Last Updated on October 29, 2023
Malleolar fractures are types of ankle injuries which include fractures malleolar regions of tibia and fibula [medial and posterior malleoli arise from the tibia, distal end of the fibula is called lateral malleolus] and/or associated ligaments.
They are intraarticular injuries because the malleoli form part of the ankle joint.
These fractures are frequently associated with soft-tissue injury is common as the bones are subcutaneous.
Unimalleolar fractures are the most common (68%), followed by bimalleolar fractures (25%) and trimalleolar fractures (7%).
Injury Pattern in Malleolar Fractures
Following injury pattern can be seen
Isolated medial malleolus fracture
Isolated lateral malleolus fracture
Bimalleolar fractures
Fracture of medial and lateral malleoli are called bimalleolar fractures. Bimalleolar fracture is also called Pott’s fracture.
Trimalleolar Fractures
- Called Cotton fracture
- Fracture of medial, lateral and posterior malleoli
Bimalleolar-equivalent fractures
- fracture of lateral malleolus with the deltoid ligament injury to make ankle stable
Posterior malleolus fractures
Bosworth Fracture-dislocations
- Rare fracture-dislocation of the ankle
- The fibula becomes entrapped behind the tibia and cannot be reduced
- The posterolateral ridge of the distal tibia hinders reduction
Associated or isolated syndesmotic injuries
Anatomy of Ankle Joint
Medial and lateral malleoli along with the lower end of tibia and syndesmosis form the upper part of the ankle joint. Posterior projection of the tibia is also known as posterior malleolus.
The ankle is stabilized by various ligaments. Medially, deep part of the deltoid ligament acts as a primary restraint to anterolateral talar displacement. Laterally, fibula acts as a buttress to prevent lateral displacement of the talus
Syndesmosis or structures which hold the tibia and fibula in position are the interosseous membrane and the syndesmotic ligaments which are posterior and anterior tibiofibular ligaments.
More on anatomy of ankle joint
Mechanism of Malleolar Fractures
The Infrasyndesmotic injury (type A fracture)
- Foot supinated and an adducted
- Lateral side breaks under tension at or just below the level of the tibial plafond
- Rupture the lateral ligament or
- Osseoligamentous avulsion or
- Transverse fracture of the lateral malleolus
- Deforming force still continues and tilting of talus causes a shearing compression fracture of the medial malleolus.
Trans-syndesmotic injury (type B fracture)
- The most common pattern of injury
- Axial loading of a supinated foot
- Inversion results in external rotation of the talus.
- Fibula breaks
- An oblique fracture starting at the level of the ankle joint
- Proximal extension from anterior to posterior.
- Progressive talar external rotation causes posterior displacement which causes
- Injury to the posterior syndesmotic ligament or
- fracture of the posterior malleolus.
- Talus subluxates posteriorly and the medial complex fails
- Rupture of the deltoid ligament or
- Transverse fracture of the medial malleolus.
The suprasyndesdesmotic injury (type C fracture)
- The foot is in pronation
- An external rotation force is applied.
- Medial structures are under tension
- Deltoid ligament rupture or
- a medial malleolar avulsion fracture.
- The medial side of the talus to translate anteriorly resulting in external rotation of talus
- Fibula to twist about its vertical axis leading to a rupture of the anterior syndesmotic ligament first, and then of the interosseous ligament.
- The tibia dislocates medially off the rotating talus
- diastasis of the fibula from the tibia [injury to syndesmosis]
- Finally an indirect fracture of the fibula shaft, the level of which depends on how far proximally the interosseous membrane ruptures.
Classification of Malleolar Fractures
Lauge-Hansen Classification
Lauge-Hansen classification is based on foot position and force of applied stress/force.
