Example | AO Classification


For clarification and a better understanding of the AO classification, 2 examples are given below:32- A1: This would be the code for a femur fracture (3) concerning the bone shaft (2). It is a simple fracture (A), which is generally classified as a light fracture (1). 21- C3: This code would be the code for a forearm fracture (2) concerning the bony shaft (1) close to the body. It is a complex fracture (C), which is generally classified as a severe (3) fracture.

AO-classification at the radius (spoke)

The AO classification at the radius (spoke) is used to classify fractures of the forearm in the wrist area. A distinction is made between three groups of fractures, which in turn can be divided into subgroups. Decisive for the classification is whether a joint injury is present.

If there is only a fracture of radius or ulna without joint involvement (extra-articular fracture), it is a type A injury according to the AO classification. In A1 only the ulna is affected and in A2 the radius is single, in A3 multiple fractures. Injuries in which the joint is partially affected (partial joint fractures) are classified in group B.

Here too, a distinction is made between injury types B1, B2 and B3, depending on which joints are involved. The most severe are radial fractures of type C according to the AO classification. These are complete joint fractures. Depending on which and how many bones are broken, a distinction is also made here between subtypes C1, C2 and C3.

AO classification on the spine

At the spine, fractures of the vertebral bodies (vertebral body fractures) are classified according to the AO classification. This classification is particularly important as it allows a distinction to be made between stable and unstable injuries of the spinal column. A stable fracture can be treated conservatively (i.e. without surgery).

An unstable fracture, on the other hand, must be stabilized by surgery. Injuries are divided into type A, B and C groups. Type A is also referred to as a compression injury.

The force that leads to the fracture comes from above (often, for example, a fatigue fracture in older women with bone loss). Type A injuries are usually stable, since the rear part of the vertebral body is intact. Vertebral body fractures of type B and type C, on the other hand, are unstable, since the posterior part of the vertebral body is also affected by the injury.

Such injuries can occur in a serious traffic accident, for example. Type C differs from type B primarily in the origin of the injury. In type C, rotational forces also lead to the injury, whereas this is not the case in type B. In both cases, however, an operation must usually be carried out promptly to prevent injury to the spinal cord and possible paralysis.