Morton Neuroma: Effect of MR Imaging Findings on Diagnostic Thinking and Therapeutic Decisions

Abstract

PURPOSE: To determine the effect of magnetic resonance (MR) imaging results on diagnostic thinking and therapeutic decisions by orthopedic surgeons in cases of a possible Morton neuroma. MATERIAL AND METHODS: Orthopedic surgeons completed a questionnaire before and after MR imaging for 54 feet in 49 patients thought to have Morton neuroma. Clinical diagnosis (Morton neuroma, differential diagnosis), location, diagnostic confidence, and therapeutic decisions were noted before and after MR imaging. The influence of the size of the neuroma on therapeutic decisions was analyzed. MR imaging diagnoses were compared with surgical results for 23 revised intermetatarsal spaces. RESULTS: After MR imaging, the clinical diagnosis of Morton neuroma was withdrawn in 15 of 54 (28%) feet. In 14 of 39 maintained diagnoses, the location or number of neuromas was changed after MR imaging. Confidence levels for Morton neuroma increased substantially after MR imaging. In 31 (57%) feet, a change in treatment plan resulted after MR imaging. Diameters of neuromas on MR images were significantly larger (P = .003) in surgically treated feet than in conservatively treated feet. MR imaging diagnoses were correct in all 23 revised intermetatarsal spaces. CONCLUSION: MR imaging has a major effect on diagnostic thinking and therapeutic decisions by orthopedic surgeons when Morton neuroma is suspected, especially because MR imaging helps in localization and size assessment of Morton neuromas.