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Tarsal Coalition (Peroneal Spastic Flatfoot)

Abnormal fibrous, cartilaginous, or osseous union between two or more tarsal bones leading to rigid flatfoot, painful peroneal muscle spasm, and recurrent ankle sprains in adolescents; treated with immobilization, orthotics, or surgical resection with interposition graft.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

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What is Tarsal Coalition (Peroneal Spastic Flatfoot)?

Tarsal coalition is a congenital condition characterized by abnormal union (fibrous, cartilaginous, or osseous) between two or more tarsal bones that should be separate, restricting subtalar and midtarsal motion. It is thought to result from failure of differentiation and segmentation of primitive mesenchyme during embryonic development. Prevalence in the general population is estimated at 1–2 percent (likely under-diagnosed), with autosomal dominant inheritance with variable penetrance; family history present in 39 percent.

Anatomic types: (1) Talocalcaneal coalition (TC, 50 percent) — most commonly involves middle facet between sustentaculum tali and talus; presents in older adolescents (12–14 years) when increasing fibrocartilage to bone progression causes symptomatic stiffness; (2) Calcaneonavicular coalition (CN, 50 percent) — between anterior process of calcaneus and lateral aspect of navicular; presents earlier (8–12 years) often as cartilaginous bar; (3) Talonavicular and other rare coalitions (5 percent each); often bilateral (50 percent for TC, 60 percent for CN); multiple coalitions occur in 30 percent.

Clinical: insidious onset of activity-related midfoot or hindfoot pain (especially after prolonged walking, running, sports), peroneal muscle spasm causing rigid pronated flatfoot (peroneal spastic flatfoot — eversion contracture, painful inversion), recurrent ankle sprains due to limited subtalar inversion, restricted subtalar joint motion (compared to normal contralateral if unilateral), valgus heel position, midfoot prominence, and calluses on lateral foot. Diagnosis: AP and lateral standing weight-bearing radiographs (anteater nose sign on lateral for CN coalition — elongated anterior process of calcaneus extending to navicular; C-sign on lateral for TC coalition — continuous arc from talus to sustentaculum), oblique view (often demonstrates CN coalition directly), CT scan (gold standard — defines bony coalition extent and degenerative changes essential for surgical planning), MRI (essential for fibrous and cartilaginous coalitions, detects bone marrow edema indicating symptomatic coalition).

Symptoms

Insidious onset midfoot or hindfoot pain in adolescent
Pain worsened by prolonged walking, running, or sports
Peroneal muscle spasm with rigid pronated flatfoot
Restricted subtalar joint motion (compared to contralateral foot)
Painful eversion-inversion at subtalar joint
Valgus heel position with absent or limited longitudinal arch on weight bearing
Recurrent ankle sprains (limited subtalar inversion forces ankle inversion)
Midfoot prominence on the dorsolateral foot
Calluses on lateral aspect of foot
Family history of similar foot problems (autosomal dominant)

Risk Factors

Family history (autosomal dominant inheritance with variable penetrance — 39 percent positive family history)
Bilateral involvement (50 percent for TC, 60 percent for CN)
Adolescent age (8–14 years for symptom onset; ossification of cartilaginous bar)
Sports participation increasing demand on stiff foot
Repeated ankle sprains (consequence as well as risk factor)
Associated congenital syndromes (rare): Apert, Nievergelt, fibular hemimelia, Crouzon, Pfeiffer
Slight male predominance (2:1)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Adolescent with insidious midfoot or hindfoot pain not relieved by rest
  • Recurrent ankle sprains in young person
  • Limited subtalar motion compared to opposite foot
  • Peroneal muscle spasm or rigid flatfoot
  • Family history of similar foot problems with new pediatric symptoms
  • Failed conservative treatment of flatfoot in adolescent
  • Pain interfering with sports or daily activities
  • Suspected coalition on imaging — orthopedic referral for further evaluation

Treatment Methods

01
Diagnostic: weight-bearing AP and lateral foot radiographs (anteater sign for CN, C-sign for TC), oblique view of foot (best for CN coalition), CT scan (gold standard for osseous coalition extent and degenerative changes), MRI (essential for fibrous and cartilaginous coalitions, detects bone marrow edema indicating symptomatic coalition), gait analysis if available
02
Conservative therapy first-line for all symptomatic coalitions: short-leg walking cast or boot for 4–6 weeks (for acute pain flare with peroneal spasm), NSAIDs for pain control, custom semirigid orthotic or UCBL (University of California Biomechanics Laboratory) insert with medial arch support and lateral heel posting, physical therapy for peroneal stretching and strengthening, activity modification (avoid impact sports during flares)
03
Corticosteroid injection (under fluoroscopic or ultrasound guidance) into the coalition or symptomatic adjacent joint for diagnostic confirmation and symptomatic relief
04
Surgical indications: failed 6-month trial of conservative therapy with persistent disabling pain, inability to participate in age-appropriate activities, severe peroneal spasm
05
Surgical resection with interposition (preferred for symptomatic non-degenerative coalitions): resection of coalition (calcaneonavicular bar resection or talocalcaneal middle facet resection) plus interposition with autologous fat, extensor digitorum brevis (EDB) muscle, or bone wax to prevent re-formation; results best for CN coalitions < 50 percent of subtalar joint area
06
Calcaneocuboid arthrodesis or talonavicular arthrodesis for limited indications
07
Subtalar fusion (subtalar arthrodesis) or triple arthrodesis (talonavicular + calcaneocuboid + subtalar) for: large coalitions involving > 50 percent of joint area, established degenerative arthritis in adjacent joints, valgus deformity, failed coalition resection, adult presentation; provides reliable pain relief but sacrifices motion
08
Recent advances: arthroscopic coalition resection for selected cases (less morbidity, preservation of soft tissues), 3D-printed patient-specific surgical guides for accurate resection
09
Postoperative: non-weight-bearing in cast or boot for 4–6 weeks, gradual return to weight bearing, physical therapy, gradual return to sports by 4–6 months
10
Long-term follow-up: symptom recurrence, adjacent joint degeneration, possible need for arthrodesis later in life if degenerative changes progress

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.