Ankle Fracture

Lara Stone D.P.M.

Basic Information

Definition

Ankle fractures involve the lateral, medial, or posterior malleolus of the ankle and may occur either alone or in some combination. Associated ligamentous and syndesmotic injuries are included.

Classification

The Danis-Weber (Fig. E1) and Lauge-Hansen classifications of ankle fractures are described in Table E1.

TABLEE1 Classifications and Treatment of Ankle FracturesFrom Parvizi J: High-yield orthopedics, Philadelphia, 2010, Saunders.

	Normal	Abnormal
Talocrural angle—angle formed by parallel line to distal tibial articular surface and line connecting malleolar tips	8-15 degrees (or 83 degrees ± 4 degrees if perpendicular used)	>2-3 degrees of difference from contralateral = fibular shortening
Medial clear space—distance between lateral border of medial malleolus and lateral border of talus	<4 mm and equal to superior clear space	4 mm = lateral talar shift and instability
Tibiofibular clear space—distance between medial wall of fibula and tibial incisura	<6 mm on AP and mortise views	>6 mm = syndesmotic disruption (instability)
Talar tilt—difference between medial and lateral superior clear space measurements	<2 mm	>2 mm = instability
Classification:
1. Danis-Weber—based on location of fibular fracture A. Below syndesmosis B. At level of syndesmosis C. Above syndesmosis	1. Lauge-Hansen—based on position of foot and deforming force A. Supination external rotation—most common B. Supination adduction C. Pronation external rotation D. Pronation abduction
Treatment: Surgical decisions mostly based on stability.
Stable	Unstable
Isolated lateral malleolar fractions if:	Lateral malleolus fractures if:
Below syndesmosis	Medial injury or tenderness (bimalleolar equivalent)
No medial ligament injury or talar shift	Talar shift
Displacement <5 mm	Above syndesmosis
No shortening	Shortened or displaced >5 mm
Isolated medial malleolus fractures (although 5%-15% nonunion rates have been reported)	Bimalleolar fractures Trimalleolar fractures (fix posterior if >25% of articular surface)
	Maisonneuve fractures

ICD-10CM CODES
S82.899	Other fracture of unspecified lower leg, initial encounter for closed fracture
S82.63XA	Displaced fracture of lateral malleolus of unspecified fibula, initial encounter for closed fracture
S82.53XA	Displaced fracture of medial malleolus of unspecified tibia, initial encounter for closed fracture

Physical Findings & Clinical Presentation

•

Deformity usually depends on extent of displacement.
•

Pain, tenderness, and hemorrhage at the site of injury.
•

Gentle palpation of ligamentous structures (especially deltoid ligament) to determine the extent of soft tissue injury.
•

Evaluation of distal neurovascular status; results recorded.

Etiology

•

The ankle depends on its ligamentous and bony support for stability. The joint, or mortise, is an inverted U with the dome of the talus fitting into the medial and lateral malleoli. The posterior margin of the tibia is often called the third or posterior malleolus.
•

The most common ankle fractures are the result of eversion or lateral rotation forces on the talus (in contrast with common sprains, which are usually caused by inversion).

Diagnosis

The diagnosis is usually established on the basis of the nature of the injury, the presence of typical findings of bony tenderness with swelling, and abnormal imaging studies.

Differential Diagnosis

•

Ankle sprain
•

Fracture of hindfoot or metatarsal
•

Osteochondral lesion
•

Tendon tear or rupture
•

Syndesmotic injury

Imaging Studies

Standard AP and lateral views (Fig. E2) accompanied by an AP taken 15 degrees internally rotated. The last view is taken to properly visualize the mortise. Fig. E3 illustrates the Ottawa rule for ankle or midfoot fracture.

FIG.E2

A, Anteroposterior view. B, Lateral view. A depressed talus fracture is visible. In B, this fracture is seen to run through the midbody of the talus. A also demonstrates a distal fibula fracture, but in B, a calcaneal fracture is seen. The patient underwent CT to characterize these fractures further.

From Broder JS: *Diagnostic imaging for the emergency physician,* Philadelphia, 2011, Saunders.

FIG.E3

Ottawa rule for ankle or midfoot fracture.

The rule for ankle pain is the top figure;

Treatment

All fractures: elevation, compression, and ice to control swelling for 48 to 72 hr; immobilization in splint or fracture boot with ambulatory aid as needed.

Acute General Rx

•

Clinical and radiographic assessment of the status of the ankle mortise and stability of the injury is mandatory to determine treatment.
•

There is potential for displacement if both sides of the joint are significantly injured (e.g., fracture of the lateral malleolus with deltoid ligament injury).
•

Deviation of the position of the talus in the mortise could lead to traumatic arthritis.
•
If there is no widening of the ankle mortise, many injuries can be safely treated with simple casting without reduction:
1. 1.
  Nondisplaced or avulsion fractures of either malleolus below the ankle joint line:
  1. a.
    
