Ankle Fractures

Etiology

Ankle fractures can be caused by various modes of trauma, e.g., twisting, impact, and crush injuries. Falling, tripping, or sports activities may cause twisting forces through the ankle. Impact injuries may result from falling from a height with impaction of the distal tibia and fibula against the talus. Ankle crush injury may be caused by a road traffic accident or crushing the ankle underneath a heavy object. The degree of bony comminution and soft tissue damage is directly related to the energy of trauma. 

Epidemiology

About 187 per 100000 adults sustain ankle fractures every year.[7] The highest incidence in the female population is between 75 and 84 years old, compared to 15 to 24 years old for males.[8] Isolated uni malleolar fractures are the most common type accounting for 70% of the yearly incidence of all ankle fractures. About 20 % of ankle fractures are bimalleolar fractures, while trimalleolar fractures represent about 7% of all ankle fractures. Open ankle fractures incidence is about 2% of all ankle fractures.[8]

Pathophysiology

The ankle joint bony and ligamentous structures from a complete ring. Whenever the ring is broken, it happens in two places. Based on the evaluation of ankle fractures, a full assessment of the whole ankle ring is necessary to avoid missing any bony or ligamentous injury. Different systems have been developed to classify ankle fractures. 

Anatomical Classification 

Classifies ankle fractures depending on the anatomical location into 

• Isolated medial malleolus fracture
• Isolated lateral malleolus fracture 
• Bimalleolar ankle fracture; two malleoli are fractured, either the medial and lateral malleoli or less commonly the poster and lateral malleoli. 
• Trimalleolar ankle fracture; the three ankle malleoli (medial, lateral, and posterior) are broken. 

Danis-Weber Classification

This system categorizes ankle fractures based on distal fibula fracture line localization relative to the syndesmosis into three types:

• Weber type A; the distal fibula fracture is below the level of the syndesmosis. This type of fracture is usually stable and can be treated conservatively. 
• Weber type B; the distal fibula fracture is located at the same level of the syndesmosis. Injuries of this type could be treated conservatively if it is a stable injury (no deltoid ligament injury nor syndesmotic injury). Unstable weber B fracture requires surgical fixation. 
• Weber type C; the fibular fracture is located above the level of the syndesmosis. This type of fracture is usually unstable and requires surgical fixation.[9]

The Lauge-Hansen Classification 

This classification depends on the foot position and the direction of the force causing the injury. This classification categorizes ankle fractures into four types. The first word of each type describes the foot position at the time of the injury and the second word describes the movement of the talus in ankle mortise relative to the tibia. When the foot is pronated, medial ligaments are stretched and prone to injury. When the foot is supinated, lateral ligaments are stretched and prone to injury.[10]

Supination-Adduction (SA)

1. Distal fibula transverse fracture
2. Medial malleolus vertical fracture

Supination-External Rotation (SER) - most common ankle injury (60% fractures)

1. Anterior inferior tibiofibular ligament injury
2. Spiral (or oblique) fracture of the distal fibula
3. Posterior inferior tibiofibular ligament injury OR posterior malleolus avulsion
4. Fracture of medial malleolus OR deltoid ligament injury

Pronation-External Rotation (PER)

1. Fracture of medial malleolus OR deltoid ligament injury
2. Anterior inferior tibiofibular ligament injury
3. Spiral (or oblique) fracture of the fibula (aspect proximal to tibial plafond)
4. Posterior inferior tibiofibular ligament injury OR posterior malleolus avulsion

Pronation-Abduction (PA)

1. Fracture of medial malleolus OR deltoid ligament injury
2. Anterior inferior tibiofibular ligament injury
3. Comminuted or transverse fibular fracture (proximal to tibial plafond)

 Injuries always occur in a cumulative pattern; for example, a SER4 injury includes injuries of SER1, SER2, and SER3.[10]

Other Types of Ankle Fractures

Maisonneuve Injury 

It is an unstable ankle injury caused by pronation external rotation injury. Maisonneuve injury combines a proximal fibular fracture with tibiofibular syndesmosis and deltoid ligament injury with or without medial malleolus fracture. This unstable injury requires operative treatment.[11]

Pilon Fracture 

This injury is the comminuted fracture of the tibial plafond (distal end of the tibia, including the articular surface). Pilon fracture usually results from high energy axial loading trauma, e.g., fall from a high distance causing impaction of the talus against the tibial plafond.[12]

Bosworth Fracture-Dislocation  

This is a rare type of ankle fracture dislocation where the fibula is posteriorly dislocated. The poster tibial border blocks the fibula reduction. Therefore operative treatment is required to reduce and fix the fibula in the incisura fibularis.[13]

History and Physical

History is an integral part of any medical evaluation. The clinician needs to obtain a full history to cover all the following: 

• Medical background; comorbidities including diabetes, peripheral vascular disease, peripheral neuropathy, inflammatory joint diseases, obesity, kidney diseases affect the prognosis of ankle fractures.  Uncontrolled diabetes, peripheral vascular disease, peripheral neuropathic disorders affect fracture and surgical wound healing and increase the risk of Charcot's joint. If indicated, all medical and systemic diseases should be addressed and optimized prior to the surgery.
• Social history; A patient's baseline/goals should be established through social history, including the patient’s level of mobility pre-injury, home situation, and regular activities, as well as their future functional goals. Smoking and alcohol overuse can complicate wound and fracture healing. 

