Lariat sign: An MRI finding associated with common peroneal nerve rupture

Area of Science:

• Orthopedic Surgery
• Neurology
• Radiology

Background:

• Traumatic knee dislocation is a severe orthopedic emergency.
• Associated vascular and neurologic injuries are common and serious.
• Prompt diagnosis and management are crucial for patient outcomes.

Observation:

• A case of knee dislocation resulted in common peroneal nerve rupture.
• Novel radiographic findings were observed at the rupture site.
• The distal nerve formed a loop, resembling a lasso or lariat.

Findings:

• The "lariat sign" describes the looped appearance of the ruptured common peroneal nerve.
• This sign is a specific radiographic finding in traumatic knee dislocation with nerve injury.
• Radiologists and orthopedic surgeons must recognize this sign to avoid misinterpretation.

Implications:

• The lariat sign may improve the diagnosis of common peroneal nerve rupture.
• Accurate identification of nerve injury is vital for surgical planning and treatment.
• This finding enhances understanding of the biomechanics of nerve injury in knee dislocations.