What is the difference between malrotation and angulation in finger fractures?

Differences Between Malrotation and Angulation in Finger Fractures

Malrotation refers to the twisting of the finger bone along its longitudinal axis, while angulation refers to the bending of the bone at the fracture site creating a non-linear alignment. 1

Key Differences

Malrotation

• Definition: Rotational deformity where the finger bone twists around its long axis
• Clinical Presentation:
  • Fingers overlap or scissor when flexed toward the palm
  • Fingernail plane not parallel to adjacent fingers
  • Abnormal finger alignment during grip
• Measurement:
  • Assessed by CT imaging comparing torsion angles between articular surfaces
  • Side differences exceeding 3 degrees strongly suggest malrotation 2
• Clinical Significance:
  • Even small degrees of malrotation (>5°) can cause significant functional impairment
  • Results in finger overlap during grip, affecting hand function
  • Often requires surgical correction if significant

Angulation

• Definition: Bending of the bone at the fracture site creating a non-linear alignment
• Clinical Presentation:
  • Visible deformity of the finger
  • Apex of deformity typically dorsal (pointing toward the back of the hand)
• Measurement:
  • Measured in degrees on lateral radiographs
  • Acceptable angulation varies by location:
    • Middle/proximal phalanx: <10 degrees acceptable for conservative treatment
    • Metacarpal: Up to 30-40 degrees may be acceptable in ring/small fingers 1
• Clinical Significance:
  • Primarily affects cosmetic appearance at lower angles
  • Functional impairment occurs with severe angulation
  • More tolerance for angulation than for malrotation

Clinical Implications

Assessment

• Malrotation assessment:
  • Have patient make a fist - all fingertips should point toward the scaphoid
  • Compare nail plate alignment with adjacent fingers
  • CT imaging may be needed for precise measurement 2
• Angulation assessment:
  • Lateral radiographs to measure the degree of angulation
  • Note that radiographic assessment has significant inter- and intra-observer variability 3

Treatment Considerations

• Malrotation:
  • Even minor malrotation (>5°) typically requires correction
  • Often needs surgical intervention for proper alignment
  • Minimally invasive corrective osteotomy techniques are available 4
• Angulation:
  • Conservative management with buddy splinting if minimal angulation (<10 degrees)
  • Reduction or surgery for larger angulations, displacement, or malrotation 1

Common Pitfalls

1. Overlooking malrotation: Malrotation is often missed during initial assessment but causes significant functional impairment. Always check for rotational alignment by having the patient make a fist.

2. Overreliance on static radiographs: Standard radiographs may not adequately demonstrate malrotation; clinical examination is crucial.

3. Inconsistent measurement: There is significant variability in measuring fracture angulation on radiographs, which can affect treatment decisions 3.

4. Delayed recognition: Malrotation identified late may require more complex corrective osteotomy procedures 5.

5. Focusing only on angulation: Treating angulation while missing malrotation will lead to poor functional outcomes despite radiographic "healing."

Remember that malrotation is generally less tolerable than angulation from a functional perspective, and even small degrees of malrotation can significantly impact hand function, while moderate angulation may be well-tolerated, especially in certain fingers.