Rigid Flatfoot

Historically, this described a foot held in rigid valgus by spasm of the peroneal muscles. We now know that the peroneal spasm is usually a protective reflex to splint a painful, stiff subtalar joint (typically due to a coalition). It may also be seen in inflammatory conditions (Subtalar arthritis).

• Infant: Congenital Vertical Talus (CVT).
• Child: Tarsal Coalition (Calcaneonavicular - ossifies earlier).
• Adolescent: Tarsal Coalition (Talocalcaneal - ossifies later).
• Any Age: Septic Arthritis, Osteomyelitis, Trauma, Tumor (Osteoid Osteoma).

Allows inversion/eversion. Essential for accommodating uneven ground. The "Torque Converter" of the foot.

• Block to Motion: A bony or cartilaginous bar (coalition) or dislocation (CVT) prevents subtalar inversion/eversion.
• Fixed Valgus: The heel is locked in valgus.
• Midfoot Unlock: Because the hindfoot cannot invert, the midfoot cannot lock (via the locking wedge mechanism of the transverse tarsal joint) to become a rigid lever for push-off.
• Peroneal Overdrive: The peroneals shorten over time or spasm to prevent painful inversion against the bar.

• Calcaneonavicular (CN): Connection between the anterior process of the calcaneus and the navicular.
• Talocalcaneal (TC): Connection typically at the middle facet of the subtalar joint.

A failure of mesenchymal segmentation during fetal development. The bar is initially cartilaginous (synchondrosis) or fibrous (syndesmosis) and allows some motion, hence why young children are asymptomatic. As the child grows and the bar ossifies (synostosis), stiffness increases, micro-fractures occur across the rigid bar during activity, and pain develops.

• Calcaneonavicular (CN): Ossifies between 8-12 years. Symptoms appear at this age.
• Talocalcaneal (TC): Ossifies between 12-16 years. Symptoms appear later in adolescence.

• Presentation: Acute onset rigid flatfoot, refusal to bear weight, fever, elevated CRP/ESR.
• Mechanism: Pus in the joint causes severe spasm (splinting) of the surrounding muscles (Peroneals).
• Urgency: Surgical emergency requiring washout.

• Presentation: Insidious onset stiffness, often bilateral (but starts unilateral). Subtalar joint is a common target.
• Signs: Warmth, swelling, morning stiffness.
• Natural History: If uncontrolled, leads to spontaneous fusion (ankylosis) of the subtalar joint. This causes a permanent rigid flatfoot in adulthood.

• Classic Site: Talar neck or Subtalar joint.
• Mechanism: The tumor secretes prostaglandins which cause intense local inflammation and reflexive muscle spasm (Peroneal Spastic Flatfoot).
• Key Symptom: Night pain relieved by Aspirin/NSAIDs.
• Imaging: CT reveals the "nidus".

• CT Scan: Essential. Assess the size of the coalition. Rule of thumb: if the bar involves greater than 50% of the joint surface, resection is likely to fail (instability/pain). Fusion is preferred.
• Hindfoot Valgus: If severe (greater than 15-20 degrees), resection alone won't correct alignment. Need calcaneal osteotomy.

1. Incision: Lateral oblique incision in the lines of tension skin.
2. Protection: Sural nerve (posterior) and Superficial Peroneal Nerve (dorsal).
3. Exposure: Elevate the Extensor Digitorum Brevis (EDB) from its origin.
4. Identification: The bar is palpable between the calcaneus and navicular.
5. Resection: Using an osteotome or burr. The resection must be generous (rectangular block).
6. Check: Visualize the talar head (medial) and cuboid (lateral) to ensure full width resection.
7. Interposition: The EDB muscle belly is sewn into the defect with absorbable suture to act as a spacer.

1. Incision: Medial curvilinear incision over the sustentaculum tali.
2. Protection: Tibialis Posterior tendon, FDL, FHL, and Neurovascular bundle (retract posteriorly).
3. Exposure: Open the sheath of FDL/Tib Post. Identify the middle facet.
4. Resection: High speed burr to remove the bony bridge.
5. Safety: Do not penetrate too deeply into the posterior facet (lateral) or sinus tarsi.
6. Interposition: Fat graft (from Kager's triangle or local fat) or bone wax.

• Upasani Classification:
  • Type 1: Fibrous/Cartilaginous (Irregular joint line).
  • Type 2: Bony (Solid bar).

Based on CT scan morphology and percentage of posterior facet involvement.

• Type I: Linear (straight bond).
• Type II: Linear with posterior hook.
• Type III: Shingled (overlapping).
• Type IV: Complete bony block.
• Type V: Posterior facet involvement greater than 50%. (Poor prognosis for resection).

1. Coronal Plane: Best for TC coalition (Middle facet).
2. Sagittal Plane: Best for C-Sign.
3. Oblique/Axial: Best for CN coalition.
4. Impingement Signs: Check for dorsal "beaking" on the talus (Traction spur, not OA) vs true joint space narrowing (OA). Resection is contraindicated if greater than 50% joint narrowing.

• Pain: Often "vague" ankle pain or sinus tarsi pain. Worse with activity or uneven ground.
• Sprains: Recurrent ankle sprains (because the subtalar joint can't accommodate, the ankle rolls).
• Stiffness: "My foot doesn't move like the other one."