• History of the injury; it is important to identify the mechanism of injury to understand the nature and severity of the injury. Higher energy mechanism should raise the specter of compartment syndrome of the leg or a more grave injury such as a pilon fracture (axial loading). The ankle position at the time of injury and subsequent direction of force generally dictates the fracture pattern, as described by the Lauge-Hansen classification system.

• Venous thromboembolism risk (VTE) assessment should be completed for all patients who sustain ankle fractures to identify the potential risk factors to develop deep venous thrombosis (DVT). Risk factors include but are not limited to smoking, previous DVT, family history of DVT, high Body mass index, hormonal therapy, and oral contraceptive pills. Patients who are at high risk for VTE  should receive the appropriate prophylaxis treatment. 

Evaluation

Clinical Assessment

1. Adult Trauma Life Support Primary and Secondary Survey

All trauma patients should be assessed according to trauma assessment principles. The primary ATLS survey should be completed in order from A to E to rule out any life-threatening injury:

• A: Airway management and cervical spine stabilization. 
• B: Breathing 
• C: Circulation and hamorrage control
• D: Disability to assess the  neurologic status
• E: Exposure[14]

2. Neurvascualr Assement

A documented neurovascular assessment is mandatory to be performed before and after any attempt for ankle manipulation. Neurovascular assessment includes the color and temperature of the foot. Pale, cold foot indicates a critical vascular compromise. Dorsalis pedis posterior tibial pulses should be assessed and compared to the contralateral side. If there is any clinical concern for vascular compromise or skin tenting, urgent ankle reduction should be attempted immediately in an attempt to regain vascular flow followed by neurovascular reassessment s Hand doppler is a quick and non-invasive method to assess the vascular flow in the foot. Neurological assessment should include the motor and sensory function of deep peroneal, superficial peroneal, tibial, sural medial, and lateral plantar nerves. 

3. Soft Tissue Assessment 

Threatened skin of a deformed ankle necessitates urgent ankle reduction and splinting to reduce soft tissue stretching. Soft tissue integrity and the degree of swelling will affect the treatment choice and the timing of surgical fixation.  

4. Examination of the Proximal Fibula

Examination of the proximal fibula and the knee joint is required to avoid missing any higher injury as Maisonneuve fracture injury.  

Ottawa Ankle Rules

Ankle radiographs should be requested if there is pain or tenderness in either malleolus AND one of the following:

• Tenderness of the bone at the posterior edge or tip (within 6 cm) of either the lateral or medial malleolus
• Patient unable to bear weight at the time of injury AND on arrival to the emergency department. Weight-bearing is determined by the patient's ability to take four steps.[15]

Imaging Modalities

1. Plain Radiographs 

X-rays are the first line of investigation to assess ankle injury. Obtaining X-rays should not delay the urgent reduction of the clinically obvious deformed ankle. Recommended X-rays views to assess ankle injuries include; anteroposterior, lateral, and Mortise views.

Anteroposterior (AP) ankle view: assess for soft tissue swelling that may lead to the discovery of other more subtle fractures

Lateral view: assess posterior malleolus, talus dome relative to the distal mortise, e.g., if it is dislocated anteriorly or posteriorly. 

Morise view is important to assess the ankle mortise(tibial plafond , medial malleus, lateral malleolus and talar dome).[16] Mortise view is an anteroposterior ankle X-ray with the leg internally rotated 15 to 20 degrees, and the ankle is dorsiflexed. This view evaluates talus positioning and syndesmosis widening. In a normal ankle, this should show a uniform width of space through the mortise joint space. 

Weight-bearing and external rotation stress views are indicated to assess fracture stability and rule out deltoid ligament and syndesmotic injury. Full tibia and fibula length X-rays are valuable to rule out proximal fibula fracture in Maisonneuve injury.

2. Computed Tomography (CT scan)

Ankle CT scan is useful to assess the articular surface, fractures configurations, and the degree of bone comminution. CT scan is usually organized for operative planning in complex ankle fractures. CT scan is also useful to assess posterior malleolar fractures.[17]

3. Magnetic Resonance Imaging (MRI) Scan

Ankle MRI is valuable to assess ligamentous injuries, e.g., deltoid ligament sprain, lateral ligament complex sprain, syndesmotic disruption, chondral lesions, and stress fractures.

Treatment / Management

Ankle fracture treatment aims to restore and stabilize the ankle mortise, which could be achieved by conservative measures in stable ankle fractures and surgical fixation in unstable ankle fractures.[18]

Non-operative Treatment

Indications

1. Stable ankle fractures, e.g., isolated unimalleolar ankle fracture with no talar shift on weight-bearing ankle X-rays. 
2. Patient unfit for surgery or refusing surgery.
3. Poor soft tissue conditions.  

