How to diagnose a fracture of the middle phalanx?

Assessment of Middle Phalanx Fractures

Standard radiographic evaluation with three views (PA, lateral, and oblique) is the essential first-line diagnostic approach for assessing middle phalanx fractures. 1, 2

Initial Clinical Assessment

• Evaluate for:
  • Point tenderness over the middle phalanx
  • Visible deformity or angulation
  • Rotational malalignment (check by having patient flex fingers - they should point toward the scaphoid)
  • Swelling and ecchymosis
  • Inability to actively flex or extend the finger
  • Neurovascular status (capillary refill, sensation)

Diagnostic Imaging Protocol

Primary Imaging

• Three-view radiographic examination is the mainstay of diagnosis 1, 2:
  • Posteroanterior (PA) view
  • Lateral view
  • Oblique view

Key Radiographic Findings to Assess

• Fracture location (particularly base of middle phalanx)
• Articular involvement
• Presence of step-off or gap (>2mm is significant) 3
• Subluxation or dislocation of proximal interphalangeal (PIP) joint
• Percentage of articular surface involved
• Comminution
• Fracture stability
• Number of fragments

Classification of Middle Phalanx Base Fractures

Middle phalanx base fractures can be classified into five types 4:

1. Single palmar fragment
2. Single dorsal fragment
3. Two main fragments
4. Non-articular fractures (including epiphyseal separation in children)
5. Complex/other fractures

Types 1 and 2 are further subclassified as avulsion, split, or split-depression fractures.

Special Considerations

• When Ottawa Rules Don't Apply: The Ottawa rules primarily address midfoot injuries and do not directly apply to finger fractures. For suspected phalanx fractures, radiographs should be obtained 1

• Pediatric Considerations: In children, be vigilant for Salter-Harris fractures, which require specific management approaches 2

• Unstable Fractures: Assess for signs of instability which may require surgical intervention:

  • Angulation >10° typically requires reduction 2
  • Articular step-off or gap >2mm 3
  • Subluxation or dislocation of the PIP joint 3

Pitfalls to Avoid

1. Missing Rotational Deformities: These can be subtle on standard radiographs. Key radiographic findings suggesting malrotation include asymmetric cortical thickness, abnormal appearance of the condyles, visible cortical step-off, and asymmetric width of the phalanx 2

2. Underestimating Stability: Fractures that appear stable on initial radiographs may be dynamically unstable during motion 3

3. Delayed Treatment: Treatment delayed beyond 24 hours may lead to increased swelling, making reduction more difficult 2

4. Inadequate Views: Failure to obtain all three standard views may result in missed fractures or underestimation of displacement

5. Overlooking Articular Involvement: Articular involvement significantly impacts treatment decisions and outcomes 4, 3

By following this systematic approach to assessment, clinicians can accurately diagnose middle phalanx fractures and determine appropriate management strategies to optimize functional outcomes and prevent long-term complications.