Cite This Article

Holmes J, Tomesch, A. MCP, are you with me? Ortho Pearls. June 19. 2024; Available: https://www.orthoempearls.com/articles/mcp-are-you-with-me

What is the diagnosis?

Right index finger metacarpophalangeal joint (MCPJ) dislocation 

• Pearl: MCP joints typically dislocate in the dorsal direction, most commonly involving the index finger [1].

Image 2. Annotated x-rays from Image 1. Author’s own images and annotation. 

What is the mechanism of injury?

Dorsal dislocations occur due to hyperextension of the joint, usually from a fall on an outstretched hand [2].  Volar dislocations occur due to hyperflexion or hyperextension of the MCP joint [2].

• Pearl: Volar and lateral dislocations are less common than dorsal due to the volar plate and strong lateral ligaments [2]. 

What physical exam findings are expected?

Typically, the MCP joint will be in extension with flexion at the interphalangeal joints [1].

• Pearl: Complex dislocations are typically not reducible. A physical exam of the complex dislocation may show less displacement due to the proximal phalanx resting on the dorsal aspect of the metacarpal head [2].

Which imaging modalities can be used?

Plain radiographs of the hand 

• Pearl: MCP joint dislocation is best viewed on lateral radiograph, showing a widened joint space due to the interposition of the volar plate [2].

What is the management in the ED?

Closed reduction with anesthesia (small hematoma block is likely to be most successful). After reduction, splint the joint in flexion [3]. 

• Pearl: Tips for reduction include flexing at the wrist, which relaxes the tendon, then providing pressure to the dorsum part of the proximal phalanx in the distal and volar direction [3]. Do not hyperextend due to the concern of making it a complete dislocation [3].

When do you consult Orthopedics?

Contact orthopedics or whomever is on call for hand for a complex dislocation or failed attempts of closed reduction.

• Pearl: Complex dislocations are not reducible by the closed reduction technique, and will likely have to go to the OR for reduction [1]. The interposition of the volar plate between the proximal phalanx and the metacarpal is most often responsible for complex dislocations [1].