A 32-Year-Old Male with Thumb Pain After a Ski Fall

Differential Diagnosis

• Bennett fracture
• Epibasal fracture
• Rolando fracture

Diagnosis

The x-ray shows a minimally displaced intraarticular fracture of the base of the first metacarpal, also known as a Bennett fracture.

Learnings/What to Look for

• Bennett fractures result from opposing traction forces by the anterior oblique ligament in combination with either axial loading onto a flexed thumb (eg, during a punch) or shearing force against the first web space (“motorcyclist thumb”)
• Trapeziometacarpal joint avulsion can manifest as soft tissue injury, but more commonly manifests as a fracture. Two-part intraarticular Bennett fracture dislocations are the most common
• Bennett fractures are associated with thumb collateral ligament injuries and fractures of the trapezium

Pearls for Urgent Care Management

Because of proximally and radially directed forces from multiple muscles, the larger radial- sided metacarpal fracture fragment is prone to proximal migration, while the ulnar-sided fracture fragment is anchored in place by the anterior oblique ligament attachment to the trapezium

• Closed reduction and thumb spica cast immobilization are effective in the treatment of Bennett fractures if the reduction can be maintained. This consists of thumb traction combined with metacarpal extension, pronation, and abduction
• If closed reduction is not possible, referral to an orthopedic surgeon is warranted. Operative repair typically consists of percutaneous pinning or open reduction with pins or interfragmentary screws

Acknowledgment: Images and case presented by Experity Teleradiology (www.experityhealth.com/teleradiology).