Medical Conditions

Tarsal Coalition (Fused Foot Bones)

Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist

Content reviewed against published OrthoInfo, AAP, NIH guidelines

Last reviewed: June 2026

If your baby has been diagnosed with or you suspect tarsal coalition (fused foot bones), here is what the evidence says.

The short answer

Key takeaways

Tarsal coalition is a condition in which two or more bones in the back of the foot are abnormally connected by a bridge of bone, cartilage, or fibrous tissue. It is usually congenital but typically does not cause symptoms until ages 8-16 when the cartilaginous or fibrous bridge ossifies (hardens into bone) and restricts foot motion. Common signs include a stiff flatfoot, foot or ankle pain that worsens with activity, and limited side-to-side motion of the hindfoot. Treatment depends on symptoms and ranges from observation and orthotics to surgical resection of the coalition.
Usually normal when: Your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition
Call your doctor if: Your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions
Varies by age — see the age-by-age breakdown below

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What Parents Should Know

According to OrthoInfo, AAP, NIH guidelines, tarsal coalition is a condition in which two or more bones in the back of the foot are abnormally connected by a bridge of bone, cartilage, or fibrous tissue. It is usually congenital but typically does not cause symptoms until ages 8-16 when the cartilaginous or fibrous bridge ossifies (hardens into bone) and restricts foot motion. Common signs include a stiff flatfoot, foot or ankle pain that worsens with activity, and limited side-to-side motion of the hindfoot. Treatment depends on symptoms and ranges from observation and orthotics to surgical resection of the coalition. At 0-3 months, tarsal coalition is present from birth but is almost never symptomatic or detectable at this age. Newborn foot exams focus on identifying structural deformities such as clubfoot or vertical talus. Tarsal coalition typically does not affect early foot development or interfere with motor milestones. It is generally considered normal when your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition. However, you should contact your pediatrician promptly if your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal

Worth Discussing

Your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition

Your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions

Your child's foot arch develops gradually and appears more prominent by age 5-6, following the normal developmental timeline

Your child with known tarsal coalition develops persistent pain unresponsive to rest, anti-inflammatories, and orthotics, which may indicate the need for surgical evaluation

Your child has occasional foot aches after a very active day that resolve with rest and do not limit activity

Your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot

Tarsal coalition was found incidentally on imaging and your child has no foot pain, stiffness, or functional limitations

Your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle

By Age

What to expect by age

0-3 months

Tarsal coalition is present from birth but is almost never symptomatic or detectable at this age. Newborn foot exams focus on identifying structural deformities such as clubfoot or vertical talus. Tarsal coalition typically does not affect early foot development or interfere with motor milestones.

3-12 months

Tarsal coalition remains clinically silent during infancy. All babies have flat feet at this age, and the coalition does not cause any symptoms or visible abnormality. Normal motor development (pulling to stand, cruising, first steps) is expected. The condition is only discovered at this age if foot imaging is obtained incidentally for another reason.

1-3 years

Tarsal coalition very rarely presents in toddlers. Most toddlers have flat-appearing feet normally, and the coalition bridge is still cartilaginous (soft), allowing some motion. If your toddler has a very rigid flatfoot, significant foot pain, or difficulty walking, evaluation is warranted, but other conditions are more likely at this age. In rare cases, a tarsal coalition may be found on imaging obtained for other foot concerns.

3-5 years

Occasional early presentations of tarsal coalition can occur in this age range, though most children remain asymptomatic until later childhood or adolescence. If your child has recurrent foot or ankle pain, stiffness, easy fatigue with walking, or a rigid flatfoot on one or both sides, mention it to your pediatrician. Calcaneonavicular coalition (the most common type) typically presents earlier (ages 8-12) than talocalcaneal coalition (ages 12-16), but early symptoms are possible. X-rays, including an oblique view of the foot, can identify calcaneonavicular coalitions, while CT or MRI may be needed for other types.

What to Tell Your Pediatrician

Describe when you first noticed tarsal coalition (fused foot bones) and how it has changed over time.
Note your baby's current age and which age-specific patterns you are seeing.
Mention if your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot.
Mention if your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle.
Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...

Your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition
Your child's foot arch develops gradually and appears more prominent by age 5-6, following the normal developmental timeline
Your child has occasional foot aches after a very active day that resolve with rest and do not limit activity
Tarsal coalition was found incidentally on imaging and your child has no foot pain, stiffness, or functional limitations

Mention at your next visit when...

Your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot
Your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle
Your child or teenager has painful flatfoot that is not improving with standard supportive shoes or inserts

Act now when...

Your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions
Your child with known tarsal coalition develops persistent pain unresponsive to rest, anti-inflammatories, and orthotics, which may indicate the need for surgical evaluation

What You Can Do at Home

Keep track of when you notice tarsal coalition (fused foot bones) — noting the time of day, duration, and any triggers can help your pediatrician.
Remember that your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition — this is generally within the range of normal.
At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
While monitoring at home, seek immediate care if your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions.

