Fractures of the extremities (general rules and nomenclature)
General rules and nomenclature of fractures should be understood by, and familiar to, anyone involved in the interpretation or management of fractures of the extremities. This article covers basic nomenclature of fractures.
Before the most appropriate treatment for a fracture can be chosen, it has to be properly described and classified. There are numerous, often overlapping, mostly eponymous classification systems for fractures of most regions (e.g. Neer classification of proximal humeral fractures, Garden classification of hip fractures, etc).
An alternative, unifying classification known as the AO system has been developed by Swiss surgeon Maurice E Müller and his colleagues as an attempt to create a uniform system for all possible skeletal trauma and that is suitable for electronic data processing.
Which classification system is used for any particular fracture varies widely geographically and radiologists should become familiar with what the local preferences are.
Fracture forms and features to report
There are some general forms and features of fractures, that must be identified on plain radiographs, typically in two orthogonal planes. For complex joints formed by multiple bones, additional features have to be reported, typically resulting in a more sophisticated classification. Certain fractures may even occur in combination with others or are associated with certain concomitant injuries, which have to be sought for. The following descriptive terms mainly apply to fractures of the long extremity bones.
Shaft fractures (from simple to more complex)
When a bone is broken in two (even if the one fragment is large and the other small (e.g. an avulsion fracture) it is still a two-part fracture, something which sometimes causes confusion.
- transverse fracture
- oblique fracture
- spiral fracture
- bending wedge fracture
- spiral wedge fracture
- segmental fracture
- segmental fracture
- fragmented wedge fracture
- irregular multifragmental fracture
- comminuted fracture
Displacement of fragments (distal in relation to proximal)
- ad latus (sideways): give direction and extent in mm or in relation to cortical or shaft diameter
- ad axim (angulation): give largest angle and direction
ad longitudinem (with shortening or elongation)
- cum contractione: shortening occurs when fracture ends of a long bone lose contact, e.g. in oblique fractures with steep angles or in lateral dislocation of more than the shaft diameter
- cum distractione: a gap between the fracture ends prevents healing
- ad peripheriam: rotational displacement (the position of both large joints of a long bone must be assessed)
- impaction - usually refers to a stable and typically simple fracture in which the fragments are driven into each other
Fractures with articular involvement and fracture-dislocations
- impression fracture
- shear (longitudinal split) fracture
- combined fracture: T-shape, Y-shape, multifragmentary
Features to report
- irregularities of articular surfaces
- plane and course of fracture lines
- size and position of displaced bones or fragments
- direction of displacement
- loose intra-articular fragments
- soft tissue signs
- missing fragments (bone defects) in open fractures
Apophyseal avulsion fractures
Features to report
- direction and measure of displacement
- tendons, muscles or ligaments involved
- 1. McRae R, Esser M. Practical Fracture Treatment. Churchill Livingstone. (2008) ISBN:1455725234. Read it at Google Books - Find it at Amazon
- 2. Thelen M, Ritter G, Bücheler E. Radiologische Diagnostik der Verletzungen von Knochen und Gelenken., Ein Leitfaden für Radiologen und Traumatologen. Thieme. (1993) ISBN:3137787017. Read it at Google Books - Find it at Amazon
- 3. Müller ME. The comprehensive classification of fractures of long bones. Springer. (1990)