Ankle Fractures

55 Ankle Fractures


Trapper A.J. Lalli and Dane K. Wukich


Abstract


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


image Isolated medial malleolar fracture.


image Isolated lateral malleolar fracture.


image Bimalleolar fracture.


image Trimalleolar fracture.


image Maisonneuve’s injury.


Danis–Weber:


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


image A: infrasyndesmotic:


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


image Most commonly stable and does not require ORIF.


image B: transsyndesmotic:


image Usually an oblique or spiral fracture.


image May or may not be stable requiring ORIF.


image Syndesmotic ligaments usually intact.


image C: suprasyndesmotic:


image An unstable fracture most commonly requiring ORIF.


image Syndesmotic ligaments usually disrupted and requires fixation.


AO/ATA:


image 44A: infrasyndesmotic.


image 44B: transsyndesmotic.


image 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.


image Supination-adduction:


image I: talofibular sprain or distal fibular avulsion.


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


image Supination-external rotation (SER):


image I: anterior tibiofibular ligament sprain.


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


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


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


image Pronation-abduction:


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


image II: anterior tibiofibular ligament sprain.


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


image Pronation-external rotation:


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


image II: anterior tibiofibular ligament disruption.


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


image 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:


image 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


55.2.4 Radiographic Evaluation


Standard Radiographs

• Anteroposterior (AP), mortise, lateral.


• Obtain radiographs of joints proximal and distal to injury:


image Evaluate for Maisonneuve’s injury and concomitant foot fractures.


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:


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


Syndesmosis Evaluation

• Decreased tibiofibular overlap:


image Normal > 6 mm on AP view.


image Normal > 1 mm on mortise view.


• Increased medial clear space widening:


image Normal less than or equal to 4 mm.


• Increased tibiofibular clear space:


image Normal < 6 mm on both AP and mortise views.


Radiographic Measurements

• Talocrural angle:


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


image 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:


image 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:


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


image Isolated, displaced medial or lateral malleolus fracture.


image Bimalleolar fracture or bimalleolar equivalent fracture.


image Talar displacement.


image Open fracture.


image Bosworth’s fracture/dislocation.


image Associated syndesmosis injury.


image Fibular shortening.


image Dynamic instability on stress views.


image 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:


image 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:


image 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):


image 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.



Jul 19, 2019 | Posted by in SPORT MEDICINE | Comments Off on Ankle Fractures
Premium Wordpress Themes by UFO Themes