Talar Neck / Body Fracture

Introduction

Fractures of the talus are rare injuries. The management and outcome can be defined upon the location of injury with the approxiate split between sites being:

  • Talar neck - 50%
  • Talar body - 25%
  • Talar process - 15%
  • Talar body - <10%

Although the talus has a rich blood supply, 70% of the surface is covered in articular cartilage which in combination with the lack of musclular attachments which otherwise provide a local blood supply and some vessels travelling in a retrograde direction means the body is at risk of avascular necrosis from talar neck fractures.

Talar Neck vs. Body Fractures

​The course of fracture line on the superior surfaces for the neck and the body of the talus is difficult to distinguish. On the inferior surface, the neck fracture line extends through sinus tarsi (extra-articular) and the body fracture line extends towards the posterior subtalar joint (intra-articular). However lack of clear defining landmarks of these fractures can be misleading in terms of their management and likely prognosis.

​Talar body fractures are more associated with articular cartilage damage resulting in subsequent arthrosis of the subtalar joint; however, the neck fractures are more associated with avascular necrosis and subsequent collapse.

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Mechanism

​Talar fractures result from high-energy injuries caused by forced dorsiflexion and axial loading of the foot. These are usually associated with multiple other injuries. Ipsilateral long bone fractures are commonly seen. There is also a rotational component implied by the presence of medial comminution and concurrent medial malleolar fracture in 11% to 28% of cases. There are associated fractures in 54% to 64% of cases and approximately 20% of these are open fractures.

 

Classification

​The most widely accepted classification for talar neck fractures is the Hawkins classification system, which is based on displacement and dislocation.  This classification was further expanded by Canale and Kelly, who added the type IV.

  • Hawkins I - Undisplaced (0-13% AVN)
  • Hawkins II - Subtalar dislocation (20-50%)
  • Hawkins III - Subtalar and tibiotalar dislocation (20-100%)
  • Hawkins IV - Subtalar, tibiotalar, and talonavicular dislocation (70-100%)

 

Presentation

​Patients with talar neck fractures typically present after a high-energy injury with foot swelling and bruising. There may be gross deformity and skin tenting with associated dislocations. Up to 38% of Hawkins type 3 fractures are open, and in these cases, the talus may be partially or completely extruded. Neurovascular status of the foot should be assessed. The patient should also be evaluated for other injuries given the mechanism (ATLS principles).

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Imaging

​Based on mechanism and clinical suspicion (swelling, bruising, tenderness, deformity) plain radiographs are obtained (AP, lateral and Canale views). CT scan is gold-standard in assessing the anatomy of the injury, extent of fracture lines, comminution, articular congruency and to exclude associated neighbouring injuries.

 

Management

Undisplaced fracture

These fractures are usually amenable to non-operative treatment if CT scan truly demonstrates no displacement of the talar neck. The patient is placed in a non-weightbearing plaster cast for 6 weeks. Weekly radiographic assessment is recommended to ensure no displacement of the talar neck occurs. After 6 weeks, the cast can be converted to a walker boot for an additional 6 weeks (or until fracture healing) with protected weight bearing. Some authors recommend internal fixation for even undisplaced fractures as this can permit early mobilisation.

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Displaced fracture

Emergency Management

​Displaced fractures are treated with an emergent reduction, temporary stabilization (external fixation or K-wire fixation) until soft tissues settle, followed by definitive fixation with ORIF. Open fractures require emergent debridement and irrigation as per BOAST guidelines and management of other injuries in a multiply-injured patient as per ATLS principles. Some authors have advocated that the use of an external fixator may provide distraction to the ankle joint to unload the talus, with a potential benefit of reducing the morbidity of AVN. However, Besch et al. reported that the external fixation had no effect in the prevention of AVN.

Definitive surgery

Stable fixation is essential for revascularisation by preventing shearing force across the fracture site. Adelaar et al. recommended that open reduction and internal fixation of any fracture with more than 3-5 mm dorsal displacement or any rotational deformity. Most authors recommend that type II, III, and IV fractures should be treated by ORIF to achieve an anatomical reduction and stable internal to restore articular congruity.

Timing of Definitive Surgery

Talar neck fractures have traditionally been considered orthopaedic emergencies requiring surgical treatment within 6 hours. Recent literature suggests that emergent ORIF versus delayed ORIF has no significant difference in outcomes, making the timing of definitive fixation controversial. The time of definitive fixation depends on multiple factors, including fracture comminution, soft tissue status, available resources, surgeon’s experience and comfort level, and medical status of the patient.

Most authors report that the definitive fixation can wait more than 8 hours, with a significant proportion reporting that treatment in more than 24 hours is acceptable.

