Second Proximal Phalanx: Causes and Treatment
Primary Causes
Fractures are the most common pathology affecting the second proximal phalanx, typically resulting from direct trauma, crush injuries, or sports-related impacts. 1, 2
Fracture Patterns
- Transverse fractures are most common, followed by oblique and comminuted patterns 2
- Base fractures occur frequently and have specific treatment considerations 3
- Proximal third location represents 51% of all proximal phalanx fractures 2
- Post-traumatic malunion can develop with volar angulation causing pseudoclaw deformity 4
Other Pathologies
- Osteoid osteoma presents as a rare benign bone-forming lesion causing persistent pain relieved by NSAIDs, with recurrence risk after excision 5
- Avulsion fractures at the volar aspect of the proximal interphalangeal joint involve volar plate injury 6
Treatment Algorithm
Initial Assessment
Obtain posteroanterior, lateral, and oblique radiographs as the first-line imaging for any suspected proximal phalanx injury. 6
- Consider CT if radiographs are equivocal but clinical suspicion remains high 6
- Use MRI to evaluate associated soft tissue injuries, including volar plate and collateral ligament integrity 6
Fracture Treatment Strategy
Stable Fractures
Treat stable, non-displaced fractures with splinting and immediate mobilization using buddy taping to the adjacent finger. 1, 3
- Splints provide sufficient treatment for stable patterns 1
- Buddy taping to the third digit with immediate mobilization yields high patient satisfaction and full flexion recovery in most cases 3
- This approach avoids the mobility limitations associated with rigid immobilization 2
Unstable Fractures
Perform open reduction with percutaneous 1.0 mm intramedullary Kirschner wire fixation for unstable fractures. 1
- This technique achieves excellent long-term results with TAM scores ≥220° in the majority of cases 1
- Non-union rates are minimal (occurring in <5% of cases) 1
- Grip strength returns to baseline compared with uninjured fingers 1
Dynamic Functional Treatment Protocol
For appropriate candidates, use dynamic functional treatment with a dorsopalmar plaster splint maintaining the wrist in 30° dorsiflexion and metacarpophalangeal joints in 70-90° flexion (intrinsic plus position). 2
- This position creates taut extensor aponeurosis covering two-thirds of the proximal phalanx, providing fracture stability 2
- Allow active exercises in proximal and distal interphalangeal joints immediately to prevent stiffness 2
- Achieves 86% full range of motion at follow-up with 100% union rates 2
- Extension deficits, when present, are typically ≤20° 2
Management of Complications
Post-Traumatic Malunion
Perform corrective "in situ" osteotomy at the malunion site with miniplate/screw fixation when malunion causes functional impairment or pseudoclaw deformity. 4
- Corrective osteoclasia is preferred when addressing malalignment within 6 weeks of injury 4
- Expect approximately 30% improvement in range of motion of metacarpophalangeal and proximal interphalangeal joints 4
- Pseudoclaw deformity from volar angulation resolves in all cases 4
- Mean DASH scores of 5 points indicate excellent functional outcomes 4
Unstable Fracture-Dislocations
Consider surgical intervention when joint instability, significant displacement, or failed conservative treatment compromises pain relief and functional recovery. 6
Special Considerations
Osteoid Osteoma
For recurrent osteoid osteoma after initial excision, use modified open thermoablation through a CT-guided Kirschner wire to deliver heat directly to the lesion. 5
- Initial treatment involves excision with bone grafting 5
- NSAIDs provide temporary pain relief but do not address the underlying pathology 5
- Modified open thermoablation achieves complete resolution without recurrence at 1-year follow-up 5
Common Pitfalls
- Avoid static plaster immobilization for extended periods, as this leads to interphalangeal joint stiffness requiring subsequent mobilization efforts 2
- Do not pursue aggressive anatomic reduction in fifth digit base fractures when functional treatment with buddy taping yields satisfactory outcomes 3
- Recognize that internal fixation, while achieving exact reduction, often results in decreased finger mobility 3
- Monitor for malrotation during conservative treatment, though surgical correction is rarely needed (occurring in <6% of cases) 3