Health condition · Clinically reviewed
Tarsal coalition, congenital fusion of hindfoot bones — from CT diagnosis to arthroscopic resection.
A congenital abnormal connection between two tarsal bones — most commonly calcaneonavicular or talocalcaneal. Presents in adolescence as painful, rigid flat foot. Modern stratified care: activity modification and orthoses; arthroscopic-assisted coalition resection for refractory cases.
Why trust this guide
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Clinically reviewed
Written by our editorial team and reviewed by a registered UK clinician before publication.
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Sourced from guidance
Every claim is checked against BSCOS, NICE and specialist society sources you can see at the end.
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Current for 2026
Reflects modern practice — CT planning, orthoses and arthroscopic-assisted coalition resection.
Key facts
Tarsal coalition at a glance.
The essentials, in plain English — what a coalition is, why it presents in adolescence, and what a modern stratified plan looks like.
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Definition
Tarsal coalition is an abnormal congenital connection — bony, cartilaginous or fibrous — between two tarsal bones of the hindfoot or midfoot.
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Most common types
Calcaneonavicular and talocalcaneal coalitions are the two most common — together accounting for the vast majority of cases.
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Adolescent onset
Symptoms typically emerge between ages 8 and 16, as the coalition ossifies and progressively restricts subtalar motion.
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Classic picture
Peroneal spastic flat foot — a painful, rigid flat foot with reflex spasm of the peroneal tendons on attempted inversion.
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CT for planning
CT of the foot is the investigation of choice — it defines the extent of the coalition and guides surgical planning.
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Modern surgery
Arthroscopic-assisted coalition resection preserves subtalar motion and offers a quicker, less morbid recovery than open surgery.
Why this guide matters
Suspect the coalition, then image it properly.
A painful, rigid flat foot in an adolescent should trigger a coalition work-up — plain films, then CT for planning and MRI for non-bony variants.
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Adolescent onset is a clue
Symptoms typically appear between 8 and 16 — the coalition ossifies as skeletal maturity approaches and starts to hurt.
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CT plans the surgery
CT defines the size and position of a bony bar and is the workhorse for surgical planning by foot and ankle specialists.
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Arthroscopy preserves motion
Arthroscopic-assisted resection is the modern minimally invasive option for refractory coalitions in suitable candidates.
How the diagnosis is made
From painful flat foot to a clear plan.
The steps a UK foot and ankle team will normally follow, in order — so you know what to expect and why.
Phase 1 · Recognising
History, standing examination and subtalar motion
Phase 2 · Confirming
X-ray, then CT for bony and MRI for non-bony
Phase 3 · Managing
Foot & ankle specialist plan
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Recognising
Symptom + adolescent onset history
A painful, stiff flat foot emerging in a school-age child or teenager — the age of presentation is a strong pointer.
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Recognising
Standing foot examination
Assessment of the standing hindfoot — flat medial arch, valgus heel and lack of arch reconstitution on tiptoe stand.
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Recognising
Assessment of subtalar motion
Passive inversion and eversion of the subtalar joint — restriction, guarding and reflex peroneal spasm are the key findings.
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Confirming
Weight-bearing X-ray + oblique + Harris view
Standard foot radiographs plus oblique and Harris (axial calcaneal) views to look for the bony bar.
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Confirming
CT foot (bony coalition)
CT is the investigation of choice — it defines a bony coalition, its size and its position for surgical planning.
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Confirming
MRI (fibrous or cartilaginous coalition)
MRI catches non-bony coalitions that CT can miss, and highlights associated oedema and secondary joint changes.
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Managing
Foot & ankle surgery consultation
A specialist review sets the plan — activity modification and orthoses first, arthroscopic resection for refractory cases.
Typical timeline: 4–8 weeks from first appointment to a confirmed plan.
Symptoms
What tarsal coalition actually feels like.
The pattern is telling — a painful, rigid flat foot in an adolescent, with peroneal spasm and pain on uneven ground.
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Stiff hindfoot
A rigid hindfoot with little inversion or eversion available on examination — the defining physical sign.
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Peroneal spastic flat foot
A painful, flattened medial arch with valgus heel — the classic clinical picture of a symptomatic coalition.
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Spasm on inversion
Attempted passive inversion of the foot triggers reflex spasm of the peroneal tendons — a very characteristic finding.
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Lateral foot pain
Aching pain along the lateral hindfoot and sinus tarsi, worse with activity and settling with rest.
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Aggravated by uneven ground
Walking on uneven surfaces — grass, cobbles, hills — reliably provokes pain because the rigid foot cannot accommodate.
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Limping
Parents often notice a limp after sport or long walks, particularly during and after growth spurts.
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Recurrent symptoms
Episodes of pain and swelling that keep coming back over months — often mistaken for repeated ankle sprains.
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Red flag
Rapidly progressive hindfoot pain or stiffness in an adolescent — needs urgent imaging to rule out coalition or other bony pathology.
Treatment
How tarsal coalition is treated in the UK.
A staged approach — activity modification and orthoses first, boot immobilisation for flares, arthroscopic-assisted resection for refractory cases.
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Activity modification
Temporary reduction of high-impact sport and uneven-ground activity — a simple first lever that often settles a flare.
