What Causes Mortons Neuroma

Overview

intermetatarsal neuromaDuring certain activities, particularly weight-bearing activities (e.g. walking or running) a compressive force, is sometimes placed on the interdigital nerves and surrounding soft tissue, between the metatarsal bones (this is often the case with tight fitting shoes or in patients with flat feet). If this force is repetitive enough and beyond what the nerve and soft tissue can withstand, swelling to the nerve and soft tissue may occur. This may result in pain, tenderness, pins and needles or numbness in the forefoot or toes. When this happens, the condition is known as a Morton’s neuroma.

Causes

Experts are not sure what exactly causes Morton’s neuroma. It seems to develop as a result of irritation, pressure or injury to one of the digital nerves that lead to the toes, which triggers a body response, resulting in thickened nerve tissue (neuroma). Feet conditions/situations that can cause the bones to rub against a nerve include high-heeled shoes, especially those over 2 inches (5cm), or a pointed or tight toe box which squash the toes together. This is probably why the condition is much more common in females than in males. High-arched foot, people whose feet have high arches are much more likely to suffer from Morton’s neuroma than others. Flat feet, the arch of the foot collapses. The entire sole of the foot comes into complete or near-complete contact with the ground. A bunion, a localized painful swelling at the base of the big toe, which enlarges the joint. Hammer toe, a deformity of the proximal interphalangeal joint of the second, third, or fourth toe causing it to be permanently bent. Some high-impact sporting activities including running, karate, and court sports. Any sport that places undue pressure on the feet. Injuries, an injury or other type of trauma to the foot may lead to a neuroma.

Symptoms

There may be pain at the end of the push-off phase when walking or running, and this pain is generally worse when the client is wearing shoes as opposed to being barefoot. Clients may also report a relief of symptoms by massaging the foot, which may spread the metatarsal heads and mobilize the entrapped nerve.

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done. Initial diagnosis of Morton’s neuroma is based on your description of the type and location of pain and discomfort in the foot. The diagnosis will be confirmed by a physical exam of the foot, including checking for mechanical abnormalities in the foot, squeezing the side of the foot, which will usually cause pain when Morton’s neuroma is present. Examination of your shoes to check for excess wear in parts of the shoe, check to see whether the shoes are too tight. Imaging tests evaluate the foot and surrounding structures. This may be done with X-ray, MRI scan, Ultrasound. Injections of local anesthetic can also be used for diagnosis.

Non Surgical Treatment

Sclerosing alcohol injections are an increasingly available treatment alternative if the above management approaches fail. Dilute alcohol (4%) is injected directly into the area of the neuroma, causing toxicity to the fibrous nerve tissue. Frequently, treatment must be performed 2-4 times, with 1-3 weeks between interventions. An 60-80% success rate has been achieved in clinical studies, equal to or exceeding the success rate for surgical neurectomy with fewer risks and less significant recovery. If done with more concentrated alcohol under ultrasound guidance, the success rate is considerably higher and fewer repeat procedures are needed. Radio Frequency Ablation is also used in the treatment of Morton’s Neuroma The outcomes appear to be equally or more reliable than alcohol injections especially if the procedure is done under ultrasound guidance.Morton neuroma

Surgical Treatment

If conservative treatment does not relieve your symptoms, your orthopaedic surgeon may discuss surgical treatment options with you. Surgery can resect a small portion of the nerve or release the tissue around the nerve, and generally involves a short recovery period.

Prevention

Women, particularly those who wear tight shoes, are at greatest risk for Morton?s neuroma. The best way to prevent the condition is to wear shoes with wide toe boxes. Tight, pointed shoes squeeze bones, ligaments, muscles and nerves. High heels may worsen the problem by shifting your weight forward. Over time, this combination can cause the nerves to swell and become painful.