MedVellum
MedVellum
Back to Library
Orthopaedics
Emergency Medicine
Trauma
EMERGENCY

Ankle Fracture

High EvidenceUpdated: 2025-12-26

On This Page

Red Flags

  • Frank Dislocation -> Urgent Sedation/Reduction (Skin/Vascular Threat)
  • Skin Tenting -> Impending Necrosis (Urgent reduction)
  • Maisonneuve Injury -> Proximal Fibula Tenderness (Missed Syndesmosis injury)
  • Open Fracture -> IV Antibiotics + Tetanus
  • Talar Shift -> Unstable (Requires Surgery)
Overview

Ankle Fracture

1. Clinical Overview

Summary

Ankle fractures are the most common weight-bearing musculoskeletal injury, involving the "Mortise" ring (Tibia, Fibula, Talus). Management is dictated by Stability—whether the talus can shift within the mortise. The Danis-Weber classification (A/B/C) based on the fibula fracture level guides surgical planning. The Lauge-Hansen classification (Supination-External Rotation) explains the ligamentous injury sequence. The critical "Don't Miss" diagnosis is the Syndesmosis Injury, where the tibiofibular bond is ruptured (Cotton Test), leading to rapid arthritis if not stabilized (Screw/TightRope). [1,2,3]

Key Facts

  • The Ring Concept: The ankle mortise is a ring comprising bone (malleoli) and ligaments (Deltoid/Lateral). A single break is stable. A double break (e.g., Fibula fracture + Deltoid rupture) is unstable.
  • The 1mm Rule: A 1mm lateral shift of the talus ("Talar Shift") reduces the tibiotalar contact area by 42%, leading to catastrophic Point Loading and early osteoarthritis. Anatomical reduction is mandatory.
  • Maisonneuve Fracture: An unstable high fibula fracture caused by external rotation. Always palpate the proximal fibula (knee) when a patient has a "sprained ankle" but is tender medially!
  • Posterior Malleolus: The "Third Malleolus". If >25% of the articular surface is involved, the talus will slide backwards (Posterior subluxation).

Clinical Pearls

"Gravity Stress View": In an apparently isolated Weber B fibula fracture, lie the patient on the injured side (lateral decubitus). Gravity pulls the foot down. If the Medial Clear Space opens >4mm on X-ray, the Deltoid Ligament is ruptured, and the fracture is unstable (equivalent to bimalleolar).

"Toes Above Nose": The only way to reduce ankle swelling is radical elevation. The foot must be higher than the heart. Pillows aren't enough—tilt the bed.

"The Wrinkle Sign": Surgery is often delayed 7-14 days to allow soft tissues to settle. You cannot cut through blistered skin. Wait for skin wrinkles to reappear.

2. Epidemiology

Demographics

  • Incidence: 187 per 100,000. One of the most common fractures treated by Orthopaedic surgeons.
  • Population: Bimodal.
    • Young Active Males: Sports, High energy.
    • Elderly Females: Osteoporotic falls (Low energy).
  • Mechanism: Rotational injury. Supination-External Rotation (SER) is most common.

Risk Factors

  • Obesity: High torque on the joint.
  • Smoking: 5x risk of non-union and infection.
  • Diabetes: Neuropathy (Charcot) complicates management significantly. A diabetic ankle fracture needs DOUBLE the fixation and DOUBLE the non-weight bearing time.
3. Pathophysiology

Anatomy: The Ankle Ring

  • Fibula: Lateral Malleolus (Primary stabilizer against lateral shift).
  • Tibia: Medial Malleolus + Posterior Malleolus (Posterior lip of tibia).
  • Syndesmosis: The ligament complex holding tibia and fibula together.
    • AITFL: Anterior Inferior Tibiofibular Ligament.
    • PITFL: Posterior Inferior Tibiofibular Ligament (Very strong).
    • IOM: Interosseous Membrane.
  • Deltoid Ligament: Medial stabilizer. Deep and Superficial layers.

Mechanism: Lauge-Hansen Classification

Based on Foot Position at time of injury + Direction of Force.

