Sinus tarsi syndrome

What is Sinus Tarsi Syndrome?

The sinus tarsi is a tunnel or funnel-shaped space on the outside between the ankle bone and the heel bone. It is lined with fatty tissue, nerve fibers, vessels, synovial tissue and parts of important ligament structures. If inflammation, scarring or irritation occurs there, it is called sinus tarsi syndrome. Stress-dependent pain in the front and side of the ankle joint is typical, with discomfort on uneven surfaces and a feeling of “bending”.

Anatomy and function

The subtalar joint between the talus and calcaneus controls the fine compensatory movements of the foot: supination/pronation and inversion/eversion. The sinus tarsi lies laterally between the anterior and posterior surfaces of this joint complex.

• Structures: Fat bodies (fat pads), synovial tissue, vessels/nerves
• Ligamentous apparatus: cervical ligament and talocalcaneal interosseum (stabilization of the subtalar joint)
• Function: Proprioception (depth sensitivity), shock absorption and guidance of the rear foot movement

After twisting injuries, micro-injuries, bleeding and scarring can occur in the sinus tarsi. These change the gliding ability and stimulus threshold of the tissue and promote pain and feelings of instability.

Causes and risk factors

• Acute inversion trauma (outward twisting) with injury to the ligamentous apparatus
• Repeated microtraumas in sports with changes of direction (e.g. football, handball, trail running)
• Hindfoot deformities (e.g. pes planovalgus/pronation tendency) with overloading of the subtalar joint
• Subtalar instability after ligamentous lesions
• Unfavorable footwear, uneven surfaces, lack of proprioceptive training
• Rare causes: ganglion/cyst, bony changes, arthritic changes of the subtalar joint

The syndrome is often part of a cascade following ankle joint sprains: initial swelling subsides, but loss of sensitivity in the fat body, synovial irritation and cicatricial changes that hurt under strain remain.

Typical symptoms

• Stabbing or dull pain on the front-lateral side of the hindfoot (in front of the outer malleolus, deeper)
• Increase in discomfort on uneven surfaces, when stopping or turning quickly
• Feeling of “folding” or unsteadiness in the rear foot
• Tenderness in the sinus tarsi upon targeted palpation
• Morning start-up pain, pain on exertion, sometimes swelling

Neurological deficits (numbness, tingling) are atypical and tend to indicate other causes. Severe pain at rest or significant redness/overheating suggest alternative diagnoses and should be clarified by a doctor.

When should I seek medical advice?

• Recent accident with inability to bear weight or visible misalignment
• Increasing pain at night when resting, severe redness/overheating
• Pronounced swelling with hematoma and significant restrictions on movement
• Repeated twisting of an ankle and feeling of instability despite protection
• Pre-existing misalignment/arthrosis with new, unexplained worsening of pain

Diagnostics: this is how we proceed

The diagnosis is based on anamnesis, clinical examination and – depending on the findings – additional imaging. The interaction between localization (sinus tarsi), triggers and provocation tests is crucial.

• Anamnesis: mechanism of accident, number of twists, sport, footwear, previous illnesses/misalignments
• Inspection/palpation: targeted tenderness in the sinus tarsi, swelling, local increase in heat
• Functional test: pain provocation during supination/inversion, test for subtalar instability, single-leg stance on uneven surfaces
• Gait analysis and axis assessment (hindfoot axis, pronation/supination)

Imaging is used in a targeted manner:

• X-ray: rule out bony injuries, assess the axial position
• MRI: evidence of inflammation, scar tissue, edema in the fat body, ligament lesions; helpful for chronic complaints
• Ultrasound: assessment of soft tissues; Injections can be placed precisely using ultrasound
• CT: rarely necessary, e.g. B. if bony variants/coalitions are suspected

Differential diagnoses

• Lateral ligament insufficiency of the upper ankle (ATFL/CFL lesions)
• Lateral soft tissue impingement of the ankle joint
• Subtalar joint arthrosis
• Peroneal tendon pathologies (tendinopathy, subluxation)
• Stress fracture of the calcaneus or lateral processus tali
• Bursitis in the hindfoot area
• Tarsal tunnel syndrome (medial, rather different symptoms)

Conservative treatment – ​​the most important building block

The initial focus is on non-surgical therapy. The aim is to dampen irritation, restore stability and coordination and reduce stressful factors. The measures are combined individually.

