What is a Neuroma? A Look at a Common Condition Among Runners
Foot and ankle pain are a common complaint among runners. After all, the feet are supporting the entire body’s weight while constantly pounding against the ground. Conditions in the foot and ankle that are experienced by runners include plantar fasciitis, stress fractures, tendinitis, and the common diagnosis of Morton’s neuroma. Most literature will state this condition is a pinching of a nerve in between the bones of the foot. The exact process of the development of this neuroma is more detailed than simply a pinched nerve.
What Exactly is a Neuroma?
A neuroma in the body is actually a tumor, most commonly benign. Morton’s neuroma is not a true neuroma, as it is more of an enlargement of the nerve in the web space of the toes, rather than a tumor. It most commonly occurs between the 3rd and 4th metatarsal bones of the toes, but may also be present within the 2nd and 3rd toes in a smaller population of those affected. The 3rd metatarsal bone is a relatively stable and fixed joint, while the 4th metatarsal is a very mobile bone. When the foot is in motion and weight bearing, especially in tight shoes, the 4th metatarsal bone can constantly compress the web space and possibly impinge on other structures.
The cause of impingement on the nerve that lies in the web space is usually inflammation of the nerve. This inflammation is mostly caused by irritation, which is the reason why this condition is common in runners. Constantly pounding with every step of running, creating this shear force of the metatarsal bone onto the nerve will eventually create inflammation. As the nerve continues to be compressed, it will turn into a chronic issue. The nerve may then develop fibrous tissue in the surrounding areas, which will lead to requiring surgical removal and repair.
There are several factors that may predispose individuals to developing Morton’s neuroma, besides being a runner. For unknown reasons, the condition is most common in women aged in the 40s and 50s, although the incidence in men increases in the running population. Women who wear tight, high-heeled shoes are more prone to developing this condition, as the web spaces between all metatarsal bones is compressed.
Anatomical and biomechanical factors in the foot and ankle joint have been shown to predispose individuals to Morton’s neuroma as well. Metatarsal bones that are abnormally too close together will increase the risk of developing a neuroma in the web spaces, and this is mostly seen in cases with higher degrees of pronation and prolonged tight-fitting footwear. Minimal fat padding underneath the bones of the foot may also lead to nerve compression. In many cases this loss of padding is due to long-term use of steroid injections. A common foot type seen in cases with Morton’s neuroma is when the 1st digit, the big toe, is shorter than the others, which causes more pressure upon the 2nd, 3rd, and 4th bones during activity. Other cases may simply have a thicker nerve in general, which will tend to be impinged even without inflammation.
Research has also found that having decreased dorsiflexion range of motion is common in athletes with Morton’s neuroma. Dorsiflexion is the movement of the forefoot up and back towards the lower leg. When there is not sufficient dorsiflexion, more of the pressure during the stance and push-off phases of running falls on the forefoot. The lack of dorsiflexion can be an anatomical issue, where the actual joint mobility is stiff, or due to muscle tightness in the calves and Achilles tendon.
Diagnosing Morton’s neuroma involves different testing procedures that must carefully rule out other conditions that present with similar symptoms. The most common symptom is pain in the affected web space and balls of the feet. Since the condition is nerve compression, this pain may radiate to the toes and up to the lower leg. Usually the pain will be intense in nature for 15 to 20 minutes of the activity, such as running, and then remain as an ache for several hours. Walking barefoot and massage is shown to alleviate the pain. Many cases will also feel as if though there is a pebble in the balls of the feet.
There are several testing maneuvers clinicians use to aide in the diagnosis of Morton’s neuroma, but the most accurate is an MRI. This condition can mimic signs of other common disorders in the forefoot with the same causes such as stress fractures of the metatarsal bones and bursitis, which is also inflammation in a similar area. Calluses in the balls of the feet are also common in runners and can have a similar pattern of pain as a neuroma.
The goal of treatment and prevention of Morton’s neuroma is to decrease any factors that are leading or may lead to pressure in the forefoot, particularly the web spaces between the toes. Initially, easy fixes such as limiting time in high-heeled or tight shoes and wearing orthotics in the cases of limited fat padding at the balls of the feet are the best forms of treatment and prevention. Once the issue becomes chronic where the inflammation and irritation is constant, more advanced treatments are required.
Taking time off of running and incorporating icing and massage are the first forms of treatment until the inflammation subsides. Once the symptoms are controlled, the contributing factors causing the inflammation must be addressed. As mentioned above the use of orthotics to provide cushion to the affected areas and choosing a shoe type with a wider toe box are simple approaches to relieve the pressure. If lack of sufficient dorsiflexion is the cause, improving joint mobility with Physical Therapy manual techniques and stretching may be prescribed. Tightness in the Achilles and calf muscles is addressed with massage and stretching.
If you are experiencing any pain in the forefoot that intensifies with running and radiates above or below the forefoot, you may be dealing with Morton’s neuroma. It is best to always monitor the pattern of pain and take time off of the aggravating activity to limit the chances of developing a chronic issue, as any nerve-related injury or disorder takes time to heal. As with many cases of injuries, wearing the proper shoe for your foot type is important, as is gradually increasing mileage and incorporating rest time. Seek advice from a medical professional if symptoms persist.
- Interventions for the Treatment of Morton's Neuroma, Online Publication, Oct 23, 2018 ,
- Morton's Metatarsalgia: Pathogenesis, Aetiology and Current Management, Online Publication, Dec 01, 2005 ,
- Equinus Deformity as a Factor in Forefoot Nerve Entrapment, Online Publication, Sep 01, 2005 ,
- The Diagnosis and Management of Morton's Neuroma: A Literature Review, Online Publication, Aug 01, 2013 ,