Supination-Adduction Injury
- Talofibular sprain or distal fibular avulsion
- 2. Vertical medial malleolus and impaction of anteromedial distal tibia
Supination-External Rotation
- Anterior tibiofibular ligament sprain
- Lateral short oblique fibula fracture (anteroinferior to posterosuperior)
- Posterior tibiofibular ligament rupture or avulsion of posterior malleolus
- Medial malleolus transverse fracture or disruption of deltoid ligament
Pronation-Abduction
- Medial malleolus transverse fracture or disruption of deltoid ligament
- Anterior tibiofibular ligament sprain
- Transverse comminuted fracture of the fibula above the level of the syndesmosis
Pronation-External Rotation
- Medial malleolus transverse fracture or disruption of deltoid ligament
- Anterior tibiofibular ligament disruption
- Lateral short oblique or spiral fracture of fibula (anterosuperior to posteroinferior) above the level of the joint
- Posterior tibiofibular ligament rupture or avulsion of posterior malleolus
Danis-Weber Classification
The basis of the classification is the location of fibular fracture.
Type A
Fracture of the lateral malleolus distal to the syndesmosis. It is below the level of the ankle joint and the tibiofibular syndesmosis intact.
Deltoid ligament is intact and medial malleolus often fractured.
Type B
The fracture of the fibula at the level of the syndesmosis and ankle joint, extending superiorly and laterally up the fibula.
The syndesmosis may be intact or only partially torn, but there is no widening of the distal tibiofibular articulation. The medial malleolus may be fractured or there may be a tear in the deltoid ligament.
Type C
Fracture of the fibula is proximal to the syndesmosis/ankle joint and there is disruption of the syndesmosis. The distal tibiofibular joint is widened. The medial malleolus is fractured or there is a tear in the deltoid ligament.
AO / ATA Classification
- 44A – Infrasyndesmotic
- 44B – Trans-syndesmotic
- 44C – Suprasyndesmotic
Clinical Presentation of Malleolar Fractures
There would be a history of trauma to ankle following which the patient may complain of painful swelling and deformity in the ankle region. There would be an inability to bear weight on the affected limb.
On examination, swelling and deformity are obvious in displaced fractures. In undisplaced injuries with minimal swelling and no obvious deformity, the ankle may be palpated for tenderness along the medial malleolus and lateral malleolus.
Associated injuries of the foot and other parts of the limb must be looked for. In case of high energy injury, other parts and systems of the body must be examined to rule out an injury.
The neurovascular examination must be done to look for any vascular or neural injury. This is done by palpation of the distal vessels and gross sensorimotor examination of the foot.
Imaging
X-rays are the basic imaging. Following x-rays may be done
- Anteroposterior view
- Lateral view
- Mortise view [taken with the foot internally rotated 15-20 degrees]
Stress-view radiographs have a limited role in evaluating an acute ankle injury.
[If needed, these should be done under anesthesia]
Generally speaking, transverse fractures usually result from avulsion forces, whereas oblique fractures generally result from the torsional stress of the talus against the malleolus. Bony injuries should be looked for in all the views to understand the fracture geometry better.
Evaluation of ligament injury requires an idea about the normal ankle.
In an ankle mortise view,
- Normal tibiofibular overlap >1 mm.
- The normal medial clear space<4 mm or a difference from medial to lateral of less than 2 mm.
- A lateral clear space > 2 mm suggests a syndesmosis sprain.
On the anteroposterior view of the ankle
- Medial clear space <3mm [> 3 mm indicates deltoid ligament or syndesmosis injury.]
- Tibiofibular space < 6 mm.
- In the standing anteroposterior view, syndesmotic widening of greater than 3 mm indicates syndesmotic sprain.
[External rotation stress radiograph is the most appropriate stress radiograph to assess the competency of the deltoid ligament. A medial clear space of >5mm with external rotation stress in a dorsiflexed ankle is predictive of deep deltoid disruption]
Talocrural angle is measured by bisection of a line through the tibial anatomical axis and another line through the tips of the malleoli. Shortening of lateral malleoli fractures can lead to an increased talocrural angle but is not a very reliable method.
- talocrural angle is not 100% reliable for estimating restoration of fibular length
Finally in the x-ray examination, do look for following [Acronym FLOAT]
- Fifth metatarsal base
- Lateral process of the talus
- Os trigonum or posterior malleolus
- Anterior process of the calcaneus
- Talar dome
Treatment of Malleolar Fractures
Any displaced malleolar fracture should be considered unstable. They are almost always associated with ligamentous injury of the opposite side.
Stable fractures can be treated non-operatively whereas unstable fractures require surgical fixation.
