Delayed Presentation of Metacarpophalangeal Joint Dislocation of the Thumb in Children Requiring Open Reduction: Two Cases Reported and Review ofLiterature

INTRODUCTION Dislocation of the metacarpophalangeal joint (MCPJ) of the thumb is rare in children and delayed presentation of this injury is even more uncommon in the literature. We report two cases, both children, who presented to fracture clinic with a dislocated thumb over one week after initial injury. In each case closed reduction was attempted but failed, and open reduction was necessary. CASE REPORT Case Presentation 1: A 4 year-old right-hand dominant girl sustained a hyper-extension injury to her right thumb while on holiday abroad. She was told she has "sprained" her thumb. On review in fracture clinic 10 days later, the MCPJ of her thumb remained swollen and bruised. Radiographs showed a dorsally dislocated MCPJ of the right thumb. Case Presentation 2: A four-year old right-hand dominant boy presented to fracture clinic after being referred from A&E with a left 'thumb injury' - his thumb had accidentally been jammed in a door 1 week previously. Radiographs were reviewed and repeated, confirming a MCPJ dislocation. CONCLUSION Dislocation of the MCPJ of the thumb is extremely uncommon in children and therefore the diagnosis can be easily missed. Two unusual cases of dislocated MCPJ of the thumb in children that presented late because both radiological and clinical features had been missed are described. Closed reduction should always be attempted first but it should be recognised that conversion to an open reduction may be needed, particularly if there is a delay in presentation. There are various surgical options for open reduction including volar and dorsal approaches and arthroscopic procedures. The optimal method is controversial. We have explained a successful open reduction using a dorsal approach. In both cases the volar plate was found to be interposed within the joint blocking reduction. At follow up the patients had regained a full range of movement, normal power and grip strength.