Sinus Tarsi Syndrome: Symptoms, Types, Causes and Treatment

Sinus Tarsi Syndrome (STS) is a condition of the foot that often goes unrecognized, yet it can cause persistent pain and instability that disrupts daily life and athletic performance. Understanding the symptoms, types, causes, and available treatments for STS is essential for patients and clinicians alike. In this article, we'll explore each aspect in detail, using the latest scientific evidence and clinical insights.

Symptoms of Sinus Tarsi Syndrome

Sinus Tarsi Syndrome can be elusive, often mistaken for other ankle or foot injuries. Recognizing its symptoms is the first step to effective management.

Symptom	Description	Frequency	Source(s)
Pain	Lateral ankle/hindfoot pain, worsens on palpation	Very common	1 3 4 5 7
Instability	Sensation of "giving way" in the hindfoot	Frequent	1 3 4 7
Swelling	Mild swelling over sinus tarsi area	Occasional	5 7
Aggravated by	Walking on uneven ground, pronation/supination	Common	1 3 4 7

Table 1: Key Symptoms

Pain and Tenderness

The hallmark of STS is a deep, aching pain over the anterolateral (front and outer) aspect of the ankle or hindfoot. This pain typically intensifies when the area over the sinus tarsi is pressed, or when the foot is subjected to side-to-side motion such as pronation or supination. Patients often report that pain increases with weight-bearing activities, especially when walking on uneven surfaces, and improves with rest 1 3 4 5 7.

Instability and "Giving Way"

Many individuals with STS describe a sensation of instability or the foot "giving way," particularly on uneven terrain. This subjective instability is a key feature that distinguishes STS from other ankle disorders. However, objective mechanical instability is often absent on examination 3 4 7.

Swelling and Functional Limitation

Some patients experience mild swelling around the sinus tarsi region. Additionally, activities such as sports, climbing stairs, or prolonged walking may become difficult due to pain and apprehension about foot stability 5 7.

Aggravating and Relieving Factors

Symptoms are commonly aggravated by walking on sloped or uneven ground, or during movements that stress the subtalar joint (pronation and supination). Relief is generally found with rest or when the foot is immobilized 1 3 4.

Types of Sinus Tarsi Syndrome

Sinus Tarsi Syndrome isn't a one-size-fits-all diagnosis. There are variations depending on the underlying pathology and clinical features.

Type	Defining Feature	Associated Pathology	Source(s)
Post-traumatic	Follows ankle/hindfoot injury (e.g., sprain)	Ligament tears, synovitis, fibrosis	1 3 10 11
Idiopathic	No obvious trauma; insidious onset	Synovial inflammation, cysts	5 6 13
Canalis Tarsi	Medial hindfoot pain + classic STS symptoms	Medial tarsal canal involvement	3

Table 2: STS Types

Post-Traumatic Sinus Tarsi Syndrome

This is the most common type, often developing after an ankle inversion injury or repeated sprains. Trauma leads to damage of the ligaments within the sinus tarsi (notably the interosseous talocalcaneal and cervical ligaments), resulting in chronic inflammation (synovitis), fibrosis, or instability of the subtalar joint 1 3 10 11.

Idiopathic or Non-traumatic Sinus Tarsi Syndrome

Some cases arise without any clear injury. Here, the syndrome may result from chronic overuse, biomechanical abnormalities, or degenerative changes. MRI may reveal synovial hypertrophy, cyst formation, or non-specific inflammation in these cases 5 6 13.

Canalis Tarsi Syndrome

A less common variant, canalis tarsi syndrome involves pain that extends to the medial aspect of the hindfoot in addition to the typical lateral symptoms. This occurs when the medial tarsal canal is involved, leading to a broader pain distribution 3.

Causes of Sinus Tarsi Syndrome

Understanding what triggers Sinus Tarsi Syndrome is vital for both prevention and targeted treatment.

Cause	Mechanism	Pathology Involved	Source(s)
Ligament Injury	Tears/sprains of subtalar ligaments	Synovitis, instability	1 3 6 10 11 12
Overuse/Biomechanics	Abnormal foot motion, excessive pronation	Chronic inflammation	1 5 7 14
Synovial Changes	Hypertrophy, fibrosis, cysts	Impingement, pain	6 10 13
Vascular/Nerve Issues	Venous congestion, nerve entrapment	Increased pressure, pain	7 8
Degenerative Changes	Arthritis, joint degeneration	Capsule thickening	7 13

Table 3: Causes of STS

Ligamentous and Soft Tissue Injury

The most widely recognized cause is injury to the ligaments that stabilize the subtalar joint, especially following an inversion sprain. Tears of the interosseous talocalcaneal or cervical ligaments lead to abnormal joint movement, synovial inflammation, and sometimes the development of fibrotic tissue within the sinus tarsi space 1 3 6 10 11 12.