Lindvall and colleagues retrospectively reviewed 26 displaced talar body and neck fractures that underwent ORIF with an average follow-up of 73 months. The series consisted of 11 Hawkins type II, 6 Hawkins type III, 1 Hawkins type IV, and 8 talar body fractures. Fractures treated within 6 hours after injury were compared with those that were treated after 6 hours. Twelve of the 26 fractures (46%) received surgical treatment within 6 hours. No significant difference in AOFAS scores, non-unions, osteonecrosis, or post-traumatic arthritis was seen between early or late ORIF groups

Vallier et al. also showed no correlation between development of osteonecrosis and surgical delay, as long as any associated dislocation was reduced emergently. Another study reported that rather than the timing of surgery, osteonecrosis was associated with degree of comminution and the presence of open fracture. Duration between the injury and surgical treatment did not seem to increase the risk of developing complications and requiring additional surgery.

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Surgical Approaches

Anatomical reduction is difficult to obtain owing to the complex anatomy of the talus and comminuted nature of the fractures. It is important to avoid reducing the talar neck fragment in supination, pronation, or axial malalignment. In order to obtain a better anatomical reduction, most authors recommend a dual anteromedial and anterolateral approach, which is associated with a medial malleolar osteotomy.

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Anteromedial Approach

Anteromedial approach to the talus is performed using an incision medial to the tibialis anterior tendon tendon. An osteotomy of the medial malleolus can be performed using this approach for better visualization of the talar body. Care should be taken to avoid stripping the dorsal aspect of the neck and deltoid ligament attachment to preserve the remainder of the blood supply.

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Anterolateral approach

Anterolateral approach is performed through an incision lateral to the extensor digitorum longus. Adequate skin bridge should be left to avoid skin necrosis when used in conjunction with the anteromedial approach. It is especially important to avoid injury to the vessels in the tarsal sinus when utilizing this approach.

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Effect of dual approach on blood supply

The effect of dual approaches on the blood supply is still unknown. Some studies have suggested it can deteriorate the already damaged soft tissue and bloody supply of the talar body and report an increased risk of skin necrosis, infection (10–20%) and increased duration of surgery. However this technique permits good visualisation of the talus and many authors believe some advantages can be obtained in preservation of the residual arterial supply of the talus because both of these two approaches use the interval between the neurovascular bundle.

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Screw fixation

Fractures can be fixed with screws used posterior to anterior or anterior to posterior. Swanson and colleagues showed superior mechanical strength using the posterior-to-anterior technique and a similar trend was also found by Attiah and colleagues in another biomechanical study. However, posterior-to-anterior screw fixation has potential disadvantages as well, as it requires an additional posterior approach with potential injury to the peroneal artery and its branches and the screw head prominence can limit ankle plantarflexion.

​To achieve stable internal fixation and decrease the rate of malunion, at least 2 screws are required. Attiah et al. studied different screw configurations in a comminuted talar neck fracture model. They compared 3 anteroposterior screws, 2 cannulated posteroanterior screws, 1 screw from anterior-to-posterior, and a medially applied blade plate. They concluded that the anteroposterior screws had approximately 20% lower yield point and stiffness compared to the posteroanterior screws or blade plate techniques, but this difference was not statistically significant.

Screws can either be conventional with counter sink technique or headless variable pitch. No biomechanical differences have been found between the two types of screws.

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Plate fixation

For comminuted fractures, many authors have recommended plate fixation with or without additional screw fixation as a solid buttress or as a bridging strut. Plates can be placed on the most comminuted column of the talus, either medial, lateral, or both sides. Plate sizes commonly used range from 2 to 2.7 mm. They not only provide longitudinal structural support, but also prevent supination or pronation of the distal fragment.

​Fleuriau Chateau et al. presented mini-fragment plates for fixation of talar neck fractures and concluded that the technique was useful to maintain anatomical reduction and decrease the chance of varus malunion.

​Vallier et al. used mini-fragment plates and found 49% radiographic evidence of osteonecrosis, while 37% of these cases demonstrated revascularisation of the talar dome without collapse.

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Screws alone vs. plate and screws

​Some authors have reported the plate fixation to result in more precise reduction avoiding malalignment due to compression through areas of comminution that can occur when using only compression screws. However, Charlson et al., in a biomechanical cadaver study, compared posteroanterior screw fixation and plate fixation in comminuted talar neck fractures, and found that while plate fixation could offer substantial advantages in the ability to control the anatomic alignment, it does not provide any significant biomechanical advantage compared with screw fixation alone.

​Another cadaveric study found no significant difference in strength when comparing various screw combinations to screw with medial plate fixation.

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Postoperative Management

​In cases where a stable fixation is achieved with no significant comminution or instability, early range of motion can be considered with caution. However, most surgeons prefer immobilization with plaster cast for first 6 weeks.

​The Hawkins sign, which is described as a prognostic indicator of revascularization to the talar body, appears between 6 and 8 weeks after talar neck fractures, and can be radiographically visualized on the AP or mortise view, which is strongly predictive of absence of AVN.

​The preserved blood supply resorbs the subchondral bone of the talar dome, creating a disuse osteopenia, which appears as a radiolucency of the talar dome and indicates preserved vascularity of the talus. The absence of one does not necessarily mean that the patient will develop osteonecrosis. Patient should remain non-weightbearing until there is evidence of healing, approximately for 3 months.

