Define Ankle Injuries & Fractures. Describe its clinical features, investigations, management and complications.

Definition & Surgical Anatomy

Ankle injuries range from ligamentous sprains to fracture-dislocations of the ankle mortise — the socket formed by the distal tibia (plafond and medial malleolus), the fibula (lateral malleolus) and the strong syndesmotic ligaments that bind them, into which the talus sits. Stability depends on both the bony malleoli and the medial (deltoid), lateral and syndesmotic ligaments. A congruent mortise is essential — even a 1–2 mm lateral shift of the talus markedly reduces the contact area and predisposes to arthritis.

Mechanism & Classification

Most ankle fractures follow a rotational injury of the foot on the leg. Two classifications are used. The Danis–Weber classification is based on the level of the fibular fracture relative to the syndesmosis (simple and surgically useful). The Lauge-Hansen classification describes the mechanism by foot position and force direction (e.g. Supination-external rotation, the commonest).

Clinical Features

Pain, swelling and inability to bear weight after a twisting injury; deformity in fracture-dislocations. Palpate for tenderness at both malleoli, the medial and lateral ligaments and — importantly — the proximal fibula (Maisonneuve). Assess the skin (fracture blisters, threatened skin over a displaced fragment) and the neurovascular status. The Ottawa ankle rules help decide who needs radiographs.

Investigations

AP, lateral and mortise-view radiographs of the ankle. Assess the talar shift, the medial clear space, and symmetry of the mortise. Radiograph the full length of the fibula if a Maisonneuve injury is suspected. CT helps in complex or posterior malleolar/pilon patterns.

Management

Stable, undisplaced fractures (most Weber A and undisplaced B without talar shift) are treated conservatively in a below-knee cast or walking boot with a period of protected weight-bearing. Unstable / displaced fractures (talar shift, displaced bimalleolar or trimalleolar, most Weber C) require open reduction and internal fixation to restore an anatomically congruent mortise — lateral malleolus with a plate and screws, medial malleolus with screws or a tension band, and syndesmotic stabilisation (screw or suture-button) where disrupted. A fracture-dislocation should be reduced urgently to relieve pressure on the skin and neurovascular structures.

Ankle Sprains & the Ottawa Rules

The commonest ankle injury is a lateral ligament sprain from an inversion force, injuring the anterior talofibular ligament (ATFL) first, then the calcaneofibular ligament. Sprains are graded I (stretch), II (partial tear) and III (complete tear with instability). The Ottawa ankle rules guide the need for radiographs: image only if there is bony tenderness at the posterior edge or tip of either malleolus, tenderness at the navicular or base of the fifth metatarsal, or an inability to bear weight for four steps both immediately and in the department. Most sprains are managed with the price/police regimen (protection, optimal loading, rest, ice, compression, elevation) and early rehabilitation; complete tears with instability occasionally need repair.

Complications

Post-traumatic osteoarthritis (from an incongruent mortise or residual talar shift) is the commonest late problem; also stiffness, malunion, non-union of the medial malleolus, wound problems over the subcutaneous fibula, and chronic instability after ligamentous injuries.

Talar shift of even 1 mm markedly reduces contact area.

• Stability of the mortise depends on the malleoli + deltoid/syndesmotic ligaments.
• Weber A (below) → C (above) — higher fibular # = more syndesmotic disruption/instability.
• Even 1–2 mm talar shift halves contact area → arthritis; restore the mortise anatomically.
• Stable/undisplaced → cast; unstable/displaced → ORIF ± syndesmotic fixation.
• Examine the proximal fibula (Maisonneuve); reduce a fracture-dislocation urgently.