Abstract
Background The second and third metacarpals are firmly attached, immobile structures which for
the stable pillar of the hand. The trapezoid has been described as the keystone of
the wrist, allowing a wide range of functional motion as well as inherent anatomic
and biomechanical stability to the carpus.
Case Description We describe a novel boxing injury with a 180-degree in situ dislocation of the right
trapezoid with concomitant second and third carpometacarpal (CMC) joint dislocations.
Open anatomic reduction of the trapezoid was obtained, and subsequent percutaneous
pinning of the metacarpals allowed for a full functional recovery and return to sports
at 6 months.
Literature Review Combined trapezoid and CMC dislocations are extremely rare and have only been previously
described in high-energy mechanism injuries, involving a direct dorsal force such
as from the steering wheel in a motor vehicle collision. There are no previous reports
of this injury occurring in the setting of direct axial load along the metacarpals
in a clenched fist such as in a punch or fighting injury.
Clinical Relevance The rare nature of this combined injury, its novel mechanism, and the difficulty
in interpreting acute injury and postreduction radiographs require that the treating
physician have a high degree of clinical suspicion for associated injuries when CMC
dislocations are identified. Treatment strategies incorporating intraoperative fluoroscopy,
open anatomic reduction of the trapezoid under direct visualization along with closed
reduction, and pinning of the metacarpals reestablish carpal stability and provide
excellent long-term results.
Keywords
carpal - instability - trapezoid
