Sonographic visibility of the sinus tarsi with a 12 MHz transducer.
OBJECTIVE
To assess the value of ultrasonography in studies of the ligaments within the sinus tarsi (ST) in healthy subjects.


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.
Ospedale di Misericordia di Navacchio, via Ruschi 34, 56011 Calci, PI Italy.
Salvatore Massimo
SM
Stella
Ospedale di Misericordia di Navacchio, Navacchio, Cascina, Pisa, Italy.
Barbara
B
Ciampi
Radiologia D.E.A., A.O.U.P. Ospedale Cisanello Pisa, Pisa, Italy.
Eugenio
E
Orsitto
Reumatologia Universitaria di Firenze, Ospedale Careggi Firenze, Florence, Italy.
Daniela
D
Melchiorre
U.O. Chirurgia Generale e d'Urgenza, A.O.U.P., Ospedale Cisanello Pisa, Pisa, Italy ; Scuola SIUMB di Ecografia di Base e Specialistica in Urgenza ed Emergenza di Pisa, Pisa, Italy.
Piero Vincenzo
PV
Lippolis
D000328:Adult; D005260:Female; D005528:Foot / Q000000981:diagnostic imaging*; D006801:Humans; D008023:Ligaments, Articular / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014159:Transducers; D014463:Ultrasonography
Compound imaging; Harmonic imaging; Musculoskeletal ultrasound; Sinus tarsi