Monarticular Nontraumatic Synovitis of the Metatarsophalangeal Joint: A New Diagnosis?

Seven patients presented with forefoot pain in the metatarsal head region, with an average age of 57 years, and no history of trauma. Six had pain in the second metatarsophalangeal joint, while one patient had pain in the third. Physical examination demonstrated generalized thickening of the involved metatarsophalangeal joint along with warmth and tenderness to compression. Range of motion was decreased in flexion and two patients had a subluxed metatarsophalangeal joint. All patients demonstrated some instability of the joint with dorsoplantar stress. Palpation of the intermetatarsal space demonstrated some evidence of irritation of the common digital nerve. The toe demonstrated some thickening. Roentgenograms demonstrated some widening of the metatarsophalangeal joint in four of these patients. One patient responded to conservative treatment, and the remaining six patients underwent synovectomy. In three cases the common digital nerve was resected. Follow-up was 16 months, and four of the six patients operated on felt their symptoms were completely relieved, one patient felt that the symptoms were improved, and one patient believed her surgery was of no benefit. Synovial tissue in all cases revealed pathologic changes of chronic synovitis. The etiology of this synovitis is unknown. The excessive synovium resulted in the joint thickening, which probably accounts for the neuritic symptoms, the generalized thickening of the toe, and the instability of the joint. Because of the poor response to conservative treatment, perhaps earlier synovectomy is the treatment of choice for this entity.