Sinus Tarsi Syndrome

Introduction

The sinus tarsi are a tube between the bone talus and calcaneus. Many connective tissues fill the sinus tarsi gap, contributing to the ankle's stability and overall proprioception. The area is filled with adipose tissue, which acts as a cushion for many mechanoreceptors and free nerve terminals, which, together with the ligaments and muscles, offer proprioceptive information on foot and ankle movement.

When injury or pain occurs in this region, it is known as sinus tarsi syndrome. The common cause of this syndrome is injury to the ankle or foot or overuse of the region due to long-standing or walking. Non-invasive treatment methods are used to treat this condition, which can help with the symptoms and can help with complete recovery. In some rare cases, surgery may be required to deal with the condition.

What Are the Causes of Sinus Tarsi Syndrome?

Some common causes are

• The sinus tarsi syndrome is most commonly caused by a traumatic lateral ankle sprain or multiple ankle sprains (primarily due to a weak anterior talofibular ligament), which results in interosseous and cervical ligament damage.

• This condition can be caused by bleeding or inflammation of the sinus tarsi, irrespective of whether with or without ligament tears.

• Some cases occur due to supination, where the person puts all their weight outside the foot while walking and running. Ankle sprains or ankles rolling outward cause 70 to 80 percent of cases of sinus tarsi syndrome.

• The remaining 30 percent of the syndrome is caused by excessive foot pronation or rolling inward.

• In some rare cases, it can affect people who have flat feet, which is a condition where there is an absence of an arch or the arch present is very low. When this happens, the person exerts excess pressure on the subtalar joint, which results in enhanced pressure over the soft tissues of the ankle, causing inflammation.

Other potential causes include:

• Subtalar joint arthritis and joint instability.

• Scar tissue is caused by frequent damage to the area.

This condition is mostly induced by synovitis and fibrotic tissue infiltration into the sinus tarsi space as a result of subtalar joint instability caused by ligamentous injuries. Sinus tarsi syndrome can also occur as a result of a compression injury, such as in patients with flat or pronated feet. As a result of the deformation, the talus and calcaneus are forced together. This results in talus and calcaneus bone-to-bone contact, as well as sinus irritation or arthritis.

What Are the Common Symptoms of Sinus Tarsi Syndrome?

Some common symptoms are

• It causes pain in the back of the foot.

• Swelling can be seen in the hollow space between the ankle and heel bones. Sometimes, the swelling can be so significant that it resembles a cyst or tumor.

• The person feels unstable and worsens the symptoms while standing, walking, or exerting pressure over the ankle.

• Symptoms should frequently be distinguished from subtalar joint pain caused by subtalar joint arthritis.

• In general, one should see the doctor to confirm the diagnosis of sinus tarsi syndrome. Other causes of ankle discomfort must be ruled out. Ankle joint arthritis, peroneal tendonitis, and lateral ligament sprain are a few examples.

How Is Sinus Tarsi Syndrome Diagnosed?

This diagnosis of this condition is usually carried out by excluding other foot conditions.

• CT (computed tomography) is suggested, which can be used to eliminate bone fracture, but this will not be enough to diagnose sinus tarsi syndrome.

• Usually, doctors recommend MRI (Magnetic Resonance Imaging), which helps to find the sinus tarsi space and the presence of any fluid or scar tissue, changes in the ligament structures, and any degenerative alterations in the subtalar joint.

• MRI (magnetic resonance imaging) is considered the best way to find the sinus space and to see the structure within the space. This also helps visualize changes in the interosseous structures and cervical ligaments.

• The results of the cadaveric investigation suggest that MR arthrograms, both original and reconstructed, along and perpendicular to the ligament axes may be helpful for additional assessment of specific tarsal sinus structures.

How Is Sinus Tarsi Syndrome Treated?

Usually, sinus tarsi syndrome is treated through non-surgical methods, which usually have a positive effect on the condition. The non-surgical treatment modalities are

• Non-steroidal Anti-inflammatory Drugs (NSAIDs):

These drugs are used to reduce the pain and inflammation caused. They can be prescribed medicine or over-the-counter drugs, such as topical gels, and medications.

• Supportive Devices:

If the joint is affected, these devices help to mobilize the joint, give support for walking, and prevent any further injury to the joint. Braces, shoes, and medical boots are some of the devices used. The doctors or physiotherapists usually recommend slippers or boots, which may provide better arch and support to the ankle.

• Steroids:

Steroids help to reduce inflammation, which in turn reduces the pain in the affected area. Steroids are usually given as injections. This way of treatment will be done when all other methods do nothing good.

Surgical Treatment:

Surgical treatment methods are advised by doctors only when the sinus tarsi syndrome is very severe, or the syndrome does not improve with non-surgical treatment methods. Surgical methods include

• Removal of Scar Tissue:

In this method, the doctor will eliminate the sacred tissues from the region using an invasive technique called arthroscopy.

• Flatfoot Surgery:

If sinus tarsi syndrome is caused due to flatfoot, then sinus tarsi syndrome should be operated on. The doctor may use various modalities to change the bone, ligaments, and other structures supporting the bone.

• Subtalar Fusion:

Subtalar fusion will be required when the subtalar arthritis causes discomfort. If the joint cannot be replaced, the doctor may recommend subtalar fusion, where the joint is fused or locked together.

Before any treatment, consultation with the doctor is required as they may guide the person to regain the pros and cons of surgical and non-surgical treatment methods.

What Is the Differential Diagnosis of Sinus Tarsi Syndrome?

Frequent illnesses that may cause similar pain sensations or characteristics like sinus tarsi syndrome are:

• Sprain of the ankle.

• Fracture of the calcaneus.

• Fracture of the talus.

• Tendonitis of the peroneal tendon.

• Arthritis of the subtalar joint.

• Tarsal tunnel syndrome.

The appearance of ankle instability and pain localized to the sinus tarsi is a solid indicator that the patient has STS. The cessation of symptoms after injection of lidocaine into the sinus tarsi has traditionally been used to confirm the diagnosis of STS.

What Are the Complications Associated With Sinus Tarsi Syndrome?

Complications associated with sinus tarsi syndrome are:

Subtalar joint instability due to injuries that cause synovitis and the production of scar tissue in the sinus tarsi. Although these issues are resolved with nonsurgical treatment, subtalar arthroscopy has been linked to consequences including neuritis, sinus tract development, and superficial wound infection.

How Does Sinus Tarsi Syndrome Get Recovered?

When a non-surgical or conservative method is chosen to correct the condition, it may take several weeks to recover. People who undergo surgeries will also need several weeks to recover completely. In rare cases, it may take months to recover back to sporting activities. The type of surgery done will have an impact on the recovery time. When flatfoot surgery is performed, the patient should not put any weight for at least six to eight weeks post-surgery. They can exert weight after ten to 12 weeks. After 12 weeks, the person can go with ordinary shoes, but the ankle needs to be immobilized, and complete recovery takes about one to two years.

Post-surgery, the patient should clarify things with the doctor, such as how to take care of the affected region and when they can return to normal activities. If no proper care is taken, the recovery time may be long, and the injury may worsen.

When to Visit a Doctor?

The person should visit the doctor when

• The symptoms do not show any improvement.

• Medications and rest do not do any good.

• The person experiences unbearable pain and cannot do any regular activities.

Conclusion

An injury to the hollow space between the ankle and the heel bone causes sinus tarsi syndrome. This is usually characterized by pain and swelling seen beneath the ankle joint. This syndrome is usually caused by injury to the ankle, such as a sprain. This condition can be treated better with non-surgical methods, but doctors recommend surgical methods in severe cases that do not respond to non-surgical treatment.