What is the sinus tarsi?

The foot is made up of 26 bones (producing 33 joints), all of which work together to provide a strong, secure, and flexible foundation that allows us to interact with the world around us with ease.

The sinus tarsi is an anatomical tunnel (see image below) formed by two bones: the talus and the calcaneus (which together also create the subtalar joint). It’s on the outside of your foot, just in front of your enormous bony hump (called the lateral malleolus), and it goes all the way down into your foot.

During inversion and eversion motions, the sinus tarsi offers support to the joints of the back foot. It’s made up of adipose (fat) and connective tissue, as well as nerve endings and proprioceptive cells (cells that help with balance and stability by providing a sense of body position) (Helgeston et al., 2009).

What is sinus tarsi syndrome?
Pain over the tunnel’s entrance on the anterolateral aspect (outside) of the ankle is a symptom of sinus tarsi syndrome. Due to the large amount of nerve endings within the area, it is capable of producing substantial discomfort and ankle instability (weakness)


A thin membrane surrounds the sinus tarsi, which is used to decrease friction caused during ankle and foot motions. This membrane is known as the synovial membrane, and it is filled with synovial fluid, a lubricating fluid. Synovitis results when the synovial membrane becomes inflamed and swollen, leading in Sinus tarsi syndrome. Prolonged walking, standing, and running might increase the pain.

The real cause of sinus tarsi syndrome remains unknown. There are, however, a number of risk factors linked to the start of this illness.
These are some of the risk factors:

  • A substantial single traumatic event/injury – study has revealed that ankle ligament rips are connected with the start of sinus tarsi syndrome in a high percentage of cases (43 percent) (Lee et al, 2008).
  • Multiple/repetitive ankle sprains – ligaments have a low blood supply and can thicken and become damaged if injured repeatedly. Impingement (pinching) within the sinus tarsi can be caused by a chronically thickened ligament (Lee et al, 2008)
  • Excessive compression in the sinus tarsi causes a pronated foot arch (flat feet) (image below)
  • General joint laxity can predispose you to sinus tarsi syndrome if you have hypermobility syndrome.

What are the symptoms of sinus tarsi syndrome?
Sinus tarsi syndrome symptoms usually appear gradually over time and are frequently linked to a previous ankle injury that never fully healed.
The following are some of the most common symptoms of sinus tarsi syndrome:

  • On the outside of the foot, there is a deep burning or shooting sensation.
  • Touching the area on the outside of the ankle immediately in front of the ankle bone causes tenderness.
  • Walking, standing for lengthy periods of time, and jogging can all cause pain. 

How do we diagnose sinus tarsi syndrome?
A thorough clinical examination is required to diagnose sinus tarsi syndrome. It is critical to have an accurate and fast diagnosis in order to choose the most effective treatment for you.

A doctor, podiatrist, or physiotherapist can do a clinical assessment for sinus tarsi syndrome, which includes:

Clinical Interview:

To determine how and why you developed your pain, a clinical interview is conducted. Your doctor will inquire as to what activities aggravate or alleviate your symptoms. In order to uncover any other pertinent medical issues, a complete medical history will be taken.

The following items are included in the physical evaluation:

  • Ankle and foot structural evaluation (including assessing the arch of your foot)
  • Range of motion of the foot and ankle joints — when evaluating sinus tarsi syndrome, examining inversion and eversion of the ankle and sub-talar joint is especially important.
  • Strength testing of the calf and intrinsic foot muscles
  • The joints of the foot are palpated (felt).
  • Walking, single-leg balance, hopping, and running are examples of functional testing.

The diagnosis of sinus tarsi can be determined through a clinical examination. However, more imaging may be needed to confirm the diagnosis and rule out other causes of outer ankle pain.

