Chauffeur Fracture

Chauffeur fracture is an intra-articular fracture of the radial styloid, also called a Hutchinson or backfire fracture. The name comes from early hand cranked car engines that kicked back.

The usual mechanism is a compressive force on the extended and ulnar deviated wrist, in which the scaphoid drives into the styloid, or an avulsion through the radioscaphocapitate and radial collateral ligaments. It affects young and middle aged adults after a fall or high energy injury.

It is often accompanied by a scapholunate ligament injury, and it can be the radial stage of a perilunate dislocation (transstyloid perilunate injury). A high index of suspicion for carpal ligament injury is therefore needed.

Complications are scapholunate dissociation, radiocarpal arthritis, intra-articular malunion, nonunion (uncommon), and stiffness.

Pathophysiology.

The radial styloid is the origin of the radial collateral and radioscaphocapitate ligaments. A shear or avulsion force breaks the styloid and can continue across the carpus, injuring the scapholunate ligament and, in severe injuries, dislocating the lunate.

Radial sided wrist pain and swelling, tenderness over the radial styloid and the snuffbox, pain with wrist radial deviation and grip. Test the median and superficial radial nerves, and examine for tenderness at the scapholunate interval (dorsal, just distal to Lister's tubercle).

• Radiographs: posteroanterior, lateral, oblique and scaphoid views. A fracture line through the styloid with the fragment displaced radially.
• Carpal alignment: scapholunate gap (over 3 mm on a posteroanterior or clenched fist view is abnormal), scapholunate angle (normal 30 to 60 degrees), and Gilula arcs.
• CT for the articular step and fragment size. MRI or arthroscopy for ligament injury.

Differential diagnosis.

• Scaphoid fracture and scapholunate ligament injury.
• Barton fracture and perilunate dislocation.
• De Quervain tenosynovitis and wrist sprain.
• Kienbock disease.

• Undisplaced fractures with a step under 2 mm and no ligament injury: short arm cast or thumb spica for 4 to 6 weeks.
• A step of 2 mm or more, or displacement: reduction and fixation. Percutaneous or open fixation with one or two 2.4 to 3.0 mm cannulated headless compression screws, or Kirschner wires 1.6 mm, through a dorsoradial approach that protects the superficial radial nerve branches.
• Arthroscopy assisted reduction shows the articular surface and the carpal ligaments, and allows scapholunate repair when it is torn.
• Perilunate dislocation components need urgent open reduction and ligament repair.
• After surgery: splint for 2 to 4 weeks, then active movement. Wires are removed at 4 to 6 weeks.

Analgesia.

• Paracetamol 1 g orally every 6 hours as needed for up to 5 to 7 days (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily); avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.
• Oral morphine 5 to 10 mg every 4 hours as needed for severe pain for up to 3 days (start 2.5 to 5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2; avoid exceeding 60 mg in 24 hours without senior review); monitor sedation and respiration and prescribe a laxative.

Monitoring. Radiographs at 1 week, 2 weeks and 6 weeks. Scapholunate gap and angle on repeat views at 6 weeks and 3 months. Wrist range and grip at 3 months. Pain at the dorsal scapholunate interval at 3 to 12 months suggests a missed ligament injury, and arthritis is assessed at 1 year.

Referral and escalation. Refer every displaced fracture and every fracture with suspected carpal instability to orthopaedics (hand surgery) within 24 hours. Same day referral for perilunate dislocation, open injury, acute carpal tunnel syndrome, or neurovascular compromise.

Special groups.

• Older adults: bone health assessment follows a fragility fracture.
• Children: radial styloid injuries are rare; fractures of the distal radial physis need specialist care.
• Kidney impairment: avoid ibuprofen; reduce morphine doses and extend intervals.