Diagnosing Malrotation in Fifth Proximal Phalanx Metaphysis Fractures
The most reliable method to diagnose malrotation in a fifth proximal phalanx metaphysis fracture is clinical examination of finger alignment during flexion, complemented by standard radiographic views (PA, lateral, and oblique), with particular attention to an internally rotated oblique projection which increases diagnostic yield for phalangeal fractures. 1, 2
Clinical Examination for Malrotation
Flexion test: Have the patient flex all fingers toward the palm
- In normal alignment: All fingertips should point toward the scaphoid tubercle
- With malrotation: The affected finger will deviate from this pattern, pointing toward or away from adjacent fingers
- Look for "scissoring" where the affected finger crosses over adjacent fingers during flexion 3
Nail plate alignment: Compare the orientation of the nail plate with unaffected fingers
- Malrotation causes the nail plate to face in an abnormal direction compared to adjacent fingers
Finger overlap: When the patient makes a fist, check for abnormal overlap of fingers
- Malrotation often causes the affected finger to overlap adjacent fingers abnormally
Radiographic Evaluation
Standard three-view radiographic examination is essential 2:
- Posteroanterior (PA) view
- Lateral view
- Oblique view (particularly an internally rotated oblique projection)
Key radiographic findings suggesting malrotation:
- Asymmetric cortical thickness on PA view (compared to contralateral hand)
- Abnormal appearance of the condyles on PA view
- Visible cortical step-off at the fracture site
- Asymmetric width of the phalanx on lateral view compared to adjacent phalanges
Additional Diagnostic Considerations
CT scanning may be helpful in complex cases where standard radiographs are inconclusive, though this is rarely necessary for isolated fifth proximal phalanx fractures 1
Rotational deformity assessment:
- Compare with contralateral uninjured hand
- Even minor degrees of malrotation (5-10°) can cause functional impairment
- Rotational malalignment rate is approximately 0.93% in properly managed fractures 3
Clinical Significance and Management
Malrotation >10° typically requires reduction or surgical intervention 2, 4
Untreated malrotation leads to:
- Finger overlap during grip
- Decreased grip strength
- Cosmetic deformity
- Functional impairment
For displaced or malrotated fractures, closed reduction should be performed with post-reduction radiographs to confirm adequate alignment 2
If closed reduction fails to correct malrotation, surgical intervention with K-wire fixation or intramedullary fixation may be necessary 2, 5
Remember that early detection of malrotation is critical, as established malrotation becomes increasingly difficult to correct over time and may ultimately require surgical intervention to prevent permanent functional impairment.