Overview
Annual incidence: approximately 137 per 100,000 population.
Ankle fractures account for 10% of all fractures.
The second most common lower limb fractures after hip fractures
Bimodal distribution: peaks in young men and older women (50-year gap)
Risk Factors:
o Obesity (BMI): -Primary risk factor, especially for women >55 years.
-29% of unstable vs. 4% of stable cases are obese.
-3x increased risk of fixation failure
o Diabetes Mellitus (DM): -Leads to a high overall complication rate of 42–43%.
o Smoking: - Increases the risk of deep surgical site infections by 6x.
- Risk reduced by post-fracture cessation.
o Alcohol: - Acute use is involved in 29% of cases within 4 hours of injury.
-Chronic abuse increases wound-related complications by 4x.
o Recurrent falls: Key predictor for geriatric malleolar injury.
Anatomy & Biomechanics
Load Sharing: Distal fibula bears ~1/6 of the axial load.
Ankle Axis: 15° external rotation (due to shorter/anterior medial malleolus).
Talar Anatomy: Broader anteriorly; 70% articular cartilage coverage.
Static Stability: Trio of complexes (Medial, Lateral, Syndesmosis).
Stability Concept: Ankle viewed as a ring (tibia, fibula, talus, ligaments); stability requires two out of the three complexes (medial, lateral, and syndesmosis) to be intact.
Instability: Two or more disruptions (bone or ligament) allow abnormal talar motion
Talar Shift: 1 mm lateral displacement 42% in tibiotalar contact area.
Dynamic Stability: 6 musculotendinous groups provide stability via antagonistic contraction.
Classification Systems
Danis-Weber (anatomical level of the fibular fracture relative to the syndesmosis) (Table 1):
Type A: Infrasyndesmotic; usually stable.
Type B: Transsyndesmotic; variable stability; most common (80–90%).
Type C: Suprasyndesmotic; high syndesmotic injury risk; inherently unstable.
AO/OTA (Fibular level vs. syndesmosis + osteoligamentous injury severity ) (Table 1):
44A: Infrasyndesmotic (A1 isolated, A2 medial, A3 with postero-medial fracture).
44B: Transsyndesmotic (B1 isolated, B2 medial, B3 medial + posterolateral tibia).
44C: Suprasyndesmotic (C1 simple, C2 complex, C3 proximal/Maisonneuve).
Lauge-Hansen (Mechanism-based) (Table 1):
SER (Supination-External Rotation): Most common (60%); short oblique fibular fracture.
SAD (Supination-Adduction): 20%, Transverse fibular avulsion + vertical medial malleolus fracture.
PAB (Pronation-Abduction): 8%, Short horizontal/oblique fibula above joint.
PER (Pronation-External Rotation): 12%,High fibular fracture (Maisonneuve) + syndesmotic rupture.
Table 1: Comparison of Classification Systems
Weber Type | Fibular Fracture Level | Lauge-Hansen Equivalent | Syndesmotic Integrity |
Type A | Infrasyndesmotic (below joint) | SAD (Supination-Adduction) | Usually intact/stable |
Type B | Transsyndesmotic (at joint line) | SER (Most common - 60%) | Variable; often requires stress test |
Type C | Suprasyndesmotic (above joint) | PER / PAB | High risk of disruption; unstable |
Detailed Fracture Patterns
Isolated Lateral: Most frequent (70%); stable if non-displaced and medial structures intact.
Isolated Medial: Rare; displaced patterns allow talar varus tilt.
Isolated Posterior: Extremely rare alone; often part of rotational/pilon complexes.
Bimalleolar: Both medial and lateral disruption; highly unstable.
Bimalleolar-equivalent: Lateral malleolus fracture + complete deltoid rupture.
Trimalleolar: Medial, lateral, and posterior malleoli involvement; often features posterior talar subluxation.
Clinical & Radiographic Assessment
Ottawa Ankle Rules: High-sensitivity screening to determine X-ray necessity.
o X-ray indication (+):
-Malleolar pain plus ≥1 of the following:
+ >55 years.
