Metacarpophalangeal Joint Dislocation Workup

Updated: May 24, 2017
  • Author: Matthew Gammons, MD; Chief Editor: Craig C Young, MD  more...
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Workup

Laboratory Studies

Laboratory studies generally are not indicated in the diagnosis of metacarpophalangeal (MCP) joint injuries.

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Imaging Studies

Static x-ray films (see the images below)

Metacarpophalangeal joint dislocation of the small Metacarpophalangeal joint dislocation of the small finger. Posteroanterior radiograph demonstrates loss of joint space.
Metacarpophalangeal joint dislocation of the small Metacarpophalangeal joint dislocation of the small finger. Oblique radiograph best demonstrates dorsal dislocation of proximal phalanx.
Metacarpophalangeal joint dislocation of the small Metacarpophalangeal joint dislocation of the small finger. Dorsally dislocated proximal phalanx is obscured by other digits. Note that the small finger metacarpal sits palmar to the other metacarpals.

Obtain anteroposterior, lateral, and oblique radiographic views. Brewerton views (MCP joint flexed 65°, with the dorsum of the proximal phalanx flat against the radiograph cassette and the beam angled 15° ulnar to radial) profile the collateral recesses and are helpful for collateral ligament avulsion fractures.

Obtain a lateral view of the injured digit, not a lateral view of the hand.

Prereduction and postreduction x-ray films are necessary to demonstrate associated fractures and joint congruency.

An incongruent joint can be caused by interposed soft-tissue or gross instability.

Joint subluxation after reduction is associated with interposed soft-tissue or severe capsular injury.

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Procedures

Closed reduction of hyperextension – Simple dorsal dislocation

Use local anesthetic or intravenous sedation.

Apply pressure over the dorsal proximal phalanx, gently pushing in a palmar and distal direction, while simultaneously placing the metacarpophalangeal joint dislocation (MCP) joint into flexion.

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Flexing the wrist initially may aid reduction by relaxing the flexor tendons.

Never use longitudinal traction because this may entrap the metacarpal head in already tightened soft tissues or pull the volar plate into the joint, converting a simple dislocation into a complex dislocation.

Postreduction x-ray films confirm satisfactory reduction.

Maintain reduction in dorsal splint with the MCP joint flexed 30º.

Closed reduction of the thumb MCP joint – Dorsal dislocation

Closed reduction may be performed with local anesthesia, intravenous sedation, or regional block.

Apply a distal and volarly directed force to the dorsal base of the proximal phalanx, followed by placement of the MCP joint in mid flexion.

Postreduction x-ray films confirm satisfactory reduction.

Closed reduction of the thumb MCP joint – Volar dislocation

Most dorsal dislocations require open reduction owing to the presence of interposed structures: dorsal capsule, volar plate, extensor pollicis longus (EPL), extensor pollicis brevis (EPB).

Consider attempts at closed reduction if sesamoids are not interposed on radiographs or any of the following physical examination findings are present [10] :

  • No palpable EPL on initial examination

  • Radial or ulnar displacement of the EPL or EPB

  • Paradoxical MCP joint flexion and interphalangeal joint extension with attempted MCP extension

Use local anesthesia, intravenous sedation, or regional block.

Apply a dorsally directed force to the volar base of the proximal phalanx with hyperflexion at the MCP joint, followed by placement of the MCP joint in extension.

Postreduction x-ray films confirm satisfactory reduction.

Closed reduction of the locked thumb MCP joint

Occasionally, instillation of local anesthetic directly into the joint distends the capsule enough to allow gentle correction of the hyperextension deformity.

This should then be immobilized in approximately 20° of MCP joint flexion.

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