Biomechanical and Overuse Factors

Faulty foot biomechanics—such as excessive pronation, flatfoot, or abnormal gait—can place repeated stress on the sinus tarsi, even without a distinct injury. Over time, this leads to chronic irritation, inflammation, and possibly subtle instability of the subtalar joint 1 5 7 14.

Synovial and Cystic Pathology

Chronic inflammation may result in synovial hypertrophy, fibrosis, or the formation of synovial cysts, all of which can occupy space within the sinus tarsi and cause impingement or pain 6 10 13.

Vascular and Neural Contributions

Disturbances in venous outflow, due to scarring or increased intrasinusal pressure, may contribute to pain. Entrapment of small nerves that traverse the sinus tarsi has also been proposed as a pain source in some cases 7 8.

Degenerative/Arthritic Causes

In older adults or those with chronic foot issues, degenerative changes in the subtalar joint or surrounding structures can lead to sinus tarsi syndrome through capsule thickening and joint space narrowing 7 13.

Treatment of Sinus Tarsi Syndrome

Fortunately, there are several effective management options for STS, ranging from conservative care to surgery.

Treatment	Approach	Indication/Goal	Source(s)
Physical Therapy	Strength, balance, proprioception training	All cases	1 4 7 14
Foot Orthoses	Correct abnormal biomechanics	Overuse/instability	4 7 14
Corticosteroid Injections	Local anti-inflammatory effect	Persistent symptoms	2 3 4
Activity Modification	Limiting aggravating activities	Early/conservative care	4 7
Surgery (Arthroscopy)	Debridement, synovectomy, ligament repair	Failed conservative care	10 11 12
Ankle Stabilization	Ligament repair/reconstruction	Chronic instability	12

Table 4: Treatment Options

Conservative (Non-Surgical) Management

The majority of patients with STS improve with conservative treatment. This typically includes:

• Physical therapy: Focused on strengthening the muscles around the ankle and improving proprioception to enhance joint stability and function 1 4 7 14.
• Custom orthoses: Shoe inserts can correct biomechanical abnormalities, offload the sinus tarsi, and reduce strain 4 7 14.
• Corticosteroid injections: Targeted injections into the sinus tarsi can reduce inflammation and provide rapid pain relief, often used as a first-line intervention for persistent symptoms 2 3 4.
• Activity modification: Temporarily reducing or modifying activities that provoke symptoms (such as running or walking on uneven ground) can allow healing 4 7.

Surgical Management

Surgery is reserved for cases that do not respond to conservative measures:

• Subtalar arthroscopy: Minimally invasive procedure allowing visualization and treatment of synovitis, fibrosis, ligament tears, or impinging tissue. Synovectomy and debridement are common interventions 10 11.
• Ligament repair or reconstruction: In cases of significant instability or chronic ligament damage, surgical stabilization of the ankle and subtalar joint may be necessary 12.
• Sinus tarsectomy: Resection of the sinus tarsi is rarely performed and typically reserved for recalcitrant cases 4.

Outcomes

Most patients respond well to conservative management, but those requiring surgery also tend to have good outcomes, with significant improvement in pain, function, and stability reported in recent studies 10 11 12.

Conclusion

Sinus Tarsi Syndrome is a complex, often misunderstood condition, but with careful assessment and a tailored approach, most individuals can regain comfort and function. Here is a summary of the main points:

• Symptoms: Lateral ankle/hindfoot pain, instability, pain on uneven ground, sometimes swelling.
• Types: Includes post-traumatic, idiopathic, and rarer forms like canalis tarsi syndrome.
• Causes: Most often due to ligament injury, but also from biomechanical, inflammatory, vascular, neural, or degenerative factors.
• Treatment: Starts with conservative care (physical therapy, orthoses, injections); surgery is reserved for persistent or severe cases.

A patient-centered, biomechanically informed evaluation is the key to identifying and effectively managing Sinus Tarsi Syndrome. If you or someone you know is struggling with persistent lateral ankle pain, don't overlook STS as a potential culprit—timely recognition and intervention can make all the difference.