Sinus Tarsi Syndrome: Why Uneven Ground Makes Ankle Pain Worse

Pain on the outside of the ankle that persists after a sprain may have several causes.

One possibility is sinus tarsi syndrome, a condition associated with pain and sometimes instability in a small space on the outer side of the hindfoot.

Quick Answer: What Is Sinus Tarsi Syndrome?

Sinus tarsi syndrome is a term used for pain and sometimes instability in a small space on the outer side of the hindfoot, just in front of and below the outer ankle bone. It may develop after an ankle sprain, repeated loading, or another joint or soft-tissue problem.

What can help? Treatment depends on the cause and may include activity modification, supportive footwear, and physiotherapy to improve strength, balance, and movement control. Persistent pain should be assessed by a qualified healthcare professional.

The discomfort may become more noticeable when walking on uneven ground, standing for long periods, or changing direction during sports.

The key is to identify what is causing the pain rather than assuming that every case is an ordinary ankle sprain.

Key Takeaways

Sinus tarsi syndrome describes pain in a small space on the outer side of the hindfoot.
Previous ankle sprains, subtalar joint instability, repetitive loading, and other joint conditions may contribute.
Symptoms can include local tenderness, pain on uneven surfaces, and a feeling that the foot is giving way.
Clinical examination helps distinguish sinus tarsi pain from tendon, ligament, bone, and joint problems.
Physiotherapy may include progressive strengthening, balance training, and functional rehabilitation.
Recovery varies according to the underlying cause, severity, and response to treatment.

Where Is the Sinus Tarsi Located?

The sinus tarsi is a small, tunnel-like space between the talus and calcaneus, the two bones that form part of the hindfoot.

It lies on the outer side of the foot, just in front of and below the outer ankle bone.

This space contains fatty tissue, blood vessels, nerves, and ligaments that help support the subtalar joint.

This joint allows the foot to adapt to uneven surfaces by moving inward and outward.

Sinus tarsi syndrome is a clinical term for pain in this region.

It does not necessarily mean that one particular structure is damaged.

A critical review by Willegger explains that sinus tarsi pain can arise from several different problems, including ligament injury, joint instability, inflammation, and impingement. (Willegger et al., 2023)

What Causes Sinus Tarsi Syndrome?

Symptoms can develop after an injury or gradually because of repeated loading on the foot and ankle.

Previous ankle sprains

An ankle sprain can affect ligaments that support the ankle and subtalar joint.

If these structures do not recover adequately, pain or instability may continue after the initial swelling settles.

Repeated sprains may increase the likelihood of persistent symptoms.

Subtalar joint instability

The subtalar joint helps the foot adapt to different surfaces.

If its supporting structures are injured or movement is poorly controlled, the sinus tarsi region may become painful during walking, running, or turning.

Some people describe this as their ankle giving way, even when they have not sustained another sprain.

Repetitive loading and sports

Running, jumping, cutting movements, and sudden changes in direction place repeated demands on the hindfoot.

Symptoms may develop when the foot cannot tolerate the current activity level or training load.

Foot alignment and biomechanics

Foot posture influences how forces travel through the hindfoot.

Certain alignment patterns may contribute to symptoms when combined with instability, irritation, or another underlying problem.

However, pronation is a normal part of foot movement.

It should not automatically be considered the cause of pain or treated as a problem on its own.

Other joint conditions

Subtalar arthritis, inflammation, scar tissue, and bony impingement can also produce pain around the sinus tarsi.

A scoping review by Arshad found that sinus tarsi syndrome covers a range of underlying conditions and that the evidence supporting specific diagnostic methods and treatments remains limited. (Arshad et al., 2020)

Symptoms You Should Recognize

The most characteristic symptom is tenderness on the outer side of the hindfoot, in the hollow just in front of and below the outer ankle bone.

Other symptoms may include:

Pain when standing or walking for long periods.
Discomfort on uneven ground, slopes, or stairs.
A feeling that the ankle or hindfoot is unstable.
Pain during side-to-side movements or quick turns.
Reduced confidence when balancing on the affected leg.
Symptoms that return when running or playing sports.

Some people mainly notice pain during weight-bearing activities, while others experience discomfort during particular foot movements.

These symptoms are not unique to sinus tarsi syndrome.

Persistent pain should be assessed rather than diagnosed by location alone.

Is It Sinus Tarsi Syndrome or Another Ankle Problem?

Several conditions can cause pain around the outside of the ankle. Distinguishing between them helps guide treatment.

