Role of MRI in detection of Morton's neuroma

Background: Distinguishing between patients with a true Morton's neuroma and other forefoot pathology can be difficult. The aim of this study was to evaluate the diagnostic accuracy of routine magnetic resonance imaging (MRI) when compared to clinical examination for Morton's neuroma.

Methods: We retrospectively identified 71 patients who underwent operative treatment due to the diagnosis of Morton's neuroma between 2007 and 2013. All patients had a MRI preoperative. Our study group comprised 58 female and 13 male patients with a mean age of 57 (range, 38-92) years. We compared the results of preoperative MRI and the patient's clinical assessment with postoperative histopathological results.

Results: Typical clinical signs were found in 65 cases. Most common symptoms were plantar pain (92%) and increased pain on walking (89%). A Morton's neuroma was detected on MRI in 59 of 71 cases. Its sensitivity was 0.84 and its specificity was 0.33. The positive and negative predictive values were 0.97 and 0.08, respectively. For the presence of main clinical symptoms we found a sensitivity of 0.94 and a specificity of 0.33. The positive predictive value was 0.97 and the negative predictive value was 0.20.

Conclusion: MRI under routine conditions had a good detection rate for the evaluation of Morton's neuroma. However, its accuracy was not as high as the accuracy of clinical assessment.

Level of evidence: Level IV, retrospective series.