Morton’s Neuroma / Intermetatarsal Bursitis

The most common symptom is pain, typically in the plantar aspect of the forefoot within the 3rd or 2nd webspace. Symptoms are aggravated by periods of ambulation and tight-fitting shoes. There may be associated paraesthesia/anaesthesia symptoms between the affected toes, and patients describe the sensation as walking on a stone or pebble.Source: Morton’s interdigital neuroma: instructional review – PMC (opens in a new tab)

Clinically there may be localised pain in the webspace with palpation; squeezing the metatarsal heads together may result in a Mulder’s sign, which is a painful, palpable click as the neuroma is displaced ventrally.

The diagnosis will be made from a combination of your clinical history, examination findings and, commonly, an ultrasound scan. The patients will have the signs and symptoms as discussed previously.

Ultrasound imaging is usually the first-line imaging modality to confirm the presence of a neuroma +/- intermetatarsal bursitis. It has been shown to have a strong sensitivity and specificity, with evidence supporting its superiority over MRI given its superior spatial resolution. MRI does remain useful, especially when patients have atypical features and to exclude different/concurrent pathology of the forefoot, such as bone stress injuries or, rarely, alternative space-occupying lesions.Source: The accuracy of ultrasonography and magnetic resonance imaging for the diagnosis of Morton’s neuroma: a systematic review – PubMed (opens in a new tab)

The presence of a neuroma on imaging does not necessarily indicate cause. It is common for asymptomatic patients to have neuromas that cause no symptoms. Furthermore, there is no clear correlation between the size of the neuroma and the severity of symptoms. Diagnosis, as always in musculoskeletal medicine, is made through imaging findings and clinical symptoms to help dictate appropriate treatment.Sources: Morton’s neuroma – Current concepts review – PMC (opens in a new tab); The role of MRI and ultrasound imaging in Morton’s neuroma and the effect of size of lesion on symptoms – PubMed (opens in a new tab)

Treatment options are divided into conservative and surgical.

Conservative options

• Activity modification/change in footwear: sometimes these simple measures will allow things to settle. Wide-fitting shoes and avoiding high heels can reduce forefoot pressure.
• Orthotics/Metatarsal pads. When placed just proximal to the metatarsal heads, they can be helpful at reducing pressure through the forefoot, displacing pressure sites and making more room for the interdigital nerves. While a common and safe treatment option, there are no convincing results in large patient cohorts.Source: The effectiveness of shoe modifications and orthotics in the conservative treatment of Civinini-Morton syndrome: state of art – PMC (opens in a new tab)
• An ultrasound-guided steroid and local anaesthetic injection into the intermetatarsal bursa or around the entrapment site can provide short-term or medium-term relief or, in certain patients, be curative. There is still debate about which cohort of patients will respond more favourably to a steroid injection, but unsurprisingly, small Morton neuromas tend to have a better, longer-term outcome than larger ones.Sources: Efficacy of Ultrasound-Guided Steroid Injections in the Management of Morton’s Neuroma: A Retrospective Cohort Study – PubMed (opens in a new tab); Morton’s neuroma – Current concepts review – PMC (opens in a new tab)

Surgical intervention

For patients with refractory/recurring symptoms that have not responded to conservative options, surgical excision is usually definitive. There are both dorsal and plantar approaches possible; surgical options include neurectomy (nerve excision), which will leave a permanent numbness in the webspace, or decompression to relieve pressure on the nerve. The risk of decompression can include the recurrence of symptoms as tissues heal.Source: Morton’s interdigital neuroma: a comprehensive treatment protocol – PubMed (opens in a new tab)