Morton’s Neuroma or Intermetatarsal Bursitis—A Prospective Diagnostic Study of Intermetatarsal Pain

TL;DR

This study finds that intermetatarsal bursitis is more common than Morton’s neuroma in patients with forefoot pain, and ultrasound can be misleading in diagnosis.

Contribution

The study provides new insights into the diagnostic accuracy of MRI versus ultrasound for differentiating intermetatarsal bursitis and Morton’s neuroma.

Findings

MRI identified 53.8% of patients with intermetatarsal bursitis and 19.2% with Morton’s neuroma.

Ultrasound detected 96.2% of intermetatarsal bursitis cases but none with Morton’s neuroma.

Morton’s neuroma patients reported more severe and longer-lasting pain than those with intermetatarsal bursitis.

Abstract

Background: Intermetatarsal bursitis (IMB) is emerging as a diagnostic consideration for patients with forefoot pain. However, few investigations have been conducted into the incidence of IMB among patients with forefoot pain. The symptoms of IMB are described as mimicking those of Morton’s neuroma (MN). Currently, the best method to differentiate between MN and IMB is radiological evaluation. Based on this, the aim of this study was to investigate the incidence of IMB and MN in a prospective cohort of patients with intermetatarsal pain diagnosed with radiological evaluation and compared to a control group. Methods: This study included 26 patients and 13 controls. All participants underwent magnetic resonance imaging (MRI) and ultrasound (US) of one forefoot. Results: Among the 26 patients, 5 (19.2%) had MN and 14 (53.8%) had IMB on MRI compared to US, with which 25 (96.2%) cases of IMB and 0 with MN were identified. In the control group, both modalities found asymptomatic web space pathology in four cases (30.8%), and US identified normal intermetatarsal bursas in five cases. Additionally, our results indicate that MN patients have more severe pain and a longer history of pain compared to IMB patients. Conclusions: Based on our MRI results, we conclude that IMB is frequent in patients with intermetatarsal pain. Differentiation between MN and IMB with US is complex and should be performed with caution and an understanding of both conditions. Normal intermetatarsal bursas are also visible on US as hypoechoic but non-expansive masses.

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