Lauge Hansen Classification in Modern Ankle Fracture Analysis

Ankle fractures are among the most common orthopedic injuries, requiring precise classification for effective diagnosis and treatment. The Lauge-Hansen system remains widely used due to its ability to correlate fracture patterns with specific injury mechanisms, aiding clinical decision-making and surgical planning.

Key Biomechanical Factors

The Lauge-Hansen classification system is based on the biomechanical forces that dictate ankle fractures, emphasizing the relationship between foot position and applied stress. The ankle joint, composed of the tibia, fibula, and talus, functions as a hinge with rotational and translational capabilities, making it particularly vulnerable when external forces exceed physiological limits. Ligamentous structures, including the deltoid ligament medially and the syndesmotic complex laterally, influence fracture propagation.

Rotational forces play a dominant role in ankle fractures. When the foot is fixed in supination or pronation, force application follows a predictable path, leading to characteristic fracture patterns. For instance, external rotation stress in a supinated foot often results in progressive failure of the anterior inferior tibiofibular ligament, followed by fibular fracture at varying levels and potential posterior malleolar involvement. Conversely, adduction forces in a supinated position generate vertical medial malleolar fractures with transverse fibular involvement.

Axial loading further complicates fracture morphology, particularly in high-energy injuries where compressive forces exacerbate bone and soft tissue damage. Pronation-dorsiflexion injuries exemplify this mechanism, as the talus is driven posteriorly and superiorly, leading to impaction fractures of the tibial plafond. The extent of energy transfer also influences associated soft tissue compromise, increasing the risk of periosteal stripping, ligamentous disruption, and compartment syndrome.

Main Classification Patterns

The Lauge-Hansen system categorizes ankle fractures based on foot position at injury and the direction of applied force. This classification helps predict associated ligamentous and osseous injuries, guiding diagnosis and treatment.

Supination-External Rotation

This is the most common ankle fracture pattern. The sequence begins with disruption of the anterior inferior tibiofibular ligament as external rotation force is applied to a supinated foot. As force progresses, a spiral fracture of the distal fibula occurs, typically at or above the syndesmosis. Further rotation may lead to posterior malleolar involvement due to posterior tibiofibular ligament failure. In advanced stages, the deltoid ligament ruptures or the medial malleolus fractures transversely. This pattern is often seen in sports injuries and falls. Management depends on syndesmotic stability, with surgical fixation required for displaced fractures or significant ligamentous disruption.

Supination-Adduction

This pattern results from an adduction force applied to a supinated foot, leading to a distinct fracture morphology. The sequence begins with a vertical fracture of the medial malleolus or rupture of the deltoid ligament. As force continues, the lateral side experiences compression, producing a transverse or comminuted fibular fracture at or below the syndesmosis. Unlike external rotation injuries, this mechanism does not typically involve posterior malleolar fractures. These fractures often result from low-energy trauma, such as missteps or minor falls, but can still cause significant instability. Treatment varies based on displacement, with nonoperative management for stable fractures and surgery for significant malalignment or joint incongruity.

Pronation-External Rotation

This pattern occurs when an externally rotating force is applied to a pronated foot. The initial stage involves disruption of the deltoid ligament or a transverse medial malleolar fracture. As rotation progresses, the anterior inferior tibiofibular ligament fails, followed by a spiral or oblique fibular fracture above the syndesmosis. In later stages, the posterior tibiofibular ligament ruptures or the posterior malleolus fractures. This pattern is frequently associated with high-energy mechanisms, such as motor vehicle accidents or contact sports injuries. Due to the high likelihood of syndesmotic injury, surgical stabilization is often required.

Pronation-Abduction

This pattern results from an abduction force applied to a pronated foot. The injury begins with failure of the medial structures, either through deltoid ligament rupture or a transverse medial malleolar fracture. As force continues, the fibula undergoes bending stress, producing a transverse or comminuted fracture at or above the syndesmosis. Unlike external rotation injuries, this mechanism does not typically involve posterior malleolar fractures. These injuries often occur in lateral-impact trauma, such as side-swipe injuries or falls with forced eversion. Displacement dictates management, with stable fractures treated conservatively and unstable patterns requiring surgical fixation to restore alignment and prevent post-traumatic arthritis.

Pronation-Dorsiflexion

This is the least common Lauge-Hansen fracture pattern, typically resulting from high-energy axial loading with the foot in a pronated and dorsiflexed position. The injury begins with impaction of the anterior tibial plafond, often producing a fracture of the anteromedial tibia. As force continues, the talus is driven posteriorly, leading to posterior malleolar fractures and potential fibular involvement. Severe cases may resemble pilon injuries. This pattern is frequently observed in falls from height or industrial accidents. Due to the high-energy nature of these injuries, associated soft tissue damage is common, increasing the risk of complications such as post-traumatic arthritis and nonunion. Surgical management is often required to restore joint congruity.

Radiographic Identification

Accurate radiographic assessment is essential for classifying ankle fractures within the Lauge-Hansen system. Standard imaging includes anteroposterior (AP), lateral, and mortise views, each offering a distinct perspective on fracture morphology and displacement. The mortise view, obtained with the ankle in 15 to 20 degrees of internal rotation, is particularly valuable in evaluating syndesmotic widening and subtle malleolar fractures. Radiographs must be analyzed for fracture orientation, step-offs at articular surfaces, and indirect signs of ligamentous injury, such as medial clear space widening or fibular shortening.

Beyond conventional radiography, stress views help assess ligamentous integrity, particularly in suspected syndesmotic injuries. The external rotation stress test, performed with the foot rotated laterally under fluoroscopy, can reveal latent instability. Gravity stress views provide similar information without manual manipulation, reducing patient discomfort while maintaining diagnostic accuracy. These techniques help differentiate stable fractures from those requiring surgical stabilization.

Advanced imaging modalities, particularly computed tomography (CT) and magnetic resonance imaging (MRI), enhance fracture characterization in complex cases. CT scans are invaluable for evaluating comminuted fractures, posterior malleolar involvement, and intra-articular step-offs. Three-dimensional reconstructions aid in preoperative planning by providing detailed visualization of fracture planes. MRI, while not routinely used for initial fracture assessment, is effective in detecting soft tissue injuries, including deltoid ligament ruptures and syndesmotic disruption. When radiographs suggest ligamentous injury without clear osseous abnormalities, MRI clarifies soft tissue damage and guides treatment decisions.

Clinical Observations

Patients with ankle fractures exhibit a range of clinical findings that correlate with Lauge-Hansen classification patterns. Swelling and ecchymosis are early indicators, with their distribution providing clues about the mechanism of injury. Medial-sided bruising suggests deltoid ligament involvement, common in pronation-external rotation injuries, while lateral swelling without medial ecchymosis is more typical of supination-external rotation fractures. Palpation refines clinical suspicion, as tenderness over the fibula signals a lateral malleolar fracture, whereas focal pain at the medial malleolus raises concern for ligamentous rupture or bony failure.

Joint stability assessment is crucial, particularly when radiographic findings do not fully explain functional impairment. Patients with syndesmotic injuries often struggle with weight-bearing, even if initial imaging shows minimal displacement. The external rotation stress test, performed manually, can elicit pain and reveal excessive lateral talar shift, suggesting syndesmotic disruption. Additionally, careful evaluation of neurovascular status is imperative, as high-energy injuries—especially those involving pronation-dorsiflexion mechanisms—can compromise arterial supply or result in peroneal nerve dysfunction, leading to foot drop or sensory deficits.