What is the treatment for recurring spontaneous subluxation and relocation of the thumb Metacarpophalangeal (MCP) joint after a jamming injury, with no fracture on X-ray?

Treatment of Recurrent Spontaneous Subluxation of Thumb MCP Joint After Volleyball Injury

For recurrent spontaneous subluxation of the thumb MCP joint following trauma with no fracture, you should initiate immediate immobilization with a thumb spica splint or orthosis for at least 3 months, combined with hand therapy, and maintain a low threshold for early surgical ligamentous reconstruction if instability persists beyond 1-2 weeks, as conservative management alone frequently fails and leads to chronic instability and post-traumatic arthritis.

Initial Management and Immobilization

Rigid immobilization is the cornerstone of initial treatment for this injury pattern. The thumb should be placed in a thumb spica splint or custom-made orthosis immediately 1. Based on evidence from thumb base injuries, long-term orthosis use (at least 3 months) is necessary to achieve beneficial effects on pain and function 1. Shorter periods of immobilization have not shown improvements 1.

• Custom-made orthoses are strongly preferred over prefabricated options, as they improve compliance and ensure proper fit 1
• The orthosis should be worn during activities of daily living to protect the healing ligamentous structures 1
• A specialized hand therapist or occupational therapist should fabricate and fit the orthosis 1

Assessment for Surgical Intervention

The critical decision point is whether ligamentous instability will resolve with conservative treatment or requires surgical reconstruction. Recurrent spontaneous subluxation at 1.5 weeks post-injury is a red flag suggesting significant ligamentous disruption that may not heal adequately with immobilization alone.

Indications for Early Surgical Reconstruction:

• Persistent instability after 1-2 weeks of proper immobilization suggests complete ligamentous disruption requiring surgical repair 2
• Recurrent subluxation episodes despite splinting indicate inadequate soft tissue healing 2
• Inability to maintain joint reduction with conservative measures 3, 4

The evidence strongly supports early ligamentous reconstruction over prolonged conservative management when instability is present. A retrospective study comparing closed reduction/pinning versus early ligamentous reconstruction (performed average 7 days post-injury) demonstrated that early surgical reconstruction significantly reduced recurrent instability and post-traumatic arthritis 2. In the closed reduction group, 50% required revision surgery for recurrent instability or degenerative arthritis, while the early reconstruction group had preserved range of motion, grip strength, and minimal radiographic changes at 2-year follow-up 2.

Advanced Imaging to Guide Treatment

MRI is the ideal imaging modality to assess the extent of ligamentous injury and guide treatment decisions 1, 5. MRI demonstrates 100% sensitivity and specificity for assessment of thumb ulnar collateral ligament tears 1. This imaging should be obtained promptly (within days) if:

• Instability persists beyond 1 week of immobilization 1
• There is concern for complete ligamentous disruption 1
• Surgical planning is being considered 1

Ultrasound can also identify ligamentous injuries and assess dynamic instability, though MRI provides more comprehensive evaluation for surgical planning 1.

Rehabilitation Protocol

Hand therapy should be initiated regardless of whether surgical or conservative management is pursued 1. The rehabilitation program should include:

• Education on joint protection strategies and use of assistive devices to prevent re-injury 1
• Exercises to improve joint mobility, muscle strength, and thumb base stability once initial healing has occurred (typically after 3-6 weeks of immobilization) 1
• Gradual progression of activities with continued orthosis use during high-risk activities 1

Exercise programs have demonstrated small but beneficial effects on pain, function, joint stiffness, and grip strength, though benefits are not sustained if exercises are discontinued 1.

Critical Pitfalls to Avoid

The most common error is prolonged conservative management of an unstable joint that requires surgical reconstruction. This leads to:

• Recurrent instability requiring delayed revision surgery 2
• Post-traumatic degenerative arthritis (seen in 62% of conservatively managed unstable joints versus minimal changes with early reconstruction) 2
• Decreased functional outcomes including 20% loss of thumb abduction and 19% loss of pinch strength with failed conservative treatment 2

Soft tissue interposition is another critical consideration. Volar subluxations can have entrapped structures (volar plate, extensor tendons, dorsal capsule) that prevent closed reduction and necessitate open surgical reduction 3, 6, 4. If closed reduction is attempted and the joint does not remain stable, do not persist with repeated manipulation attempts - this indicates soft tissue interposition requiring surgical intervention 3, 4.

Recommended Treatment Algorithm

1. Immediate immobilization with custom thumb spica orthosis 1
2. Clinical reassessment at 1 week: If joint remains unstable or subluxation recurs, obtain MRI and refer for surgical evaluation 1, 2
3. If stable at 1 week: Continue immobilization for minimum 3 months with hand therapy 1, 2
4. Follow-up radiographs at 2 weeks to assess for any displacement or early degenerative changes 7
5. If instability persists beyond 2 weeks despite proper immobilization: Proceed with early ligamentous reconstruction rather than prolonged conservative management 2

Given that this patient is already experiencing recurrent spontaneous subluxation at 1.5 weeks post-injury, there should be a very low threshold for proceeding with MRI evaluation and surgical consultation 1, 2. The evidence clearly demonstrates superior outcomes with early reconstruction when instability is present, compared to failed conservative management requiring delayed revision surgery 2.