Boutonnière Deformity Management
For a boutonnière deformity (PIP flexion with DIP hyperextension), initiate relative motion flexion splinting immediately if presenting within 6 weeks of injury, as this allows full hand use during healing and achieves superior outcomes compared to traditional immobilization. 1
Diagnosis: Distinguishing True from Pseudo-Boutonnière
The key diagnostic distinction is identifying whether this represents a central slip injury (true boutonnière) versus a volar plate hyperextension injury (pseudo-boutonnière), as treatment differs significantly 2. Both present with PIP flexion and DIP hyperextension, but:
- True boutonnière: Results from central slip rupture at the PIP joint
- Pseudo-boutonnière: Results from volar plate injury with PIP flexion contracture
The clinical examination should focus on the mechanism of injury and passive correctability of the deformity to differentiate these entities 2.
Treatment Algorithm Based on Timing and Severity
Acute Injuries (< 6 weeks)
Relative motion flexion splinting is the preferred approach 1:
- Position the injured digit in 15-20° greater MCP flexion than neighboring digits
- Permit full active ROM and functional hand use while maintaining this relative position
- Continue for 6 weeks
- This approach achieves excellent ROM with significantly less morbidity than conventional immobilization
- No additional therapy needed after the 6-week splinting period 1
Critical pitfall: Starting treatment beyond 6 weeks significantly reduces the likelihood of improvement 3. Digits beginning treatment within 6 weeks showed the greatest improvement (p = 0.02) 3.
Chronic/Fixed Deformities (> 6 weeks to years)
For established deformities, a staged non-operative approach should be attempted before considering surgery 1:
- Serial casting to achieve PIP extension to at least -20° (ideally better)
- Once adequate extension obtained, transition to relative motion flexion splinting for 12 weeks
- Maintain full hand use during this period
In a series of chronic cases (averaging 31 weeks post-injury), all patients achieved:
- Maintenance of extension gains
- Full flexion to palm
- "Excellent" outcomes by Steichen-Strickland criteria
- No recurrent deformities or RSD/CRPS 1
When Splinting Fails or Is Not Appropriate
If the deformity remains fixed despite serial casting or if the patient cannot achieve -20° PIP extension, surgical options include 4:
- Flexible deformities: Extensor reconstruction, terminal tenotomy
- Fixed deformities with intact articular surface: Extensor reconstruction with joint mobilization
- Arthritic/destroyed joints: Arthrodesis (preferred for DIP) or arthroplasty (preferred for PIP except index finger) 5, 4
Important Caveats
Surgical caution for boutonnière: Unlike swan neck deformities, boutonnière deformities maintain functional PIP flexion and fist-making ability despite being aesthetically displeasing 6. Surgical attempts to improve PIP extension can paradoxically impede flexion, resulting in worse functional outcomes 6. Therefore, exhaust conservative management before surgery.
Inflammatory arthritis: Deformities secondary to rheumatoid arthritis or other inflammatory conditions respond less favorably to conservative treatment (p = 0.045) 3 and may require earlier consideration of synovectomy, injections, or reconstructive procedures 4.
Expected outcomes with conservative treatment: Even with dedicated management, 44% of digits showed no improvement in ROM grade, while 50% improved by one or two grades 3. This underscores the importance of early intervention and realistic patient counseling.