Morton's metatarsalgia: Sonographic findings and correlated histopathology

The results of 79 high resolution ultrasound examinations of the forefoot t hat were performed for suspected Morton's metatarsalgia were retrospectivel y assessed. Scans were only obtained if the pain was poorly localized or if there were atypical features that made the clinical diagnosis uncertain. U ltrasound detected 92 hypoechoic intermetatarsal web space masses in 63 pat ients. Surgery was performed on 23 web spaces in 22 patients where the resp onse to nonsurgical management had been poor. The surgical specimens were r etrieved and reviewed by a pathologist in 21 cases. The histopathology in 2 0 of 21 operated cases was that of Morton's neuroma; however, prominent muc oid degeneration was also found to involve the adjacent loose fibroadipose tissues in 19 of 20 neuroma specimens. Ultrasound was sensitive in the dete ction of web space abnormality (sensitivity, 0.95), but could not clearly s eparate Morton's neuroma from associated mass-like mucoid degeneration in t he adjacent loose connective tissues. The implications of these observation s for both diagnosis and treatment are discussed.