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Outcomes

Functional outcomes have been shown to vary inversely with increasing Hawkins grade. Studies have shown approximately 56% good-to-excellent outcomes after talar neck fracture, and 44% poor-to-fair outcomes. In the presence of a concomitant calcaneal fracture, the outcomes have been reported to be to be worse.

​Aminian et al. reported a 61% risk of requiring a below-knee amputation in cases of open talar fractures. Out of the remaining patients, 80% patients developed subtalar arthritis.

Huten et al. reported the longest available follow-up study on talar neck fractures. They reviewed the results of 114 central talar fractures that had been treated by internal fixation over a duration of 24 years in nine hospitals in France with an average clinical and radiological follow-up of 111 months and minimum follow-up of 5 years. Poor reduction was observed in 33% cases with osteonecrosis in 34% and post-traumatic arthrosis in 74%. Secondary fusion was required in 25% of cases with an average follow-up of 24 months.

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Complications

​Skin necrosis, wound dehiscence and infection are common early complications. Late complications include avascular necrosis, post-traumatic arthrosis, malunion and non-union.

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Avascular necrosis

​AVN is the most dreaded late complication after talar neck fractures. Greater displacement, comminution, and open fractures lead to an increased risk of AVN, which then weakens the talar trochlea, leading to an ultimate collapse.

​The risk of developing AVN goes higher with increasing Hawkins grade. In a Hawkins type I fracture AVN risk is 0% to 15%, in Hawkins type II fractures it is 20%-50% and in Type III and IV fractures the risk is 69%-100%, with all 3 main sources of blood supply damaged.

More recent studies have reported a lower incidence of osteonecrosis, which may be attributable to early and anatomic fixation. Studies have shown that approximately 40% patients with AVN become symptomatic.

​Metzger et al. considered that the development of AVN is almost completely determined at the time of injury. Elgafy et al. also agreed that proper surgical techniques and anatomical reduction cannot necessarily stop the development of AVN. Therefore it may be impossible to prevent AVN resulting from rupture of the tenuous blood supply in a grossly displaced talar neck fractures.

​Plain radiography shows suggestions of AVN as a relative sclerosis of the talar body when compared with surrounding bone. MRI is the most sensitive imaging to assess the presence and the extent of AVN and can help guide appropriate treatment.

​Tang et al. reported on the use of a vascularized cuboid pedicle bone graft, combined with internal and external fixation, and showed that this method could effectively prevent AVN in their preliminary study.

​Mei-Dan et al. suggested that the addition of hyperbaric oxygen therapy to both operative and rehabilitative therapy may be associated with significantly improved outcomes. However there is no sound evidence available for a routine use of these modalities.

​Once the diagnosis of AVN has been established, non-weightbearing, or partial weight bearing, should be recommended to prevent talar collapse. The talus will often revascularize spontaneously if given enough time. This occurs from medial to lateral through creeping substitutionand takes several years.

​Canale and Kelley found that patients who were kept non-weightbearing with crutches for an average duration of 8 months had fair-to-excellent results, and those who were allowed partial weight bearing in a Sarmiento type cast with limited ankle motion had poor-to- good results.

​No consensus exists on either the duration or degree of restricted weight bearing, or on the utility of immobilization. Some authors believe that non-weightbearing is of questionable value in preventing collapse after AVN.

​Surgical management of AVN includes the options of talectomy, bone grafting, tibiocalcaneal fusion, and pantalar fusion. Talectomies generally lead to poor outcomes, resulting in frequent pain, a short limb, and significant loss of ankle and subtalar motion

Arthrodesis is generally reserved as a salvage treatment following failure of internal fixation, AVN and collapse.

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Malunion and Non-union

​Talar neck fractures frequently develop varus malunion (30%) and non-union (2.5%). Sangeorzan et al. stressed that malalignment of only 2 mm can lead to significant changes in the subtalar contact pressures resulting in post-traumatic arthritis. Chat et al. concluded that the most accurate imaging method to measure malunion was CT scan, in particular, 3D CT reconstruction. Arthrodesis is the primary salvage procedure for talar neck malunion or non-union.

​If malunion or non-union occurs in the presence of complete AVN or infection, removal of all necrotic and infected bone combined with bone grafting or shortening and hindfoot arthrodesis are recommended.

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Post-traumatic Arthrosis

​Causes of post-traumatic arthritis may be multifactorial, and include damage to articular cartilage at the time of injury, progressive cartilage degeneration from fracture malunion, non-union causing malalignment and incongruence or osteonecrosis.

The reported incidence ranges from 50%-100% and primarily involves the subtalar joint, but may also affect the ankle and talonavicular joints. Not all patients with arthrosis become symptomatic. However in cases of severe arthrosis causing chronic pain and stiffness, arthrodesis may be required if conservative management fails.

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