Sinus Tarsi Syndrome
Despite its name, Sinus Tarsi Syndrome has nothing do with your nose, but rather something at the other end of it – your ankle. Sinus Tarsi Syndrome refers to a collective condition of pains at the Sinus Tarsi area of your ankle and not specifically to a particular type of problem like ligament strain or impingement.
Sinus Tarsi – Cavity in the Subtalar Joint
The sinus tarsi is a cylindrical canal in the joint between two bones in your feet, along the outer side (lateral side) where your ankle and shin creases when your foot flexes – the subtalar joint.
This subtalar joint allows you to roll your foot inwards and outwards.
As an aside, sinus means a cavity within a bone or tissue, not just the ones in your nose.
This area contains many anatomical structures such as ligaments and joint capsules. We get pains when these structures get strained and inflamed. See the image of the sinus tarsi on the right looking on from the front towards the back heel – T= talus, C= calcaneus, a= cervical ligament, b= talocalcaneal interosseous ligament, 1-3= lateral, intermediate, and medial roots of the inferior extensor retinaculum.
Patients with Sinus Tarsi Syndrome feel pain over the outside of the ankle. There may also be swelling and tenderness in the region. The pains are typically worse in the morning and may present as pain and stiffness that slowly improves as the patient warms up.
The pain may also get worse during walking or running especially on slopes or uneven surfaces which causes the joint to bend even more than when walking on a flat surface.
What causes it?
As with most cases, these structures get strained either from
- one big event such as an severe ankle sprain or
- many smaller repetitive ones from an abnormal biomechanical movement such as a walking or running with excessively pronated foot (flat foot).
Physiotherapy treatment works well for such strains. Your physiotherapist will first get the swelling down and help getting the joint moving smoothly again with mobilisation.
Prevention of Sinus Tarsi Syndrome
Prevention depends on the underlying cause of the syndrome.
It can range from exercises and flexibility if due poor ankle muscle strength or endurance, proprioception training and ankle strapping when playing sports, if due to poor proprioception, to walking or running gait retraining or corrective orthotics if it is due to poor foot biomechanics.