Practical US of the forefoot

Abstract

Disorders affecting the forefoot are common in the clinical practice. Accurate history and physical examination are the mainstays of diagnosis but imaging modalities are frequently obtained to confirm the clinical suspicion and plan appropriate treatment. In this article we will present the ultrasound (US) technique of examination of the forefoot followed by a brief description of the normal US anatomy and of US appearance of the most frequent forefoot disorders; rheumatoid arthritis, osteoarthritis, overuse arthropathy, Morton neuromas, bursitis, mucoid cysts, foreign bodies, bone disorders.

Utility of power Doppler ultrasonography for detecting forefoot bursae in early rheumatoid arthritis

“…[23,24] Depending on their location, synovial bursae within the forefoot are of 2 types: submetatarsal and intermetatarsal bursae. [5,25] Both bursae can be evaluated by MSUS. [4,6] Submetatarsal bursae are adventitial bursae defined as fluid-filled spaces without a synovial lining.…”

“…[26] They are located in the subcutaneous tissues at the level of the metatarsal heads, and they are considered mechanically derived due to chronic local overload. [23,25] Conversely, the intermetatarsal bursae are anatomic bursae that have a synovial lining, [27,28] and these bursae are clinically significant due to their close cohesion with the intermetatarsal neurovascular bundle. [22,29] Intermetatarsal bursae with hypertrophy can appear on US as a well-defined fluid collection with hypoechoic or anechoic zones usually bulging >1 mm under the level of the metatarsal heads.…”

Intermetatarsal bursitis is frequent in patients with established rheumatoid arthritis and is associated with anti-cyclic citrullinated peptide and rheumatoid factor

“…Ultrasound is sensitive for detection of inflammatory changes in patients with rheumatoid arthritis (RA) 1. Intermetatarsal bursitis (IMB) is located on the dorsal side of the deep intermetatarsal ligament and may easily be detected by use of longitudinal and transverse dorsal scans between the metatarsophalangeal (MTP) joints 2. In a longitudinal scan, they are relatively large and have usually a round shape, caused by hypoechoic synovitis and they may contain fluid.…”

Should the webspaces be a review area for Mortons neuroma on computed tomographies performed for metatarsalgia?

“…The US studies were performed by various different members of the team. Nonetheless, ultrasound is widely accepted as a reliable method of detecting MNBC [ 11 ], with a sensitivity and specificity of 91% and 85% respectively in a recent review [ 8 ]. Typically, US depicts a rounded, well defined hypoechoic mass which is non-compressible in the intermetatarsal space [ 9 ].…”