Morton's Neuroma
A perineural fibrosis of a common plantar digital nerve, most often in the third intermetatarsal space, producing forefoot pain and paraesthesia.
Overview
Morton's neuroma is not a true neoplasm but a perineural fibrosis with nerve degeneration, most commonly involving the third common plantar digital nerve where medial and lateral plantar contributions converge. Mechanical compression against the deep transverse intermetatarsal ligament and footwear-related forefoot loading are key contributors.
Epidemiology
Morton's neuroma is much more common in women, with a peak between 40 and 60 years. Narrow or high-heeled footwear is strongly associated. The third web space accounts for 70 to 80 percent of cases; the second web space is less commonly affected.
Symptoms
Burning plantar forefoot pain radiating into the affected toes, relieved by removing the shoe and rubbing the foot. A positive Mulder click and focal web-space tenderness are characteristic. Sensory symptoms may involve the adjacent toes in the affected web space.
Imaging
Ultrasound is the imaging modality of choice, sensitive and specific for hypoechoic masses greater than 5 mm. MRI is useful when diagnosis is uncertain or alternative pathology is suspected. Imaging is also useful for guided injection.