Chauffeur fractures, also known as Hutchinson fractures are intra-articular fractures of the radial styloid process. The radial styloid is within the fracture fragment, although the fragment can vary markedly in size.

Terminology

The term backfire fracture should not be used. Backfiring occurs when ignition occurs somewhere other than the cylinders, such as the exhaust system. If the timing is delayed the petrol/air mixture combusts in the exhaust pipe causing a loud bang!

Pathology

Mechanism

In the era preceding starter motors, car engines were ‘turned over’ manually using a handle to turn the crankshaft clockwise and overcome the inertia of the engine parts, a task requiring considerable effort. The spark which ignites the combination of petrol and air must be mechanically timed to apply downward pressure on the piston after it has passed top dead center (TDC) so that the direction of rotation is maintained. If the ignition occurs prematurely, the piston will be forced backwards causing a powerful kickback, forcibly hyper-extending the wrist and forcing the scaphoid into the radius. The typical fracture was an intra-articular fracture of the radius, sometimes unstable ⁹.

Associations

Several associated injuries are frequently encountered and may significantly impact on management:

• scapholunate dissociation: this is especially true when the fracture line involves the articular surface near the scapholunate interval ⁷

• trans-scaphoid perilunate dislocation ^ref

• ulnar styloid fracture: equates to a Frykman type IV fracture ^ref

Radiographic features

Plain films usually suffice in the assessment of chauffeur fractures.

Plain radiograph

The fracture extends proximally in a variable oblique direction (from essentially transverse to almost sagittal) from the distal radial articular surface through the lateral cortex of the distal radius, thus separating the radial styloid from the rest of the radius ^4,5. Although often the fracture is undisplaced ⁵, depending on how sagittal the fracture orientation is, variable proximal migration of the fracture occurs, with an articular step which comes into contact with the scaphoid ⁴.

Radiology report

In addition to reporting the presence of the fracture a number of features should be sought and in many instances commented upon as relevant negatives:

• fracture description

  • direction: transverse/oblique/longitudinal ⁸

  • articular step-off and the gap distance ⁸

  • where along the articular surface it begins (especially relative to the scapholunate interval) ^ref

  • fracture fragment displacement and/or rotation ⁸

  • any comminution ⁷

• presence or absence of any associated injuries (see above) ⁸

Treatment and prognosis

Although these fractures are often undisplaced, they are relatively unstable and often benefit from percutaneous lag-screw fixation ⁶.

History and etymology

It was originally described by British surgeon Jonathan Hutchinson (1828-1913) and the occupational association was noted by French surgeon Just Lucas-Championnièr who named it chauffeur fracture. Chauffeur translates as "someone who warms" (the car engine). During the warm-up, the carburetor mixture was adjusted using a choke to keep the engine ticking over and the engine oil warmed and circulated.

Differential diagnosis

• radial styloid avulsion fracture ⁸

  • forced dorsiflexion/supination and abduction/ulnar deviation results in the scaphoid forcibly impacting the radial styloid ^7,8

  • radiocarpal ligaments remaining attached to the radial styloid ⁷

  • similar imaging appearance to chauffer fracture ⁸

See also

• eponymous fractures

• wrist series