Pilon Fractures

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Definition: A Pilon (French for "Pestle") fracture is an intra-articular fracture of the distal tibia metaphysis involving the weight-bearing dome (plafond). It typically results from high-energy axial loading.

Epidemiology:

• 1-10% of lower extremity fractures.
• Bimodal:
  • Young males: High energy (fall from height, MVA).
  • Elderly females: Low energy (rotational ankle fracture variant).
• Associations:
  • Open fracture (20-25%).
  • Fibula fracture (75-85%).
  • Polytrauma.

Bony Anatomy:

• Tibial Plafond: The weight-bearing articular surface. It is wider anteriorly than posteriorly (trapezoidal).
• Three Pillars (AO Concept):
  1. Medial Column: Medial malleolus and anteromedial cortex.
  2. Lateral Column: Anterolateral tibia (Chaput tubercle).
  3. Posterior Column: Posterior malleolus (Volkmann).
• Fibula: Acts as a lateral buttress. If fractured, it indicates significant instability.

Soft Tissue Envelope:

• Subcutaneous: The anteromedial face of the tibia is strictly subcutaneous with no muscle cover. This is the "danger zone" for wound breakdown.
• Fascial Compartments:
  • Anterior (Deep Peroneal N, Anterior Tibial A).
  • Lateral (Superficial Peroneal N).
  • Posterior (Tibial N, Posterior Tibial A).
  • Deep Posterior.

Angiosomes:

• Knowledge of vascular supply is critical for incision planning.
  • Anteromedial approach: Safe zone, supplied by Saphenous/Posterior Tibial branches? No, risky.
  • Anterolateral approach: Supplied by Anterior Tibial artery (perforators).
  • Bridge: The skin bridge between an anterolateral and posteromedial incision must be at least 7cm.

Blood Supply Details

• Anterior Tibial Artery: Becomes the Dorsalis Pedis. Main supply to anterior compartment structures. Perforators supply the anterolateral skin.
• Posterior Tibial Artery: Main supply to the medial ankle and deep posterior compartment. The medial malleolar artery (branch) is at risk during medial approaches.
• Peroneal Artery: Supplies the lateral compartment. Branches contribute to the syndesmotic region.
• Watershed Zone: The anteromedial tibial skin is a "watershed" area between the anterior and posterior tibial angiosomes, making it highly susceptible to necrosis.

Ligamentous Anatomy

• Syndesmosis: AITFL, PITFL, Transverse ligament, Interosseous membrane. Unlike rotational ankle fractures, the syndesmosis is often intact in axial Pilon because the force is vertical, not rotational.
• Deltoid Ligament (Medial): Deep and superficial components. Important for medial stability. Assess for injury by palpating the medial gutter.
• Spring Ligament (Calcaneonavicular): Supports the talar head. Can be injured in high-energy Pilon variants with significant foot injury extension.

History:

• Mechanism (Fall from height vs Twisting).
• Smoking status (Critical for wound healing prognosis).
• Diabetes/Neuropathy.

Physical Exam:

• Inspection: Look for open wounds (medial side), tenting of skin, fracture blisters.
  • Clear fluid blisters: Epidermal injury. Can operate through (carefully).
  • Hemorrhagic blisters: Dermal/Subdermal injury. Do NOT incise. Wait for epithelialization.
• Neurovascular: Pulses and Sensation.
• Compartments: Pain with passive extension of toes? (Leg and Foot).

Systematic Examination

Look:

• Deformity - Varus/Valgus, Shortening.
• Skin - Open wounds, Tenting, Blisters, Degree of swelling.
• Foot position - External rotation (suggests PER)?

Feel:

• Tenderness - Entire tibia, Ankle mortise, Medial malleolus, Fibula.
• Compartments - Tense? (Anterior and Deep Posterior at highest risk).
• Pulses - DP and PT. Document pre- and post-reduction.

Move:

• Do NOT attempt active motion if clearly fractured.
• Assess passive motion gently to evaluate joint stability.

Neurovascular:

• Deep Peroneal N: Sensation in 1st web space. EHL motor function.
• Tibial N: Sensation on plantar foot. FHL motor function.
• Document meticulously - Neurologic injury may occur from swelling or compartment syndrome.

