Radiographic analysis of the Canale view for displaced talar neck fractures

Management of Talus Fractures

Fractures of the talus are life-changing events. The talus is of vital importance to normal gait. Given its importance, great care is needed in diagnosing and treating these injuries. The threshold for operative treatment and accurate anatomic reduction should be low. Surgical tenets include the avoidance of extensive subperiosteal dissection to minimize vascular disruption. The complications with injuries to the talus are extensive and include avascular necrosis (AVN). Although AVN can prove to be a devastating sequela from this injury, it occurs less frequently than posttraumatic arthritis.

Parameters That Can Be Used to Quantify Reduction Accuracy in Talar Neck Fractures and Malunions: A PRISMA-Compliant Scoping Review and Meta-Analysis

Understanding the three-dimensional anatomy of the talar neck is essential in assessing the accuracy of reduction in talar neck fractures as well as for planning surgical correction for talar malunions. However, the geometrical parameters that describe this anatomy are sparsely reported in the orthopedics literature. We aimed to identify from the existing literature, geometrical parameters that describe the anatomy of the talar neck, determine how these are measured, and their normative values. A scoping literature review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews (PRISMA-ScR) guidelines. The primary searches were conducted on the PubMed, Embase, and Scopus databases. Any original research study looking at the human talus neck geometry was included. Parameters that described the anatomy of the talar neck were identified, and pooled estimates were determined by the random-effects meta-analysis model. Heterogeneity was assessed by the I2 test and leave-one-out meta-analysis. Subgroup analysis was done to compare the values of parameters between the Asian and Non-Asian populations. The risk of bias was assessed by the National Institutes of Health (NIH) Case Series Tool. The combined searches yielded 6326 results, of which 21 studies were included in the review and 15 in six different sets of metanalysis. The majority of the studies (n=19, 90.5%) evaluated adult tali, and only two (9.5%) evaluated pediatric tali. In most of the studies (n=13, 61.9%), talus neck geometry was evaluated on dry bones or anatomical specimens; evaluation by imaging techniques (radiographs, CT, MRI, and radiostereometric analysis) was used in eight studies, (39.1%). A total of eight different geometrical parameters (neck length, height, width, declination angle, inclination angle, torsion angle, circumference, and cross-sectional area) were identified. Except for talar torsion, variability was noted in methods of measurement of all other parameters. Subgroup analysis revealed that Asians had a higher neck height as compared to non-Asians; other parameters were not significantly different. Although the literature reports geometrical parameters to assess the talar geometry, the methods of measurement of these parameters are variable. Most of the available literature describes measurement techniques on cadaveric tali, and there is no literature on how these parameters should be measured on conventional CT or MRI slices. Further research needs to focus on the standardization of measurement techniques for these parameters on conventional CT and/or MRI scans.

Current Concepts in Talar Neck Fracture Management

PURPOSE OF THE REVIEW

Talar neck fractures are a rare but potentially devastating injury, which require a comprehensive understanding of the unique osteology, vasculature, and surrounding anatomy to recognize pathology and treat correctly. The purpose of this article is to describe both classic and current literature to better understand the evolution of talar neck fracture management.

RECENT FINDINGS

Urgent reduction of displaced fractures and dislocations remains the standard of care to protect the soft tissue envelope and neurovascular structures. Delayed definitive fixation has proven to be safe. CT is the imaging modality of choice to fully identify the fracture pattern and associated injuries. Anatomic reduction and restoration of the peritalar articular surfaces are the pillars of talar neck fracture treatment. Dual incision approach with plate and screw fixation has become the modern surgical strategy of choice to accomplish these goals. Although complications such as osteonecrosis (ON) and posttraumatic arthritis (PTA) can still occur at high rates, treatment should be dictated by patient symptoms. Talar neck fractures pose treatment challenges with both initial injury and potential sequelae. Future research will determine whether modern treatment algorithms will decrease complication rate and improve patient outcome.

