Management of Lateral Dislocation of the First Metacarpophalangeal Joint
Attempt closed reduction immediately, and if the joint is stable post-reduction with congruent radiographic alignment, immobilize in a thumb spica splint for 6 weeks followed by progressive mobilization. 1
Initial Assessment and Reduction
Perform closed reduction as the first-line intervention for lateral dislocation of the first MCP joint, as non-operative management with splinting is effective when the joint demonstrates stability after reduction. 1
Key Steps in Closed Reduction:
- Apply longitudinal traction with the MCP joint in slight flexion 1
- Assess for immediate post-reduction stability through gentle stress testing 1
- Obtain post-reduction radiographs to confirm joint congruency 1
Critical Decision Point: Stability Assessment
If the joint is stable post-reduction with congruent radiographic alignment:
- Immobilize in thumb spica splint for 6 weeks 1
- Begin immediate active finger motion exercises for all uninvolved digits to prevent stiffness 2, 3
- Obtain repeat radiographs at 10-14 days to ensure maintained reduction 2
If closed reduction fails or the joint is unstable post-reduction:
- Proceed directly to open reduction, as complex MCP dislocations cannot be managed closed when anatomic obstacles prevent reduction 4, 5, 6
Surgical Management When Indicated
Indications for Open Reduction:
- Failed closed reduction attempts 4, 5, 6
- Post-reduction instability 1
- Associated displaced fractures requiring fixation 4
- Entrapped volar plate or other soft tissue interposition 6
Surgical Approach Options:
Dorsal approach is feasible and effective, particularly when complicated by fractures requiring internal fixation. 4 This approach provides adequate visualization for reduction and allows screw fixation when needed. 4
Volar approach is preferred when the mechanism is undefined or volar plate entrapment is suspected, as this route allows direct control and repair of the volar plate for long-term MCP joint stability. 7
Post-Reduction Rehabilitation Protocol
Immobilization Phase (0-6 weeks):
- Maintain thumb spica splint immobilization for full 6 weeks 1
- Begin immediate active finger motion exercises for all uninvolved fingers to prevent hand stiffness, which is one of the most functionally disabling complications 2, 3
- Finger motion does not adversely affect adequately stabilized fractures 2, 3
Mobilization Phase (6-9 weeks):
- Remove splint at 6 weeks 1
- Initiate active range of motion exercises for the thumb 1
- Progress to full activities as tolerated 1
Expected Outcomes:
- Pain should subside by 6-9 weeks 1
- Full range of motion typically achieved by 9 weeks post-injury 1
- Normal joint anatomy without subluxation or osteoarthritic changes at 2-year follow-up 1
Critical Pitfalls to Avoid
Do not restrict finger motion of uninvolved digits during immobilization, as failure to encourage early finger motion leads to significant stiffness requiring multiple therapy visits or surgical intervention. 2, 3
Do not accept incomplete reduction or persistent instability, as these require surgical intervention rather than prolonged conservative attempts. 1, 6
Do not delay surgical referral when closed reduction fails, as complex MCP dislocations with anatomic obstacles (volar plate entrapment, interposed ligaments, flexor tendon interposition) will not reduce closed and require open management. 5, 6