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Sinus tarsi syndrome steroid injection
What is sinus tarsi syndrome?
The sinus tarsi is an anatomical tunnel (space) that starts outside the foot and continues deep within the foot. It is located between two bones within the back of the foot, the talus and calcaneum, just in front of the large bony bump at the outside of the ankle (called the lateral malleolus). The sinus tarsi provides stability to the hindfoot (joints at the back of the foot). It contains fatty tissue, small nerves and vessels. The structures within the tarsal sinus can be injured secondary to repeated ankle sprains or if there are biomechanical abnormalities that would put extra stress on the area (like flatfoot of hypermobility).
What are the symptoms of sinus tarsi syndrome?
Pain at the opening of the tunnel at the front and outside of the ankle, just below the ankle joint.
A feeling of instability when walking (especially on uneven surfaces).
What conditions can mimic sinus tarsi syndrome?
Ankle joint arthritis (or a joint just underneath it called the subtalar joint).
Lateral ankle ligaments sprain.
Differentiating these conditions can be difficult on clinical assessment only and therefore further imaging is very useful.
How to diagnose sinus tarsi syndrome?
MRI examination is very useful in establishing the diagnosis and differentiating it from the other conditions mentioned above. The MRI examination should be interpreted by a specialist musculoskeletal radiologist doctor with experience in reading ankle MRI examinations.
Ultrasound guided sinus tarsi steroid injection
Treatment starts with simple measures like using special orthotics to support the medial arch of the foot in patients with flatfoot, and physiotherapy to increase the strength of the foot muscles. A steroid injection can be useful if the above measures are failing. Usually, a sinus tarsi injection is done under ultrasound guidance to improve accuracy and reduces side effects such as skin thinning and depigmentation.
Foot & Ankle conditions and treatments
The Musculoskeletal Ultrasound & Injections clinic
169 Richmond Road
Kingston upon Thames
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