What is the longhorn sign in hand injury?

The Longhorn Sign in Hand Injury

The longhorn sign is a radiographic finding in hand injuries characterized by the presence of a die-punch fracture, which involves depression of the lunate facet of the distal radius, creating a pattern resembling longhorn cattle horns on imaging. 1

Definition and Clinical Significance

• The longhorn sign specifically refers to the radiographic appearance of an intra-articular fracture of the distal radius where the lunate facet is depressed, creating a characteristic pattern that resembles longhorn cattle horns 1
• This sign is important to recognize as it indicates an intra-articular fracture pattern that may require surgical intervention to restore articular congruity and prevent long-term complications such as osteoarthritis 2
• Die-punch fractures with depression of the lunate facet are considered complex intra-articular injuries that often require more aggressive management than extra-articular fractures 1

Radiographic Identification

• Standard 3-view radiographic examination of the wrist (posteroanterior, lateral, and 45° semipronated oblique views) is the initial imaging modality to identify the longhorn sign 2, 1
• The presence of a coronally oriented fracture line or die-punch depression on initial radiographs should raise suspicion for this injury pattern 2
• In some cases, the longhorn sign may be subtle on plain radiographs, requiring additional imaging for proper characterization 2

Advanced Imaging Considerations

• CT without IV contrast is particularly valuable for better visualization of the longhorn sign when radiographs are equivocal, as it is superior for detecting intra-articular extension of distal radius fractures 2, 1
• Three-dimensional CT reconstructions can be particularly helpful in preoperative planning for complex articular injuries showing the longhorn sign 2
• MRI without IV contrast may be useful to evaluate for concomitant ligamentous injuries that often accompany these intra-articular fractures, particularly scapholunate ligament tears 1

Clinical Implications and Management

• The presence of the longhorn sign (die-punch depression) is often an indication for operative intervention, as it represents a significant intra-articular injury 2
• Operative fixation is typically necessary when there is >2 mm of residual articular surface step-off to avoid long-term complications such as osteoarthritis 2
• CT arthrography may be considered if there is concern for associated ligamentous injuries, as it has high sensitivity and specificity for detecting scapholunate and lunotriquetral ligament tears 2

Common Pitfalls

• Failure to obtain adequate radiographic views may lead to missed diagnosis of the longhorn sign; a minimum of 3 views is necessary 2
• Relying solely on 2 radiographic views is inadequate for detecting this and other complex wrist fractures 3
• Initial radiographs may be negative despite the presence of an intra-articular fracture; if clinical suspicion remains high, advanced imaging or repeat radiographs in 10-14 days should be considered 3
• The longhorn sign should not be confused with other patterns of distal radius fractures, as the specific treatment approach may differ 1