Tarsal coalition is a condition where two or more bones in the back of the foot (the tarsal bones) are abnormally connected. This connection may be made of bone, cartilage, or fibrous tissue. While some people never experience symptoms, others may develop pain, stiffness, or flatfoot deformity as they grow and the bones of the foot mature. Early recognition and treatment can help prevent long-term problems and restore normal motion.
How Common It Is and Who Gets It? (Epidemiology)
Tarsal coalition occurs in about 1–2% of the population. Most cases are congenital, meaning the condition is present from birth, though symptoms usually appear between the ages of 8 and 16 as the bones mature.
- Calcaneonavicular coalition (between the heel and navicular bones) often appears between ages 8–12.
- Talocalcaneal coalition (between the talus and heel bone) typically presents between ages 12–15.
It affects both males and females equally, and both feet are involved in about half of cases.
Why It Happens – Causes (Etiology and Pathophysiology)
Most tarsal coalitions are congenital, caused by a developmental error during fetal growth when the tarsal bones fail to separate properly. This results from failure of mesenchymal segmentation in the embryo. Over time, the fibrous or cartilaginous bridge may harden into bone.
Less common acquired causes include:
- Trauma
- Infection
- Degenerative arthritis
Genetic factors may also play a role, with some cases linked to mutations in the FGFR3 gene.
The abnormal connection limits motion between the tarsal bones—especially in the subtalar joint—and changes the way the foot moves. This restricted motion causes mechanical stress, leading to flatfoot, heel valgus (heel tilting inward), and painful muscle spasms in the leg.
How the Body Part Normally Works? (Relevant Anatomy)
The tarsal bones—including the calcaneus (heel), talus, navicular, cuboid, and cuneiform bones—form the rear and midfoot. They provide flexibility, absorb shock, and allow smooth walking and running. When a coalition forms, these bones lose their ability to move independently, which limits flexibility and can alter normal gait mechanics. The two most commonly affected joints are:
- Talocalcaneal joint (between the talus and calcaneus)
- Calcaneonavicular joint (between the calcaneus and navicular)
What You Might Feel – Symptoms (Clinical Presentation)
Symptoms often develop gradually and may include:
- Pain in the foot or ankle, especially when walking or standing
- Tired or fatigued legs
- Muscle spasms that cause the foot to turn outward (peroneal spastic flatfoot)
- Flatfoot deformity in one or both feet
- Stiffness and decreased motion in the ankle or hindfoot
- Recurrent ankle sprains due to limited flexibility
Some individuals remain symptom-free and are diagnosed incidentally on imaging.
How Doctors Find the Problem? (Diagnosis and Imaging)
Diagnosis begins with a clinical evaluation and imaging studies.
- Physical Exam: The doctor assesses range of motion, arch height, and hindfoot alignment. The arch does not reappear when standing on tiptoe if a coalition is present.
- X-rays: The first-line test.
- Calcaneonavicular coalition shows the “anteater nose” sign on oblique X-ray.
- Talocalcaneal coalition may show a “C-sign” on lateral X-ray.
- CT Scan: Best for identifying the type, size, and exact location of a coalition and ruling out multiple coalitions.
- MRI: Useful for detecting fibrous or cartilaginous coalitions not visible on X-rays and for evaluating soft tissue inflammation.
Classification
Tarsal coalitions are classified by location and tissue type:
- By location:
- Calcaneonavicular (most common)
- Talocalcaneal (second most common)
- Less common: talonavicular, calcaneocuboid, naviculocuneiform
- By tissue type:
- Fibrous (syndesmosis)
- Cartilaginous (synchondrosis)
- Osseous (synostosis)
Other Problems That Can Feel Similar (Differential Diagnosis)
Conditions that may mimic tarsal coalition include:
- Flexible flatfoot
- Posterior tibial tendon dysfunction
- Sinus tarsi syndrome
- Subtalar arthritis
- Peroneal spastic flatfoot from other causes
Treatment Options
Non-Surgical Care
Conservative treatment is the first step for most symptomatic patients.
- NSAIDs: Reduce pain and inflammation.
- Physical Therapy: Includes stretching, massage, ultrasound therapy, and range-of-motion exercises.
- Orthotics: Custom shoe inserts or arch supports relieve pressure and improve alignment.
- Casting or Immobilization: Short-term immobilization in a cast or boot can rest the foot and reduce symptoms.
- Steroid Injections: Reduce inflammation and pain in the affected joint.
- Activity Modification: Avoiding high-impact sports or uneven terrain can help manage symptoms.
Surgical Care
Surgery is considered if symptoms persist after conservative treatment.