Possible condition	Clues that may help distinguish it
Sinus tarsi pain	Tenderness in the hollow below and in front of the outer ankle bone
Lateral ankle sprain	Pain and tenderness around the outer ankle ligaments, often after the foot rolls inward
Peroneal tendon disorder	Pain along the tendons behind the outer ankle bone or along the outer foot
Osteochondral lesion of the talus	Persistent deep ankle pain, sometimes with swelling, catching, or discomfort during loading
Subtalar arthritis	Pain and stiffness during hindfoot movement, particularly on uneven surfaces

These patterns can overlap, and more than one problem may be present. The comparison is a guide, not a way to diagnose yourself.

How Is Sinus Tarsi Syndrome Diagnosed?

Diagnosis usually begins with a detailed history and physical examination.

A clinician will ask about previous sprains, sporting activities, the location of pain, and episodes of the foot giving way.

Physical examination

A physiotherapist or clinician may assess:

Tenderness around the sinus tarsi.
Ankle and subtalar joint movement.
Ligament stability and foot alignment.
Walking pattern and tolerance for weight-bearing.
Calf strength, single-leg balance, and movement control.

The assessment helps determine whether the symptoms are more consistent with instability, a tendon problem, joint irritation, or another cause.

When is imaging needed?

Imaging may be appropriate if symptoms persist, the diagnosis is uncertain, or a more significant injury is suspected.

X-rays can help identify fractures, alignment problems, and some arthritic changes.
MRI can assess ligaments, soft tissues, inflammation, cartilage, and other potential causes of hindfoot pain.
CT scans may be useful when a bony abnormality needs closer assessment.

Khan describe MRI as an important method for examining the sinus tarsi and identifying possible causes of pain in this region.(Khan et al., 2023)

An MRI finding alone does not always confirm the cause of symptoms. Imaging needs to be interpreted alongside the person’s history and clinical examination.

Physiotherapy for Sinus Tarsi Syndrome

Physiotherapy aims to reduce aggravating loads, restore comfortable movement, and improve the strength and control needed for daily activities.

The programme should be tailored to the underlying cause, particularly when instability or another structural injury is present.

1. Modify activities that trigger pain

Temporarily reduce activities that repeatedly worsen symptoms, such as running on uneven ground, jumping, or rapid changes in direction.

Complete rest is not always necessary.

Comfortable walking and other tolerable activities can often continue, provided they do not cause a significant or lasting increase in symptoms.

Supportive footwear, taping, or an ankle brace may help selected patients.

A physiotherapist can assess whether these options are appropriate.

2. Restore comfortable ankle movement

Gentle ankle movements may help maintain mobility when stiffness is present.

The type and range of movement should depend on the injury and examination findings.

Avoid repeatedly forcing the foot into positions that produce sharp pain around the sinus tarsi.

3. Build strength gradually

When tolerated, rehabilitation may include:

Calf raises to improve calf strength and pushing-off ability.
Resistance-band exercises to strengthen the muscles controlling ankle movement.
Controlled heel raises and step exercises to build tolerance for everyday loading.
Functional strengthening to prepare for walking, stairs, and eventually sporting activities.

Exercise selection and progression should reflect the person’s symptoms, strength, and movement quality.

4. Improve balance and foot control

Balance training is particularly relevant when the person reports instability or repeated ankle sprains.

A programme may progress from supported weight shifts to standing on one leg, reaching in different directions, and controlled stepping tasks.

More demanding exercises should be introduced only when simpler tasks are well tolerated.

Helgeson describes examination and rehabilitation strategies for sinus tarsi syndrome that include strengthening, proprioceptive training, bracing, and taping.

However, research specifically testing individual rehabilitation program for this condition remains limited. (Helgeson et al.,2009)

5. Return to running and sports gradually

Returning to sport too quickly may cause symptoms to recur, particularly if balance, strength, or subtalar stability has not recovered.

Before progressing to running, jumping, or cutting movements, the person should be able to walk comfortably and complete appropriate strength and balance tasks without a significant flare-up.

The progression should increase one demand at a time, such as duration, speed, or complexity.

Persistent giving-way episodes or recurring pain warrant reassessment.

Common Rehabilitation Mistakes to Avoid

Pushing through sharp pain: Pain that repeatedly worsens during an exercise is a reason to modify the movement and reassess the programme.

Returning to sport as soon as swelling settles: Swelling alone does not indicate that strength, balance, or joint control has recovered.

Treating every case as a simple sprain: Persistent pain may involve the subtalar joint, tendons, cartilage, bone, or other structures.

Assuming foot posture is the whole problem: Foot alignment is only one part of the assessment. Treatment should address the factors actually contributing to symptoms.

Doing balance exercises without progression: Balance work should become more challenging as control improves, rather than remaining the same exercise indefinitely.

