Lateral radiograph of a 56 year-old woman with a several-month history of left forefoot pain.
Anteroposterior radiograph of the patient’s foot.
A 56-year-old woman presents with a several-month history of left forefoot pain. She denies prior injury or known precipitating event. The pain seems to be located between the second and third toes and is made worse with tight shoes. It is worst when she wears high heels or works out at the gym. On examination, increased pain is noted when squeezing the metatarsal heads together. Anteroposterior and lateral radiographs of the left foot are taken.
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Interdigital neuritis, often referred to as Morton neuroma, is a compressive neuropathy that most commonly involves the third interdigital nerve between the third and fourth metatarsal heads. The condition is most prevalent in middle-aged women.
The pathophysiology of the condition is poorly understood but many believe it is the result of mechanical trauma, entrapment, and/or tethering of the nerve. Symptoms include burning and paresthesia in the involved toes that is made worse with narrow toe shoes or high heels. Patients may feel like they are walking on a small pebble in their shoe. The pain is often relieved by removing the shoe and taking a rest from walking.
Examination generally reveals no obvious deformity of the foot, but pain can be palpated at the involved interspace between the metatarsal heads. Pain may be made worse by compressing the metatarsal heads together.1,2
The diagnosis of Morton neuroma is often made after documenting medical history and performing physical examination alone. If there is any doubt about the diagnosis, 1 mL of lidocaine can be injected into the dorsal intermetatarsal ligament between the metatarsal heads. Temporary relief of pain after the injection confirms the diagnosis. Magnetic resonance imaging and ultrasound can identify interdigital neuroma but are rarely used because of the diagnostic accuracy of medical history and physical examination alone.
Conservative treatment includes nonsteroidal anti-inflammatory drugs, shoes with wide toe boxes, and metatarsal pads to push the metatarsal heads away from each other. Steroid injections may also provide short-term relief from pain. Morton neuroma is generally treated surgically because only 20% of patients get better with conservative treatment. Standard surgical treatment involves resection of the interdigital nerve (neurectomy).1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Hidalgo-Ovejero AM, Martinez-Grande M, Sanchez-Villares JJ, Garcia-Mata S, Lasanta P. Clinical examination and imaging studies in the diagnosis of interdigital neuroma. J Bone Joint Surg Am. 2002;84-A:1276-1277.
- Watts E. Interdigital (Morton’s) neuroma. http://www.orthobullets.com/foot-and-ankle/7041/interdigital-mortons-neuroma. 2017. Accessed May 26, 2017.