- Coalition Resection: The abnormal bridge is removed, and soft tissue (fat, muscle, or tendon) is placed between the bones to prevent recurrence.
- Calcaneonavicular coalitions: Often filled with extensor digitorum brevis muscle.
- Talocalcaneal coalitions: May use a portion of the flexor hallucis longus tendon.
- Osteotomy or Realignment Procedures: Performed if there is significant deformity such as valgus alignment.
- Arthrodesis (Fusion): Used for large coalitions (>50% of the joint surface) or advanced arthritis.
- Subtalar arthrodesis or triple arthrodesis (fusion of subtalar, calcaneocuboid, and talonavicular joints) may be performed for severe cases.
Recovery and What to Expect After Treatment
After surgery, patients usually wear a cast or boot for 3–6 weeks, remaining non-weight-bearing initially. Gradual physical therapy follows to restore motion and strength. Most patients return to normal activity within 3–6 months. Younger patients typically recover more fully and regain better motion than adults with long-standing coalitions.
Possible Risks or Side Effects (Complications)
- Incomplete resection or recurrence of the coalition
- Persistent pain or stiffness
- Infection or wound problems
- Degenerative arthritis if the coalition involves a large joint area
- Malalignment or residual flatfoot deformity
Long-Term Outlook (Prognosis)
The prognosis is excellent for patients who undergo coalition resection before significant degenerative changes occur. About 80–85% experience long-term pain relief and restored motion. Patients with large or arthritic coalitions may require joint fusion but still achieve reliable pain relief and improved stability.
Out-of-Pocket Costs for Treatment
Medicare
CPT Code 28116 – Coalition Resection (Calcaneonavicular/Talocalcaneal): $153.96
CPT Code 27685 – Achilles Tendon Lengthening (for Valgus Correction): $151.57
CPT Code 28300 – Calcaneal Osteotomy (for Valgus Correction): $153.01
CPT Code 28725 – Subtalar Fusion (for Advanced Arthritis or Failed Resection): $182.74
Medicare Part B typically covers 80% of the approved cost for these procedures after your annual deductible has been met, leaving you responsible for the remaining 20%. Supplemental Insurance plans such as Medigap, AARP, or Blue Cross Blue Shield generally cover that remaining 20%, minimizing or eliminating out-of-pocket expenses for Medicare-approved procedures. These plans coordinate with Medicare to fill the coverage gap and reduce overall patient costs.
If you have Secondary Insurance such as TRICARE, an Employer-Based Plan, or Veterans Health Administration coverage, it acts as a secondary payer. These plans often cover any remaining coinsurance or small deductibles, which typically range from $100 to $300, depending on your plan and provider network.
Workers’ Compensation
If your tarsal coalition developed due to a work-related injury or overuse condition, Workers’ Compensation will cover all treatment costs, including surgery, physical therapy, and postoperative care. You will not have any out-of-pocket expenses, as the employer’s insurance carrier pays for all approved treatments directly.
No-Fault Insurance
If your tarsal coalition or related foot condition was caused or aggravated by an automobile accident, No-Fault Insurance will typically cover the total cost of treatment, including coalition resection, tendon lengthening, and subtalar fusion. The only possible out-of-pocket expense may be a small deductible or co-payment depending on your insurance policy.
Example
Emily Carter was diagnosed with a calcaneonavicular tarsal coalition that limited her motion and caused chronic pain. She underwent coalition resection (CPT 28116) and Achilles tendon lengthening (CPT 27685). Her estimated Medicare out-of-pocket cost for the resection was $153.96. Since Emily had supplemental insurance through Blue Cross Blue Shield, her remaining balance was fully covered, leaving her with no out-of-pocket expenses for the procedures.
Frequently Asked Questions (FAQ)
Q. What is a tarsal coalition?
A. A tarsal coalition is an abnormal connection between two or more bones in the foot, usually the calcaneus, talus, and navicular bones, which can be made of bone, cartilage, or fibrous tissue.
Q. What causes a tarsal coalition?
A. Most cases of tarsal coalition are congenital, meaning present at birth, due to failure of bones to separate properly during fetal development.
Q. When do symptoms of tarsal coalition typically appear?
A. Symptoms usually appear during adolescence when the bones begin to harden, causing stiffness and pain in the foot.
Q. What are the common symptoms of tarsal coalition?
A. Common symptoms include foot pain, stiffness, flat feet, muscle spasms, and difficulty walking or participating in sports.