• Look:
  • Flattened arch (Pes Planus).
  • Heel Valgus (Hindfoot Valgus).
  • "Too Many Toes" Sign (Forefoot abduction).
• Feel:
  • Tender Sinus Tarsi (CN Coalition/Arthritis).
  • Tender Medial Malleolus/Sustentaculum (TC Coalition).
  • Tight Peroneal Tendons (bowstringing behind lateral malleolus).
• Move:
  • Subtalar ROM: Lock the talus in the mortise (dorsiflex ankle) and swing the heel. Restricted or Absent in rigid flatfoot.
  • Tiptoe Test: Heel fails to invert.
  • Jack's Test: Arch fails to rise.

• AP Foot: "Talonavicular uncoverage".
• Lateral Foot:
  • C-Sign: Continuous C-shaped line from talar dome to sustentaculum (TC Coalition).
  • Anteater Nose Sign: Elongated anterior process of calcaneus (CN Coalition).
  • Talar Beak: Dorsal osteophyte on talar head (traction spur from navicular capsule).
  • Vertical Talus: Talus axis points to sole, Navicular dorsal.
• Harris Heel View: Special view to see the posterior and middle facets.

• CT Scan: Gold Standard for defining bony anatomy and mapping coalitions. Essential for surgical planning (size of bar, hindfoot valgus angle).
• MRI: Useful for Fibrous or Cartilaginous coalitions (which may be invisible on CT) and for assessing soft tissue/inflammatory causes (synovitis).

1. Incision: Lateral Ollier's incision (extended).
2. Exposure: EDB reflected. Retract peroneals plantarwards.
3. Joint Prep (Resection):
   • CC Joint: Resect cartilage to bleeding bone.
   • Subtalar Joint: Resect posterior and anterior facets. Remove the coalition.
   • TN Joint: Exposed from lateral side (challenging) or separate medial incision. Remove cartilage.
4. Correction:
   • Reduce the Talonavicular joint first (key to alignment).
   • Correct Valgus at the Subtalar joint.
   • Correct Abduction at the CC joint.
5. Fixation:
   • Subtalar: large screw (6.5mm/7.0mm) from heel to talus.
   • TN: screws or staples.
   • CC: screws or staples.
6. Closure: Layered closure over a drain.

• Position: Supine, sandbag under ipsilateral hip.
• Tourniquet: Thigh.
• Post-op: NWB for 6-12 weeks until union.

• Weeks 0-2: Splint/Cast, Non-Weight Bearing (NWB). Elevate significantly to prevent wound breakdown.
• Weeks 2-6:
  • Motion: Start active ROM exercises (writing alphabet with foot).
  • Physio: Focus on peroneal strengthening and subtalar eversion/inversion.
  • Weight: Touch down weight bearing in a boot.
• Weeks 6+:
  • Weight bearing as tolerated in shoes.
  • Continue physio for 3-6 months.
  • Return to sport at 3-4 months.

• Weeks 0-2: Backslab, strictly NWB. Elevation.
• Weeks 2-6: Conversion to lightweight fibreglass cast or CAM boot (locked). Still NWB to protect the fusion mass.
• Weeks 6-12:
  • Progressive weight bearing in CAM boot.
  • X-ray at 6 weeks to check alignment.
  • X-ray at 12 weeks to confirm union.
• Months 3-6:
  • Wean out of boot into stiff-soled shoe.
  • Gait retraining (expect stiff gait).
  • No impact sports.

• CRPS (Complex Regional Pain Syndrome): High risk in foot surgery. Early movement and desensitization are key prevention strategies. Vitamin C 500mg daily is often prescribed.
• Stiffness: Failure to mobilize after resection leads to fibrosis.

• Headlight: Essential for visualization, especially medial approach.
• Bone Wax: Use liberally on the raw bone surfaces after resection to prevent hematoma and re-ossification.
• Fat Graft: Don't skimp. Harvest a large plug from the Kager's triangle (retro-calcaneal fat pad). It has a robust blood supply.
• Intra-op Fluoroscopy: Use it to confirm the amount of bone removed. The "Harris Line" (middle facet) must be clear.
• Dynamic Check: After resection, the subtalar motion should return immediately. If it's still stiff, you haven't taken enough bone, or there's another coalition.

• Order of Fixation:
  1. Talonavicular (TN): This sets the version of the foot. Reduce this first.
  2. Subtalar (TC): Corrects the valgus/varus.
  3. Calcaneocuboid (CC): Follows the others.
• Screw Position:
  • Subtalar screw should aim for the talar dome but NOT penetrate it.
  • TN screws should be placed from navicular into talar head (or vice versa), avoiding the joint surface.
• Bone Graft: Use local autograft from the resected wedges to pack the fusion sites.

Also known as "Rocker Bottom Foot". It is a dorsolateral dislocation of the talonavicular joint. The talus is locked in a vertical (plantarflexed) position, and the navicular is dislocated onto the dorsal neck of the talus. This is the hallmark of a rigid flatfoot in a newborn.

• Hindfoot: Severe valgus and equinus (calcaneus is plantarflexed).
• Midfoot: Dorsally dislocated.
• Forefoot: Abducted and dorsiflexed.
• Soft Tissue Contractures: Tight Achilles, Peroneals, Tibialis Anterior, and Extensor Digitorum Longus.

• Idiopathic: 50% of cases.
• Syndromic: 50% of cases. Highly associated with Arthrogryposis, Spina Bifida (Myelomeningocele), and Genetic Syndromes (Trisomy 13, 15, 18).

• CVT: Rigid. Navicular does not reduce on plantarflexion X-ray.
• Oblique Talus: Flexible/Reducible. Navicular slides back on plantarflexion.