Müller AO Classification of fractures

AO Fracture Classification - Adult

Müller AO Classification of Fractures is a system used in orthopedic surgery to classify bone fractures. It was developed by the AO Foundation (Arbeitsgemeinschaft für Osteosynthesefragen), a Swiss-based international organization. This classification is widely used around the world for its systematic approach to categorizing fractures, which aids in diagnosis, treatment planning, and research.

Overview

The Müller AO Classification system divides fractures into three main categories based on the bone involved and the type of fracture. These categories are further subdivided into groups and subgroups to provide a more detailed description of the fracture. The system is applied to long bones, such as the femur, tibia, and humerus, as well as to other skeletal regions including the spine, pelvis, and hands.

Classification System

The classification is alphanumeric, with the first letter indicating the bone, the second number indicating the part of the bone (proximal, diaphyseal, distal), and the third and fourth characters providing information about the specific fracture type and its characteristics.

Long Bones

For long bones, the classification is as follows:

• 1st character (letter): Indicates the bone (e.g., A for humerus, B for radius/ulna, C for femur)
• 2nd character (number): Indicates the segment of the bone (1 for proximal segment, 2 for diaphyseal segment, 3 for distal segment)
• 3rd and 4th characters: Describe the fracture type and subgroup, detailing the fracture pattern and complexity.

Pelvis and Acetabulum

The pelvis and acetabulum fractures are classified differently, focusing on the location and severity of the fracture.

Spine

Spinal fractures are categorized based on the mechanism of injury and the area of the spine affected (cervical, thoracic, lumbar).

Applications and Limitations

The Müller AO Classification is extensively used in clinical practice and research to standardize the reporting of fractures. It helps clinicians to communicate effectively about patient cases and to select appropriate treatment strategies. However, the system's complexity and the requirement for detailed imaging to accurately classify fractures can be challenging.

Conclusion

The Müller AO Classification of Fractures is a comprehensive system that plays a crucial role in the field of orthopedic surgery. By providing a standardized method for classifying fractures, it facilitates effective communication among healthcare professionals and supports the advancement of research and treatment strategies.