Recommended Imaging for Morton's Neuroma
Ultrasound and MRI are the preferred imaging modalities for diagnosing Morton's neuroma, with ultrasound offering the advantages of dynamic examination and direct clinical correlation while maintaining high sensitivity (90%). 1, 2, 3
Initial Imaging Approach
- Radiographs are insensitive for diagnosing Morton's neuroma but should be performed first to exclude other causes of webspace pain such as osteoarthritis, Freiberg's infraction, and stress fractures 4, 2
- After negative or equivocal radiographs, proceed to advanced imaging 4
Advanced Imaging Options
Ultrasound
- Sensitivity of 90% for detecting Morton's neuroma 3
- Advantages:
MRI
Comparative Effectiveness
- Meta-analysis shows no significant difference between ultrasound and MRI in sensitivity for Morton's neuroma diagnosis (p = 0.88) 5
- Both modalities have high sensitivity (US: 91%, MRI: 90%) 5
- Agreement between the two techniques can be poor (kappa statistic 0.31), suggesting they may detect different aspects of the condition 8
Clinical Considerations
- False negatives can occur with both imaging modalities 8, 9
- Ultrasound results are operator-dependent and subject to variability based on technique and experience 7
- MRI is recommended when differential diagnosis is complex or when ultrasound results are equivocal 1, 2
Common Pitfalls
- Relying solely on imaging for diagnosis without clinical correlation may lead to misdiagnosis 8
- Negative imaging does not exclude the diagnosis of Morton's neuroma (false negative rate for MRI: 17%) 8
- Small neuromas (<5mm) may be missed on both ultrasound and MRI 7
- Multiple neuromas can coexist, particularly in the second and third intermetatarsal spaces 7, 8