Sinus Tarsi Syndrome

What is Sinus Tarsi Syndrome?

Sinus tarsi syndrome is a consequence of excessive movements of the subtalar joint (talocalcaneal joint). It leads to the onset of subtalar joint synovitis as well as infilitration of fibrotic tissue into the sinus tarsi space.

Sinus tarsi syndrome represents a clinical disorder characterized by the presence of anterolateral ankle pain. It is caused by the traumatic injuries to the ankle.⁽¹⁾

The sinus tarsi represents an anatomical space in the foot that is surrounded with the talus and calcaneus bones, the talonavicular and posterior subtalar joint. The sinus tarsi consists of fatty tissue, arterial vessels, joint recesses at the posterior side, nerve fibers and five ligaments.

The ligaments of sinus tarsi are lateral, intermediate, medial parts of the inferior extensor retinaculum, the cervical ligament and the interosseus ligament.

Etiopathogenesis

The sinus tarsi syndrome is caused by a traumatic event or a concomitant ankle distortions. Such injuries lead to the severe impairment of the talocrural interosseus and cervical ligaments.

Consequently, there is an instability of the subtalar joint that leads to overexpressed supination and pronation in this ankle. In that case, there is higher pressure on the sinus tarsi space and its the corresponding tissues.

The overforced subtalar joint and synovitis associated with chronic inflammatory process along with the fibrous infiltration are the characteristics of anterolateral ankle pain in the sinus tarsi syndrome.

Additionaly, such injuries may lead to the more severe impairment of the tibiotalar and talocalcaneal joints that lead to increased mobility and instability of the foot in general. In athletes, there is an increased risk for the onset of instability following an ankle injury.

The most commonly reported mechanism of the injury is after a jump or fall leading to a whiplash type of injury. In such case, there is the movement of talus anteriorly and over the calcaneus.

Anatomy

The subtalar joint consists of the articulation of the talus and calcaneus on the anterior, middle and posterior surface. There are supportive external and internal ligaments that provide static stability for the subtalar joint. External ligaments are the calcaneofibular and the deltoid ligament. They stabilize the talocrural joint.

Of the internal ligaments, there are the talocalcaneal, interosseuous and cervical ligament.

In case of the ruptured internal ligaments, movement of the subtalar joint is impaired and leads to the instability. In case of supination and pronation of the subtalar joint, such movement is impaired and causes additional damage.

The sinus tarsi space is comprised of various connective tissues that stabilize the subtalar joint. Its adipose tissue consists of various mehanoreceptors and nerve fibers for the adequate proprioceptive sensations. In the sinus tarsi space there are numerous vascular anastomoses of the tarsal canal arteries.

The extensor digitorum brevis muscle is attached to the medial, lateral and distal portion of the sinus tarsi space. It crosses over the calcaneocuboid joint.

The inferior extensor muscle portions are positioned over the lateral parts of the sinus tarsi space and are its surface cover.

Signs And Symptoms

The major symptoms of the sinus tarsi syndrome are lateral pain foot, local pain at the site of palpation – mostly over the tarsal sinus and foot instability.

The sinus tarsi syndrome is a consequence of previous inversion injurie type of the lower extremity. The most accurate diagnostic modality is the use of magnetic resonance (MRI) in the investigation of corresponding pathological findings.

The most prominent clinical signs are localised pain in the region of the sinus tarsi if applied pressure force. In case of more severe symptoms, there is a laterla opening of the sinus tarsi.

In case of an acute ankle injury, clinical signs are pain, swelling, ecchymosis and tenderness in the anterolateral parts of the ankle.

Diagnosis

The thorough physical examination of the talocrural and subtalar joint is of vital importance. It is necessary to detect the signs of hypermobility of the corresponding extremities.

The most prominent signs of the sinus tarsi syndrome are discomfort of sinus tarsi space and feeling of instability in combination with pronatory and supinatory movements of the subtalar joint. ⁽²⁾

There are certain tests for the sinus tarsi syndrome and the subtalar joint. In order to investigate talocrural joint stability, a talar tilt test may be performed along with the anterior and posterior parts of the talus. ⁽³⁾ Additionally, mobility of the contralateral ankle may be investigate to assess whether the individual has increased joint mobility.

The stability test is performed with the individual in supine position of the ankle in 10 degrees of dorsiflexion, holding the talocrural joint in a stable position. The foot is then stabilized with the physician’s hand, while an inversion and internal rotational pressure is applied to the calcaneus.

Additional diagnostic imaging may be required in order to asses the stabilitz of the subtalar joint. Radiographic imaging is performed according to Boden stress views that represents a series of oblique- laterally conducted imagingof the ankle and foot.

Stress fluoroscopy allows the visualization of the movements of the subtalar joint with the application of low level radiation^{, (4)}

Magnetic resonance imaging represents the most accurate method so far in the visualization of the structures within the interosseus and cervical ligaments.MRI findings may include degenerative changes in the subtalar joint and corresponding ligaments.

he most accurate diagnostic approach is the injection of local anaesthetic followed by the absence of pain.

Treatment

The most important is to direct medical treatment to stabilize subtalar joint and the overall function of the lower extremities.

Rehabilitation

It is recommended to continue physical rehabilitation with balance and proprioceptive training to strenghten muscles. The application of ankle braces, shoes, taping and foot orthosis is also advisable in selected cases.

In case of no documented progress, there is a need to perform an arthroscopic exploration as well as the reconstruction of the subtalar joint. Nowadays, there is a possibility to perform a synovectomy of the subtalar joint, an arthrotomy in order to eliminate chronic synovitis and arthrofibosis.

The cervical and interosseus ligaments may be reconstructed by splitting the tendon of the peroneus brevis and applying the graft. A tri-ligamentous reconstruction is a procedure reserved for patients with the severe instability of the talocrural and subtalar joints. In individuals with constant debilitating symptoms there is a need for arthodesis. ⁽⁵⁾

REFERENCES

1. Pisani G et al. Sinus tarsi syndrome and subtalar joint instability.Clin Podiatr Med Surg. 2005 Jan;22(1):63-77, vii.
2. Kevin Helgeson. Examination and Intervention for Sinus Tarsi Syndrome.N Am J Sports Phys Ther. 2009 Feb; 4(1): 29–37.
3. Hale SA, Hertel J. Reliability and sensitivity of the Foot and Ankle Disability Index in subjects with chronic ankle instability. J Athl Train. 2005;40:35–40
4. Hertel J, Denegar CR, Monroe MM, Stokes WL.Talocrural and subtalar joint instability after lateral ankle sprain.Med Sci Sports Exerc. 1999 Nov;31(11):1501-8.
5. Magee DJ, Zachazewski JE. Principles of stabilization training. In: Magee DJ, Zachajewski JE, Quillen WS, editors. Scientific Foundations and Principles of Practice in Musculoskeletal Rehabilitation. St. Louis: Elsevier; 2007: 388–413