Dynamic sonography of the forefoot in Morton's syndrome: correlation with magnetic resonance and surgery

The aim of this paper is to demonstrate the efficacy of the dynamic study of the forefoot during lateral compression of the metatarsal heads (Mulder's manoeuvre) in the visualisation of Morton's neuroma. The data were compared with clinical signs, conventional ultrasound (US), magnetic resonance (MR) and surgical findings.

Forty forefeet in 38 patients were investigated with conventional and dynamic US using a 10-MHz linear probe (Esaote Technos). MR was performed in 26 forefeet with a 0.2-T scanner (Esaote Artoscan). Twenty intermetatarsal spaces in 18 forefeet were explored surgically.

Thirty-seven intermetatarsal masses were identified through dynamic US in the 40 forefeet investigated (two double localisations). This method was clearly more effective than conventional US, which could only locate 25. In those forefeet investigated with MR, it was possible to confirm dynamic US findings in 16 out of 22. In one of the six cases unconfirmed by MR, a neuroma was removed following surgery. Twenty masses (19 neuromas and one synovial ganglion) were found in the 18 forefeet treated by surgery.

Clinical evaluation, which is fundamental for accurate diagnosis, can make use of dynamic US in the first instance in order to confirm clinical signs and identify the correct site and number of masses. In our opinion, MR maintains a primary role in differential diagnosis with other diseases (mainly stress fractures, bursitis, ganglion cysts or tendon tumour sheaths).