• Stress control: temporary reduction in impact- and twist-intensive activities, measured return with symptom monitoring
• Cooling in the acute phase and elevation if there is a tendency to swell
• Short-term anti-inflammatory pain medication after medical consultation
• Tape/orthosis to support the rear foot (limited inversion/supination)
• Insoles/orthoses for pronation tendency or hindfoot valgus; suitable footwear with good heel support
• Physiotherapy: manual mobilization of the subtalar joint, proprioception and coordination training, strengthening of the peroneal muscles and internal foot muscles, calf muscle flexibility
• Return-to-sport concept with step-by-step plan and sport-specific training

Injections and regenerative procedures: sensible – with a sense of proportion

If symptoms persist despite solid basic therapy, targeted injections into the sinus tarsi can be considered. Some of them also serve to confirm the diagnosis.

• Local anesthetic with low-dose cortisone: can relieve pain and reduce irritation in the short term; Risks (e.g. skin/fatty tissue atrophy, infection) are discussed previously; preferably ultrasound targeted
• PRP (platelet-rich plasma): is discussed for chronic soft tissue irritation; Evidence for sinus tarsi syndrome is limited; Use only after careful indication and explanation
• Hyaluronic acid or other preparations: not established as standard for the sinus tarsi

Injections do not replace active therapy. You can save time to effectively implement physiotherapy and stabilization.

When should surgery be considered?

Only when conservative measures have been exhausted over several months and relevant restrictions still exist can a surgical procedure be discussed - depending on the findings and life situation.

• Arthroscopic repair of the sinus tarsi: removal of scar tissue/synovitis, smoothing, if necessary denervation
• Treatment of accompanying instabilities: reconstruction/reinforcement of the subtalar ligament in selected cases
• Correction of misalignments for structural causes (in cooperation with foot surgery), if indicated
• Subtalar arthrodesis only with proven osteoarthritis - not primary therapy for sinus tarsi syndrome

A surgical decision is made individually after weighing the benefits and risks. A promise of healing cannot be made; The goal is a reliable functional improvement.

Rehabilitation and prognosis

Many patients achieve noticeable improvement within 6-12 weeks with conservative therapy. If chronicity occurs, a longer period of consistent training is necessary.

• After arthroscopic repair: usually early functional, gradual increase in load; Return to sport individually, often after 6-12 weeks
• Regular proprioceptive training reduces the risk of repeated twisting events
• Persistent complaints suggest associated causes (instability, misalignment, tendon problems) - these are specifically addressed

Prevention and self-help

• Development program for peroneal muscles and internal foot muscles
• Balance and coordination training (balance pad, one-legged stand, sensorimotor exercises)
• Footwear with a stable heel cap; If necessary, insoles if you have a tendency to pronate
• Taping/orthoses for sports with a high risk of spraining, especially in the return phase
• Increase the load in small steps, approach uneven terrain in a measured manner
• Regular stretching of the calf muscles to relieve pressure on the rear foot

Exercises should be adapted to the pain. Short-term moderate pulling or muscle fatigue are tolerable, stabbing pain is a stop signal.

Example exercises (general, can be adapted)

Please let us show you the process and intensity of physiotherapy individually - especially if you are unstable or misaligned.

Your orthopedic care in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg, we provide you with structured support: from precise diagnosis to targeted conservative therapy to the decision as to whether further measures make sense. Make an appointment easily online or by email – we will provide you with transparent, evidence-based advice.