What are the steps for an open reduction procedure in an adult or adolescent patient with a metacarpophalangeal joint dislocation, with or without a history of conditions such as rheumatoid arthritis or previous hand injuries?

Open Reduction of Metacarpophalangeal Joint Dislocation

Indications for Open Reduction

Open reduction is indicated when closed reduction attempts fail, which occurs when the volar plate becomes interposed within the MCP joint, creating a mechanical block to reduction. 1, 2

Key anatomical barriers requiring open reduction include:

• Volar plate interposition (most common barrier) - the metacarpal head buttonholes through the volar plate 1, 2
• Flexor tendons and lumbrical muscle blocking reduction 2
• Sesamoid bone entrapment (in adults; less common in pediatric patients who lack sesamoid bones) 1

Surgical Approach Selection

Two primary approaches exist with ongoing debate about superiority:

Volar Approach

• Provides direct visualization of the volar plate, flexor tendons, and lumbrical muscle 2
• Allows identification and release of all interposed structures 2
• Particularly useful when the metacarpal head is buttonholed between flexor tendons and lumbrical muscle 2

Dorsal Approach

• Equally effective alternative that avoids potential injury to neurovascular structures on the volar surface 1
• Allows reduction using a Freer elevator as a lever while applying gentle traction and flexion 1
• Successfully used in pediatric cases with full recovery of range of motion 1

Surgical Steps for Open Reduction

Volar Approach Technique:

1. Make a Bruner zigzag incision over the volar aspect of the MCP joint 2
2. Identify and protect the digital neurovascular bundles laterally 2
3. Expose the volar plate and identify the interposed structures (volar plate, flexor tendons, lumbrical muscle) 2
4. Release the volar plate from the metacarpal head by carefully extracting it from the joint space 2
5. Reduce the joint by applying gentle traction and flexion while manipulating the metacarpal head back into anatomic position 2
6. Verify stability through full range of motion testing 2
7. Close the wound and immobilize in palmar splint at 30° flexion 2

Dorsal Approach Technique:

1. Make a longitudinal or curved incision over the dorsal MCP joint 1
2. Identify the extensor mechanism and split it longitudinally or retract it 1
3. Visualize the buttonholed metacarpal head through the volar plate 1
4. Use a Freer elevator as a lever to gently pry the metacarpal head out of the volar plate 1
5. Apply gentle traction and flexion simultaneously to complete the reduction 1
6. Assess joint stability and extensor mechanism integrity 1
7. Close in layers and immobilize appropriately 1

Alternative Minimally Invasive Technique

A percutaneous technique can be attempted before proceeding to formal open reduction, particularly in the emergency department setting. 3

Percutaneous reduction steps:

• Make a small dorsal incision over the MCP joint 3
• Use a skin hook or similar instrument to manipulate the volar plate percutaneously 3
• Apply traction and flexion while manipulating the interposed structures 3
• This technique achieved successful reduction in all 4 reported cases without complications 3
• Avoids the cost and morbidity of formal open surgery 3

Post-Reduction Management

Immobilize the joint in 30° of flexion using a palmar splint for 2 weeks 2

• After 2 weeks, allow unrestricted mobilization 2
• Near full, painless range of motion is typically achieved by 4 weeks 1, 2, 3
• No recurrent instability was reported in successful reductions 3

Special Considerations in Pediatric Patients

Pediatric MCP dislocations have unique anatomical features that affect surgical planning: 1

• Ligamentous laxity may make the injury appear less severe initially 1
• Absence of sesamoid bones eliminates one potential barrier to reduction 1
• Cartilage fractures are possible and may not be visible on plain radiographs 1
• Growth plate injury risk requires careful surgical technique to avoid physeal damage 1

Critical Pitfalls to Avoid

Aggressive closed reduction attempts can convert a simple dislocation into a complex one by driving the volar plate further into the joint. 1, 2

• Recognize complex dislocations early - characterized by parallel alignment of the proximal phalanx and metacarpal on lateral radiograph, rather than the typical hyperextension seen in simple dislocations 1
• Do not delay surgical intervention once complex dislocation is identified, as this can lead to permanent stiffness and functional impairment 4
• Protect neurovascular structures during volar approach dissection 2
• Avoid excessive force during reduction to prevent iatrogenic cartilage or ligament injury 1