Sinus Tarsi Syndrome

The sinus tarsi synovectomy is a treatment for a condition known as sinus tarsi syndrome. Sinus tarsi syndrome comes from having excessive motion of the subtalar joint where it connects with the calcaneus.

What is Sinus Tarsi Syndrome?

Sinus tarsi syndrome is a condition that is derived from too much motion of the subtalar joint so that the joint develops subtalar joint synovitis and fibrous tissue into the sinus tarsi space. There is localized discomfort in the ankle along with a sense of instability of the ankle. There is excessive pronation and supination of the subtalar joints.

The sinus tarsi syndrome is almost always associated with traumatic ankle injuries. It causes pain in the front and side of the ankle, leading to instability of the subtalar joint. It leads to synovitis of the joint and the infiltration of the joint with fibrous tissue.

The subtalar joint is made up of the talus and calcaneus, joint together with cartilage and ligaments in the lower ankle. There are three facets associated with the joint: the anterior, middle and posterior facets. There are intrinsic and extrinsic ligaments that make the joint stable at rest. The joint helps with pronation and supination of the foot.

The sinus tarsi syndrome can come out of just one traumatic event or out of several ankle sprains the damage the talocrural interosseous and cervical ligaments. The instability allows for excessive pronation and supination of the ankle. It puts too much force on the synovium, causing synovitis. Other ligaments of the ankle joint can be affected, such as the tibiotalar and talocalcaneal joint ligaments. With this increased instability, there is an increased risk for ankle sprains and worsened instability of the affected ankle.

It is estimated that up to twenty-five percent of the patients with chronic talocrural injury also have problems with the subtalar joints. It is also estimated that 9 out of 12 patients with several ankle sprains also had evidence of instability as seen on x-ray.

The following are the major findings in sinus tarsi syndrome:

  • Tears of the interosseous talocalcaneal ligament
  • Osteochondral joint injures involving the subtalar joint
  • Instability of the subtalar joint
  • Fibrosis infiltrating the subtalar joint
  • Degeneration of the subtalar joint
  • Coalition of fibrotic tissue of the subtalar joint
  • Inflammation of the sinus tarsi connective tissue
Signs and Symptoms of Sinus Tarsi Syndrome

Most patients with STS will admit to a traumatic injury to the ankle, particularly a supination and inversion injury. This can occur as a result of a motor vehicle accident or a sports injury, among other causes. A sudden planting of the foot results in a “whiplash injury” that occurs to the back of the foot with the talus sliding anteriorly over the calcaneus. There will be bruising, swelling and tenderness along the anterior and lateral side of the foot. It takes time for the fibrotic tissue infiltration and synovitis to occur so the injury may be felt as a minor injury in the beginning.

There will be instability when walking on uneven ground or when stepping off a curb.

Running and sprinting will be hard. Athletes that have to jump on the court or field will definitely feel instability of the subtalar joint. They will point to the subtalar space and will describe the pain as being deep in the ankle. The doctor will examine the foot and ankle, sometimes finding instability and sometimes not finding instability.

The doctor may be able to reproduce the feeling of instability of the ankle by having the patient stand on the affected side and rotate the leg or foot in order to see if the patient feels unstable. In other cases, the activities of walking, stepping down, running, and hopping can duplicate the symptoms. There is an index called the Ankle

Disability Index that looks at what the patient can and cannot do because of the injury.

Causes of Sinus Tarsi Syndrome

There are several causes of sinus tarsi syndrome. They include:

  • Motor vehicle accident
  • Suffering a severe sprained ankle
  • Having multiple sprained ankles
  • Sports injuries with ankle sprain
Diagnosis of Sinus Tarsi Syndrome

Plain film x-rays do not usually show the injury. Stress fluoroscopy, in which the joints are stressed under ongoing x-ray filming, will show instability of the subtalar joint. The advantage of doing fluoroscopy is that the doctor can use low level radiation to stress the joint in exactly the same way that it is stressed when it causes the injury.

An MRI is perhaps the best method of detecting problems with the subtalar joint.

There is a bright signal visualized on images located in the area of the fatty tissue of the sinus tarsi. It shows up there because the normal tissue has been replaced by fibrosis and inflammatory cells. The MRI might also show damage to the cervical ligament and the interosseous ligament.

Treatment of Sinus Tarsi Syndrome

There is a rehabilitation program for sinus tarsi syndrome that includes balance training, proprioceptive training, bracing, taping, muscle strengthening exercises and the use of a foot orthoses. Improvements are usually seen in the athlete’s joint position sense, balance and in his or her functional ability of the joint. Some athletes still go on to have synovitis of the joint and will need to use nonsteroidal anti-inflammatory medications to ease the inflammation. Ice to the affected area seems to work well, too.

Orthotic devices have been used on STS patients with some success. They may work better for everyday activities and less so for sporting events. The orthoses help limit the movement about the joint and improve symptoms. The types of shoes worn in athletics should be taken into consideration because they need to restrict movements of the rear foot. There are specialized shoes that can protect the joint during practices and competition. There are taping techniques that can limit mobility of the subtalar joint as well.

There are training programs that improve the stability of the ankle joints. These improve the strength of the muscles that cross over the subtalar joint. Endurance of these muscles is vital for the ongoing stability of the subtalar joint over the course of a game or practice. Training programs for this type of injury are multiphasic and begin at a low level, increasing the intensity of the training as time goes on. There are three phases to training: 1) attain, 2) maintain, and 3) sustain. Attaining will help decide the postures that are already stable. Maintaining means developing the strength of the muscles that cross over the joint. Sustaining involves the integration of all the neuromuscular abilities needed to keep the joint stable during sports specific activities.

When the athlete can move in all directions at all necessary speeds, he or she may return to play. Cutting and jumping maneuvers, such as are done in volleyball and basketball should really wait until the ankle is stable before returning to play. If not treated properly, chronic inflammation will set in the sinus tarsi tissues.

There is surgery to treat chronic inflammation of the synovium and fibrous tissue within the joint.

Surgery can be done to control the disease process. One of these is a sinus tarsi synovectomy, in which the inflamed tissue is removed, usually with an arthroscope. Another procedure is an arthrotomy of the subtalar joint. It gets rid of the excess fibrosis that has built up in the course of the disease. Patients can have surgical correction of the interosseous ligament and the cervical ligament, which is done by splitting the tendon of the peroneus brevis muscle and bringing the graft to where the interosseous and cervical ligaments lie. Some people need three ligamentous repairs.

In severe cases, the patient needs a fusion of the subtalar joint but this is reserved for severe cases after the ligamentous reconstruction fails to control the pain and instability.

Complications of Sinus Tarsi Syndrome

Patients who do not get proper treatment or who have treatment that fails will have the following complications:

  • Chronic pain in the affected ankle and foot
  • Instability of the ankle when planting the foot
  • Chronic inflammation in the subtalar joint
  • Scar tissue within the joint

If you or a loved one has suffered Sinus Tarsi Syndrome as a result of someone else's negligence and would like to discuss your legal options with an experienced Sacramento Personal Injury Attorney, contact us online or call us at 916-921-6400 or toll-free at 800-404-5400 to set up a FREE consultation.

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