AO classification

The AO classification - also called Müller classification (named after Maurice E. Müller ) - of the working group for osteosynthesis issues aims to provide a worldwide unambiguous description of fractures in the human skeleton . The exact classification is the basis for standardizing modern bone fracture treatment .

Structure & application

The AO classification consists of a 4-digit alphanumeric code for the localization and description of a broken bone. Each Fraktur can thus be described with two digits, one letter and another number (for example 11A1). Extended or differently structured codes are used for special regions such as broken feet and hands as well as breaks in childhood.

The AO classification is most commonly used to classify the fractures of the long tubular bones of the arms and legs. In everyday clinical practice, however, alternative classifications are used, particularly in joint regions, which tend to provide information about therapy and prognosis or which are simply traditionally used.

1. Numbering of the body region

• 1 = upper arm, ie humerus (upper arm bone), shoulder blade and collarbone
• 2 = forearm, i.e. radius (spoke) and ulna (ulna)
• 3 = thigh, i.e. femur (thigh bone) and patella ( kneecap )
• 4 = lower leg, ie the tibia ( shin bone ) and fibula ( calf bone )
• 5 = spine
• 6 = basin
• 7 = hand
• 8 = foot
• 9 = Other: skull and lower jaw

2. Positioning within the region

• 1 = proximal (i.e. bone end close to the body)
• 2 = diaphyseal (i.e. bone shaft is affected)
• 3 = distal (i.e. bone end remote from the body)
• 4 = only in region 1 (shoulder blade), 3 (patella) and 4 (malleolus - ankle )
• 5 = only in region 1 (collarbone)

3. Assessment of the fracture according to complexity, prognosis, etc .: letters A to C

• For shaft fractures
  • A = simple fracture
  • B = wedge fracture
  • C = complex fracture
• For joint fractures
  • A = extra-articular
  • B = partial joint fracture
  • C = complete joint fracture

4. Assessment of the severity within these guidelines

Fragments and subgroups. This information differs depending on the type and location. In general, the severity can be given as 1 = easy, 2 = medium, 3 = difficult.

5th digit

There is also a 5th digit, but it has more academic meaning.

Examples

• 22-A1 would therefore be a simple fracture in the middle of the forearm, in medical terms an ulnar shaft fracture, radius shaft fracture or forearm shaft fracture (if both bones are broken)
• 23-C3 would be a severe fracture of the distal forearm with both ulna and radius splintered several times (comminuted fracture of the wrist)
• 32-A3 would be a transverse fracture in the center of the femur

Pediatric AO classification

There is a version of the AO classification adapted for children, which essentially refers to the AO classification for adults, but introduces 1–2 additional letters.

Web links

• The official website of the AO Foundation
• AO Surgery Reference . Retrieved April 25, 2014.
• Software for classifying fractures

Individual evidence

1. ↑ Dr FF Fernandez, O. Eberhardt: Classifications of fractures in childhood . In: Trauma and Occupational Disease . 12, No. 3, August 1, 2010, ISSN  1436-6274 , pp. 323-328. doi : 10.1007 / s10039-009-1586-y . Retrieved April 25, 2014.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !