Morton’s disease

Morton’s disease (other names are: Morton’s neuroma, Mortona neuralgia, interphalangeal neuroma) – is a condition characterised by the pain in the common digital plantar nerve.

The name „neuroma” is misleading, as it refers to a benign peripheral nerve tumour in a form of a small red-brunescent nodule. In Morton’s disease, however, the real common digital plantar neuroma occurs very rarely. In most cases it is just the nerve irritation. As a result of this irritation, inflammatory or degenerative lesions may develop within the nerve. That is why the name “neuroma” is not appropriate. However, it is deeply rooted in the minds of both the patients and the orthopaedists.

Common digital plantar nerve

What is the common digital plantar nerve? Tibial nerve is one of the three main nerve roots within the crus. Below the ankle, the nerve divides into medial and lateral plantar branches. The medial plantar nerve divides into a proper digital nerve supplying the medial side of the great toe, and three common plantar digital nerves extending to the first, second, and third intermetatarsal spaces. Then, they divide into the proper plantar digital nerves, which supply the plantar side of the toes. Lateral plantar nerve divides into the common plantar digital nerve, which extends to the 4th intermetatarsal space and the proper lateral nerve, which provides the innervation to the lateral side of the 5th toe.

Morton’s neuralgia – symptoms

Morton’s disease affects mostly 2nd and 3rd intermetatarsal space i.e. the spaces between the 2nd and 3rd toes, as well as between the 3rd and 4th toes. Morton’s neuralgia occurs more often in women, mostly after 50 years of age. The symptoms of Morton’s neuralgia involve pain situated on the plantar side of intermetatarsal space at the level of metatarsal heads (near the proximal phalanges). The pain is often described as burning sensation. It often spreads to the toes and rarely to the ankle. The pain occurs at walking, and diminishes or disappears after a rest. It occurs mostly when a patient is wearing pointed toe shoes.

The aetiology has not been fully explained and can be determined only in some cases. One of the most common causes is the injury of the involved area. The other may be wearing high-heeled shoes. In such shoes, the toes are dorsiflexed, which pulls the nerve. Sometimes, the onset of the condition is related to other lesions in the involved area, e.g. ganglion cyst (a nodule filled with jelly-like fluid, often contacting the joint), which compresses the nerve.

Morton’s disease – diagnosis

Diagnosis is based on a thorough clinical examination of the involved foot. Mulder’s test is useful, which consists in grasping and squeezing the metatarsal heads together, which causes pain. Against the commonly held beliefs, the MRI and ultrasound scanning rarely contribute to the diagnosis.

Morton’s neuralgia is initially treated using non-invasive methods – anti inflammatory drugs are administered, functional rehabilitation is used, footwear is changed into soft, wide, flat-heeled shoes. Local steroid injection (so-called nerve block) may also be administered. If there is no improvement, surgical nerve resection may be performed. Also other treatments are tested, e.g. permanent nerve damage by means of ultrasound-controlled injection of alcohol solution.