Intermetatarsal Bursitis

Abstract

Patients with intermetatarsal bursitis experience pain and tenderness over the affected intermetarsal spaces, with the pain made worse by wearing high-heeled shoes or shoes that are too narrow. Obesity may also predispose to this condition. The pain may radiate distally into the toes, especially if the adjacent interdigital nerve is involved. Often the patient is unable to stand on tiptoes or walk up stairs. Activity worsens the pain. The pain is constant; is characterized as sharp and may interfere with sleep. Coexistent neuritis, neuropathy, Morton’s neuroma, stress fractures, metatarsalgia, and synovitis may confuse the clinical picture. As the bursitis worsens, the affected intermetatarsal bursae tend to expand, surrounding the adjacent interdigital nerves and making the patient’s clinical presentation indistinguishable from the pain of Morton’s neuroma. If the inflammation of the intermetatarsal bursae becomes chronic, calcification of the bursae and fibrosis of the surrounding interdigital space may occur. On physical examination, pain can be reproduced by squeezing the affected web space between the index finger and thumb.

Keywords

intermetatarsal bursitis, Morton’s neuroma, Joplin’s neuroma, foot pain, interdigital nerve, compression neuropathy, metatarsalgia, magnetic resonance imaging, diagnostic sonography, ultrasound guided injection

ICD-10 CODE M71.572

The Clinical Syndrome

Bursae are formed from synovial sacs whose purpose is to allow easy sliding of muscles and tendons across one another at areas of repeated movement. These synovial sacs are lined with a synovial membrane that is invested with a network of blood vessels that secrete synovial fluid. Inflammation of the bursa results in an increase in the production of synovial fluid with swelling of the bursal sac. With overuse or misuse, these bursae may become inflamed, enlarged, and on rare occasions infected. Although significant intrapatient variability as to the number, size, and location of bursae is seen, anatomists have identified a number of clinically relevant bursae, including the intermetatarsal bursae. The intermetatarsal bursa lies between the metatarsophalangeal joints in a position that is just dorsal to the deep transverse intermetatarsal ligament. The bursae extend approximately 1 cm beyond the distal border of the ligament in the web spaces between the second and third and third and fourth digits.

Signs and Symptoms

Patients with intermetatarsal bursitis experience pain and tenderness over the affected intermetatarsal spaces, with the pain made worse by wearing high-heeled shoes or shoes that are too narrow ( Fig. 131.1 ). Obesity may also predispose to this condition. The pain may radiate distally into the toes, especially if the adjacent interdigital nerve is involved. Often the patient is unable to stand on tiptoes or walk up stairs. Activity worsens the pain. The pain is constant; is characterized as sharp, and may interfere with sleep. Coexistent neuritis, neuropathy, Morton’s neuroma, stress fractures, metatarsalgia, and synovitis may confuse the clinical picture. As the bursitis worsens, the affected intermetatarsal bursae tend to expand, surrounding the adjacent interdigital nerves and making the patient’s clinical presentation indistinguishable from the pain of Morton’s neuroma ( Fig. 131.2 ). If the inflammation of the intermetatarsal bursae becomes chronic, calcification of the bursae and fibrosis of the surrounding interdigital space may occur.

On physical examination, pain can be reproduced by squeezing the affected web space between the index finger and thumb. If the interdigital nerve is involved or if a Morton’s neuroma has developed, a positive Mulder sign can be elicited by firmly squeezing the two metatarsal heads together with one hand while placing firm pressure on the interdigital space with the other hand ( Fig. 131.3 ).