Sinus Tarsi Syndrome

Flat Foot and Pain with Walking • Xray of the Week 2016 • Week #41

56 y/o female with chronic anterior talofibular ligament (ATFL) tear, flat foot, and pain with walking. What is the diagnosis?

Fig. 1. Images show loss of fatty tissue, edema as well as scarring (arrows).

Fig. 2 Normal appearance of the sinus tarsi with preserved fatty tissue – 3T

Fig. 3 Note pes planus and mid foot arthrosis on sagittal image. Coronal Fat Sat image shows edema and scar.

Fig. 4 Axial fat sat (left image) and T1 image shows loss of fatty tissue, edema as well as scarring (orange arrows).

Fig. 5 Edema and scarring and reactive osseous edema (blue arrows)

Fig. 6 Normal ligaments of the sinus tarsi.

Discussion

Sinus Tarsi Syndrome usually presents with lateral foot pain and tenderness. There may be subtalar micro-instability; however, frank ankle instability is usually not present. Pathologically there is scarring and degenerative changes of soft-tissue structures in the sinus tarsi. Seventy percent of patients have a history of inversion injury with lateral ligament complex tears, and it is frequently associated with posterior tibial tendon injury. On MRI, in the acute setting there is increased signal in fat on T2 weighted images due to edema. [Fig. 3-5] There may also be reactive osseous edema with high signal on PD and T2 weighted fat saturation images[Fig.5]

Treatment of sinus tarsi syndrome is usually conservative, with initial immobilization and anti-inflammatory drugs, followed by physiotherapy.

References:

1. Helgeson K. Examination and intervention for sinus tarsi syndrome. N Am J Sports Phys Ther. 2009;4 (1): 29-37.

2. Lee KB, Bai LB, Park JG et-al. Efficacy of MRI versus arthroscopy for evaluation of sinus tarsi syndrome. Foot Ankle Int. 2008;29 (11): 1111-6.

3. Klein MA, Spreitzer AM. MR imaging of the tarsal sinus and canal: normal anatomy, pathologic findings, and features of the sinus tarsi syndrome. Radiology. 1993;186 (1): 233-40.

4. Herrmann M, Pieper KS. [Sinus tarsi syndrome: what hurts?]. Unfallchirurg. 2008;111 (2): 132-6.

5. Rosenberg ZS, Beltran J, Bencardino JT. From the RSNA Refresher Courses. Radiological Society of North America. MR imaging of the ankle and foot. Radiographics. 2000;20 Spec No : S153-79.

Phillip Tirman, MD is the Medical Director of Musculoskeletal Imaging at the Renaissance Imaging Center in Westlake Village, California. A nationally recognized expert in the applications of MRI for evaluating MSK and spine disorders, Dr. Tirman is the co-author of three textbooks, including MRI of the Shoulder and Diagnostic Imaging: Orthopedics. He is also the author or co-author on over sixty original scientific articles published in the radiology and orthopedic literature.

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