Ankle & Lower Leg

What It Is

If you have an os trigonum, you have a small extra (accessory) bone behind the ankle bone (talus). It is joined to the talus by a fibrous band (American College of Foot and Ankle Surgeons, n.d.). It forms during adolescence, when a small area at the back of the talus does not fuse with the rest of the bone (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.). It can be present in one or both feet. A large review found an os trigonum in about 9 in every 100 feet (Preinl et al., 2025), and many people never know they have one because it causes no problems (American College of Foot and Ankle Surgeons, n.d.).

Having the extra bone is not necessarily painful, but it can cause impingement (pinching) when pointing your foot, which is the painful condition known as os trigonum syndrome. When you point your toes downward, the os trigonum can be squeezed between the shin bone, the ankle bone and the heel bone. This is called a nutcracker injury: similar to an almond inside a nutcracker, the os trigonum is crunched in between the bones (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.; American College of Foot and Ankle Surgeons, n.d.). If the bone pulls loose, the tissue that connects it to the talus can be stretched or torn and the area becomes inflamed (American College of Foot and Ankle Surgeons, n.d.).

Most commonly it occurs following injury or repeated stress. This often happens in ballet dancers, footballers and other people who repeatedly put stress through a pointed foot (Yasui et al., 2016; American College of Foot and Ankle Surgeons, n.d.). It can also occur following an injury such as an ankle sprain.

If you have this condition, you will usually have a deep, aching pain at the back of the ankle. The pain is mostly felt when pushing off with your foot (as in walking) or when pointing your toes downward, such as going up on to tiptoes. The back of the ankle is often tender to touch and can be swollen (American College of Foot and Ankle Surgeons, n.d.). Because it can feel similar to an Achilles tendon injury, an ankle sprain or a fracture, a doctor will usually examine the ankle and may arrange an X-ray or other scan to confirm the diagnosis (American College of Foot and Ankle Surgeons, n.d.).

Os Trigonum Syndrome Anatomy

Ankle joints have two bones that pivot and glide over each other, the talus and the tibia. There is a thick covering surrounding the entire ankle joint that keeps the joint fluid within the ankle joint. Synovial fluid and the smooth cartilage lining the end of the bone in the joint let the ankle joint move with a minimal amount of friction.

Not a diagnosis — for more information, contact me or another trusted healthcare provider.

Treatment

Self-Care & Treatment

How to Treat Os Trigonum Syndrome

Physiotherapy, including exercises and taping techniques, is part of the usual non-surgical treatment (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.). I can help with hands-on treatment, exercises and taping, and guide you on which activities to change while the ankle settles. See the My Approach tab for how I work.

1. Rest and Avoid Painful Activities

It is important that you stay away from aggravating sports to allow the inflammation time to settle (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.). In many cases this involves taking a break from dancing or ballet. Give the area recovery time and see if that is enough to stop the pain.

2. Ice

Ice can help to reduce swelling (American College of Foot and Ankle Surgeons, n.d.). Wrap an ice pack (or a bag of frozen vegetables) in a tea towel and apply it for up to 20 minutes every 2 to 3 hours (NHS, 2024). Don't apply ice directly onto the skin.

3. Oral Medication

The American College of Foot and Ankle Surgeons (n.d.) says that non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be helpful in reducing the pain and inflammation of os trigonum syndrome.

(This medicine information comes from the American College of Foot and Ankle Surgeons, not from me. Always check with a pharmacist or your family doctor or nurse practitioner before taking any medicine.)

Treatments you may want to discuss with your family doctor or nurse practitioner

Options outside my scope

Walking boot: a doctor may recommend a walking boot for a time to restrict ankle movement and let the injured tissue heal (American College of Foot and Ankle Surgeons, n.d.).
Steroid (cortisone) injection: an injection into the area to reduce pain and inflammation, which can also help doctors decide whether an operation is likely to help (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.; American College of Foot and Ankle Surgeons, n.d.).
Surgery: if other treatments have not worked, the extra bone can be removed, as it is not needed for the foot to work normally. This is now usually done with keyhole surgery, and your surgical team will give you their own instructions for recovery and rehabilitation (Royal Orthopaedic Hospital NHS Foundation Trust, n.d.).