All displaced medial malleolus fractures and oblique fibular fractures that are 2-3 inches proximal to the joint line should be considered unstable [assumed to have associated ligament injury]
Nonoperative Treatment
Non-operative treatment is in form of short leg cast or walking boot. It can be done in
- Isolated nondisplaced medial malleolus fracture or tip avulsions
- Isolated lateral malleolus fracture with < 3mm displacement and no talar shift
- Posterior malleolar fracture with < 25% joint involvement or < 2mm step-off
Operative Treatment
Surgical treatment for malleolar fractures is by open reduction and internal fixation.
Indication for surgical treatment include
- Talar displacement
- Displaced isolated medial malleolar fracture
- Displaced isolated lateral malleolar fracture
- Bimalleolar fracture and bimalleolar-equivalent fracture
- Posterior malleolar fracture with > 25% or > 2mm step-off
- Bosworth fracture-dislocations
- Open fractures
The goal of the treatment is to provide a stable anatomic reduction of the talus in the ankle mortise. In order to achieve that, the fibula should be restored to its original length and rotational alignment, followed by fixation of other fractures in anatomical fashion.
Treatment of Individual Fracture Patterns
Isolated Medial Malleolus Fracture
Isolated medial malleolus fracture can be treated by non-operative means [short leg walking cast or cast boot] in following situations
- Undisplaced fractures
- Tip avulsions [deep deltoid inserts on posterior colliculus]
Operative treatment is indicated if a talar displacement is noted.
Fixation could be done using
Isolated Lateral Malleolus Fracture
Depending on the fracture pattern, it can be treated both by non-operative means and surgery.
Nonoperative treatment is done by short leg walking cast/ cast boot. Indications are
Indications for non-operative treatment are intact mortise, no talar shift, and < 3mm displacement
Surgery is indicated for talar shift or > 3 mm of displacement
The fixation can be done in the following ways
- Plating
- Lateral plating
- lag screw fixation with neutralization plating
- Bridge plate technique
- Lateral plating
- Posterior plating
- Antiglide plate
- Lag screw fixation with neutralization plating
- Peroneal irritation is disadvantage otherwise posterior antiglide plating is biomechanically superior
- Intramedullary retrograde screw placement
- Isolated lag screw fixation
- Kwire/ Rush rod intramedullary fixation
Bimalleolar Fracture and Trimalleolar Fractures
Bimalleolar fractures are rarely stable and require surgical fixation. Non-operative treatment is only for those who are unable to undergo surgical intervention.
Both fibula and medial malleolus need to be fixed. Surgical options are the same as given for individual malleoli.
Trimalleolar fractures are also treated on the same lines. Fixation of the third malleoli, the posterior malleolus is discussed below.
Bimalleolar Fracture Equivalent or Deltoid ligament Tear with Fibular Fracture
Also called functional bimalleolar fracture.
This also requires open reduction and fixation of fibular fractures. Deltoid ligament repair is rarely done. Medial exploration is necessary only if one is unable to reduce the mortise
Posterior Malleolar Fracture
If the posterior malleolus is part of other fractures, it is operated if
- > 25% of the articular surface involved
- > 2 mm articular step off
- Syndesmosis injury
Otherwise, it can be left as such and treated by cast application.
For surgery, the posterior malleolus can be approached by the posterolateral or posteromedial approach. The fragment is fixed by anterior to posterior lag screws or posterior to anterior lag screw and buttress plate
Stress examination of syndesmosis still required after posterior malleolar fixation
Bosworth Fracture-Dislocation
Requires open reduction and fixation
Associated Syndesmotic Injury
The syndesmotic injury is seen most commonly in Weber C type fracture patterns. It often requires fixation by a syndesmotic screw. Indications for surgery are
- Widening of medial clear space
- Tibiofibular clear space in AP greater than 5 mm
- Tibiofibular overlap in mortise view is narrowed
Prognosis
Overall, malleolar fractures have a good prognosis and a success rate of 90%. The Weber type C and open fractures have a worse prognosis. Prolonged recovery up to 2 years may be required to obtain final functional result).
Time for proper braking response time during driving returns to baseline at nine weeks after surgery.
