Flexible Flatfoot (Pediatric)

Flat foot. Technically defined as valgus of the hindfoot, abduction of the forefoot, and depression of the medial longitudinal arch.

Emphasizes the valgus component of the heel.

The deformity is reducible. The joints (Subtalar, TN, CC) are mobile.

A lateral column lengthening procedure. The "Workhorse" for severe flatfoot correction.

"To prop up". Surgical limitation of joint motion (without fusion) using an implant.

The Talonavicular joint is the keystone of the arch. In flatfoot, the talus head uncovers medially and plantarward (Peritalar subluxation).

• Hindfoot Valgus: The calcaneus goes into valgus.
• Forefoot Abduction: The midfoot breaks, and forefoot abducts relative to hindfoot.
• Achilles Tension: With the hindfoot in valgus, the Achilles tendon becomes a DEFORMING force (it is now lateral to the axis of the subtalar joint), acting as an evertor.
• Medial Column: The Spring Ligament (Calcaneonavicular) and Tibialis Posterior stretch out.
  • Spring Ligament:
    • Superomedial band: The most important stabilizer.
    • Inferoplantar band: Supports the head of talus.
  • Tibialis Posterior:
    • Primary dynamic stabilizer of the arch.
    • Inserts on the Navicular tuberosity + slips to cuneiforms/cuboid/metatarsals (2,3,4).
    • Failure leads to flatfoot (Adult Acquired), but in kids, it's usually laxity not rupture.
• Lateral Column: Theoretically shortened relative to the medial column in flatfoot (hence lengthening corrects it).

• Heel Strike: Calcaneus everts (unlocking subtalar joint) for shock absorption.
• Mid-Stance: Subtalar joint inverts (locking MTJ) to create a rigid lever for push-off.
• In Flatfoot, the foot remains everted and unlocked throughout stance, leading to inefficient gait.

• Extending the Hallux pulls the Plantar Aponeurosis.
• This shortens the distance between calcaneus and metatarsal heads.
• This elevates the arch and inverts the hindfoot.
• In Flexible Flatfoot, this mechanism is INTACT.
• In Rigid Flatfoot, it is blocked.

1. Observe barefoot in standing and gait. Record arch height, hindfoot valgus, forefoot abduction, too-many-toes sign, heel-cord orientation, callosity and shoe wear. Compare both sides and inspect the child walking, running and rising on tiptoe.
2. Test correction, not appearance. With the child standing, ask for a double- then single-leg heel raise. A flexible foot should recreate the arch and move the heel into varus; pain, inability or persistent valgus suggests a symptomatic tendon problem, coalition or neuromuscular weakness.
3. Perform Jack's test correctly. Stabilise the hindfoot, passively extend the hallux at the metatarsophalangeal joint and watch the medial arch and calcaneal position. A rising arch is a positive flexibility response; pain at the plantar fascia or no correction is not a positive result and should prompt a search for rigidity or another pain generator.
4. Measure ankle dorsiflexion with the knee extended and flexed. Hold the hindfoot in neutral so the midtarsal joint cannot substitute for ankle motion. A meaningful increase after knee flexion indicates gastrocnemius tightness; persistent equinus in both positions indicates soleus/Achilles tightness or a structural block.
5. Assess subtalar and midtarsal motion. Move the calcaneus through inversion and eversion while palpating the talar head. Marked restriction, pain or peroneal spasm is abnormal for an idiopathic flexible foot and warrants coalition imaging.
6. Palpate the medial column and sinus tarsi. Localise tenderness to the navicular prominence, tibialis posterior insertion, plantar fascia, sinus tarsi or calcaneocuboid joint. Test resisted inversion and plantarflexion, and document skin pressure from footwear.
7. Screen the whole child. Record limb-length asymmetry, tibial torsion, femoral version, genu valgum, Beighton laxity and neuromuscular signs. A unilateral, progressive or neurologically associated deformity is not presumed physiological.

allowing the child to pronate the forefoot during dorsiflexion measurement; calling a painful forced manoeuvre “rigid” without checking subtalar motion; and diagnosing a coalition from a flat arch alone.

• Only if suspecting coalition (CT) or tendon pathology (MRI). Not routine.

• Request standing AP and lateral foot radiographs when pain, rigidity, asymmetry, atypical age or operative planning makes imaging useful. Add a 45-degree oblique view for a suspected calcaneonavicular coalition and a Harris (Saltzman) axial hindfoot view when coronal hindfoot alignment matters.
• On the weight-bearing lateral view, draw the long axes of the talus and first metatarsal for Meary's angle (normally approximately colinear); record the calcaneal pitch from the inferior calcaneal surface to the floor (roughly 20–30° in a typical foot); and assess talar beaking, talocalcaneal overlap and the height of the medial column.
• On the weight-bearing AP view, assess talonavicular coverage, talo–first-metatarsal alignment and forefoot abduction. Describe direction and severity rather than treating one angle as an isolated surgical threshold.
• A CT scan is the best study to define a suspected osseous coalition, its location and extent, subtalar joint degeneration and the bony anatomy needed for resection or fusion planning. A thin-slice hindfoot CT is not routine for a painless flexible foot.
• MRI is useful for a fibrous or cartilaginous coalition, tibialis posterior or spring-ligament pathology, marrow oedema and an unexplained pain generator. It is not a substitute for weight-bearing alignment films when deformity correction is being planned.
• In a child with a rigid rocker-bottom foot, obtain a forced-plantarflexion lateral radiograph to distinguish a reducible oblique talus from congenital vertical talus; persistent dorsal navicular dislocation and a vertical talus support congenital vertical talus.

measurements support the examination; they do not overrule symptoms, flexibility, skeletal maturity, neuromuscular status or the distribution of deformity.

• There is no dedicated implant registry for paediatric flatfoot. Arthroereisis "spacers" are device implants, so where national implant or device registries exist (e.g. orthopaedic device tracking schemes), outcomes and removal events should be captured the same way as any implant; the absence of long-term registry data is itself a reason for caution.

• High-resource settings: Risk is over-investigation and over-treatment (unnecessary X-rays, custom orthoses, premature surgery) for what is usually a normal variant; ethical counselling — "we treat the child, not the radiograph" — is the priority.
• Limited-resource settings: Custom orthoses and elective reconstruction may be unaffordable; emphasis falls on examination-based diagnosis, reassurance, simple calf-stretching programmes, and reserving theatre time for genuinely disabling or rigid deformity.

• Rigid foot or absent subtalar motion (suspect tarsal coalition or congenital vertical talus).
• Unilateral or asymmetric deformity.
• Pain or callosity limiting walking/sport.
• Failure of a supervised calf-stretching programme over roughly 6 months.