Defining Talar Head and Neck Pathology: The Malvern Classification System

Talar fractures account for <1% of all fractures in the body and 3% to 6% of pedal fractures. Of these fractures, avulsion and neck fractures represent the most and second most common type, respectively. Several classification systems exist for talar fractures of the talar dome (Berndt-Hardy), talar neck dislocation (Hawkins), and talar body (Sneppen) anatomic locations. Although diverse, they are not all encompassing for fracture patterns of the talus. Another set of pathologic issues occur about the talar head and neck region that can be seen in the clinical setting. Thus, a new classification system (Malvern classification system for talar head/neck fractures) was devised and defined for this location. The system represents a comprehensive review of the available published data and synthesis into an organized classification system.

Fractures of the talus: Current concepts and new developments

Fractures of the talus are challenging to manage, with historically poor outcomes and a high rate of complications. The rare nature of this injury limits the number of studies available to guide treatment. Fortunately, a number of advancements have been made in the last decade. There is increased recognition regarding the importance of anatomic reconstruction of the osseous injury. Advanced imaging is used to assess the subtalar joint, where even slight displacement may predispose to arthritis. Increasing use of dual anteromedial and anterolateral approaches, along with plate fixation, has improved our ability to accurately restore the anatomy of the talus. Modification of the original Hawkins classification can both guide treatment and allow us to better predict which patients will develop avascular necrosis. Lastly, improved reconstructive techniques help address the most common complications after talus fracture, including arthritis, avascular necrosis, and malunion.

Fractures of the Talus: State of the Art

Talus fractures occur rarely but are often associated with complications and functional limitations. Urgent reduction of associated dislocations is recommended with open reduction and internal fixation of displaced fractures when adjacent soft tissue injury permits. Delayed definitive fixation may reduce the risks of wound complications and infections. Restoration of articular and axial alignment is necessary to optimize ankle and hindfoot function. Despite this, posttraumatic arthrosis occurs frequently after talar neck and body fractures, especially with comminution of the talar body. Osteonecrosis is reported in up to half of talar neck fractures, although many of these injuries will revascularize without collapse of the talar dome. Initial fracture displacement and presence of open fractures increase the risk of osteonecrosis. Talar process fractures may be subtle and easily missed on plain radiographs. Advanced imaging will provide detail to facilitate treatment planning.

LEVEL OF EVIDENCE

Therapeutic Level V. See Instructions for Authors for a complete description of levels of evidence.

Safe zone for placement of talar screws when fusing the ankle with an anterior plating system

BACKGROUND

Ankle fusions fixed with anterior plates use fluoroscopic guidance to direct screws toward the subtalar joint. Special imaging views that visualize the subtalar joint are difficult to use and can be unreliable. This study evaluated whether a single lateral ankle view would provide adequate information to judge whether a screw penetrated the subtalar joint and identified strategies that would improve this technique.

METHODS

In 5 cadaveric ankles fixed with anterior plates, talar screws were placed up to the subtalar joint without penetration using lateral fluoroscopy to guide screw length. After dissection, the true distance from the screw tip to subchondral surface was measured. In addition, 4 readers measured the perceived distance from screw tip to subchondral surface using direct lateral, 10 degrees cephalad tilt lateral, and 10 degrees caudal tilt lateral fluoroscopic images on 2 separate occasions.

RESULTS

Nineteen (63%) of 30 screws penetrated the subchondral bone, and screw length determined using fluoroscopy was significantly longer than screw length measured directly (29.4 ± 5.5 mm vs 27.3 ± 8.5 mm, P = .014). Measurement of screw tip to bone distance demonstrated a high level of within-reader (kappa = .871, P < .001) and between-reader agreement (kappa = .807, P < .001), but poor specificity of determining screw penetration (0.50, χ(2) = 22.1, P < .001) and poor correlation between radiographically measured and actual distances between screw tip and bone margin (r = .35, P < .001). Tilting the c-arm 10 degrees cephalad and directing screws toward the posterior facet improved the ability to detect screw penetration and directing screws toward the middle facet diminished it (P < .05). A safe zone of screw placement was defined by region.

CONCLUSION

Use of a lateral fluoroscopic image to guide talar screw placement may lead to an unacceptably high rate of subtalar joint penetration.

CLINICAL RELEVANCE

Understanding the limitations of lateral fluoroscopy when using anterior ankle fusion plates may minimize screw penetration into the subtalar joint and diminish development of subtalar arthropathy.