• Wound Dehiscence / Infection (10-30%):
  • Highest rate in orthopaedic trauma.
  • Deep infection often requires free flap coverage or amputation.
• Post-Traumatic Arthritis (50%+):
  • Almost inevitable in Type III injuries.
  • Correlates with quality of reduction (less than 2mm stepoff).
  • Treatment: Ankle Arthrodesis or Arthroplasty (in elderly).
• Nonunion (5-10%):
  • Metaphyseal junction nonunion.
• Malunion:
  • Varus malunion common.
• Stiffness:
  • Arthrofibrosis from prolonged immobilization.
• Chronic Pain:
  • CRPS type symptoms.

Hardware Complications

• Hardware Failure (Plate Breakage):
  • Risk factors: Early weight bearing, Severe comminution, Poor reduction.
  • Management: Plate out, Bone graft, Re-plate. Consider IM nail.
• Prominent Hardware:
  • Due to thin soft tissue over anteromedial tibia.
  • Management: Remove once union achieved (6-12 months post-op).
• Screw Irritation:
  • Periarticular screws can cause synovitis if protruding into joint.
  • Remove prominent screws.

Deep Venous Thrombosis (DVT)

• Risk: High due to lower limb trauma, NWB, immobilization.
• Prophylaxis: LMWH or Aspirin. Decision based on bleeding risk and institutional protocol.
• Diagnosis: Clinical suspicion (calf swelling, pain). Duplex US.
• Treatment: Anticoagulation.

Stiffness (Near Universal)

• Cause: Intra-articular scarring, cartilage damage, prolonged immobilization.
• Prevalence: Loss of 10-20 degrees dorsiflexion is common.
• Impact: Affects gait (requires greater knee flexion).
• Management: Early ROM exercises. Aggressive physiotherapy. MUA rarely helpful.

Checklist for Complications:

• Wound Healing:
  • The anteromedial skin is precarious.
  • Vacuum dressings (PICO) often used prophylactically.
  • Any necrosis must be debrided early and covered (Flap).
• Stiffness:
  • Ankle stiffness is universal.
  • Loss of dorsiflexion is most debilitating.
• Infection:
  • Deep infection rate is 5-15% in closed fractures, higher in open.
  • Staph aureus is most common pathogen.
  • Management: Debridement, retention of hardware (if stable) or removal (if loose) + antibiotics.
• CRPS (Complex Regional Pain Syndrome):
  • Vitamin C 500mg daily proposed for prevention (controversial evidence but low harm).

• Return to Work: Average 12 months.
• Make it clear: "Your ankle will never be normal again." (Manage expectations).
• Score: AOFAS scores typically 70-80/100.
• Arthrodesis Rate: 10-20% require fusion within 5-10 years.

• Trauma Networks: Pilon fractures are usually transferred to Major Trauma Centres (MTC) like The Alfred, Royal Melbourne, or John Hunter.
• Referral: If you are in a peripheral hospital, SPAN IT (ExFix) and SHIP IT. Do not attempt definitive fixation without CT and planning.
• Implants: LCP plates (Synthes/Stryker) are standard availability.

Transfer Considerations

• Rural and Remote Settings:
  • Apply a spanning ExFix (using available equipment - even a unilateral frame is sufficient initially).
  • Ensure adequate analgesia and elevation.
  • Arrange retrieval to MTC via RFDS or road ambulance.
  • Communicate with receiving MTC orthopaedic registrar for handover.
• Documentation for Transfer:
  • X-rays (AP, Lateral, Mortise).
  • Neurovascular status pre- and post-reduction.
  • Compartment status.
  • Tetanus status.
  • Antibiotics given (timing and dose) for open fractures.

Medicolegal Considerations

• Consent: Must include discussion of:
  • High complication rate (wound, infection, arthritis).
  • Likelihood of stiffness and reduced function.
  • Possibility of future arthrodesis.
  • Alternative treatments (Non-op, Circular Frame).
• Documentation: Detailed operative notes are critical given the high complication rate.
• Follow-Up: Ensure clear return instructions for wound review (2 weeks) and signs of compartment syndrome.