Sinus tarsi syndrome – Pain on the outside of the ankle

Ross Hauser, MD

Sinus tarsi syndrome causes pain in the outer or lateral side of the ankle. The conditions diagnosis is often difficult to make because on first examination the injury is often confused with a lateral ankle ligament sprain. The first step then is to differentiate between to two injuries or maybe more importantly, discover if both injuries have occurred.

People with chronic ankle sprains, especially those where the ankle rolls to the outside, are susceptible to damage to the structures of the rear foot and causes pain and tenderness in the sinus tarsus. This injury is especially seen in athletes but the condition may also be found in people who are overweight or have problems with flat feet or pronated flat foot.

Typically people who contact us will reveal a long history of ankle problems and foot pain. They will talk about their lateral or outside ankle pain, their history of ankle sprains, their regular routine of running or power walking that is now disturbed by their ankle pain. They may also describe a new unset of ankle instability, sprains or weakness that is of course concerning them. Some will tell us about atrophy in the muscles of their legs.

They will also tell us about therapies they have had to improve their gait and balance because of instability issues with their feet and ankles. They will tell us about foot orthotics and shoe inserts that are not helping as much as they and their doctor had hoped.

Mostly they will tell us about the pain, instability and difficulty walking up steps or a slope but they also tell us that they have delayed medical treatment because most of the time, as their day progresses, their foot and ankle pain gets better. That is until they suffer another sprain.

In this image we see an injection treatment into the area of the sinus tarsus. A cavity between the bones of the ankle where ligaments, blood vessels, nerves and other soft tissue pass through.

As discussed above, many people that reach out to us give us a medical history where the complexity of their ankle pain demonstrates why sinus tarsi syndrome can be difficult to understand. Here is one such communication edited for clarity.

I had a right ankle ligament partial rupture injury two years ago. It healed well, I had a great orthopedist that did PRP injections three times on that ankle. It did take about a year to heal as I did not have the PRP treatments right away, I had been on crutches for four months. (PRP injections utilize your blood platelets by taking a blood draw, concentrating the blood to separate blood cells from plasma. This plasma solution is then reinjected back into the ankle to facilitate soft tissue healing. This treatment is discussed further later in the article.)

After healing of the right foot I started having a tendinitis of the peroneal tendons on the left foot that did not go away. I had physical therapy for almost two years. I had to go back on the crutches because I could not use my leg and subsequently had two cortisone shots (which I felt weakened my leg even more). I also suffered from burning pain that won’t go away. This pain has now moved to the sinus tarsi area. I have shoe inserts as I have foot pronation as well but I just feel that the shoe inserts moved the pain to the area of the sinus tarsi instead.

Six out of ten patients with sinus tarsi syndrome returned to their pre-injury type of sport after being treated with a subtalar arthroscopy.

An August 2021 study lead by the University of Amsterdam and published in the medical journal Knee surgery, sports traumatology, arthroscopy (1) examined the return to sport rates, long-term clinical outcomes and safety for subtalar arthroscopy for sinus tarsi syndrome.

Twenty-two patients were assessed (average age of about 28 years old) who were followed for an average of five years after their surgery.
All patients were active in sports prior to the injury.
Results: Fifty-five percent of the patients returned to their preoperative type of sport at an average time of 23 weeks post-operatively
95% of the patients returned to any type and level sport at an average time of 12 weeks post-operatively
18% returned to their preoperative performance level at an average time of 25 weeks post-operatively
and 5% returned to improved performance postoperatively at 28 weeks
Conclusion: Six out of ten patients with sinus tarsi syndrome returned to their pre-injury type of sport after being treated with a subtalar arthroscopy. Subtalar arthroscopy yields effective outcomes at long-term follow-up concerning patient-reported outcome measures in athletic population, with favorable return to sport level, return to sport time, clinical outcomes and safety outcome measures.

In March 2019, orthopedic surgeons in Brazil published these findings (2) in eight patients who underwent arthroscopic debridement of the subtalar joint who did not respond to six months of conservative care treatment.

All patients showed severe synovitis (inflammation of the synovial fluid in the ankle region).
Seven patients had remnants of the talocalcaneal ligaments and six of the cervical ligament.
Six patients described the result as excellent and two as good. No complications were reported. All patients returned to sports after six months of follow-up.

Identifying the talocalcaneal interosseous ligament injury as a cause of chronic lateral ankle instability and sinus tarsi pain

A November 2021 study (3) examined the the high rate of talocalcaneal interosseous ligament tears found in chronic lateral ankle instability with sinus tarsi pain. (The talocalcaneal interosseous ligament connects the talus to the calcaneus (talus ankle bone to heal complex)).

In this paper a total of 118 ankles (109 patients) having chronic lateral ankle instability with sinus tarsi pain who had a subtalar arthroscopy and lateral ankle ligament surgery were evaluated.

Talocalcaneal interosseous ligament tears were classified into 4 grades:

Grade 0 (no tear), grade 1 (mild), grade 2 (moderate), and grade 3 (severe).

Results:

Talocalcaneal interosseous ligament tear was seen in 107 of the 118 ankles (90.7%).
There were:
- 29 ankles (23.6%) with grade 1 tear,
- 42 ankles (35.6%) with grade 2 tear, and
- 36 ankles (30.5%) with grade 3 tears.

Conclusion: A high rate (90.7%) of Talocalcaneal interosseous ligament tears was noted in chronic lateral ankle instability patients with sinus tarsi pain. Talocalcaneal interosseous ligament tears damage may play an important role in subtalar instability in patients with chronic lateral ankle instability and sinus tarsi pain. Subtalar arthroscopic evaluation for Talocalcaneal interosseous ligament tears is important for correct diagnosis for chronic lateral ankle instability with sinus tarsi pain.

Platelet Rich Plasma Therapy

PRP treatment re-introduces your own concentrated blood platelets into areas of chronic tendinopathy
Your blood platelets contain growth and healing factors. When concentrated through simple centrifuging, your blood plasma becomes “rich” in healing factors, thus the name Platelet RICH plasma.
The procedure and preparation of therapeutic doses of growth factors consisting of an autologous blood collection (blood from the patient), plasma separation (blood is centrifuged), and application of the plasma rich in growth factors (injecting the plasma into the area.)
In our clinic, patients are generally seen every 4-6 weeks. Typically three to six visits are necessary per area.

1 Lauf K, Dahmen J, Altink JN, Stufkens SA, Kerkhoffs GM. Six out of ten patients with sinus tarsi syndrome returned to pre-injury type of sport after subtalar arthroscopy. Knee Surgery, Sports Traumatology, Arthroscopy. 2021 Aug;29(8):2485-94. [Goggle Scholar]
2 Mansur NS, Baumfeld TS, Lemos AV, Azevedo RM, Fonseca LF, Doering J, Nery CA. Subtalar arthroscopic debridment for the treatment of sinus tarsi syndrome: case series. Revista da Associação Médica Brasileira. 2019 Apr 11;65:370-4. [Goggle Scholar]
3 Song WT, Lee J, Lee JH, Lim JW, Im JM, Lee DO, Jung HG. A high rate of talocalcaneal interosseous ligament tears was found in chronic lateral ankle instability with sinus tarsi pain. Knee Surgery, Sports Traumatology, Arthroscopy. 2021 Nov;29(11):3543-50. [Goggle Scholar]

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