55 Ankle Fractures

Ankle fractures account for approximately 9% of all fractures and are among the most common fractures treated by orthopaedic surgeons, second only to proximal femur fractures as the most common lower extremity fracture.¹ The complexity in treating ankle fractures arises in their variable presentation and mechanism of injury. Due to these factors, every patient with an ankle fracture should be thoroughly evaluated. Each ankle fracture should be assessed for specific characteristics, including bone quality, fracture comminution, marginal impaction, presence of additional fractures, soft-tissue injury, and host factors. Detailed preoperative evaluation, surgical planning, meticulous surgical technique, and management of soft tissues are keys to help obtain good outcomes. This chapter provides surgical tips and pearls to achieve excellent outcomes and maximize patient function.

Keywords: ankle fracture, bimalleolar, trimalleolar, open reduction, internal fixation

55.1 Introduction

55.1.1 Pathology/Classification

• Anatomic

Isolated medial malleolar fracture.

Isolated lateral malleolar fracture.

Bimalleolar fracture.

Trimalleolar fracture.

Maisonneuve’s injury.

• Danis–Weber:

Describes the level of the medial aspect of the fibular fracture:

A: infrasyndesmotic:

Usually a transverse avulsion-type fracture as a result of an inversion mechanism.

Most commonly stable and does not require ORIF.

B: transsyndesmotic:

Usually an oblique or spiral fracture.

May or may not be stable requiring ORIF.

Syndesmotic ligaments usually intact.

C: suprasyndesmotic:

An unstable fracture most commonly requiring ORIF.

Syndesmotic ligaments usually disrupted and requires fixation.

• AO/ATA:

44A: infrasyndesmotic.

44B: transsyndesmotic.

44C: suprasyndesmotic.

• Lauge-Hansen:

The first descriptor describes the position the foot was in at the time of the deforming injury mechanism. The second descriptor describes the direction of force on the ankle at the time of injury. Each type of injury has a subset of sequential progression of injury severity.

Supination-adduction:

I: talofibular sprain or distal fibular avulsion.

II: vertical medial malleolus and impaction of anteromedial distal tibia.

Supination-external rotation (SER):

I: anterior tibiofibular ligament sprain.

II: lateral short oblique fibula fracture (anteroinferior to posterosuperior).

III: posterior tibiofibular ligament rupture or avulsion of posterior malleolus.

IV: medial malleolus transverse fracture or disruption of deltoid ligament.

Pronation-abduction:

I: medial malleolus transverse fracture or disruption of deltoid ligament.

II: anterior tibiofibular ligament sprain.

III: transverse, comminuted fibula fracture above the level of the syndesmosis.

Pronation-external rotation:

I: transverse medial malleolus fracture or disruption of deltoid ligament.

II: anterior tibiofibular ligament disruption.

III: short oblique/spiral fracture of fibula above the level of the joint.

IV: posterior tibiofibular ligament rupture or avulsion of posterior malleolus.

55.2 Nonoperative Treatment

55.2.1 Indications

• Isolated fibula fracture with < 3-mm displacement:

Negative stress radiograph.

• Isolated, nondisplaced medial malleolus fracture or tip avulsion.

• Posterior malleolus fracture with < 25% joint involvement or < 2-mm displacement.

55.2.2 Treatment

• Short leg cast or controlled ankle motion (CAM) boot.

55.2.3 Clinical Evaluation

• Assess soft-tissue envelope.

• Assess neurovascular status.

• Physical examination is an unreliable indicator of deltoid ligament injury.²

Gravity Stress Radiograph³

• Equivalent to manual stress radiograph.

• Use for initial screening tool to distinguish SER II from SER IV equivalent.

External Rotation Stress Radiograph

• Intraoperative stress radiograph to assess competency of deltoid ligament:

Medial clear space of > 5 mm with external rotation stress is predictive of deep deltoid disruption.

Syndesmosis Evaluation

• Decreased tibiofibular overlap:

Normal > 6 mm on AP view.

Normal > 1 mm on mortise view.

• Increased medial clear space widening:

Normal less than or equal to 4 mm.

• Increased tibiofibular clear space:

Normal < 6 mm on both AP and mortise views.

Radiographic Measurements

• Talocrural angle:

Measured by bisection of line through tibial anatomical axis and another line through the tips of the malleoli.

Shortening of lateral malleoli fractures can lead to increased talocrural angle.

55.2.5 Contraindication to Open Reduction and Internal Fixation

• Medical health precluding surgical treatment.

• Poor vascularity to the affected limb.

• Poor soft-tissue envelope at the surgical site.

• Active surgical-site infection.

55.3 Goals of Procedure

• Stable, anatomic reduction of the talus within the ankle mortise.

• Ensure less than 1-mm shift of the talus within the mortise:

Greater than 1-mm shift causes 42% decreased tibiotalar contact area.⁴

• Allow early range of motion of stable ankle joint.

55.4 Advantages of ORIF

• Anatomic reconstruction of the ankle mortise.

• Reconstruction of tibiotalar congruency.

• Rigid fracture fixation.

• Early range of motion of the ankle joint.

• Prevention of posttraumatic arthritis of the ankle.

55.5 Key Principles of the Surgical Procedure

• Outcomes correlate with anatomic reduction.

• Restore length and rotation of fibula.

• Use “dime sign” (Shenton’s line) to determine proper length of fibula.

• Ensure rigid fixation of the ankle bony fractures to allow early ankle motion.

55.6 Operative Technique

• Indications:

Medial clear space widening of > 4 to 5 mm on the ankle mortise radiograph.⁵

Isolated, displaced medial or lateral malleolus fracture.

Bimalleolar fracture or bimalleolar equivalent fracture.

Talar displacement.

Open fracture.

Bosworth’s fracture/dislocation.

Associated syndesmosis injury.

Fibular shortening.

Dynamic instability on stress views.

Marginal impaction of the tibial plafond.

55.6.1 Patient Positioning

• Supine on a radiolucent table.

• Operative extremity is placed on a radiolucent bump or stack of blankets.

• Place a bump under the ipsilateral hip to put the extremity in a neutral position:

If the medial malleolus requires fixation, the bump can be removed to allow external rotation.

• Place 4-5 sterile towels under the distal leg, proximal to the heel:

Avoids anterior translation of the talus.

55.6.2 Surgical Approach

• The distal fibula is approached through a lateral incision over or just posterior to the fibula, centered over the fracture site (Fig. 55.1):

The superficial peroneal nerve (SPN) crosses the fibular from posterior to anterior at a level 7 cm proximal to the tip of the fibula. This needs to be dissected out, mobilized, and protected for fractures requiring an incision extended down to this level.

Fig. 55.1 Lateral view of the operative extremity with skin incision drawn out.

Fig. 55.2 Dissection to fracture site with soft tissues retracted.

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