HIGH ANKLE SPRAINS(Syndesmosis Injuries)

HIGH ANKLE SPRAINS(Syndesmosis Injuries)

Prepared by Dr.Murat BIRINCI

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SUMMARY

High ankle sprains involve injury to the distal tibiofibular syndesmosis and typically result from external rotation forces.
They are less common than low ankle sprains but are associated with longer recovery times and higher morbidity.
Diagnosis requires a high index of suspicion and often stress radiographs or advanced imaging.
Treatment depends on stability, with operative fixation indicated for diastasis or instability.

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EPIDEMIOLOGY

Incidence

• 0.5% of ankle sprains without fracture
• 13% of ankle fractures

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ETIOLOGY & PATHOPHYSIOLOGY

Mechanism of Injury

• External rotation of the ankle
• Talus rotates laterally, forcing fibula away from tibia

Pathoanatomy

• Disruption of syndesmotic ligaments
• Incongruent ankle mortise
• Increased compressive and shear forces

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ANATOMY

Distal Tibiofibular Syndesmosis

• Anterior inferior tibiofibular ligament (AITFL) – most commonly injured
• Posterior inferior tibiofibular ligament (PITFL) – strongest stabilizer
• Interosseous ligament – prevents proximal talar migration
• Inferior transverse ligament

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PRESENTATION

Symptoms

• Anterolateral ankle pain proximal to joint line
• Difficulty bearing weight
• Recovery significantly longer than lateral sprains

Physical Examination

• Syndesmosis tenderness
• Squeeze test (Hopkin’s)
• External rotation stress test
• Fibular translation test

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IMAGING

Radiographs

Views
• AP, lateral, and mortise ankle views
• AP and lateral views of entire tibia

Findings
• Decreased tibiofibular overlap
• Increased tibiofibular clear space (>6 mm)
• Medial clear space widening (>4 mm)

CT

• Detects subtle syndesmotic diastasis
• Useful postoperatively to assess reduction

MRI

• High sensitivity for syndesmotic ligament injury
• Lambda sign suggestive of syndesmosis disruption

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TREATMENT

Nonoperative

Indications
• Stable syndesmotic sprain
• No diastasis or ankle instability

Management
• Non–weight-bearing CAM boot or cast (2–3 weeks)
• Delayed weight bearing until pain-free
• Brace limiting external rotation

Outcomes
• Prolonged and variable recovery
• May take twice as long as low ankle sprains

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Operative

Indications
• Tibiofibular diastasis
• Instability on stress radiographs
• Syndesmotic injury with associated fracture

Techniques
• Syndesmotic screw fixation
• Suture-button fixation

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COMPLICATIONS

• Tibiofibular synostosis
• Chronic pain and instability
• Missed injury → end-stage ankle arthritis

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PROGNOSIS

• Excellent outcomes if syndesmosis anatomically reduced
• Delayed diagnosis worsens long-term results