Morton's neuroma is an entrapment neuropathy of an interdigital nerve resulting in the formation of a fusiform swelling called a neuroma between contiguous distal metatarsals. The most common area affected is between the 3rd and 4th toe, followed by the 2nd and 3rd. Middle-aged women are more affected than men.
Causes
The exact causes is still a point of contention. However current theories postulate that Morton's neuroma is a consequence of the combination of repetitive mechanical and ischemic trauma, entrapment and tethering caused by:
1) pressure against the deep trasverse metatarsal ligament by:
- Tight toe box (ex. rock climber)
- Hyperextension of the toes (ex. high heels)
2) hard surfaces or high-impact activities (ex. dancers, runners).
3) metatarsal mobility (ex.4th relatively mobile, 3rd relatively immobile, 2nd least mobile).
4) high arches or flatfeet (ex. lax trasverse metatarsal ligaments allow spreading of the toes which further pulls the ligament down causing compression of the nerve.
Diagnosis
Forefoot pain is the most common complain, patients may also complains of a burning, sharp pain or paresthesia, llocated in between the 3rd and 4th toe. The pain is exacerbated with wearing tight or constricted shoes, toe extension or walking on the toes and relieved with non-weight bearing postures or walking barefoot.
No history of trauma should be reported by the patient (otherwise stress fracture may also be considered in the differential diagnosis), sensation of a stone or pebble under the toe or forefoot when walking can also be mentioned by the patient.
Useful test for Morton's neuroma is the squeeze test or the digital nerve stretch test.
Imaging may be necessary to rule out serious condition (infection, tumors) or less serious (stress fracture, metatarsalgia, peripheral neuropathy, tarsal tunnel sydrome, etc.).
MRI and ultrasonography are helpful to confirm the diagnosis, inflammation will be shown in the former and non compressible hypoechoic interdigital mass in the latter.
Treatment
Researches suggested that conservative treatment should be tried from 3 months to 1 year (1-2).
Conservative treatment
Patient should avoid wearing high heel shoes or with a narrow toe box, instead should wear wide, low-heeled and confortable shoes with a large toes box. Pad under the metatarsal should be used to cushion (do not position pad to increase pressure on neuroma).
Manipulation of the ankle, back, knee,foot may be performed by an osteopath, chiropractor or physiotherapist. Ultrasound and electrical stimulation may help.
GP may prescribe anti-inflammatory medications
Operative treatment
Many surgical methods have been used:
- Interdigital nerve excision with intermetatarsal ligament division, with or without submuscular transposition.
- Isolated intermetatarsal ligament division.
- Isolated interdigital nerve excision.
References.
1. Singh A IJ, Chiodo C. The surgical treatment of Morton's neuroma. Current Orthopaedics 2005;19:379-84.
2. Wu KK. Morton's interdigital neuroma: a clinical review of its etiology, treatment, and results. The Journal of foot and ankle surgery : official publication of the American College of Foot and Ankle Surgeons 1996;35:112-9; discussion 87-8.
Dott. Emanuele Luciani
Osteopath, physiotherapist, hatha yoga teacher
Osteopath registered with the General Osteopathic Council (GOsC)
(number 8232http://www.osteopathy.org.uk/home/)
"Centro Studi Tre Fontane"
Via Luigi Perna 51, Rome