Sinus Tarsi Syndrome: The Missed Diagnosis After Ankle Sprain | Michigan

Quick answer: Sinus Tarsi Syndrome Michigan 2 is a clinical condition that responds to evidence-based treatment when caught early. Symptoms include pain, swelling, and altered function. Diagnosis requires clinical exam, often imaging. Treatment ladder: conservative care first (4-6 weeks), then targeted interventions if needed. Call (810) 206-1402.

Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Township, MI. Last updated April 2026.

Sinus tarsi syndrome is pain arising from the sinus tarsi — a canal between the talus and calcaneus on the outer ankle — typically after a lateral ankle sprain that damages the soft tissue structures within this space. It presents as persistent lateral ankle pain, instability, and a specific point of maximum tenderness directly over the sinus tarsi opening that does not resolve with standard ankle sprain treatment. Dr. Tom Biernacki, DPM at Balance Foot & Ankle in Howell and Bloomfield Township, Michigan diagnoses and treats sinus tarsi syndrome as part of comprehensive post-sprain ankle evaluation.

What Is the Sinus Tarsi?

The sinus tarsi is a cone-shaped bony canal located between the talus and calcaneus on the outer ankle — its opening is visible as a small depression approximately 1 cm anterior and inferior to the lateral malleolus (outer ankle bone). The canal contains fat, three interosseous ligaments (the cervical ligament and talocalcaneal interosseous ligament), nerve endings (a branch of the peroneal nerve), and a synovial fold. These structures provide proprioceptive input for subtalar joint stability and coordinate hindfoot motion during gait. When the ankle inverts during a sprain, the sinus tarsi structures are compressed and torn — resulting in inflammation, scarring, and abnormal neural signaling that causes the chronic pain and instability of sinus tarsi syndrome.

Clinical Presentation

Sinus tarsi syndrome presents after a lateral ankle sprain (usually after incomplete recovery) with: persistent lateral ankle pain localized to the sinus tarsi opening (one finger-breadth anterior and inferior to the lateral malleolus); pain worsening with standing on uneven surfaces, hills, or prolonged walking; a sensation of ankle instability or “giving way” despite the ligaments being intact; and relief of pain with a diagnostic corticosteroid injection into the sinus tarsi. The diagnostic injection is both therapeutic and confirmatory — if injecting the sinus tarsi resolves the pain significantly, sinus tarsi syndrome is confirmed.

Diagnosis: Imaging and Clinical Correlation

Standard ankle X-rays are normal in sinus tarsi syndrome. MRI is the most useful imaging study — it identifies fibrosis (replacement of normal fat signal with scar tissue within the sinus tarsi), synovitis, and fluid within the canal. The MRI finding of obliterated fat in the sinus tarsi is the most specific imaging sign of sinus tarsi syndrome. Ultrasound can identify fluid and synovitis and guide diagnostic injection. The most important diagnostic step is the targeted intra-sinus-tarsi corticosteroid injection — significant pain relief confirms the diagnosis and differentiates sinus tarsi syndrome from lateral ankle instability, peroneal tendon pathology, and subtalar arthritis.

Conservative Treatment

Conservative management is successful in approximately 70% of cases. Custom orthotics with lateral heel wedging (varus post) reduce the inversion stress on the sinus tarsi during gait and can eliminate the repetitive provocation of scar tissue in the canal. Physical therapy focusing on peroneal strengthening, proprioceptive training, and manual therapy to restore subtalar joint motion addresses the functional instability component. Corticosteroid injection into the sinus tarsi provides anti-inflammatory treatment and diagnostic confirmation simultaneously — most patients benefit from 1–2 injections over 6–8 weeks. A period of immobilization in a CAM boot (4–6 weeks) reduces acute inflammation in severe cases.

Surgical Treatment

When conservative management fails after 3–6 months, arthroscopic sinus tarsi debridement (removal of the fibrotic and inflamed tissue within the canal) provides excellent pain relief in over 80% of appropriately selected patients. The procedure is performed arthroscopically through two small portals, with minimal recovery time compared to open ankle surgery. Return to sport: 6–10 weeks for most patients after arthroscopic debridement. If there is associated lateral ankle instability (which is common), a Brostrom-Gould ligament reconstruction may be performed at the same time.

Most Common Diagnostic Mistake

The most common mistake is continuing to treat chronic lateral ankle pain after a sprain as residual ligament injury without palpating directly over the sinus tarsi. Chronic anterior talofibular ligament (ATFL) pain is located slightly more anteriorly; sinus tarsi syndrome pain is a specific tender point over the sinus tarsi opening. Failing to distinguish these two presentations leads to months of ligament-focused rehabilitation in a patient whose primary pain generator is the sinus tarsi. A single diagnostic injection that resolves the pain confirms the correct diagnosis in seconds.

When to See Dr. Biernacki

See a podiatrist if lateral ankle pain persists more than 6–8 weeks after an ankle sprain, particularly if the pain is located directly anterior to the lateral malleolus rather than over the ligament itself, if you feel ankle instability on uneven surfaces, or if standard ankle sprain rehabilitation has not resolved the pain. Dr. Biernacki performs targeted sinus tarsi injection for diagnosis and treatment, provides custom orthotics with subtalar offloading, and refers for arthroscopic debridement when conservative management is inadequate.

Book online or call (810) 206-1402 — Howell and Bloomfield Township, Michigan.

Get Expert Help at Balance Foot & Ankle

If this condition is affecting your daily activities or hasn’t improved with home treatment, schedule an evaluation with Dr. Tom Biernacki. We offer same-day appointments at our Howell and Bloomfield Township locations and accept most insurance including Medicare. Most patients are walking comfortably within 4-6 weeks of starting our protocol — conservative care first, surgery only when needed.

Call (810) 206-1402 or request an appointment online. Our team responds within 1 business hour during clinic days.

Visit Balance Foot & Ankle — Same-Day Appointments Available

Our podiatry team serves patients throughout Michigan including Howell, Brighton, and Bloomfield Township. If you’re dealing with heel pain, ingrown toenails, or a foot injury, we have same-day appointment availability.