+ Inability to bear weight immediately/in ED.
+ Bone tenderness over the posterior edge or the tip of either malleolus
Standard Series: AP, lateral, and mortise (15° internal rotation) views. (Table 2)
ABCS Sequence: Radiographic interpretation should follow a systematic assessment of Adequacy, Bone, Cartilage, and Soft tissues
Maisonneuve Screen: Palpation of the proximal fibula is mandatory in rotational injuries to exclude high syndesmotic disruption
Stress Views: Gravity or manual stress views confirm stability in isolated-appearing lateral fractures.
CT Scan: Essential for posterior malleolus morphology and SAD-type articular impaction assessment.
Table 2.Radiographic Evaluation of Ankle Fractures
Radiographic Feature | Normal Threshold / Parameter | Clinical Spot Insights |
Medial Clear Space (MCS) | < 5 mm/ ≤ 4 mm* (Symmetric with tibiotalar space) | -Affected by rotation & arthritis - >5mm under external rotation/dorsiflexion stress predicts deep deltoid injury |
Tibiofibular Clear Space | > 5 mm/ 6 mm* on both AP and mortise views (Measured 10 mm above joint line) | -A rotation-independent indicator of diastasis |
Tibiofibular Overlap | AP: ≥ 5 mm/ >6 mm* Mortise: ≥ 1 mm/ >1 mm* | -Highly rotation-dependent and lack a proven correlation with syndesmotic injury. |
Fibular Length | Parallel joint margins; (+) Dime (Ball) sign | -Fibular shortening results in lateral and valgus subluxation of the talus. |
Talocrural Angle | ~83° (Symmetrical with contralateral side) | -Indirect measure of fibular length |
Medial Malleolus | < 2 mm displacement | -Displacement increases talar shift risk |
Lateral Malleolus | <2 mm shortening or AP displacement. | -Isolated lateral malleolar fractures are typically managed nonoperatively. |
Posterior Malleolus | < 25% surface; < 2 mm displacement | -Surgical stabilization is mandatory for Bartoníček classification types 3–4 - Double contour sign - Misty mountains sign - Spur sign |
Note: * Varies in the literature, Abbreviations: mm: millimeter, AP: Anteroposterior
Treatment:
Non-operative Indications:
General Principle: Fractures that are stable, non-displaced, and maintain a congruent mortise (anatomical alignment of the talus under the tibial plafond) (Table 3).
Table 3. Indications for Non-operative Treatment
Fracture Pattern / Condition | Non-operative Criteria & Spot Insights |
Weber A & B | Permissible only if there is no talar shift and no instability. |
First and Second Stage of Supination-External Rotation | Characterized by an intact medial complex and minimal lateral displacement. |
First Stage of Supination-Adduction | Considered a stable ligamentous equivalent; manage with functional bracing. |
Isolated Medial | Displacement must be ≤ 2 mm with a strictly stable mortise. |
Isolated Posterior | Fragment involves < 25% of articular surface and ≤ 2 mm displacement. |
Undisplaced Bimalleolar | Entirely undisplaced; often reserved for elderly or infirm patients. |
Weber C | Suprasyndesmotic (proximal 2/3) fractures with an objectively stable syndesmosis. |
The "Walking Test" | Success is defined as no talar shift on X-ray after 1 week of full weight-bearing. |
Abbreviations: mm: millimeter
Non-operative Management: Short-leg cast/CAM boot for 4–6 weeks; weight-bearing based on stability.
Operative (ORIF) Primary Indications (Table 4):
° The primary objective is to restore joint congruency and ensure structural stability of the ankle mortise.
