Radiographic Analysis of Feet with and Without Morton's Neuroma

Background: The aim of this research was to investigate the association of various structural measurements of the forefoot with Morton's neuroma (MN). Methods: Weightbearing anteroposterior and lateral foot radiographs of subjects attending the University of Western Australia (UWA) Podiatry Clinic and the first author's private practice were included in this study. A single assessor measured the following angles: lateral intermetatarsal angle (LIMA), intermetatarsal angle (IMA), hallux valgus angle (HVA), digital divergence between the second and third digits (DD23), digital divergence between the third and fourth digits (DD34) and relative metatarsal lengths of the first to fifth metatarsals (Met1-5), and the effect of MN size as measured by ultrasonograph on digital divergence. Intratester reliability of all radiographic measurements was assessed on all radiographic measurements. The study included 101 subjects, of whom 69 were diagnosed with MN and 32 were control subjects without MN. The mean (± standard deviation) age of MN subjects was 52 (±15) years and for control subjects, 48 (±12) years. Results: When comparing all feet, there were no significant differences in the LIMA, HVA, IMA, digital divergence angles and the relative metatarsal distances between subjects with MN and control subjects. No relationship between MN size and digital divergence was found in either foot, or in either neuroma location. Conclusion: We were unable to demonstrate any relationship in this study between radiographic metatarsal length and angular measurements in a symptomatic MN group compared to a control group. In addition, we did not find any correlation between the size of MN as measured from ultrasonographic images and radiographic evidence of digital divergence. Level of Evidence: Level III, case control study.