Imaging for diagnostic purposes
Magnetic resonance imaging (MRI)

An MRI scan is the gold standard diagnostic method for identifying sinus tarsi syndrome, according to research (Lee et al., 2008). Helgeson and colleagues (Helgeson et al., 2009). An MRI scan, on the other hand, is an expensive and time-consuming treatment that requires you to lie still inside a metal cylinder for 30-60 minutes (see above image). From front to back, the MRI creates a series of images of your ankle. These slices produce a highly detailed 3D image that can be used to make an accurate diagnosis.

Ultrasound imaging of the musculoskeletal system for diagnostic purposes

Diagnostic musculoskeletal ultrasound imaging is an excellent imaging tool for evaluating sinus tarsi syndrome (Shields et al., 2003). Ultrasound imaging is useful for confirming the diagnosis of sinus tarsi and determining the extent of inflammation (known as’synovitis’). It can also determine whether there are any ligament injuries, ganglions (fluid-filled swellings from the sinus tarsi or surrounding a joint), or capsular swelling. If your problems are related to movement, such as soft issue impingement, ultrasound can be used to check the ankle and foot dynamically.

What is the best way to treat sinus tarsi syndrome?
The most common treatment for sinus tarsi syndrome is a course of physiotherapy.

The following are examples of physiotherapy interventions for sinus tarsi syndrome rehabilitation:

  • Advice on activity adjustment, that is, limiting the activities that aggravate your pain.
  • Increase ankle proprioception with balance and stability exercises.
  • Strengthening workouts for the calf and intrinsic foot muscles
  • Ankle taping to relieve discomfort and enhance ankle stability.
  • Orthotics (arch support) are available to help with back foot placement. In some circumstances, a referral to a podiatrist for bespoke orthotics may be required (Dugarte et al., 2016). (see image below)

Here are a few pointers you might want to try for yourself:

  • Avoid strenuous activity like jumping or running on uneven ground.
  • An ankle brace may help to stabilise the back foot and alleviate your pains.
  • Heel lifts and other calf strengthening exercises can help strengthen and stabilise your ankle muscles (see image below)
  • Balance training is one aspect of ankle stability. Practice standing on one leg.
  • Pain relief from osteoarthritis can be achieved with over-the-counter oral medications like paracetamol or ibuprofen, or a topical anti-inflammatory gel like Voltarol (talk to your pharmacist before taking medication)

What if conservative management isn’t successful? 
An ultrasound-guided corticosteroid injection can be a very successful therapy method in situations of persistent sinus tarsi pain where synovitis is the primary cause of symptoms.

Corticosteroid or steroid injections (a powerful, injectable anti-inflammatory medication) have been used to effectively relieve pain and inflammation in musculoskeletal medicine for decades. The corticosteroid injection provides pain relief for a period of time, giving you a ‘window of opportunity’ to effectively rehabilitate your ankle. Injections of corticosteroids should not be utilised as a stand-alone treatment. We feel that combining a corticosteroid injection with physiotherapy improves outcomes significantly.

Sinus tarsi syndrome is a condition that Joint Injections physicians are quite familiar with assessing and treating. Fully qualified independent prescribers, physiotherapists, musculoskeletal sonographers, and injectable therapists make up our highly skilled team. Your clinician will be able to analyse and diagnose your problem during your first appointment, as well as perform an ultrasound-guided injection if necessary. You don’t need a referral from your doctor. You can simply walk into the clinic and self-refer.

Surgical procedure

If both conservative management and injectable therapy fail to cure your symptoms, a referral to a foot and ankle orthopaedic physician may be necessary. Arthroscopy is a keyhole surgery that removes persistently thickened synovium (synovectomy) or fibrotic tissue (arthrofibrosis) from the sinus tarsi (Helgeston et al., 2009).

Joint Injection’s experts are dual-trained, highly specialised physiotherapists and musculoskeletal sonographers with extensive experience diagnosing all foot and ankle disorders. We provide a ‘one-stop’ clinic, which means you’ll get an examination, a diagnostic ultrasound, and, if necessary, an ultrasound-guided injection.