Traumatic Floating 1st Metacarpal in a 14-Year-Old Boy Managed by Close Reduction and Thumb Spica Immobilization: A Rare Case Report.

Introduction: Double dislocation of thumb metacarpal (MC) is a rare injury which may be secondarily complicated by growth plate injury in children. The management of floating 1st MC is also controversial since the treatment ranges from simple reduction to complex reconstruction surgeries. It is also important to understand the long-term results of different management strategies (close reduction, K-wire fixation, ligament reconstruction) as any residual stiffness or instability of thumb may result in severe disability of the hand.

Case Report: A 14-year-old boy with an alleged history of injury to the thumb due to a fall. The postulated mechanism of injury was forced hyperextension of thumb and axial loading of hand in the prone position. On examination, there was prominent bony swelling over the dorsal aspect of carpometacarpal (CMC) and metacarpophalangeal (MCP) joints which was very tender with diffuse swelling over entire thumb. X-ray showed dorsal dislocation of both MCP and CMC joints, without any fracture (bony avulsion) or volar plate avulsion. Treatment was by way of closed reduction performed by axial traction followed by forced flexion at MCP joint with continuous pressure over the dorsal aspect of the joint. The reduction of CMC joint was done by direct pressure over the dorsal aspect and full abduction of thumb. Following reduction, the thumb was immobilized in a thumb spica.

Conclusion: Thus, we conclude it is possible to manage a case of floating 1st MC by closed reduction and immobilization, using proper reduction technique. However, a careful clinical and radiological assessment should be done beforehand for signs of bony injury or ligamentous instability.