Sinus Tarsi Syndrome: Myth vs Fact

MYTH: All outer ankle pain is a sprain.

FACT: Pain in this region can also involve the subtalar joint, peroneal tendons, cartilage, bone, or other structures.

MYTH: An MRI alone confirms the diagnosis.

FACT: Imaging findings need to be interpreted alongside symptoms and clinical examination.

MYTH: Rest is the only treatment needed.

FACT: Depending on the cause, recovery may also require progressive strengthening, balance training, and movement-control exercises.

MYTH: Everyone recovers in the same amount of time.

FACT: Recovery depends on the underlying condition, severity, activity demands, and response to treatment.

How Long Does Recovery Take?

There is no single recovery timeline for sinus tarsi syndrome because the term covers different underlying problems.

Milder symptoms may improve over several weeks with appropriate activity modification and rehabilitation.

Persistent instability, recurrent sprains, significant ligament injury, or joint disease may require several months of treatment or specialist assessment.

Progress should be judged by function, not just the number of weeks since symptoms began.

Comfortable walking, improved balance, better strength, and tolerance for increasingly demanding activities are useful milestones.

If symptoms repeatedly return, the diagnosis and rehabilitation plan may need to be reviewed.

When Should You Seek Medical Attention?

Arrange an assessment if pain on the outside of the ankle persists, repeatedly returns after sprains, or is accompanied by a feeling that the foot is giving way.

Seek urgent medical attention after an injury if you cannot bear weight, have severe pain, develop marked swelling or deformity, or notice a cold, pale, or numb foot.

A hot, red, swollen joint accompanied by fever also requires prompt assessment.

These symptoms may indicate a fracture, significant injury, infection, or another condition that needs care beyond routine rehabilitation.

Lesser-Known Facts About Sinus Tarsi Syndrome

Pain may remain after the original sprain appears to have healed. Ongoing irritation or instability can persist even after visible swelling settles.

The subtalar joint matters as much as the ankle joint. The subtalar joint helps the foot adapt to uneven surfaces, so assessing only ankle movement may miss relevant problems.

An MRI does not tell the whole story. Imaging can reveal abnormalities, but these must be matched to symptoms and examination findings.

Rehabilitation should reflect the cause. A person with instability may need progressive balance and strength training, while someone with a different underlying joint or bone problem may need a different approach.

Final Thoughts: Don’t Ignore Persistent Ankle Pain

Sinus tarsi syndrome is one possible explanation for pain on the outer side of the hindfoot, particularly after an ankle sprain or when walking on uneven surfaces causes discomfort or instability.

The most useful next step is to identify the underlying cause. A tailored physiotherapy programme may help restore strength, balance, and confidence, while persistent or worsening symptoms may require further medical investigation.

Remember: recurring ankle pain deserves a proper assessment. The right rehabilitation plan should address the cause of your symptoms, not just the location of the pain.

Final Thoughts

Sinus tarsi syndrome is one possible explanation for persistent pain on the outer side of the hindfoot, particularly after an ankle sprain or when walking on uneven ground causes discomfort or instability.

The most useful next step is to identify what is causing the pain.

A tailored physiotherapy programme may help restore strength, balance, and confidence, while persistent or worsening symptoms may require further medical investigation.

Frequently Asked Questions

1. Can sinus tarsi syndrome occur without an ankle sprain?

Yes. Although it often follows an injury, repetitive loading, joint irritation, arthritis, and other conditions may also cause pain in this region.

2. Does sinus tarsi syndrome always require an MRI?

No. A clinical assessment may be sufficient initially. MRI may be recommended when the diagnosis remains unclear, symptoms persist, or another injury is suspected.

3. Can physiotherapy help sinus tarsi syndrome?

Physiotherapy may improve strength, balance, movement control, and activity tolerance when these factors contribute to symptoms. Treatment should be tailored to the underlying cause.

4. Should I continue walking if my ankle hurts?

Comfortable walking may be possible, but reduce activity if pain increases significantly or remains worse afterwards. Severe pain or difficulty bearing weight requires medical assessment.

5. Can sinus tarsi syndrome return?

Yes. Symptoms may recur if the underlying problem persists or activity increases too quickly. Appropriate strengthening, balance work, and gradual return to activity may help reduce recurrence risk.

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Medical Disclaimer

This article is for general educational and informational purposes only. It does not replace professional medical advice, diagnosis, or individualised physiotherapy. Persistent ankle pain, recurrent instability, or difficulty bearing weight should be assessed by a qualified healthcare professional. Seek urgent medical attention for severe pain, significant deformity, a cold or numb foot, or a hot, red, swollen joint accompanied by fever.