Posterior ankle pain can be incredibly limiting — especially if you’re a dancer, athlete, or performer who relies on deep plantarflexion and powerful push‑off movements. One of the most common causes of pain at the back of the ankle is os trigonum syndrome, a condition frequently seen in ballet dancers, footballers, gymnasts, and runners.
If you’re experiencing pain when pointing your toes, jumping, sprinting, or going en pointe, early assessment is essential. With the right diagnosis and treatment plan, most people return to full performance — and many sooner than they expect.
What Is the Os Trigonum?
The os trigonum is a small accessory bone located behind the talus (ankle bone). It forms during adolescence and usually fuses with the talus. In some people, it remains separate — often without causing any issues.
However, activities involving repeated forced plantarflexion (pointing the toes downward) can compress this bone between the tibia and heel bone, leading to irritation and pain.
This condition is especially common in:
- Ballet dancers (particularly en pointe or demi‑pointe)
- Footballers and soccer players
- Runners and sprinters
- Gymnasts and cheerleaders
- Cricket fast bowlers
- Martial artists
What Is Os Trigonum Syndrome?
Os trigonum syndrome occurs when the accessory bone becomes pinched at the back of the ankle, irritating surrounding soft tissues such as:
- The posterior ankle capsule
- The flexor hallucis longus (FHL) tendon
- Synovial tissue
- Supporting ligaments
This condition is also known as posterior ankle impingement syndrome (PAIS).
Common Symptoms
Symptoms often appear only during specific movements.
Typical signs include:
- Pain at the back of the ankle when pointing the foot
- Pain en pointe or demi‑pointe
- Pain when pushing off during sprinting
- Reduced relevé height
- Loss of power in jumps
- Swelling behind the ankle
- Clicking or catching sensations
- Stiffness after activity
Classic dancer description: “It feels blocked when I go onto pointe.”
Many athletes can walk normally but struggle to perform at a high level — a key diagnostic clue.
Diagnosis
A podiatrist will assess:
- Pain during forced plantarflexion
- FHL tendon irritation
- Comparison with the opposite ankle
- Functional loading tests (relevé, hops, jumps)
Imaging
- X‑ray: confirms the presence of an os trigonum
- MRI: identifies inflammation and rules out stress fractures or tendon tears
- Ultrasound: useful for tendon involvement and guided injections
It’s important to note: Not all os trigonum bones cause pain — imaging must match symptoms.
Conservative (Non‑Surgical) Treatment
Most patients respond well to conservative care.
Activity Modification
Temporary reduction of:
- Pointe work
- Deep lunges
- Sprint starts
- Kicking drills
Rehabilitation Focus
- Improving FHL tendon mobility
- Calf strength and control
- Hip stability
- Technique optimisation (especially in dancers)
Immobilisation
A short period in a boot (2–4 weeks) may help settle inflammation.
Injection Therapy
Ultrasound‑guided corticosteroid injections can be highly effective for both diagnosis and symptom relief.
Many athletes improve with this approach — but not all.
When Is Surgery Recommended?
Surgery may be advised when:
- Pain persists for 3–6 months
- Symptoms return immediately after resuming sport
- Repeated injections fail
- Performance remains limited
- MRI confirms ongoing impingement
For dancers and elite athletes, delaying surgery when clearly indicated can prolong time away from training and performance.
The Surgical Procedure
Modern os trigonum surgery is typically performed via posterior ankle arthroscopy (keyhole surgery).
What Happens During Surgery?
Through two small incisions at the back of the ankle, the surgeon:
- Inserts a small camera
- Removes the os trigonum
- Clears inflamed tissue
- Releases the FHL tendon if required
This approach removes the mechanical block while preserving ankle stability and mobility.
Benefits of Arthroscopic Surgery
- Minimal scarring
- Less tissue trauma
- Faster rehabilitation
- Earlier return to sport
- Excellent outcomes in dancers and athletes
Open surgery is rarely needed today.
Recovery Timeline
Recovery is often faster than patients expect.
Week 0–2
- Non‑weight bearing
- Splint and crutches
Week 2–6
- Weight bearing as tolerated
- Aircast boot with heel raise (weaning off by weeks 4–6)
- Gentle rehabilitation begins
Week 6–10
- Full weight bearing
- Progressive strengthening and resistance exercises
Week 8–12
- Continued rehab focusing on strength and range of motion
Week 12+
- Sport‑specific training
- Restoring power, control, and performance
Expected Outcomes
Os trigonum excision has excellent success rates in active populations.
Patients commonly report:
- Increased plantarflexion range
- Improved push‑off power
- Return to previous performance level
- Resolution of catching or blocking sensations
Removing the bone does not reduce ankle stability.
Why Early Assessment Matters
Dancers and athletes often push through pain — but this can lead to:
- Chronic tendon irritation
- Longer recovery times
- Compensation injuries (Achilles, plantar fascia, knee)
Early diagnosis and timely referral to a foot & ankle specialist can dramatically shorten time away from training and performance.
Take the Next Step
Os trigonum syndrome is highly treatable. With the right care, most dancers and athletes return to full performance — often stronger than before.
If you’re experiencing persistent posterior ankle pain, especially when pointing your toes or during sport, our Sydney CBD, Darlinghurst, and Randwick‑based clinicians can help. Book an appointment HERE
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