Morton’s syndrome is an entrapment of a digital nerve between the metatarsal heads in the foot causing pain between the metatarsal heads. 41 subjects with signs and symptoms of Morton’s syndrome were prospectively examined with an ultrasound scan and the size of the bifurcation of the interdigital nerve was recorded if it was visible. Each subject completed a Visual Analogue Scale and short form McGill Pain Questionaire before an injection of local anaesthetic and corticosteroid was administered. The subjects were reviewed after 6 weeks and the pain scores repeated.

26 subjects had positive ultrasounds with a mean width of 5.1 mm, range 2.7–9.8 mm and 15 subjects had negative ultrasounds. Differences in mean ranks of VAS scores between the two groups were borderline statistically significant for scores before injection (p=0.064). Difference in mean rank of VAS score was significant after injection (p=0.013).

Differences in mean ranks of MPQ scores were borderline statistically significant for changes in scores (p=0.062). Difference in mean rank of MPQ score was significant after injection (p=0.007). None of the correlations between nerve width and any of VAS or MPQ outcome measures were statistically significant.

This study demonstrates that the larger the neuroma on the ultrasound, the more painful it is for the patient. This study suggests that patients who have a small or absent neuroma demonstrated on the ultrasound scan are more likely to have their pain reduced to an acceptable level with an injection of local anaesthetic and corticosteroid than those patients with a large neuroma. Ultrasound examination is a useful tool in the management of patients with Morton’s syndrome.