Fracture general principles
The basics principles of radiological fracture evaluation.
Introduction
Read all about the different types of fractures and how they should be described. This is an important module that forms the basis for assessing all types of X-rays.
It is particularly recommended that you read this module before you start with the specific lectures on the various X-ray examinations of the extremities (for instance X-Wrist).
Some of the key topics are pathological fracture, Greenstick fracture and Salter & Harris.
KEY TOPICS/TERMS:
- Fracture types
- Stress fracture
- Pathological fracture
- Greenstick fracture
- Torus fracture
- Epiphysiolysis (Salter & Harris)
Terms
Fracture: interruption of the continuity of part of the skeletal system (=broken bone)
Luxation: dislocation, interruption of the normal interrelation between the components of a joint.
When asked to confirm a fracture, the area in question is always imaged in (at least) 2 different directions. A fracture is generally visible in one direction only. Therefore, never settle for an image in only one direction.
If bone fragments are displaced as a result of a fracture, the X-ray beam will not be absorbed by the bone at the fracture site (= the gap) (fig. 1a). This is visible as a lucent line (= black line). Bone fragments may also be compressed (= impacted fracture), causing overlap of bone structures (fig. 1b). In this case there will be increased X-ray absorption at the fracture site, resulting in increased density (= whiter).
Fracture Types
Terms:
- Uncomplicated fracture: fracture where the adjacent skin is intact.
- Complicated/open fracture: fracture with skin penetration of a fracture fragment.
- Comminuted fracture: fracture with > 2 bone fragments.
- Intra-articular fracture: fracture line continues up to the joint surface (fig. 2)
- Stress fracture: fracture resulting from excessive stress on the bone. Can be seen e.g. in the metatarsal bones of fanatical sportsmen (fig. 3a)
- Pathological fracture: fracture line at the level of abnormal bone, as in a bone metastasis or bone cyst (fig. 3b)
- Insufficiency fracture: fracture secondary to reduced bone strength, e.g. osteoporotic vertebral collapse.
- Avulsion fracture: fracture at the site of a tendon insertion. The bone is ripped loose from the insertion site by the tendon/muscle (excessive traction on the bone).
Pediatric:
- Greenstick fracture: incomplete fracture where the bone is bent (one-sided cortical interruption). These fractures are seen in the distal radius and ulna in particular (fig. 4)
- Torus fracture (= buckle fracture): incomplete fracture creating a 'buckle’ of the cortex. The picture resembles the bottom of a Greek pillar.
Torus fractures heal quicker than greenstick fractures.
- Epiphysiolysis: fractures of the epiphyseal plate (=growth plate)
Classification according to Salter & Harris (fig. 5):
Type I: fracture through the epiphyseal plate.
Type II: fracture through the epiphyseal plate and the metaphysis (most common)
Type III: fracture through the epiphyseal plate and the epiphysis.
Type IV: fracture through the epiphyseal plate, metaphysis and epiphysis.
Type V: crush injury of the epiphysis.
Memory aid based on the epiphyseal plate: SALTeR Same level (I),Above (II), Lower (III), Through (IV), Ruined (V).
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Text & Illustrations
drs. A. van der Plas, MSK radiologist Maastricht UMC+
Sources:
- Radiologic reporting of skeletal trauma.M J MJ Pitt and D P DP Speer Radiol Clin North Am 28(2):247-56 (1990)
- B.J. Manaster et al. The Requisites – Musculoskeletal Imaging. 2007
- N. Raby et al. Accident & Emergency Radiology – A Survival Guide. 2005.
24/01/2014
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