Q. How is tarsal coalition diagnosed?
A. Diagnosis involves a physical examination, review of symptoms, and imaging studies such as X-rays, CT scans, or MRIs.
Q. What non-surgical treatments are available for tarsal coalition?
A. Non-surgical treatments include rest, immobilization, orthotics, physical therapy, and anti-inflammatory medications.
Q. When is surgery considered for tarsal coalition?
A. Surgery is considered when non-surgical treatments fail to relieve symptoms, and the patient has ongoing pain or limited mobility.
Q. What surgical options exist for tarsal coalition?
A. Surgical options include resection of the coalition or fusion of the affected joints, depending on the severity and location.
Q. What is the recovery time after tarsal coalition surgery?
A. Recovery varies but often includes a period of immobilization followed by physical therapy, with gradual return to activity over several months.
Q. Can tarsal coalition lead to long-term complications if untreated?
A. If untreated, tarsal coalition can lead to chronic pain, joint degeneration, and loss of foot function.
Q. Is physical therapy useful in managing tarsal coalition?
A. Yes, physical therapy can help improve foot mobility, strengthen muscles, and reduce pain.
Q. Can a person with tarsal coalition continue to play sports?
A. Some individuals can continue sports with proper treatment, but others may need to limit or modify activity based on pain and stiffness.
Q. Is tarsal coalition always painful?
A. No. Up to 75% of people with a coalition are asymptomatic, and the condition may only be found incidentally.
Q. Can children outgrow tarsal coalition?
A. No, the coalition does not go away, but early treatment can prevent long-term deformity.
Q. Can both feet be affected?
Yes, about half of patients have bilateral coalitions.
Q. Will I be able to play sports again?
A. Most patients return to sports after full recovery, especially if the coalition is resected successfully and rehabilitation is followed closely.
Summary and Takeaway
Tarsal coalition is an abnormal connection between two or more bones in the foot that limits motion and may cause flatfoot, stiffness, and recurrent sprains. It usually develops during fetal growth but becomes symptomatic in adolescence. Diagnosis is made through X-rays, CT, or MRI. Treatment begins with conservative care, including rest, orthotics, and anti-inflammatory medications, but surgery may be needed for persistent pain or deformity. With proper treatment, most patients regain mobility and return to normal activity.
Clinical Insight & Recent Findings
A recent study in the HSS Journal® examined tarsal coalition in adolescent athletes, highlighting its impact on foot biomechanics and athletic performance. The condition, which occurs when two or more tarsal bones fuse abnormally, can lead to pain, stiffness, instability, and recurrent sprains due to restricted subtalar motion.
While mild cases may be managed with rest, orthotics, or physical therapy, most symptomatic athletes eventually require surgery. The study found that open surgical resection with fat graft interposition remains the gold standard, offering pain relief, restored motion, and prevention of recurrence.
Overall success rates after surgical treatment exceeded 80%, with low complication rates and high rates of return to sport, especially when both coalition type and foot alignment were carefully evaluated before surgery. (“Study on surgical management of tarsal coalition in young athletes – see PubMed.“)
Who Performs This Treatment? (Specialists and Team Involved)
Treatment is performed by an orthopedic foot and ankle surgeon or podiatric surgeon. The care team may include radiologists, anesthesiologists, and physical therapists who assist with diagnosis, surgery, and rehabilitation.
When to See a Specialist?
You should see a specialist if you or your child experiences persistent foot pain, stiffness, frequent sprains, or flatfoot that does not improve with supportive footwear.
When to Go to the Emergency Room?
Go to the emergency room if you have severe pain after an injury, inability to bear weight, visible deformity, or signs of infection such as redness, swelling, and fever.
What Recovery Really Looks Like?
Recovery may include several weeks of rest, followed by gradual rehabilitation. Mild stiffness or soreness may persist initially, but most patients regain near-normal motion. Consistent physical therapy and proper footwear are key for optimal results.
What Happens If You Ignore It?
Untreated tarsal coalition can lead to progressive flatfoot deformity, chronic pain, arthritis, and reduced mobility. Early diagnosis prevents long-term joint damage and deformity.
How to Prevent It?
While congenital coalitions cannot be prevented, proper footwear, maintaining a healthy weight, and early medical evaluation for recurring ankle pain can reduce complications and deformity.
Nutrition and Bone or Joint Health
A balanced diet rich in calcium, vitamin D, and protein supports bone development and healing after treatment. Avoiding smoking and maintaining good hydration also aid recovery.
Activity and Lifestyle Modifications
After treatment, patients should gradually return to activities. Low-impact exercises like cycling, swimming, or yoga are recommended. Supportive shoes and orthotics can protect the foot from excess stress and help prevent recurrence of pain or stiffness.
Dr. Mo Athar
