Talar Neck Fracture: Following a Small Radiographic Clue

Case: A 50-year-old man undergoes radiography in the emergency department for an ankle sprain and suspected fracture.

Does anything catch your attention on the radiograph?

• 

• 

The lateral radiograph shows a small contour irregularity that could be overlooked at first glance. Comparison with the MR images makes its relationship to the fracture clearer.

A small irregularity is seen along the dorsal contour of the talar neck. This finding, which is not obvious at first glance, becomes more meaningful when compared with the MR images.

• 

• 

• 

• 

The arrows indicate the fracture line in the talar neck region.

On T1W sagittal MR images, a low-signal fracture line is more clearly seen in the talar neck region, corresponding to the contour irregularity on the radiograph.

Working Diagnosis: Traumatic Talar Neck Fracture

The radiographic and MRI findings are consistent with a talar neck fracture. A traumatic fracture is favored because an ankle sprain is described in the referral.

However, the referral note does not clarify exactly when the pain began or whether symptoms were present before the sprain. We therefore cannot establish the fracture mechanism conclusively from this brief information alone.

Differential Diagnosis: Could This Be a Stress Fracture?

Yes. Stress fractures can also develop in the talar neck. Fracture lines extending approximately parallel to the talonavicular joint have been described in talar neck stress/insufficiency fractures. Therefore, a stress-related mechanism cannot be excluded based solely on the fracture location.

The imaging findings of acute traumatic and stress fractures may overlap. The onset of pain and loading history are important in distinguishing them:

• Sudden pain beginning with a single traumatic event supports an acute traumatic fracture.

• Gradually increasing pain associated with repetitive loading and present before the injury supports a fatigue-type stress fracture.

• A fracture developing under normal loading in the presence of a condition that reduces bone strength warrants consideration of an insufficiency fracture.

In this case, the reported history of an ankle sprain favors a traumatic fracture. However, pain preceding the sprain or a recent substantial increase in activity would warrant reassessment of the possibility of a stress fracture.

A subtle radiographic finding alone is not an indicator of a stress fracture.

What Can We Learn from This Case?

When reviewing ankle radiographs, it is important to systematically trace the talar cortical outline in addition to examining the malleoli. In this case, a small dorsal contour irregularity provides the radiographic clue to the fracture demonstrated on MRI.

Identifying a fracture and determining its mechanism are separate assessments. While imaging demonstrates the fracture, the distinction between a traumatic fracture and a stress fracture should be made in conjunction with the clinical history.

Radiology Pearl

A small cortical irregularity may be the clue to a fracture. When distinguishing a traumatic fracture from a stress fracture, evaluate the imaging findings alongside the onset of pain and loading history.

Put your heads together. 🤔