Non-operative Treatment

1. Below knee cast 
2. Fracture reduction and application of a close contact cast under image guidance: could be a valid option for unstable ankle fracture in patients above 60 or who are unfit for surgery.[19]
3. Walking boot 
4. Proper analgesia
(A1)

Operative Treatment

Open Reduction and Internal Fixation (ORIF)

Urgent open reduction of ankle fracture dislocation may be required if closed reduction attempts have failed or there is a neurovascular deficit. Ankle fractures ORIF is usually indicated for patients with unstable ankle mortise who are fit for surgery and have a good soft tissue condition. Surgical fixation is usually performed either in the first 24 hours or after few days to allow soft tissue swelling to subside reduce the risk of wound dehiscence. Ankle fracture ORIF is a suitable treatment for:

1. Uni malleolar fractures with talar shift on weight-bearing ankle X-rays
2. Bimalleolar ankle fractures
3. Trimalleolar ankle fractures
4. Pilon fracture
5. Maisonneuve fracture

 Fibula fractures can be fixed by plate and screws or fibular nails. Fibular nails are more suitable for comminuted fractures with poor bone quality. Transverse medial malleolus fracture can be fixed by partially threaded screws or tension band wiring to allow compression at the fracture site. Vertical medical malleolus fractures require buttressing fixation by an anti-glide plate. Posterior malleolus fracture can be fixed by a posteroanterior lag screw or by an anti-glide plate. The ankle syndesmosis should be assessed intraoperatively either by performing the Hook test (Cotton test) or by obtaining intraoperative stress external rotation views.[20][21] The Hook test can be performed by the lateral distraction of the fibula by using a bone hook under the image intensifier screen.  If there is >2mm displacement of the fibula, the hook test is positive.[22] If the hook test is positive and there is a syndesmosis diastasis, the syndesmosis should be reduced by applying a big reduction clamp to the medial and lateral malleoli then fixed either by syndesmotic screws or tight robes.(B2)

Spanning External Fixator 

This is usually indicated as a temporary fixation method for unstable ankle fractures in case of severe soft tissue swelling or open fractures. Application of an external fixator will hold the ankle mortise in a safe position allowing the soft tissue to heal and settle. Then ankle fracture ORIF can be done in a second-stage surgery when the soft tissue is ready and can be closed safely. On application of the external fixation, the planning for surgical fixation should be considered, and pins should be inserted away from the site of the surgical approach for ankle ORIF. 

Differential Diagnosis

Ankle fractures should be differentiated from other foot and ankle traumatic conditions.

Deltoid Ligament Sprain

Examination usually shows tenderness and swelling over the medial malleolus. Weight-bearing ankle  X-rays may show a talar shift. MRI scan could be useful but for the diagnosis of the deltoid ligament sprain.   

Lateral Collateral Complex Sprain 

Examination usually shows tenderness and swelling over the medial malleolus. Weight-bearing ankle  X-rays may show a talar shift. MRI scan could be useful but for the diagnosis of the lateral ligament complex sprain.  

Tendon Achilles Rupture

There is usually a history of sharp pain or a feeling of a snap in the back of the affected ankle. Clinical assessment may reveal a palpable gap over the tendon Achilles and positive Simmonds test. Simmonds test should be performed in a prone position. Squeezing of the calf muscles by the examiner should move the foot to a plantarflexion position (negative Simmonds test). In tendon Achilles rupture, no foot plantar flexion will occur on squeezing the calf (positive Simmonds test). X-rays are usually negative in case of tendon Achilles rupture. Ultrasound scan is useful in the tendon Achilles rupture setting to assess the degree of rupture and length of tendon gap.

Prognosis

For patients with stable fractures that do not require operative repair, the prognosis is excellent. They can gradually bear weight and be back at baseline as early as 6 to 8 weeks after the initial injury. In those with unstable fractures that undergo ORIF, although full weight-bearing can occur as early as 6 to 8 weeks, it may take longer until full final functional results. The incidence of ankle joint post-traumatic arthritis is about 14 % of ankle fractures even with anatomical reduction and stable fixation, possibly caused by chondral injury.[23]

Complications

Complications following ankle fractures can occur after both conservative nonoperative management and operative management.[24]

Nonoperative Management Complications May Include

1. Ankle stiffness 
2. DVT and pulmonary embolism 
3. Ankle mortise redislocation and requirement of a further ankle manipulation. 
4. Skin ulceration due to cast pressure
5. Fracture delayed union
6. Fracture non-union
7. Fracture malunion
8. Ankle chronic instability
9. Delayed return to functional activity 
10. Ankle arthritic changes 

 Operative Management Complications May Include

1. Infection
2. Painful scar
3. Wound dehiscence
4. Metalwork failure (e.g., broken plate and loose screw )
5. Mal positioned metal work (e.g., screw protrusion into the joint)
6. Prominent screws
7. Fracture non-union
8. Fracture delayed union 
9. Nerves damage
10. Vascular damage 

Another complication of ankle fracture seen in people with diabetes is Charcot arthropathy, also known as neuropathic arthropathy. This condition occurs when there is a progressive degeneration of the ankle joint, which leads to the destruction of the bone, increased bone resorption, which ultimately leads to deformity. Long-term complications of this may lead to ulceration, infection, or eventual amputation.