Peroneal Spastic Flatfoot in Children and Adolescents

Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

Peroneal spastic flatfoot is a painful, rigid flatfoot deformity in children and adolescents characterized by involuntary peroneal muscle spasm and limited subtalar motion. Unlike flexible flatfoot — which is typically painless and requires no treatment — peroneal spastic flatfoot warrants prompt evaluation because an underlying structural abnormality (most commonly tarsal coalition) drives the spasm and the deformity will not resolve spontaneously.

The Connection to Tarsal Coalition

Tarsal coalition — an abnormal fibrous, cartilaginous, or bony bridge between two or more tarsal bones — is found in approximately 90% of adolescents presenting with peroneal spastic flatfoot. Calcaneonavicular and talocalcaneal coalitions are the most common forms. These bridges restrict the normal gliding motion of the subtalar and midtarsal joints; as the growing skeleton attempts to move through a restricted range of motion, the peroneal muscles contract reflexively to protect the abnormal joint — producing the characteristic spasm, rigid valgus deformity, and pain.

Presentation and Diagnosis

Typical presentation is an adolescent, often male, between ages 8–16 who reports gradually worsening lateral ankle or hindfoot pain, difficulty with sports, and recurrent ankle sprains. Examination reveals a rigid flatfoot that does not reconstitute (restore normal arch height) on tiptoe standing — distinguishing it from flexible flatfoot. The subtalar joint shows markedly reduced or absent inversion and eversion. Standing foot radiographs and CT scan are the primary diagnostic tools; MRI adds soft tissue detail and is valuable for fibrous coalitions that may be radiographically subtle.

Conservative Management

Initial treatment focuses on relieving muscle spasm and pain. Immobilization in a short-leg walking cast or boot for 4–6 weeks frequently breaks the pain-spasm cycle and provides temporary relief. Custom orthotics with arch support and hindfoot control maintain pain reduction following immobilization. Many patients with fibrous (non-ossified) coalitions achieve acceptable long-term symptom control with orthotic management alone.

Surgical Options

Surgical resection of the coalition is indicated for patients with bony coalitions, failed conservative management, or progressive deformity. Calcaneonavicular coalition resection with interposition of the extensor digitorum brevis muscle belly produces reliable pain relief and restored motion in appropriately selected patients. Talocalcaneal middle facet coalition resection is technically demanding and has more variable outcomes — larger coalitions (over 50% joint surface involvement) may not benefit from resection alone and may require hindfoot fusion. Dr. Biernacki at Balance Foot & Ankle provides evaluation and management of pediatric and adolescent foot deformities including tarsal coalition and peroneal spastic flatfoot. Call (810) 206-1402 to schedule an evaluation at our Bloomfield Hills or Howell office.

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When to See a Podiatrist

Many foot conditions can be managed conservatively at home, but some require professional evaluation. See a podiatrist promptly if you experience:

• Pain that persists for more than 2 weeks despite rest
• Swelling, redness, or warmth that isn’t improving
• Numbness, tingling, or burning in the feet
• A wound or sore that is not healing within 2 weeks
• Any foot concern if you have diabetes or poor circulation
• Nail changes that suggest fungal infection or other problems

At Balance Foot & Ankle, our three board-certified podiatrists — Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin — provide comprehensive foot and ankle care at our Howell and Bloomfield Township offices. Most insurance plans are accepted.

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Board-certified podiatrists Dr. Tom Biernacki, Dr. Carl Jay, and Dr. Daria Gutkin see patients daily at our Howell and Bloomfield Township, MI offices.

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Pediatric Flatfoot Specialists in Michigan

Peroneal spastic flatfoot in children can signal tarsal coalition or other conditions requiring specific treatment. Our pediatric foot specialists provide thorough evaluation and individualized care.

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Clinical References

1. Mosca VS. Subtalar coalition in pediatrics. Foot Ankle Clin. 2015;20(2):265-281.
2. Crim JR, Kjeldsberg KM. Radiographic diagnosis of tarsal coalition. AJR Am J Roentgenol. 2004;182(2):323-328.
3. Jayakumar S, Cowell HR. Rigid flatfoot. Clin Orthop Relat Res. 1977;(122):77-84.