Medically reviewed by Dr. Tom Biernacki, DPM
Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Township, MI
Last reviewed: May 2026
The os trigonum is a small accessory bone at the back of the ankle that causes posterior ankle pain in dancers and soccer players — and the key finding on plantarflexion X-ray that confirms it is the source of pain (not tendinopathy) changes the treatment approach entirely. Call (810) 206-1402 — expert podiatric care across Michigan.
Os trigonum removal — surgical excision of the accessory ossicle at the posterior talus — is the definitive treatment for os trigonum syndrome that has failed conservative management. The os trigonum is present in approximately 7-14% of the population and causes posterior ankle impingement when it is pinched between the tibia and calcaneus during plantarflexion. Dancers, soccer players, and gymnasts are most commonly affected. Both open and arthroscopic excision produce excellent outcomes.
Open vs. Arthroscopic Os Trigonum Excision
| Feature | Open Excision | Arthroscopic Excision |
|---|---|---|
| Approach | Posteromedial incision; direct visualization | Two posterior portals (medial and lateral to Achilles) |
| Visualization | Direct; excellent for large or fused os trigona | Excellent with 30-degree scope; panoramic posterior ankle view |
| Concurrent FHL tendonitis | Easy access to FHL sheath | Also accessible arthroscopically |
| Recovery time | 6-8 weeks to return to sport | 4-6 weeks to return to sport |
| Complications | Sural nerve risk; wound healing; slightly longer scar | Portal site numbness; technically demanding |
| Outcomes | 85-95% good/excellent results | 90-95% good/excellent results |
Conservative vs. Surgical Treatment Decision
| Approach | Indication | Duration | Success Rate |
|---|---|---|---|
| Rest + activity modification | First-line; acute flare; avoid plantarflexion activities | 4-6 weeks | 50-60% resolve acute episode |
| Corticosteroid injection | Persistent pain; diagnostic and therapeutic | 1-2 injections over 6 weeks | 60-70% temporary relief; recurrence common in athletes |
| Immobilization (boot/cast) | Failed injection; acute exacerbation | 4-6 weeks NWB or protected WB | 60-70% symptomatic improvement |
| Surgical excision | Failed 3-6 months conservative; high-level athlete needing definitive solution | 4-8 weeks recovery | 85-95% good/excellent; very low recurrence |
At Balance Foot & Ankle in Howell and Bloomfield Township, os trigonum excision is planned based on MRI confirmation of ossicle bone marrow edema — indicating the ossicle is symptomatic and not just an incidental finding. Call (810) 206-1402.
American Academy of Orthopaedic Surgeons: Os Trigonum Syndrome
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Doctor Answer
What is os trigonum removal surgery and when is it needed?
The os trigonum is an accessory bone behind the ankle that can become impinged with plantarflexion, causing posterior ankle pain — especially in dancers and soccer players. When conservative treatment with rest, injections, and physical therapy fails, arthroscopic or open removal relieves symptoms definitively. Recovery involves non-weight-bearing for 1-2 weeks, then a boot, with return to sport typically at 6-10 weeks.
Dr. Tom Biernacki, DPM is a board-certified foot & ankle surgeon (ABFAS & ABPM) 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 made him one of the most-followed foot & ankle educators on YouTube.