non-surgical treatment generally results in good outcomes, according to expert opinion and scant observational data [6]. Treatment consists of a non-weightbearing short-leg cast for six weeks, followed by gradual resumption of weight-bearing in a cast boot for two to four weeks, and finally a gradual return to normal activity [6,7]. If pain persists despite appropriate conservative treatment, the patient should be referred for surgical evaluation [9]. Larger stage I or II lesions and all stage III and IV lesions should be referred to an appropriate surgeon [6,7].

ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of definitive fracture management".)

●(See "General principles of acute fracture management".)

●(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Lower extremity (excluding hip) fractures in adults" and "Society guideline links: Acute pain management".)

SUMMARY AND RECOMMENDATIONS

●Epidemiology and mechanism of injury – Most talus fractures are sustained after falling from a significant height or from high energy trauma. Approximately 50 percent occur from automobile or motorcycle accidents. Axial loading of the ankle or impact sustained with the ankle in extreme plantar flexion or dorsiflexion is often involved. The subset of lateral process talus fractures, most often seen in snowboarders, frequently occurs during a hard landing after a jump and involves an uncontrolled axial load. (See 'Epidemiology' above and 'Clinical anatomy' above and 'Mechanism of injury' above.)

●High-energy trauma – Talus fractures often result from major trauma, which may have caused severe internal injuries or other significant orthopedic injuries. If there is any doubt about the nature or extent of injury, it is best that the patient be evaluated in the emergency department. (See "Initial management of trauma in adults".)

●History and physical examination – The patient with a talus fracture typically presents following trauma with pain and swelling around the ankle and difficulty with weight bearing. Swelling may obscure ankle landmarks or, if the fracture is displaced or the ankle dislocated, bone contours may be obscured or deformed. Ankle range of motion is often limited. The symptoms and signs associated with lateral process fractures of the talus (snowboarders fracture) are similar to an ankle sprain and thus are often missed. (See 'History and examination findings' above.)

Typically, patients manifest tenderness at and below the ankle. Tenderness may be focal or generalized. Palpation should include the talar head and neck (just distal and anterior to the ankle joint) (picture 1), talar body (just anterior, inferior, and posterior to each malleolus) (picture 2 and picture 3 and picture 4), talar dome (on the anterior joint line with the foot and ankle plantar-flexed) (picture 5), and posterior talus (deep palpation just anterior to the Achilles tendon from both the medial and lateral aspect). A neurovascular assessment of the involved lower extremity is required.

●Diagnostic imaging – A standard three-view ankle series (anterior-posterior, mortise, and lateral views) should be obtained if there is any suspicion of a talus or other ankle fracture. Computed tomography (CT) should be obtained for any confirmed talus fracture or whenever clinical suspicion for a fracture remains high despite negative plain radiographs. (See 'Diagnostic imaging' above.)

●Indications for surgical referral – Immediate surgical referral is required for open fractures, fractures associated with neurovascular injury, and fractures associated with dislocation (which must be reduced immediately). Comminuted and displaced fractures should be referred urgently by contacting the surgeon at the time of diagnosis. (See 'Indications for surgical referral' above.)

●Management – The management of talar fractures varies depending upon the location and severity of the injury. The major types of talar fractures and their management are described in the text. Talar body and neck fractures are at substantial risk for developing avascular necrosis. (See 'Talus fracture types: Special aspects of presentation and management' above.)