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Medial arch orthosis
A supportive medial arch orthotic offloads the coalition and improves comfort during walking and standing.
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Boot immobilisation (acute flare)
A short period in a walker boot or below-knee cast for an acute painful flare — usually 4–6 weeks.
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NSAIDs
A short course of anti-inflammatories to settle pain during flares, alongside offloading and rest.
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Physiotherapy
Peroneal stretching, calf conditioning and gait re-education to protect the hindfoot and improve function.
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Coalition resection with fat / muscle interposition
Open resection of the bony bar with fat or muscle graft interposed to prevent recurrence — a well-established option.
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Arthroscopic-assisted resection
Modern minimally invasive resection preserves subtalar motion and offers a quicker recovery than open surgery.
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Subtalar / triple arthrodesis (arthritic coalition)
Reserved for coalitions complicated by established subtalar or triple joint arthritis, where resection is no longer appropriate.
What this guide is based on
The sources behind every claim on this page.
UK national guidance and specialist society standards, current at the time of last review.
Key references
Guidelines and standards we relied on.
A quiet reminder
This guide is for information, not medical advice.
Your GP, podiatrist or foot and ankle team knows your history and can tell you which parts apply to you. If in doubt, get seen.
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British Society for Children’s Orthopaedic Surgery (BSCOS). Paediatric foot standards.
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NICE. Musculoskeletal conditions — clinical guidance.
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American Orthopaedic Foot & Ankle Society (AOFAS). Tarsal coalition patient information.
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Pediatric Orthopaedic Society of North America (POSNA). Paediatric foot resources.
Red flags
When a stiff flat foot needs specialist review.
Most adolescent flat feet are flexible and painless. These are the situations where a coalition or complication needs to be actively considered.
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Missed coalition in painful flat foot
A painful, rigid flat foot in an adolescent that is treated as a routine sprain — coalition needs to be actively considered and imaged.
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Post-op recurrence
Return of pain and stiffness after resection can signal reformation of the coalition — imaging and specialist review are needed.
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Progressive arthritis
Long-standing untreated coalitions can progress to subtalar or triple joint arthritis, changing surgical options significantly.
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Post-op non-union
After arthrodesis, persistent pain and a non-healing fusion site suggest non-union and require orthopaedic review.
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Post-op sinus tarsi syndrome
Persistent lateral hindfoot pain after resection can reflect sinus tarsi syndrome — a recognised post-operative complication.
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Post-op wound complication
Increasing pain, redness, swelling, discharge or fever in the days after surgery — contact your surgical team the same day.
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Bilateral coalition
Coalitions are bilateral in around half of cases — a symptomatic side warrants active review of the opposite foot.
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Concurrent peroneal spasm
Marked, persistent peroneal spasm can lock the foot in valgus and complicate rehabilitation after any intervention.
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Post-op stiffness
Some residual stiffness is expected after surgery, but progressive loss of motion needs prompt physiotherapy and review.
Living with it
A rigid foot, but a manageable one.
Four things that make the biggest difference day to day — load, footwear, rehab and scheduled reviews.
A quiet reminder
Small changes, kept up, add up.
Consistent orthosis use, sensible activity choices and a supportive shoe make more difference than any single intervention.
- 01 Load
Modify activity during flares
Cut high-impact and uneven-ground activity while symptoms are settling — return gradually as pain allows.
- 02 Footwear
Wear supportive footwear
Supportive shoes with a firm heel counter and a medial arch orthosis offload the hindfoot day to day.
- 03 Rehab
Keep the calf and peroneals mobile
Gentle calf and peroneal stretching, plus targeted strengthening, protects the hindfoot in the long run.
- 04 Reviews
Reassess after growth spurts
Symptoms often flare during and after growth — a scheduled review at these points prevents surprises.
Frequently asked
Everything we get asked about tarsal coalition.
Quick answers on imaging, orthoses, surgery and what to expect after arthroscopic resection.
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What is a tarsal coalition?
A tarsal coalition is a congenital abnormal connection between two tarsal bones of the hindfoot — bony, cartilaginous or fibrous. The two commonest types are calcaneonavicular and talocalcaneal coalitions.
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When does it usually present?
Symptoms typically emerge between ages 8 and 16 as the coalition ossifies and progressively restricts subtalar joint motion. Many people have a coalition without ever knowing about it.
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What does it feel like?
A painful, rigid flat foot — with lateral hindfoot pain, reflex peroneal muscle spasm on attempted inversion, and pain that is aggravated by walking on uneven ground.
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What is the best scan?
CT of the foot is the investigation of choice for a bony coalition, because it defines the extent and position of the bar for surgical planning. MRI is used when a fibrous or cartilaginous coalition is suspected.
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Do I need surgery?
Not always. Many patients settle with activity modification, orthoses and a period of boot immobilisation for flares. Surgery — arthroscopic-assisted resection — is reserved for refractory symptoms.
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What is the red flag?
Rapidly progressive hindfoot pain and stiffness in an adolescent — that pattern needs urgent imaging to look for a coalition or other bony pathology, not repeated courses of sprain treatment.
Related content
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Foot MRI
When and why MRI is used to image the foot and ankle.
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Subtalar arthritis
Arthritis of the subtalar joint — a late complication of coalition.
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