Trümmerfraktur Os trapezium

Fraktur Os trapezium Radiopaedia • CC-by-nc-sa 3.0 • de

Trapezium fractures are uncommon carpal bone injuries. They can either occur in isolation or combination with another carpal bony injury.

Epidemiology

Isolated fractures of the trapezium are only thought to account for 3-5% of all carpal fractures .

Pathology

They can be broadly classified into ridge (most common ) and body fractures.

Mechanism

They often occur as a result of a high energy trauma and usually involve either direct or indirect axial loading . These are most commonly transverse loading injuries in the setting of an adducted thumb in which the first metacarpal is driven into the trapezium.

Trapezial ridge fractures may result from a direct blow to the volar surface, dorsoradial impaction or an avulsion injury. Fractures of the trapezial body result from an axial loading or shearing force through the first carpometacarpal joint.

Associations

Trapezial fractures are often associated with a fracture of the first metacarpal base and/or subluxation or dislocation of the first carpometacarpal joint.

Trapezial ridge fractures may be associated with wrist injuries, including distal radial fractures.

Radiographic features

General

Non displaced fractures can sometimes be occult. A Robert’s AP view, with the hand in full pronation, is a good way of visualizing the trapezium on plain radiographs. If the diagnosis is still in question, a CT or bone scintigraphy could be considered.

Trapezial ridge fractures may be overlooked at routine wrist radiography. Carpal tunnel radiographs may be helpful to detect this fracture , whereas CT imaging can be diagnostic.