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

Sinus tarsi syndrome is a cause of lateral ankle and hindfoot pain that is frequently misdiagnosed as a chronic ankle sprain — and therefore often undertreated for months or years. Understanding this condition is important for anyone with persistent outer ankle pain following a sprain that never fully resolved.

What Is the Sinus Tarsi?

The sinus tarsi is a cone-shaped anatomical canal between the talus (ankle bone) and calcaneus (heel bone), located on the outer side of the hindfoot just in front of and below the lateral malleolus. The canal contains: the cervical ligament, the interosseous talocalcaneal ligament, fatty tissue, nerves, and vessels. Together, these structures provide proprioceptive information about subtalar joint position — essentially the ankle’s position-sensing system.

What Causes Sinus Tarsi Syndrome?

The two primary causes are:

• Post-traumatic — accounts for approximately 70% of cases; sinus tarsi contents are injured during lateral ankle sprains (the same mechanism that injures the ATFL and CFL); synovitis, fibrosis, and nerve damage within the canal produce chronic pain even after the ligaments appear healed
• Overpronation/flatfoot — chronic excessive foot pronation places the subtalar joint in valgus, creating repeated compressive and shear forces within the sinus tarsi that produce synovitis and inflammatory fibrosis without prior trauma

Symptoms

Classic sinus tarsi syndrome presentation: persistent lateral hindfoot and ankle pain that is worse with weight-bearing, uneven terrain, and athletics; improving with rest. There is a characteristic point of maximum tenderness directly over the sinus tarsi opening (the “opening” on the outer foot, anterior to the lateral malleolus and superior to the calcaneus). Hindfoot instability and a sense of “giving way” on uneven surfaces is common. Unlike most ankle sprains, pain persists for months without improvement.

Diagnosis

Clinical examination identifies the characteristic point tenderness. MRI confirms the diagnosis — demonstrating fatty tissue replacement with synovitis, fluid in the sinus tarsi, or ligamentous tears within the canal. Diagnostic injection of local anesthetic into the sinus tarsi is both diagnostic (complete pain relief confirms the diagnosis) and therapeutic.

Treatment

• Custom orthotics — medial posting to control pronation reduces chronic stress on the sinus tarsi; highly effective for the overpronation subtype and as adjunct treatment for post-traumatic cases
• Cortisone injection into the sinus tarsi — targeted injection provides 3–6 months of relief and is often curative for post-traumatic cases; typically performed 2–3 times over 6–12 months if needed
• PRP injection — for cases where cortisone provides insufficient benefit; promotes healing of the ligamentous structures within the canal
• Ankle rehabilitation — peroneal strengthening and proprioception training (shared with chronic ankle instability rehabilitation)
• Arthroscopic sinus tarsi debridement — reserved for refractory cases; synovitis and fibrotic tissue within the canal is removed arthroscopically with generally excellent results

Sinus Tarsi Syndrome & Lateral Ankle Pain Treatment in Michigan

Chronic outer ankle pain after a sprain that won’t resolve? Our podiatrists diagnose and treat sinus tarsi syndrome with targeted therapies to restore ankle stability.

Learn About Our Ankle Instability Treatment → | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Helgeson K. Examination and intervention for sinus tarsi syndrome. North American Journal of Sports Physical Therapy, 2009;4(1):29-37.
2. Klausner V, McKeigue ME. Sinus tarsi syndrome: a review. Journal of the American Podiatric Medical Association, 2000;90(6):318-322.
3. Lee KB, et al. Subtalar joint instability: diagnosis and surgical treatment using the sinus tarsi approach. Foot & Ankle International, 2008;29(11):1115-1119.

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Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.