Morton's metatarsalgia due to intermetatarsophalangeal bursitis as an early manifestation of rheumatoid arthritis.

Of 50 patients in whom Morton's metatarsalgia was diagnosed during an 18-year period, 12 (24%) had rheumatoid arthritis at the time of presentation. After conservative management had failed, 20 patients had subtotal excision of the intermetatarsophalangeal bursa and associated digital nerve; in two patients, only the nerve was excised. During the follow-up period ranging from two months to 15 years, an additional eight patients developed sero-positive rheumatoid arthritis. Thus, a total of 20 patients (40%) presenting with Morton's metatarsalgia had rheumatoid disease at initial presentation or later developed this disease. Histological changes in the intermetatarsophalangeal bursa consistent with rheumatoid arthritis were found in ten patients. Of these, two were known already to have rheumatoid arthritis, three subsequently developed rheumatoid arthritis, and five do not yet have other evidence of the disease. The evidence suggests that Morton's metatarsalgia is associated with rheumatoid arthritis and is the basic etiology in a significant number of patients.