Trapezium Fracture

Trapezium fractures, though rare (3-5% of carpal fractures), are clinically significant due to their role in thumb function. They typically result from axial loading or avulsion forces on the thumb. Fractures are classified as ridge avulsions, vertical body fractures, or comminuted types. Diagnosis requires specialized X-ray views (like Robert's view) or CT scans. Nondisplaced fractures are treated with immobilization, while displaced or articular fractures often require surgical fixation to restore joint alignment and prevent complications like post-traumatic arthritis and long-term thumb impairment.

Trapezium fractures are relatively uncommon, accounting for approximately 3% to 5% of all carpal bone fractures. Despite their rarity, these injuries carry significant clinical importance due to their involvement in thumb biomechanics and the high risk of long-term functional impairment.

Anatomy and Biomechanics

The trapezium is a key carpal bone forming the base of the thumb through its articulation with the first metacarpal at the carpometacarpal (CMC) joint. This joint enables the wide range of thumb motion essential for grip and opposition.

Trapezium Fractures, particularly the body, often disrupt one or more of its four articular surfaces, frequently leading to subluxation or instability of the thumb CMC joint.

See Also: Wrist Anatomy

Mechanism of Injury

The most common mechanisms include:

Axial loading of an adducted thumb: This force drives the base of the first metacarpal into the trapezium, often resulting in vertical or body fractures.
Avulsion forces: Forceful deviation, traction, or rotational stress on the thumb can lead to ridge avulsion fractures.
Direct trauma: Impact to the palmar aspect of the hand may avulse the trapezial ridge via tension from the transverse carpal ligament.

Classification of Trapezium Fractures

Trapezium fractures are typically categorized as:

Ridge avulsion fractures (most common)
Vertical fractures of the body
Comminuted fractures involving articular surfaces

Body fractures are particularly concerning due to their frequent involvement of the CMC joint.

See Also: Scaphoid Fractures

Walker’s classification

Type I: horizontal sagittal split,
Type IIa: medial distal avulsion,
Type IIb: medial proximal avulsion,
Type III: lateral distal avulsion,
Type IV: vertical sagittal split,
Type V: communitive.

Clinical Presentation

Patients usually present with:

Localized tenderness over the radial aspect of the wrist
Pain exacerbated by thumb movement
Reduced range of motion at the first CMC joint
Possible swelling and decreased grip strength

A high index of suspicion is required, as these injuries may be overlooked on initial assessment.

Diagnostic Evaluation

Radiographic Imaging

Standard imaging includes:

Posteroanterior (PA) view
Lateral view
Robert view: A specialized true PA projection of the thumb CMC joint with the hand in maximum pronation, which minimizes overlap of the first metacarpal base.

Additional imaging:

Carpal tunnel view: Useful for detecting dorsal ridge fractures
CT scan: Highly sensitive for occult fractures and detailed assessment of articular involvement