How I can help (see the My Approach tab)

Hands-on treatment for the calf, ankle and foot
Exercises and taping, including showing you how to tape it yourself
Guidance on changing activities and a gradual return to dance or sport

Tips

When participating in sporting activities, make sure to wear the proper equipment at all times.
Once you have an os trigonum, there is little that can be done to prevent os trigonum syndrome entirely.
If you notice certain activities make the condition worse, cut back on them until the pain settles, and ask me how to build them back up.
Most people's symptoms improve with non-surgical treatment (American College of Foot and Ankle Surgeons, n.d.).

Treatment

My Approach

Os trigonum syndrome flares when the small extra bone at the back of your ankle gets pinched as you point your foot or push off. My aim is to settle that irritation and build strength and control in your foot and lower leg so you can get back to walking, dancing or sport.

I start by assessing how your ankle and foot move, which positions bring the pain on, the strength and flexibility of your calf, and how you walk, land and push off. If you've had an X-ray or scan, please bring the report and any notes to your first visit.

When It's Sore

Cutting back pointing, jumping and pushing-off activities, rather than stopping everything
Hands-on work for the calf and the muscles around the ankle and foot, keeping pressure off the tender spot
Gentle, low-velocity mobilisation of stiff ankle and foot joints, never forcing the foot into a pointed position
Warm or cool applications in the clinic, and I'll show you how to use ice safely at home
Taping to limit painful pointing in the short term, and I'll show you how to tape it yourself

As It Settles

Strength for the calf, ankle and foot, from pain-free holds to heel raises and single-leg work
Balance and control work, so the ankle stays steady when you land or rise onto your toes
A home programme to do between visits
For dancers and athletes, a step-by-step return to pointing, jumping and sport-specific work

If you've had surgery, I need your surgeon's okay before any hands-on treatment; then I can help with swelling, stiffness, scar work once the wound has healed, and rebuilding strength, following your surgical team's plan.

If the pain keeps coming back despite treatment, or you can't put weight on the foot, see your family doctor or nurse practitioner.

What to Expect

Typical Course

Typical course: Most people come once or twice a week at first, then weekly, with a reassessment at about 4 to 6 weeks, then less often as you manage more on your own. Most people improve with non-surgical treatment, usually over about 6 to 12 weeks, with a gradual return to full dance or sport after that.

What I Focus On

Assessment

Calf & Ankle Release

Activity Changes

Strength & Control

Gradual Return to Dance & Sport

Sources

References

Royal Orthopaedic Hospital NHS Foundation Trust (n.d.) Posterior Impingement Surgery (os trigonum). Available at: https://roh.nhs.uk/services-information/foot-and-ankle/posterior-impingement-surgery-os-trigonum (Accessed: 7 October 2026).
American College of Foot and Ankle Surgeons (n.d.) Os trigonum syndrome. Foot Health Facts. Available at: https://www.foothealthfacts.org/conditions/os-trigonum-syndrome (Accessed: 8 October 2026).
Preinl, M. et al. (2025) 'Prevalence and clinical aspects of os trigonum: a meta-analysis', Anatomical Science International, 100(3), pp. 287–297. doi: 10.1007/s12565-024-00811-4
Yasui, Y. et al. (2016) 'Posterior ankle impingement syndrome: A systematic four-stage approach', World Journal of Orthopedics, 7(10), pp. 657–663. doi: 10.5312/wjo.v7.i10.657
NHS (2024) Sprains and strains. Available at: https://www.nhs.uk/conditions/sprains-and-strains/ (Accessed: 7 October 2026).

Massage therapy · Kitchener–WaterlooOs Trigonum Syndrome

What It Is

Os Trigonum Syndrome Anatomy

Self-Care & Treatment

How to Treat Os Trigonum Syndrome

1. Rest and Avoid Painful Activities

2. Ice

3. Oral Medication

Treatments you may want to discuss with your family doctor or nurse practitioner

Tips

My Approach

When It's Sore

As It Settles

Typical Course

References

Related Conditions

Book a session

Massage therapy · Kitchener–WaterlooOs Trigonum Syndrome

What It Is

Os Trigonum Syndrome Anatomy

Self-Care & Treatment

How to Treat Os Trigonum Syndrome

1. Rest and Avoid Painful Activities

2. Ice

3. Oral Medication

Treatments you may want to discuss with your family doctor or nurse practitioner

Tips

My Approach

When It's Sore

As It Settles

Typical Course

References

Related Conditions

Ankle Impingement (Anterior)

Ankle Sprains (Medial and Lateral)

Calf Strain / Calf Tear

Chronic Ankle Instability

Book a session