Sagittally Split Fracture of Trapezium Associated With Subluxed Carpometacarpal Joint of Thumb

ABSTRACT

Fractures of the trapezium usually are associated with other hand or wrist injuries. They are rare, constituting approximately 3.5%-5% of all carpal bone fractures. Isolated fractures are rare and impossible to produce experimentally.

Two cases of trapezial fractures with associated subluxation of the thumb carpometacarpal joint are presented. In both cases, radiographs revealed an unusual displaced, intra-articular, longitudinal sagittally split fracture of the trapezium with associated subluxation of the thumb carpometacarpal joint. In both fractures, open reduction and internal fixation with a mini fragment 2.7-mm lag compression screw was performed. No tendinous augmentation of the intermetacarpal ligament was performed. A below elbow plaster cast extending to the interphalangeal joint of the thumb was applied for 6 weeks.

At 1-year follow-up, an excellent radiographic and functional result was noted with the patients performing normally at their jobs, having no limitation of daily living or sporting activities, and reporting no pain or instability symptoms.

Vertical fractures typically result from a cleavage through the midsagittal axis accompanied by proximal radial subluxation of the dorsal fragment with attached metacarpal and exacerbated by the pull of abductor pollicis longus tendon. Carpometacarpal joint dislocation with an associated vertical intra-articular fracture of the trapezium has been described and treated by open reduction and internal fixation with a Kirschner wire, and in addition, reconstruction of the dorsal oblique intermetacarpal ligament, using a slip of abductor pollicis longus tendon

Longitudinal injuries of the thumb carpometacarpal joint are unstable and accompanied by subluxation of the thumb metacarpal. If these injuries are not accurately diagnosed and treated, they may cause pain, motion limitation, or weakness, leading to permanent function impairment. Fixation with K-wires, Herbert’s type compression screws, or interfragmentary lag compression screws may be required in these unstable, displaced fractures. Reconstruction of the intermetacarpal and capsular structures, such as an intermetacarpal abductor pollicis longus augmentation may be required, especially in isolated dislocations, but this may not be necessary in fracture-subluxations (as in our paper), where the metacarpal base and dorsal trapezial fragment remain connected by the dorsal capsule. A temporary additional stabilizing K-wire ensures intermetacarpal orientation and relationship.