    Stability of the joint is not compromised, and a short leg walking cast or ankle support is sufficient.
  2. b.
    
    Weight bearing is allowed as tolerated.
  3. c.
    
    In 4 to 6 weeks, protection may be discontinued.
2. 2.
  Isolated nondisplaced fractures of the medial, lateral, or posterior malleolus:
  1. a.
    
    Usually stable and require only the application of a short leg walking cast with the ankle in the neutral position or fracture cast boot.
  2. b.
    
    Immobilization should be continued for 6 weeks.
  3. c.
    
    Fracture line of lateral malleolus may persist radiographically for several months, but immobilization beyond 6 weeks is usually unnecessary.
  4. d.
    
    Nondisplaced bimalleolar fractures are treated with a long leg cast flexed 30 degrees at the knee to prevent motion and displacement of the fracture fragments. In 4 weeks, a short leg walking cast may be applied for an additional 4 weeks.
3. 3.
  Isolated fractures of the lateral malleolus that are slightly displaced:
  1. a.
    
    May be treated with casting if no medial injury is present.
  2. b.
    
    A below-knee walking cast is applied with ankle in the neutral position; weight bearing is allowed as tolerated.
  3. c.
    
    Six weeks of immobilization is sufficient.
  4. d.
    
    If medial tenderness is present, suggesting deltoid ligament rupture, a carefully molded cast may suffice if weight bearing is not allowed and the patient is followed up closely for signs of instability, especially after swelling recedes. If significant widening of the medial ankle mortise (increase in the “medial clear space”) develops as a result of lateral displacement of the talus, referral for possible reduction is indicated.
  5. e.
    
    If signs of instability are already present at initial examination (widening of the medial clear space with medial tenderness), referral is indicated.
4. 4.
  Nondisplaced fracture of the distal fibular epiphysis:
  1. a.
    
    Often diagnosed clinically.
  2. b.
    
    There is tenderness over the epiphyseal plate.
  3. c.
    
    Radiographic findings are often negative.
  4. d.
    
    A short leg walking cast or fracture boot is applied for 4 to 6 weeks.
  5. e.
    
    Growth disturbance is rare.
5. 5.
  
  Isolated posterior malleolar fractures involving less than 25% of the joint surface on the lateral radiograph:
•

Safely treated by applying a short leg walking cast or fracture brace. (Fractures involving >25% of the weight-bearing surface should be referred because of the potential for instability and subsequent traumatic arthritis.)

Chronic Rx

•

Early motion is encouraged through a home exercise program. Trials have shown that a supervised exercise program does not confer additional benefits in activity limitation or quality of life compared with advice alone for patients with isolated and uncomplicated ankle fracture. These findings do not support the routine use of supervised exercise programs after removal of immobilization for patients with isolated and uncomplicated ankle fracture.
•

Protection from reinjury is appropriate for 4 to 6 weeks after cast or brace removal.
•

A temporary increase in lower extremity swelling that frequently occurs after short leg cast removal may benefit from the use of support hose.

Disposition

Significant factors involved in the development of traumatic arthritis:

•

Amount of joint trauma at the time of injury
•

Eventual position of the talus in the mortise
•

Fracture nonunion is uncommon unless displacement is significant.

Referral

Orthopedic consultation for:

•

Unstable ankle joint.
•

Widened ankle mortise.
•

Posterior malleolar fracture over 25% of joint with incongruity.
•

Marked displacement of fracture fragment.
•

Box E1 summarizes ankle fractures for which orthopedic consultation in the emergency department is recommended.

BOX E1Ankle Fractures for Which Orthopedic Consultation in the Emergency Department Is Recommended

Unimalleolar fractures

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Displaced medial malleolar fracture
•

Medial malleolar fracture with lateral collateral ligament rupture
•

Displaced lateral malleolar fracture
•

Lateral malleolar fracture with deltoid ligament rupture
•

Lateral malleolar fracture with widened medial clear space
•

Unimalleolar fracture with syndesmotic diastasis
•

Fibula fracture at or proximal to the tibiotalar joint line
•

Displaced posterior malleolar fracture
•

Posterior malleolar fracture involving more than 25% of articular surface

All bimalleolar fractures

All trimalleolar fractures

All intraarticular fractures with step deformity

All open fractures

All Pilon fractures

From Marx JA et al: Rosen’s emergency medicine, ed 8, Philadelphia, 2014, Saunders.

Ferri – Ankle Fracture