Sinus Tarsi Syndrome
The PDFS and the T2 coronal images show ill defined edematous soft
tissue in the sinus tarsi with edema also of the talus forming the
roof of sinus tarsi and of the calcaneum forming the floor as well
[better appreciated on the sagittal images]. The ligaments of the
sinus tarsi are also not distinctly seen.
The sinus tarsi is an anatomical space located laterally between the
talus and the calcaneus. It contains the cervical ligament, medial,
intermediate and lateral roots of the inferior extensor retinaculum
and the interosseous talocalcaneal ligament.
Sinus tarsi syndrome is due to inflammation of the sinus tarsi with or
without ligament injuries. It most often occurs due to injury to the
sinus tarsi ligaments due to repetitive ankle sprains or following
trauma and hence more often
seen in young individuals. It is frequently associated with
lateral ligament and posterior tibial tendon injuries.
Patients usually present with relatively long standing pain along the
lateral side of the hind foot.
MRI is the imaging modality of choice for diagnosing sinus tarsi
syndrome as CT and radiographs are usually normal unless the disease
has advanced to secondary subtalar degenerative arthritis. The MRI
shows obliteration of fat in the sinus tarsi, which is replaced by ill
defined edematous soft tissue [T1 hypointense and T2 hyperintense].
The soft tissue may also progress to fibrosis over time which is
usually hypointense on both T1 and T2W images. The sinus ligaments are
not separately visualised. There can also be edema of the adjacent
bones, i.e. the talus and the calcaneum, forming the roof and the
floor of the sinus tarsi, respectively. In more advanced cases,
osteoarthritic changes with subchondral cysts may also be seen.
Contrast enhancement is often seen but is non-specific.
Majority of the patients respond to conservative treatment including
physiotherapy, NSAIDs and local steroid injections. In cases of
failure, surgical measures like synovectomy or arthrodesis may be
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