The Lauge-Hansen classification is a system developed to categorize ankle fractures. This system helps medical professionals understand the injury mechanism, guiding treatment. It was developed in the mid-20th century by Danish orthopedic surgeon Niel Lauge-Hansen.
Understanding the Classification Principles
The Lauge-Hansen classification system is built upon two main factors that describe the mechanism of injury. The first factor considers the position of the foot at the exact moment of the traumatic event. This position is typically either supination, where the foot is turned inward, or pronation, where the foot is turned outward.
The second factor details the direction of the deforming force applied to the ankle. These forces can be categorized as adduction, abduction, or external rotation. Adduction involves an inward force, abduction an outward force, and external rotation refers to an outward twisting motion of the foot relative to the leg.
By combining these two factors—foot position and force direction—the classification system aims to predict the specific patterns of bone and ligament damage that occur. The original methodology involved manipulating cadaveric limbs to observe these predictable injury patterns.
Common Ankle Fracture Patterns
The Lauge-Hansen classification outlines several common patterns of ankle fractures, each stemming from a unique combination of foot position and deforming force.
Supination-External Rotation (SER)
One frequently observed pattern is the Supination-External Rotation (SER) injury. This injury typically begins with a tear of the anterior tibiofibular ligament, followed by an oblique or spiral fracture of the lateral malleolus. Further force can lead to a tear of the posterior tibiofibular ligament or a fracture of the posterior malleolus, and finally, a fracture of the medial malleolus or rupture of the deltoid ligament.
Supination-Adduction (SA)
Another pattern is the Supination-Adduction (SA) injury, where the foot is supinated and an inward force is applied. This mechanism often results in a fracture of the lateral malleolus, specifically a transverse fracture below the syndesmosis. This can be accompanied by a vertical fracture of the medial malleolus or rupture of the medial collateral ligaments.
Pronation-Abduction (PAB)
Pronation-Abduction (PAB) injuries occur when the foot is pronated and an outward force is applied. This pattern often starts with a rupture of the deltoid ligament or a transverse fracture of the medial malleolus. Subsequent damage can include a fracture of the posterior malleolus and an oblique fibular fracture located above the ankle joint.
Pronation-External Rotation (PER)
Pronation-External Rotation (PER) injuries involve a pronated foot with an external rotation force. This sequence typically begins with a deltoid ligament rupture or a transverse avulsion fracture of the medial malleolus. This can progress to involvement of the anterior inferior tibiofibular ligament, leading to widening of the distal tibiofibular distance, and a spiral or oblique fibular fracture located above the talotibial joint.
Why Classification Matters for Treatment
The Lauge-Hansen classification aids medical professionals in accurately diagnosing ankle fractures. Understanding the specific injury mechanism helps doctors predict which bones and ligaments are likely to be damaged, even before detailed imaging. This predictive capability helps in forming a more complete picture of the injury.
The classification system also plays a role in guiding treatment decisions. Knowing the specific pattern and extent of the injury, including associated ligamentous damage, helps determine whether a surgical or non-surgical approach is more appropriate. For example, unstable fractures often require surgical intervention to restore joint alignment and stability.
The Lauge-Hansen system assists in predicting potential complications and the overall prognosis for recovery. It allows healthcare providers to anticipate the challenges associated with different fracture types, leading to more informed patient discussions and rehabilitation planning. This systematic approach also standardizes communication among medical teams.