Definition
· Compression of interdigital nerve against the distal end of the transvers metatarsal ligament during dorsiflexion of the toes.
· Generally seen between 3rd and 4th metatarsals
· Histological examination:
o perineural fibrosis, degeneration of nerve fibers, endoneural thickening
· A true neuroma is not present
· Females are affected more common than males
o most likely from wearing high heels
· Deviation of the toe, inflammation of the intermetatarsal bursa, thickening of the transvers metatarsal ligament and forefoot trauma are other precipitating factors.
Evaluation
· Diagnosis is made by history and physical examination
· A burning pain just distal to and between metatarsal heads is characteristic
· Symptoms are aggrevated by activity or by wearing high heel shoes, and relieves immediately after removing the shoes
· The Mulder sign is elicited by squeezing the foot while palpating the web space.
A painful click is diagnostic of Morton’s Neuroma
· Neuromas are rare in 1st and 4th web spaces
o so if there is pain MTP joint instability?
Imaging
· X-Rays are useful for excluding a stress fracture of the metatarsal neck
· MRI may be useful, and iv contrast administration increases its accuracy
· Local anesthetic injection of the involved web space that results in relief is diagnostic
Treatment
· Non-Surgical
o Shoe modification : lower heel, wider toe box, metatarsal pad
o Corticosteroid injections provide temporary relief
o In 60% of patients, they result in permanent relief
o Repeated injections may cause MTP joint instability
o A randomized prospective study showed local anesthetic alone provided equivalent symptom relief compared to combination of local anesthetic and corticosteroid at 3- and 6- months follow ups
· Surgical
o Indicated for patients who did not respond to conservative options
o Dorsal incision are used for primary cases
§ Transverse metatarsal ligament is cut
§ Digital nerve is disected 2-3 cm from intermetatarsal ligament
§ Success rate: 80% / Main complication: incomplete resection
o Plantar incision are used for recurrent Morton’s Neuromas
§ Transvers metatarsal ligament is preserved
§ Main complication: painful, hypertrophic scars
o Decompression of interdigital nerve without neuroma resection has been used