Sinus tarsi syndrome as cause of lateral ankle pain

Sinus Tarsi Syndrome can cause pain and swelling (not always present) over the outside of the ankle, about in the same area as when you’ve sprained your ankle. It can cause your foot or ankle to feel unstable when you walk, and the symptoms often increase after sport or walking on uneven ground. In this article, I discuss what causes it and how it can be treated.

In this article:

• Anatomy of the foot/ankle

• What happens when you get Sinus Tarsi Syndrome?

• Treatment for Sinus Tarsi Syndrome

I've discussed this in a lot more detail in this video:

Anatomy of the foot/ankle

Your ankle joint is formed by the bones in your lower leg (the fibula and tibia) resting on the talus bone in your foot. The movements of pointing your foot down into plantar flexion and pulling it up into dorsiflexion happen mostly at this joint.

The talus rests on the calcaneus (your heel bone) and between these two bones they form the subtalar joint. When you turn your foot in and out (supination and pronation) a large part of the movement happens in this joint.

The sinus tarsi is a tunnel between the talus and calcaneus.

What happens when you get Sinus Tarsi Syndrome?

Sinus Tarsi Syndrome can be caused by trauma, like after you sprain your ankle. In fact, it most often occurs in people who have an ongoing instability in their ankles after spraining it several times.

An ongoing instability can have two causes:

1. It can be a functional instability which means that your ligaments are actually all intact, but your muscles aren’t controlling your ankle and foot properly which is causing it to sprain repeatedly when you walk or run. This type of instability reacts really well to rehab exercises.

2. It can be a structural instability which means that you’ve fully torn several ligaments and they’ve not grown back together or they are more lax than before and not providing your joint with enough stability. This type of instability can sometimes be helped through rehab exercises, but often requires surgery – it depends on the person, what activities they want to be doing and how bad the instability is.

This trauma (either sudden or repetitive) can cause inflammation and irritation of the lining of the capsule that surrounds the subtalar joint and the sinus tarsi. We call this synovitis. Over time the synovitis can cause the joint lining to thicken and catch in the joint when you move, cause quite sharp pain. If the ligaments haven’t healed properly, some of the loose ends can also get caught in the joint and contribute to the pain.

Something else that can cause irritation and synovitis in the sinus tarsi is when your foot hyper-pronates as this causes more compression over the outside of the ankle and foot joints.

Treatment for Sinus Tarsi Syndrome

You should always try up to 6 months of conservative treatment first before considering surgery. In my experience, combining several things from the list of conservative treatments work best. It is for instance not really useful to take anti-inflammatory medication if you’re going to continue irritating the joint by walking with your foot in a hyper-pronated position. Combining the use of anti-inflammatory drugs with orthotics may give you better results.

Conservative treatment could include:

• A short course of anti-inflammatory medication to calm the synovitis down. Make sure you check with your doctor before taking any medication.

• Semi-rigid orthotics to ensure that your foot does not go into hyper-pronation so that it can stop irritating the joint. These orthotics may just be a temporary thing if your over-pronation is caused by muscle weakness, but it may have to be permanent if you have a structural cause for it. Buy them here.

• Rehab exercises consisting of strengthening the muscles that bend your ankle up and down, the ones that turn it in and out as well as the ones that support your foot. Your exercise programme should also include exercises for correcting foot posture and balance (static and dynamic). Strengthening your glutes may also help – I explain why this is in the video.

• Avoid stretching your ankle into deep dorsiflexion! It causes the sinus tarsi to compress and will make it feel worse.

• Corticosteroid injections can also be very useful in cases where the pain doesn’t want to subside. They are best done under ultrasound guidance so that you can be sure that the steroid is injected into the sinus tarsi.

If you’ve followed all the conservative treatment for at least 6 months and is still struggling, you may have to think about surgery. Surgery for sinus tarsi syndrome usually involves:

1. That they just go in with a small camera and trim away all the swollen and loose bits that are getting caught in the joint or;

2. If they think that the reason for your pain is due to a structural instability of the subtalar joint, they may perform surgery where they actually stabilise the joint for you or;

3. They can also combine both procedures in step 1 and 2.

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

About the Author

Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Masters Degree in Sports Injury Management. Follow her on LinkedIn, ResearchGate.

References:

1. López-Valenciano, A., et al. (2016). "Impact of dynamic balance and hip abductor strength on chronic ankle instability." European Journal of Human Movement 36: 137-149.

2. Mansur, N. S. B., et al. (2019). "Subtar arthroscopic debridment for the treatment of sinus tarsi syndrome: case series." Revista da Associação Médica Brasileira 65(3): 370-374.

3. Tu, P. (2018). "Heel pain: diagnosis and management." American Family Physician 97.