An isolated complex dorsal dislocation of the MP joint of the ring finger

Late presentation of a complete complex thumb metacarpophalangeal joint dislocation: A case report

Metacarpophalangeal (MP) joint injuries and dislocations of the fingers and thumb are not uncommon. They can be classified directionally as either being volar or dorsal, and are further categorized as incomplete, simple complete or complex complete. Complex dislocations are described as dislocations that are irreducible and often require surgical intervention. This is often because tissue has become entrapped within the MP joint, precluding its anatomical reduction. For the thumb MP joint, anatomical structures that may become trapped include the volar plate, sesamoid bones, bony fracture fragments or the flexor pollicis longus tendon. Both dorsal and volar surgical approaches have been described, and their relative merits will be discussed. The unusual case of a late presentation (two months postinjury) of a complex complete dorsal dislocation of the thumb MP joint approached from a dorsal incision is presented.

The volar surgical approach in complex dorsal metacarpophalangeal dislocations

OBJECTIVE

To describe the surgical treatment of complex dorsal metacarpophalangeal dislocations, emphasising the volar approach.

METHODS

Seven cases of isolated, closed, complex dorsal metacarpophalangeal dislocation, treated surgically using the volar approach, were retrospectively evaluated. The median follow-up period was 91 months.

RESULTS

Five of the injuries involved children. The thumb was involved in four cases and the index finger in three. The volar plate was found to impede reduction in all cases. The operated joint was immobilised in a functional brace for a median of 3 weeks. At final follow-up (median 91 months), the metacarpophalangeal range of motion, grip power, stability and sensation were normal.

CONCLUSIONS

Using the volar surgical approach, the strangulated metacarpal head can be directly visualised and the volar plate, which is longitudinally split for reduction, can be repaired. Reduction should be performed within the first day from injury, and the joint should be immobilised in a functional position no more than 3 weeks.

Dorsal approach for open reduction of complex metacarpophalangeal joint dislocations

The metacarpophalangeal (MP) joint is resistant to injury due to its strong capsuloligamentous structures, which include the volar plate and deep transverse metacarpal and collateral ligaments. Complex MP joint dislocations are, by definition, irreducible by closed means and require open reduction, as the volar plate becomes entrapped between the metacarpal head and proximal phalanx. The dorsal approach may offer the following advantages: 1) reduced risk to palmarly displaced neurovascular structures, 2) facilitated management of osteochondral fractures, and 3) full exposure of the volar plate. However, the dorsal approach requires splitting of the volar plate for adequate reduction, which may delay recovery.

A dislocated finger

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