Interdigital neuroma (Morton’s Neuroma) affects the web spaces of the toes and is common forefoot condition that is seen in Podiatry practice. It involves entrapment neuropathy (nerve compression) of the common digital nerve below and between the metatarsal heads, typically between the 3rd and 4th metatarsal heads however is less commonly seen between the 2nd and 3rd. The predominate bifurcation point of the nerve is between the 3rd /4th and this is the reason as to why it is more common to see it here.
Symptoms of interdigital neuroma typically manifest as a sharp, burning or tingling sensation in the forefoot. The pain radiates toward the lesser toes and is definitely aggravated by poor footwear subsequently making it more common in females. The pain is relieved when the shoe is removed. Sometimes the symptoms involve specific toes. The cause of this problem is often due to impingement of the plantar nerve fibres between the metatarsal heads and the intermetatarsal ligament. It is essentially a biomechanical concern that commonly requires the attention of PODIATRIST.
Differential diagnoses include stress fracture, capsulitis, bursitis or ligament injury at the metatarsal-phalangeal joint, a tendon sheath ganglion, metatarsalgia, foreign-body reaction and plantar plate tears.
The diagnosis of interdigital neuroma is usually made by physical examination and review of the patient’s medical history. MRI and Ultrasound examination may be useful to confirm the diagnoses however is more critical in determining the severity of the problem and whether more invasive treatment is necessary such as surgery.
Poor biomechanics play a huge role in contributing to the problem. Inadequate footwear and overpronation play a role in causing the impingement.
Conservative treatment involves a reduction in the inflammation and removing the impingement factor. Reduction in inflammation is achieved via rest, elevation, ice, and massage with anti-inflammatory gels. Removing footwear and and/or wearing wider footwear may also help.
The first pit stop however is attending to poor mechanics that the patient may display and coupled with footwear advice and education can help relieve the symptoms.
Injection therapy is useful in reducing symptoms but not very successful in providing long term relief. The only time when it is most appropriate is when the cause of the concern is not a neuroma but an inflamed bursa ( Bursitis). Injection would help to relieve symptoms. There are different type injection therapies that include corticosteroid, ethanol and recently cryotherapy has shown some success. However further research is needed for more information on efficacy and success rates.
For true neuromas surgery is a very effective method of treatment if all conservative measure fail. It is relatively successful and post operative recovery is relatively short. For most cases a Neurectomy is performed whereby part of the nerve is removed due to it fibrotic thickening.