Complete dorsal dislocation of the metacarpophalangeal joint of the thumb

Does Irreducibility Always Mean a Complex Dislocation? An Analysis of 33 Pediatric Metacarpophalangeal Joint Dislocations

BACKGROUND

Previous failed reduction and certain radiographic indicators historically have been used to differentiate simple and complex metacarpophalangeal joint (MPJ) dislocations in children, the latter of which warrants open reduction. This investigation aimed to determine the necessity for open reduction with these indicators and establish a new treatment algorithm and educational focus for these rare injuries.

METHODS

A 12-year retrospective study was conducted on all children with MPJ dislocations at a single pediatric hospital. The rates of successful closed reduction, number of reduction attempts, and radiographic findings were detailed. Operative details and postoperative outcomes were also gathered.

RESULTS

Thirty-three patients with a mean age of 11.1 years were included. Most were male [ n = 27 (82%)] and had undergone two or more previous reduction attempts at an outside facility. Stable closed reduction was then achieved outside of the operating room in five patients and in the operating room under general anesthesia in another 14, for a total of 19 of 33 patients (57.6%). The thumb was injured most often [ n = 19 (57.6%)] and more likely to undergo successful closed reduction ( P = 0.04). There was no relationship between number of previous reduction attempts and ability to achieve closed reduction ( P = 0.72). Neither joint-space widening nor proximal phalanx bayonetting was correlated radiographically with failure of closed reduction ( P = 0.22 and P = 1, respectively).

CONCLUSIONS

This study supports closed reduction of pediatric MPJ dislocations in the operating room under general anesthesia before conversion to open reduction, regardless of injury characteristics or previous reduction attempts. This strategy is likely to limit unnecessary open surgery and related risks.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, IV.

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.

Metacarpophalangeal joint dislocation

Traumatic dislocation of the metacarpophalangeal joint is a relatively uncommon injury. The dislocation may be easily reducible (ie, simple) or require surgical intervention (ie, complex). The flexor tendons, lumbrical muscle, natatory ligament, and superficial transverse metacarpal ligament combine with the displaced volar plate to create a tight noose, preventing reduction. Surgical approach may be dorsal or volar; however, the radial digital nerve to the index finger is especially at risk through the volar approach. Reported complications include stiffness, arthritis, osteonecrosis of the metacarpal head, and even premature closure of the physis.

Metacarpophalangeal joint dislocation of the thumb in children

There are few reports describing dislocation of the metacarpophalangeal joint of the thumb in children. This study describes the clinical features and outcome of 37 such dislocations and correlates the radiological pattern with the type of dislocation. The mean age at injury was 7.3 years (3 to 13). A total of 33 children underwent closed reduction (11 under general anaesthesia). Four needed open reduction in two of which there was soft-tissue interposition. All cases obtained a good result. There was no infection, recurrent dislocation or significant stiffness. So-called 'simple complete' dislocations that present with the classic radiological finding of the joint at 90 degrees dorsal angulation may be 'complex complete' injuries and require open reduction.