What it is

Sinus tarsi syndrome is a painful condition characterised by inflammation and synovitis in the canal/tunnel between 2 bones (talus and calcaneus), located on the outside of the foot, known as the sinus tarsi (where your ankle bone meets your heel bone).

It follows repeated inversion sprains or ongoing instability of the subtalar/ankle joints. People describe hindfoot pain, tenderness and swelling on the outside of the foot as well as a feeling of instability on uneven ground, which worsens with movement or bearing weight. Without balance and peroneal strength work, symptoms persist. With bracing, stability training, and graded terrain exposure, function returns.

What happens when it occurs

Ligament injury and synovial irritation in the region of the sinus tarsi and subtalar joint can result in persistent pain and instability following a sprain.

Common causes and risk factors

  • History of lateral ankle sprains
  • Poor balance and peroneal weakness
  • Early return to uneven terrain without stability training
  • Obesity and having flat feet
  • Are pregnant: When you're pregnant, you have an increased risk of overpronation.

Who is most affected?

Athletes in the field and on the court, trail runners, and individuals with chronic ankle instability.

Typical symptoms

  • Pain and tenderness in the hindfoot on the outside
  • Swelling in the space between your ankle bone and heel on the outside
  • Instability sensation on uneven ground
  • Pain with inversion (twisting) and sudden direction changes

When to seek care

If pain persists beyond two weeks after a sprain or if instability limits activity.

How we diagnose

Clinical examination, ultrasound or MRI when symptoms persist or to rule out osteochondral (bony or joint) injury. Response to image-guided injection, such as corticosteroids, supports the diagnosis.

Management

  • Physical therapy/ physio
  • Bracing or taping to limit inversion early
  • Balance and peroneal strength with perturbation training
  • Graded exposure to uneven terrain
  • Over-the-counter pain relievers
  • Orthotics that you can buy over the counter or have custom-made
  • Image-guided corticosteroid with structured rehab in selected cases
  • Surgery: It’s rare to need surgery for sinus tarsi syndrome, and will only be considered if other treatments don’t work and you’re still experiencing severe pain or swelling.

Rehabilitation milestones

Phase 1, weeks 0–2: brace for uneven ground, balance drills, isometrics.

Phase 2, weeks 2–6: eversion strength, perturbation training, controlled hopping.

Phase 3, weeks 6–10: trail progression, agility and cutting work.

Phase 4, weeks 10–14: unrestricted sport demands.

Readiness to progress

  • Pain-free lateral hopping and trail walking
  • Eversion strength is within 90% of the other side
  • Agility tasks completed without giving way

Prevention

  • Complete the full balance and hopping programme after any ankle sprain
  • Maintain peroneal strength
  • Wear the proper protective equipment (including the right type of shoes or footwear).
  • Don’t “play through the pain” if your ankle hurts during or after physical activity.
  • Give your ankles time to rest and recover after intense activity.
  • Stretch and warm up before playing sports or working out.
  • Cool down and stretch after physical activity.

Australia snapshot

  • Approximately one-quarter of people with a lateral ankle sprain develop persistent symptoms without undergoing structured rehabilitation.
  • Sinus tarsi pain is a common contributor to the ongoing lateral ankle discomfort.
  • Netball and football codes provide the bulk of cases

Latest insights

Early balance work reduces chronic instability.

Eversion strength combined with graded terrain exposure speeds return and lowers recurrence.

Frequently Asked Questions

Individuals with flat feet and those who engage in activities that involve cutting maneuvers may be more susceptible to this syndrome. Additionally, repetitive activities on uneven surfaces can increase the likelihood of developing symptoms.

Surgery is usually not necessary in most patients who develop sinus tarsi syndrome. Non-surgical treatment can be highly effective in alleviating pain and swelling. Before considering surgery, it is essential to consult a foot and ankle orthopaedic surgeon to determine the cause of the sinus tarsi syndrome and the most suitable treatment for that condition.

Timeframes depend on the grade and your starting capacity. Mild injuries often settle within weeks when loading is matched to tolerance. Moderate injuries take longer as strength and control are rebuilt. Severe injuries or those with instability need a longer block and closer supervision. Progress is criteria-based.

Yes, if pain during activity stays at or below 3 out of 10 and does not worsen the next morning. Reduce volume and intensity, maintain a tidy technique, and avoid movements that exacerbate symptoms.

Imaging helps when red flags are present, progress stalls after two weeks, or if instability is suspected. Your clinician will advise on whether an X-ray, ultrasound, or MRI is most useful.

Use a brace or tape during the early return or on uneven ground. Remove it for controlled strength and balance work so that muscles can relearn their job.

Ice helps early when swelling and pain dominate. Heat helps later when stiffness is the main issue.

When the pain is 2 out of 10 or less the next morning, strength is within 90% of the other side, and you pass the functional test for this condition, such as single-leg hops, figure-of-eight runs, or step-downs.

Cut the next session’s volume by 20 to 30 per cent, keep strength work, and retest the following day. Progress again when baseline settles.

They can unload sensitive tissue early. Keep them while strength and control improve, then review fit and need.

Most people continue working on tasks and making standing adjustments. Drive when you can load and move the ankle safely and brake firmly without pain.