Sinus tarsi syndrome is a clinical disorder characterised by specific signs and symptoms localised to the opening on the outside of the foot between the ankle and heel bone. Sinus tarsi means “eye of the foot” and disorders in the region are also referred to as Sinus Tarsitis.
First described by Denis O’Connor in 1957. He also described a surgical procedure to address this problem (called the O’Connor procedure) that involves removal of all or a portion of the contents of the sinus tarsi.
The most common cause of the syndrome is following an inversion ankle sprain (70-80% of the time). Less commonly, sinus tarsitis may be due to an impingement or “pinching” of the soft tissues in the region from an over-pronating foot (20-30% of the time).
Patients present with localised pain to the sinus tarsi region with a feeling of instability and aggravation by weight bearing activity. These patients do poorly on uneven surfaces, i.e. grass and gravel. Physical examination reveals pain on palpation of the sinus tarsi with symptoms being aggravated on foot inversion and/or eversion. Further instability of the adjacent ankle and foot joints may also be present.
May include x-rays, bone scan, CT scan and MRI evaluation. Injection with local anesthetic is diagnostic for localising this problem to the sinus tarsi. Often this is an issue made found via differential diagnosis as definitive diagnostic findings are rarely present, therefore more common foot and ankle problems should be excluded first. MRI is probably the most accurate tool to view changes in the tissues of the sinus tarsi involving either inflammation or scar tissue from previous injury. Ankle arthroscopy may also be beneficial to directly evaluate the sinus for damaged tissue.
Once the diagnosis has been confirmed, conservative treatment may be initiated, which is generally very effective in eliminating the problem. Treatment may include anti-inflammatories, stable footwear, a brief period of immobilisation, ankle sleeves and over-the-counter orthoses. Cases that persist may require a course of oral steroids, a series of steroid injections, physical therapy or custom orthoses. Rarely is surgery indicated and if required, open surgery (through an incision) or closed surgery (via arthroscopy) can be considered. Excellent results should be expected but surgery is not a panacea and should be considered as a last resort.