  1. Supination-External Rotation (SER): Most common (60%).
    • Stage 1: AITFL rupture.
    • Stage 2: Spiral Fibula fracture (Weber B).
    • Stage 3: PITFL rupture (or Posterior Malleolus fracture).
    • Stage 4: Medial Malleolus fracture (or Deltoid rupture).
  2. Pronation-External Rotation (PER):
    • High Fibula fracture (Weber C).
    • Syndesmosis disrupted.
    • Medial injury first.
  3. Supination-Adduction (SA):
    • Vertical Medial Malleolus fracture.
    • Transverse Fibula fracture (Weber A).
  4. Pronation-Abduction (PA):
    • Comminuted fibula.
4. Clinical Presentation

Symptoms

Signs

Pain, swelling ("Balloon Ankle").
Common presentation.
Inability to 4-step weight bear (Ottawa Rule).
Common presentation.
Audible snap.
Common presentation.
5. Investigations

Imaging

  • X-Ray Ankle (3 Views):
    1. AP: General overview.
    2. Mortise (15° Internal Rotation): The "Money View". Removes the overlap of fibula/tibia.
      • Medial Clear Space (MCS): Should be <4mm.
      • Tibiofibular Overlap: Should be >10mm (implies intact syndesmosis).
      • Talar Shift: Check symmetry.
    3. Lateral: Check for Talar subluxation and Posterior Malleolus fracture ("Volkmann's Triangle").
  • X-Ray Knee: To rule out Maisonneuve.

Ottawa Ankle Rules

  • X-Ray only if:
    • Bone tenderness at posterior edge of Lateral or Medial Malleolus (distal 6cm).
    • Inability to bear weight (4 steps) at time of injury AND in ER.
  • Sensitivity: 98% (Good for ruling out).
6. Management Algorithm
                 ANKLE FRACTURE
                        ↓
             DISLOCATION / SKIN THREAT?
            ┌─────────────┴─────────────┐
           YES                          NO
            ↓                           ↓
    URGENT REDUCTION            WEBER CLASSIFICATION
   (Sedation/Quigley)          (Fibula Fracture Level)
            ↓                 ┌─────┼─────┐
                          TYPE A  TYPE B  TYPE C
                         (Below)   (At)   (Above)
                         Stable  Variable Unstable
                            ↓       ↓        ↓
                          BOOT   MEDIAL   SURGERY
                                 CLEAR
                                  SPACE
                                 &gt;4mm?
                                ┌─┴─┐
                               NO  YES
                               ↓    ↓
                             BOOT  SURGERY
                             (6w)  (ORIF)
7. Management: Conservative

Indications

  • Stable Fractures:
    • Isolated Weber A.
    • Isolated Weber B with Medial Clear Space <4mm (Intact Deltoid).
  • Patient Factors: High surgical risk (vascular disease, uncontrolled diabetes, dementia).

Protocol

  • Functional Bracing (Walking Boot): Superior to casting.
  • Weight Bearing: Full weight bearing allowed immediately (as pain permits). Axial load compresses the fracture (healing).
  • Thromboprophylaxis: LMWH usually indicated while in boot.
  • Follow-up: X-ray at 1 week (Weight bearing) to ensure Talus hasn't shifted.
8. Management: Surgical

1. Open Reduction Internal Fixation (ORIF)

  • Lateral Malleolus: Anatomical reduction + Lag Screw (Compresses fracture) + Neutralization Plate (Protects screw).
  • Medial Malleolus: 2x Cancellous Screws (4.0mm partially threaded) or Tension Band Wire. Note: Remove periosteum from fracture site (interposition prevents union).
  • Posterior Malleolus: Fix if >25% of surface or unstable. Buttress Plate (Posterolateral approach).

2. Syndesmosis Stabilization

  • Indication: Intra-operative Cotton Test (Hook Test) shows separation >3mm.
  • Options:
    • Syndesmotic Screw: Rigid. 3 or 4 cortices. Needs removal (usually at 12 weeks) before weight bearing fully, as it will snap.
    • Suture Button (TightRope): Flexible. No removal. Earlier loading. Physiologic motion preserved.

3. Close Contact Casting (CCC)

  • For elderly patients with poor skin. A perfectly moulded cast can hold unstable fractures (AIM Trial).
9. Complications

Early

  • Wound Dehiscence: Thin skin envelope. Don't operate on swollen ankles!
  • Infection: 2-5%.
  • DVT/PE: High risk.
  • Nerve Injury: Superficial Peroneal Nerve (Lateral incision).

