What it is

A tarsal coalition is an abnormal connection or fusion between two or more bones in the midfoot or back of the foot. It is a congenital condition (from birth) affecting the tarsal bones, located at the back of the foot. The connection can be fibrous, cartilaginous, or bony, causing restricted movement and often presenting with pain, stiffness, and a rigid flat foot during late childhood or adolescence.

Initially, many children have no symptoms. Those who do usually report pain and stiffness in their teens when the coalition stiffens, or when the foot undergoes more stress due to growth and maturation.

Symptoms can include pain and stiffness, reduced range of motion, and peroneal tendon spasms. Treatment is often conservative with rest, orthotics, or immobilisation, but surgical removal of the coalition may be necessary for severe cases

What happens when it occurs

Reduced motion in the rearfoot makes shock absorption and uneven terrain more difficult. Neighbouring joints take extra load and become sore.

Common Types

  • Calcaneonavicular coalition: A connection between the heel bone (calcaneus) and the navicular bone.
  • Talocalcaneal coalition: A connection between the heel bone (calcaneus) and the talus bone (a key ankle bone).

Common causes and risk factors

  • Congenital difference that becomes apparent as the foot matures
  • Family history in some cases
  • Coalitions most often involve the calcaneonavicular or talocalcaneal joints.

Who is most affected?

Adolescents with new stiffness, frequent ankle sprains, or pain on uneven ground.

Typical symptoms

  • Pain and stiffness around the outer ankle or hindfoot
  • Frequent sprains or trouble on uneven ground
  • Flat foot that is less flexible than expected
  • Muscle pain or spasms: Particularly in the lower leg.
  • Frequent ankle sprains: This can occur due to instability.

When to seek care

If hindfoot stiffness and pain persist, or if sprains are frequent despite rehabilitation.

How we diagnose

The examination reveals reduced subtalar motion and tenderness. An X‑ray can show bony bridges. CT or MRI clarifies the type and extent.

Management

Conservative Treatment:

  • Rest and activity modification to reduce stress on the foot.
  • Orthotics (arch supports and shoe inserts) to provide stability.
  • Immobilisation in a cast or boot to prevent movement.
  • Anti-inflammatory medications or steroid injections for pain relief.

Surgical Treatment:

  • If conservative treatments are ineffective, surgery may be performed to remove the coalition, which can sometimes require further joint procedures like arthrodesis (bone fusion) if there's significant arthritis.

Rehabilitation milestones

Phase 1 weeks 0 to 2: pain control, footwear and terrain changes, balance basics.

Phase 2 weeks 2 to 6: heavy slow peroneal and calf loading, proprioception.

Phase 3 weeks 6 to 12: hopping and agility, graded return to sport.

Phase 4 months 3 to 6: performance work or post‑op criteria as advised.

Readiness to progress

  • Comfortable walking on uneven ground
  • Peroneal strength within 90 per cent
  • Hop and agility tests without next-day flare

Prevention

  • You cannot prevent a coalition, but you can reduce its symptoms with proper footwear, effective load planning, and targeted strength training.
  • Avoid abrupt terrain changes while building capacity

Australia snapshot

  • Coalitions are uncommon but regularly identified in adolescent clinics
  • Trail and field sports feature in symptomatic cases
  • Advanced imaging access is good in metropolitan areas

Latest insights

Support the foot and strengthen stabilisers. Consider surgery when symptoms persist.

Balance training reduces the risk of sprains in individuals with stiffer feet.

Frequently Asked Questions

Less common than other foot issues, but not rare in clinics. Many are painless and found incidentally.

If there are no arthritic changes, the union between the bones is usually removed (resected), with fat or muscle placed where the tarsal coalition was so that normal range of motion can occur. In more severe cases, surgery is aimed at limiting the range of motion in the joint that causes pain.

In some cases, people may experience enough pain and discomfort that it prevents them from engaging in the activities they enjoy. Left untreated, a tarsal coalition can lead to a stiff foot later in life.

Yes, with adjustments for footwear, terrain, and strength. Modify during flares.

Often. Support and shock absorption reduce symptoms on uneven ground.

Yes, when X‑rays are unclear or when planning surgery.

Whilst rare, a resection or separation of the joined bones can be used to restore motion when joints are fused or degenerated.

Rehabilitation spans months, with clear milestones and return-to-sport criteria.

Yes. Coalitions can limit motion and create a flatter, stiffer foot.