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 condition’s 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, which 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 feet.

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, and their regular routine of running or power walking that is now disturbed by their ankle pain. They may also describe a new onset 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.

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.

Is Sinus tarsi syndrome a real diagnosis?

An October 2023 study in the Journal of Clinical Medicine (1) writes: “Sinus tarsi syndrome is defined as pain located at the lateral opening of the tarsal sinus. The exact etiology of sinus tarsi syndrome is not completely understood. Some do not believe it to be a true pathology. ”

The authors suggest the following diagnosis should be explored in a Sinus tarsi syndrome diagnosis to better determine what is happening in the patient’s foot.

subtalar joint synovitis
synovial cysts
ankle instability
subtalar instability
chronic inflammation – post-traumatic arthrofibrosis
partial tear of the interosseous talocalcaneal ligament (ITCL) or cervical ligament (CL)
rheumatoid arthritis, gouty arthritis
calcium pyrophosphate (CPP) disease/chondrocalcinosis
cartilage injury/osteochondral lesion, − osteochondritis dissecans (OCD) (of the posterior facet)
loose bodies
tarsal coalition (talocalcaneal, calcaneonavicular)
posterior tibial tendon tear/insufficiency
pes planovalgus/flatfoot/hindfoot valgus
calcaneofibular impingement (can be caused by flat foot deformity or injury).
elongated lateral talar process
degenerative joint disease/osteoarthritis (subtalar)
neuroma (deep peroneal nerve)

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 (2) 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 (3) 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.

A review of surgical techniques for the management of Sinus tarsi syndrome

An April 2024 paper in the Arthroscopy Techniques (4) reviewed and suggested surgical techniques for the management of Sinus tarsi syndrome. “There is a particularly high density of nociceptive free nerve endings (these are nerves that sense pain) and proprioceptive mechanoreceptors (nerves that sense movement or the position of body parts) in the synovial tissue and fat pad of the sinus tarsi, and various pathologies of the sinus tarsi can cause the pain and subjective feeling of instability described in Sinus tarsi syndrome.

Arthroscopic debridement has a denervation effect that may be successful regardless of what the underlying pathology is so long as the nociceptors and proprioceptors in the synovium and fat pad are excised (removed). Removal of the ligamentous structures has no additional benefit owing to a lack of nociceptors and proprioceptors in these structures. (Removal of ligaments does not help pain and will increase instability). Therefore, identification of an intra-articular diagnosis more specific than Sinus tarsi syndrome is not necessary given that arthroscopic debridement with synovectomy may be a suitable universal treatment to relieve the symptoms caused by a variety of underlying intra-articular pathologies in the sinus tarsi stability.”

To this end the study authors introduced a new minimally invasive approach that they suggest would result in better cosmetic results, minimal soft-tissue trauma, complete debridement of all zones of injury, decreased postoperative pain, early mobilization, and faster postoperative recovery. The potential risks of this surgery would include injury to the branches of the superficial peroneal nerve, the nerve to the extensor digitorum brevis (terminal branch of the deep peroneal nerve), the sural nerve, the sinus tarsi ligaments, or the articular cartilage of the subtalar joints, as well as recurrence of symptoms.

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

A November 2021 study (5) 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.

Treatment with corticosteroid and local anesthetic group, PRP group, and ozone injections.

A January 2023 paper in the Journal of the American Podiatric Medical Association (6) looked at sixty patients with sinus tarsi syndrome who were randomly divided into three treatment groups: treatment with corticosteroid and local anesthetic group, treated with PRP group (see below for information on PRP), and treated with ozone injections group.

Outcome measures were visual analog scale (pain scale 0 – 10), American Orthopedic Foot and Ankle Society Ankle-Hindfoot Scale (pain and function), Foot Function Index, and Foot and Ankle Outcome Score before injection compared with 1, 3, and 6 months after injection.

At the end of months 1, 3, and 6 after injection, significant improvements were observed in all three, ozone, corticosteroid and local anesthetic groups, or PRP injections compared with baseline. At 6-month follow-up, there were no significant differences in visual analog scale and Foot Function Index results among the groups. All three treatments provided similar results.

Corticosteroid injections were effective in the short term with a 65% recurrence rate of symptoms within 1 year.

An April 2024 study in the China Journal of Orthopaedics and Traumatology (7) “showed that the incidence rate of sinus tarsi syndrome after lateral ankle sprain was 22.5%. Corticosteroid injections were effective in the short term with a 65% recurrence rate of symptoms within 1 year. For patients with no significant long-term effect of conservative treatment, clinicians may explore alternative approaches, including options like ankle arthroscopy.”

Platelet Rich Plasma Therapy – PRP Prolotherapy

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.

Our published research

Avascular Necrosis Case Report of Direct Bone Marrow Injections and Prolotherapy Treatment

References

1 Willegger M, Bouchard M, Schwarz GM, Hirtler L, Veljkovic A. The evolution of sinus tarsi syndrome—what is the underlying pathology?—a critical review. Journal of Clinical Medicine. 2023 Oct 31;12(21):6878.
2 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]
3 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]
4 Leung K, Lui TH. Arthroscopic Management of Sinus Tarsi Syndrome. Arthroscopy Techniques. 2024 Aug 1;13(8):103003. [Goggle Scholar]
5 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]
6 Toy S, Tuncer K, Topal M, Aydın A. Corticosteroid, Platelet-Rich Plasma, and Ozone Injections for Sinus Tarsi Syndrome. Journal of the American Podiatric Medical Association. 2023 Jan 1;113(1). [Goggle Scholar]
7 Xu XX, Zhang L, Jiang B, Sun J, Liu XH, Zhang S, Li Y. Clinical observation of sinus tarsi syndrome after lateral ankle sprain. Zhongguo gu Shang= China Journal of Orthopaedics and Traumatology. 2024 Apr 1;37(4):387-91. [Goggle Scholar]