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Mortons-interdigital Neuroma
Definition: A Mortons neuroma is a benign nerve tumour of one of the intermetatarsal plantar nerves, usually affecting the third or fourth intertarsal spaces.
Causes: There is no exact cause for the development of a Mortons neuroma, this condition is usually described as idiopathic. However, certain research points towards mechanical imbalances of the foot, inflammation, soft-tissue trauma, and transient ichaemia as potential causative factors for Morton neuromas.
Examination: A Mortons neuroma is characterised by pain and anaesthesia or paraesthesia in the region of the forefoot, that is relieved by the removal of footwear. The patient will usually complain of pain upon weight-baring caused by the pressure exerted on the enlarged section of the nerve as it travels between the metatarsal heads. Erythema, signs of inflammation and a reduced range of motion are not associated with a Mortons neuroma.
Orthoapedic test for Mortons neuromas:
Mulder's sign: palpation between the metatarsal heads will replicate the symptoms, as will compression of the transverse arch of the foot.