Definition
A tarsal coalition is an abnormal connection between two or more tarsal bones. The bridge may be fibrous, cartilaginous or osseous.
The commonest clinically important coalitions are:
- calcaneonavicular
- talocalcaneal
Presentation
Symptoms often emerge as the coalition becomes more rigid during skeletal maturation.
Typical features:
- activity-related hindfoot pain
- recurrent ankle sprains
- rigid flatfoot
- reduced subtalar movement
- peroneal spasm in some patients
Bilateral coalitions are common, although symptoms may be unilateral.
Examination
Assess:
- hindfoot valgus
- medial arch
- subtalar motion
- heel rise
- calf tightness
- focal sinus-tarsi or medial subtalar tenderness
A key distinction is flexible versus rigid flatfoot.
Assess:
- hindfoot alignment
- subtalar motion
- heel rise
- peroneal spasm/tenderness
- calf tightness
- rigidity of deformity
A rigid valgus hindfoot that fails to correct on heel rise should raise suspicion.
Imaging
Weight-bearing radiographs may show indirect signs, but CT defines osseous anatomy best. MRI is useful for fibrous or cartilaginous coalitions and associated marrow oedema.
Weight-bearing radiographs may show indirect signs. Oblique views can demonstrate calcaneonavicular coalition.
CT provides excellent definition of osseous anatomy and coalition extent. MRI can identify fibrous/cartilaginous coalition and associated marrow or soft-tissue change.
Treatment
Initial management:
- activity modification
- analgesia
- orthoses or immobilisation for symptomatic flares
Surgery is considered for persistent symptoms.
Resection
Best suited to selected younger patients with:
- localised coalition
- preserved surrounding joints
- correctable hindfoot alignment
Interposition tissue may be used depending on the coalition and technique.
Reconstruction or fusion
More appropriate when there is:
- large coalition
- significant fixed valgus
- degenerative subtalar change
- failure of previous resection
Principle
Treat the painful mechanical problem, not the radiographic coalition alone. An asymptomatic coalition requires no operation.
Definition and types
A tarsal coalition is an abnormal connection between tarsal bones that may be fibrous, cartilaginous or osseous.
The commonest clinically relevant patterns are:
- calcaneonavicular coalition
- talocalcaneal coalition
Symptoms often appear when the coalition ossifies or becomes mechanically restrictive during later childhood or adolescence.
Clinical presentation
Typical features include:
- activity-related hindfoot pain
- recurrent “ankle sprains”
- rigid or poorly mobile flatfoot
- peroneal spasm in some patients
- reduced subtalar motion
The foot may look flat, but the key finding is restriction of hindfoot motion.
Non-operative management
Initial options include:
- activity modification
- analgesia
- short period of immobilisation
- orthoses
- physiotherapy
Some patients remain manageable without surgery.
Resection
Coalition resection is considered in symptomatic patients when:
- deformity is limited or correctable
- adjacent joints are not significantly arthritic
- coalition size/location is suitable
- symptoms correlate with the coalition
Interposition may be used to reduce risk of reformation.
Fusion
When there is:
- large coalition
- significant degenerative change
- severe rigid deformity
- failed resection
fusion of the symptomatic joint complex may be more appropriate.
FRCS synthesis
Do not diagnose coalition from “flatfoot” alone. The important triad is pain, restricted subtalar motion and rigid hindfoot deformity, supported by appropriate cross-sectional imaging.