Late

  • Post-Traumatic Arthritis: 100% chance if anatomical reduction not achieved.
  • Stiffness: Loss of dorsiflexion.
  • CRPS (Complex Regional Pain Syndrome):
    • Burning pain, shiny skin, hypersensitivity.
    • Prevention: Vitamin C 500mg daily for 50 days reduces risk (ZOE Trial).
10. Evidence & Guidelines

The AIM Trial (2016)

  • Comparison of Surgery vs Close Contact Casting in >60s with unstable ankle fractures.
  • Result: Functional outcomes (OMA score) equivalent at 6 months. Infection rate higher in surgery group.
  • Conclusion: Casting is a safe alternative for the elderly to avoid surgical risks.

Syndesmosis Fixation

  • TightRope vs Screw: Systematic reviews show TightRope allows faster return to work/sport and avoids the need for a second "removal of metalwork" surgery. However, cost is higher.

Diabetes

  • Diabetic ankle fractures have a 40% complication rate. Recommendations: Fixation should be "augmented" (Stronger plates, multiple screws, prolonged NWB).
11. Patient Explanation

What is the injury?

The ankle is a ring of bone and ligament. You have broken the ring in two places, so the joint is unstable—like wobbly furniture.

Why do I need surgery?

If it heals in a wobbly position, the cartilage will rub away within 2 years, leaving you with painful arthritis. Surgery puts the pieces back perfectly so the joint glides smoothly.

The Recovery

  • Swelling: Will persist for 6-12 months. This is normal.
  • Walking:
    • Plate/Screws: Usually non-weight bearing for 2 weeks, then partial in boot.
    • TightRope: Can walk sooner.
  • Driving: Not until you can stomp the brake pedal (usually 9 weeks for right foot).
12. References
  1. Lauge-Hansen N. Fractures of the ankle. II. Combined experimental-surgical and experimental-roentgenologic investigations. Arch Surg. 1950.
  2. Willett K, et al. Close contact casting vs surgery for initial treatment of unstable ankle fractures in older adults (AIM): a randomised equivalence trial. JAMA. 2016.
  3. Schepers T. Acute distal tibiofibular syndesmosis injury: a systematic review of suture-button versus syndesmotic screw repair. Int Orthop. 2012.
13. Examination Focus (Viva Vault)

Q1: What defines the stability of a Weber B fracture? A: The integrity of the medial structures (Deltoid ligament and Medial Malleolus). If the medial side is intact, the talus cannot shift laterally. If the medial side is ruptured (MCS >4mm), it is unstable.

Q2: What is the "Cotton Test"? A: An intra-operative stress test for syndesmosis instability. The fibula is pulled laterally with a bone hook. Intra-operative fluoroscopy checks for widening of the tibiofibular clear space.

Q3: Describe the Maisonneuve Fracture mechanism. A: An External Rotation force travels through the interosseous membrane, exiting as a proximal fibula fracture. It implies total disruption of the syndesmosis and medial structures.

Q4: Differentiate Supination-External Rotation (SER) vs Pronation-External Rotation (PER). A:

  • SER: Foot supinated. AITFL tears first. Weber B spiral fracture.
  • PER: Foot pronated. Deltoid tears first. Weber C high fracture.

(End of Topic)

Last updated: 2025-12-26

At a Glance

EvidenceHigh
Last Updated2025-12-26
Emergency Protocol

Red Flags

  • Frank Dislocation -> Urgent Sedation/Reduction (Skin/Vascular Threat)
  • Skin Tenting -> Impending Necrosis (Urgent reduction)
  • Maisonneuve Injury -> Proximal Fibula Tenderness (Missed Syndesmosis injury)
  • Open Fracture -> IV Antibiotics + Tetanus
  • Talar Shift -> Unstable (Requires Surgery)

Clinical Pearls

  • **"Toes Above Nose"**: The only way to reduce ankle swelling is radical elevation. The foot must be higher than the heart. Pillows aren't enough—tilt the bed.
  • **"The Wrinkle Sign"**: Surgery is often delayed 7-14 days to allow soft tissues to settle. You cannot cut through blistered skin. Wait for skin wrinkles to reappear.
  • **Emergency Reduction**. The medial malleolus often threatens the skin.

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines