Objectives To assess the value of ultrasonography in studies of the ligaments within the sinus tarsi (ST) in healthy subjects. Materials and methods We examined 20 healthy volunteers using a 12-MHz transducer with THI and compound imaging. With the foot in inversion, the following structures were examined with coronal and transverse scans: (1) the root of the inferior extensor retinaculum (RIER); (2) the interosseous talocalcaneal ligament (ITCL); (3) the cervical ligament (CL); (4) the bifurcate ligament (BL); (5) the synovial recesses, which were examined for possible distention (distended synovial recesses, DSR). The sonographic features, orientation, and thickness of each ligament were assessed. Results The easiest structure to identify (visualized in 20/20 subjects) was the RIER, which formed a semiarch. The two deeper layers were hypoechoic, the superficial layer hyperechoic. The ITCL was situated posteriorly and deep with an oblique course. It appeared hypoechoic with a mean thickness of 4.06 mm ± 0.7. It was visualized in 18/20 (90 %) subjects. The CL (isoechoic/hyperechoic) was located more anteriorly at an intermediate depth. The orientation was almost vertical. It was visualized in 17/20 (85 %) subjects, with a mean thickness of 2.28 mm ± 0.34. The BL appeared hypoechoic. It was visualized in 19/20 (95 %) subjects with transverse (anterior end of the ST) and longitudinal scans. The calcaneonavicular and calcaneocuboid components displayed mean (SD) thicknesses of 2.09 mm ± 0.37 and 2.7 mm ± 0.32, respectively. The ITCL and RIER were visualized in the same scan as a semiarch. DSR was observed in 4/20 (20 %) subjects. Conclusions The present study shows that, in patients with suspected ST pathology, the anatomic structures that make up this recess can be adequately examined with ultrasonography performed with ordinary 12-MHz transducers.Keywords Musculoskeletal ultrasound Á Sinus tarsi Á Harmonic imaging Á Compound imaging Sommario Obiettivi indagare la capacità degli ultrasuoni (US) di identificare le strutture legamentose del seno del tarso (ST) in un gruppo di soggetti sani. Materiali e Metodi abbiamo studiato 20 volontari sani, utilizzando sonde da 12 MHz, Compound e THI attivati. Sono stati indagati con piede in inversione: (1)
123J Ultrasound (2016) 19:107-113 DOI 10.1007/s40477-014-0145-y retinacolo inferiore degli estensori (RIER) (2) legamento interosseo (ITCL) (3) legamento cervicale (CL) (4) legamento biforcato (BL) (5) eventuali distensioni di recessi sinoviali (DSR), con scansioni coronali e trasversali, valutando ecostruttura, orientamento e spessore dei legamenti. Risultati (1) la RIER, repere ecografico, è stata la struttura di più agevole identificazione: con decorso a semiarco, ipoecogena nei 2 strati profondi, iperecogena in quello superficiale, visualizzata in 20/20 soggetti (2) il ITCL in situazione posteriore e profonda, con andamento obliquo ha presentato spessore medio di 4.06 mm ± 0.7, ipoecogeno, visualizzato in 18/20 (90 %); (3) il CL, più anteriore e orientamento qua...