OrthoDx: Thumb Dislocation in Child

Slideshow

  • Figure 1. Anteroposterior radiograph of dislocated thumb.

  • Figure 2. Lateral view of injured thumb.

  • Figure 3. Anteroposterior view of thumb after reduction.

  • Figure 4. Lateral view of treated thumb.

A 9-year-old child presents to urgent care with an obvious deformity to his right thumb. He was playing football and fell on his hand. He had immediate pain and deformity to the right thumb after the fall. Radiographs of the thumb show a metacarpophalangeal (MCP) joint dislocation (Figures 1 and 2). Post-reduction radiographs are shown in Figures 3 and 4. Post-reduction examination of the thumb reveals no laxity with varus and valgus stress to the MCP joint.

The patient has a dorsally angulated thumb MCP joint dislocation. The most common mechanism of injury is a fall on the hand causing hyperextension of the MCP joint. The classic radiographic finding is the proximal phalanx at 90 degrees from...

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The patient has a dorsally angulated thumb MCP joint dislocation. The most common mechanism of injury is a fall on the hand causing hyperextension of the MCP joint. The classic radiographic finding is the proximal phalanx at 90 degrees from the metacarpal head. With an MCP joint dislocation, the volar plate avulses off the metacarpal neck and the collateral ligaments may be injured if rotation of the finger occurs. Thumb MCP joint dislocations can be irreducible if the volar plate, sesamoids, or flexor pollicis longus tendon become interposed dorsally in the joint.1,2 

The reduction method includes dorsal to volar pressure to the proximal phalanx to push it over the metacarpal head. After a closed reduction is performed, assessment of the collateral ligaments should be performed by applying a varus and valgus force to the MCP joint. Straight traction alone should be avoided to prevent entrapping the volar plate.1,2

The ideal treatment for reducible, stable dislocations has not been established. A dislocation with a stable reduction can be splinted with the MCP joint in slight flexion for 3 to 4 weeks. Prolonged immobilization beyond 4 weeks may result in permanent stiffness of the digit. A follow-up radiograph of the thumb in 1 to 2 weeks after reduction should be performed to confirm continued stability.1,2

Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.

References

1. Kim JS, Hussain K, Higginbotham DO, Tsai AG. Management of thumb carpometacarpal joint dislocations: a systematic review. J Orthop. 2021;25:59-63.

2. Dinh P, Franklin A, Hutchinson B, Schnall SB, Fassola I. Metacarpophalangeal joint dislocation. J Am Acad Orthop Surg. 2009;17(5):318-24. doi:10.5435/00124635-200905000-00006

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