Toddler Flat Feet (Pes Planus)

Flat feet in babies and toddlers are completely normal. All babies are born with flat feet because the arch has not yet developed, and a fat pad fills the arch area. The arch gradually forms between ages 3-6, and most children develop normal arches without any treatment or special shoes.

My Baby Has Flat Feet - Is This Normal?

Flat feet are completely normal in babies and toddlers. Nearly all babies are born with flat feet because a fat pad fills the arch area. Arches typically develop between ages 3-6 as the fat pad decreases and foot muscles strengthen. Most children with flat feet have no symptoms and need no treatment.

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is tarsal coalition (fused foot bones) normal?

When should I call the doctor about tarsal coalition (fused foot bones)?

Your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions Your child with known tarsal coalition develops persistent pain unresponsive to rest, anti-inflammatories, and orthotics, which may indicate the need for surgical evaluation

When is tarsal coalition (fused foot bones) normal?

Your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition Your child's foot arch develops gradually and appears more prominent by age 5-6, following the normal developmental timeline Your child has occasional foot aches after a very active day that resolve with rest and do not limit activity

What causes tarsal coalition (fused foot bones)?

Tarsal coalition is a condition in which two or more bones in the back of the foot are abnormally connected by a bridge of bone, cartilage, or fibrous tissue. It is usually congenital but typically does not cause symptoms until ages 8-16 when the cartilaginous or fibrous bridge ossifies (hardens into bone) and restricts foot motion. Common signs include a stiff flatfoot, foot or ankle pain that worsens with activity, and limited side-to-side motion of the hindfoot. Treatment depends on symptoms and ranges from observation and orthotics to surgical resection of the coalition. Common explanations include: Your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition. Your child's foot arch develops gradually and appears more prominent by age 5-6, following the normal developmental timeline.

What should I mention to my pediatrician about tarsal coalition (fused foot bones)?

You should mention tarsal coalition (fused foot bones) at your next visit if: Your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot. Your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle. Your child or teenager has painful flatfoot that is not improving with standard supportive shoes or inserts.

Is tarsal coalition (fused foot bones) normal at 0-3 months?

Is tarsal coalition (fused foot bones) normal at 3-12 months?

Should I go to the ER for tarsal coalition (fused foot bones)?

Seek emergency care if your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions, or if your child with known tarsal coalition develops persistent pain unresponsive to rest, anti-inflammatories, and orthotics, which may indicate the need for surgical evaluation. When in doubt, call your pediatrician's after-hours line for guidance.

Does tarsal coalition (fused foot bones) go away on its own?

In many cases, tarsal coalition (fused foot bones) resolves on its own, especially when your baby or toddler has flexible flat feet, which is a normal finding in young children that does not suggest tarsal coalition. By 3-5 years, occasional early presentations of tarsal coalition can occur in this age range, though most children remain asymptomatic until later childhood or adolescence. If your child has recurrent foot or ankle pain, stiffness, easy fatigue with walking, or a rigid flatfoot on one or both sides, mention it to your pediatrician. Calcaneonavicular coalition (the most common type) typically presents earlier (ages 8-12) than talocalcaneal coalition (ages 12-16), but early symptoms are possible. X-rays, including an oblique view of the foot, can identify calcaneonavicular coalitions, while CT or MRI may be needed for other types.

ORTHOINFO AAP NIH

References

[1]American Academy of Orthopaedic Surgeons. Tarsal Coalition. OrthoInfo, 2022. OrthoInfo
[2]American Academy of Pediatrics. Flat Feet and Fallen Arches. HealthyChildren.org. AAP
[3]National Institutes of Health. Tarsal Coalition. StatPearls, NCBI Bookshelf, 2023. NIH

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Tarsal Coalition (Fused Foot Bones).

Things to mention

Describe when you first noticed tarsal coalition (fused foot bones) and how it has changed over time.
Note your baby's current age and which age-specific patterns you are seeing.
Mention if your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot.
Mention if your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle.
Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

Your child has recurrent foot or ankle pain that limits their activity, especially if they have a noticeably stiff or rigid flatfoot
Your child's foot has very limited side-to-side motion compared to the other foot, or they frequently roll or sprain their ankle
Your child or teenager has painful flatfoot that is not improving with standard supportive shoes or inserts

Urgent signs to report immediately

Your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions
Your child with known tarsal coalition develops persistent pain unresponsive to rest, anti-inflammatories, and orthotics, which may indicate the need for surgical evaluation

My notes

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Bottom line

Most cases of tarsal coalition (fused foot bones) are normal. Talk to your pediatrician if your child has sudden onset of severe foot pain, inability to bear weight, and visible foot or ankle swelling, which needs prompt evaluation to rule out fracture, infection, or other acute conditions.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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