Table 4. Indications for Surgical Treatment
Fracture Pattern | Operative Indications & Spot Insights |
Medial Malleolus | Displaced fractures (typically >2 mm). Also, vertical shear patterns (second stage of Supination-Adduction) |
Lateral Malleolus | Displaced fractures associated with talar shift, MCS>4-5 mm or a positive stress/walking test (indicating occult instability). |
Bimalleolar / Equiv. | All displaced patterns. Includes lateral malleolus fracture with a complete deltoid ligament rupture |
Posterior Malleolus | Bartonicek Types 3 & 4; fragments >25% of plafond, >2mm step- off; or any fragment causing talar subluxation or marginal impaction. |
Suprasyndesmotic | surgery is required if the syndesmosis is unstable. |
Complex Variants | Open fractures, irreducible dislocations (e.g., Bosworth variant), |
Abbreviations: mm: millimeter, Equiv: Equivalents, MCS: Medial Clear Space
Surgical Treatment Options
Lateral Malleolus:
Plating: 1/3 tubular or anatomical distal fibular plates; neutralization or compression modes.
Antiglide Plating: Posterolateral placement; biomechanically superior for Weber B; acts as a buttress against proximal migration.
Lag Screws: Two 3.5 mm screws for simple oblique patterns in patients <50 years.
Intra Medullary Fixation: Retrograde nails/rods for poor soft tissue or high-risk diabetics.
Medial Malleolus:
Lag Screws: Two 4.0 mm cancellous screws perpendicular to fracture; 3.5 mm bicortical screws provide increased strength.
Tension Band Fixation: For poor bone quality, small, or avulsion fragments.
Antiglide Plate: Required for vertical shear
Posterior Malleolus:
Anteroposterior Screw Fixation
-Elderly patients
-Vulnerable soft tissues
Open Reduction Posterior Screws/Plate Fixation
-Younger patients
-Marginal impaction
-Syndesmotic injury
- Buttress plating provides better resistance to cyclical load-induced
displacement in biomechanical models
o Posterior malleol fixation restores superior syndesmotic stability (70%) compared to syndesmotic screws alone (40%)
Syndesmosis:
Fixation: 3.5/4.5 mm cortical screws or dynamic suture-buttons.
Assessment: Intraoperative Cotton test; >3–4 mm displacement confirms instability.
Technique: Positioned 2–3 cm proksimal to joint, angled 30° anteriorly.
Clinical Pearls
Diabetic Management: Requires rigid fixation (locking plates, multiple screws) and 8–12 weeks Non-weight-bearing.
Dime (Ball) Sign: Continuous curve between lateral talus and distal fibula indicates restored length.
Mercedes-Benz" Sign: Confirms anatomic reduction of the tibia-talus-fibula margin (Optimal in neutral position/dorsiflexion)
Soft Tissue Technique: Handle skin with care, reflecting flaps intact with underlying subcutaneous tissue (full-thickness) to avoid sloughing.
Driving: Brake response returns to baseline 9 weeks post-ORIF.
Bosworth Fracture: Fibula trapped behind posterolateral tibial ridge; irreducible by manipulation.
Prognosis
Anatomic reduction yields a 90% success rate.
Full functional recovery may require up to two years.
Arthritis rates rise from <5% in unimalleolar to 20% in bimalleolar fractures.
Age, female sex, diabetes, and dislocation predict poorer outcomes.
Initial cartilage damage predicts arthritis regardless of reduction quality.
Hardware removal improves outcomes in only 50% of patients.
References
1. White TO, Carter T. Ankle fractures. In: Tornetta P III, Ricci WM, Ostrum RF, McQueen MM, McKee MD, de Ridder VA, Ollivere BJ, editors. Rockwood and Green's Fractures in Adults. 10th ed. Philadelphia: Wolters Kluwer; 2025. p. 2577-2736.
2. Rudloff MI. Fractures of the lower extremity. In: Azar FM, Beaty JH, editors. Campbell's Operative Orthopaedics. 14th ed. Philadelphia: Elsevier; 2021. p. 2812-2825.
3. Miller MD, Thompson SR. Miller's Review of Orthopaedics (Miller Ortopedi Gözden Geçirme). Aktekin CN, translation editor. 7th ed. Ankara: Gunes Tip Kitabevleri; 2019. p. 565-570. Turkish.
4. Koehler SM. Ankle fractures in adults. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.
5. Lin J. Ankle fracture. ClinicalKey Clinical Overview. Elsevier; 2024. Updated October 12, 2024.
by Dr Ali