FRACTURES 

A fracture is a pathology that can be caused by a variety of traumas, including blunt force, sharp force, projectiles (such as bullets), and rapid deceleration (such as car accidents or airplane crashes).  It is, therefore, important to understand how different types of fractures are formed.  There are a number of factors that effect the formation of a fracture.  Some of these factors have to deal with the bone itself, while others deal with the force that can potential cause a break.

FACTORS EFFECTING A BONE'S FRACTURE POTENTIAL:

1.) Age

• Human bones are the strongest after puberty, but before the age of 40.  This is because bones are not fully formed yet during puberty thus allowing one to grow in length; they have an end referred to as the epiphysis, which is where new bone is formed.  While one's bones are more flexible during puberty, they are relatively weaker due to the presence of epiphyses, which are cartilaginous in nature.  After the age of 40, bones tend to become less flexible and more brittle due, respectively, to demineralization (the loss of calcium and other essential minerals) and to the loss of collagen fibers that give a bone its tensile strength.

• Statistically, between the ages of 6 years and 40, males get more fractures than females.  The reason for this is thought to be because males tend to engage in more dangerous work and leisure activities than females do.

• Some diseases can cause bones to become weak and thus more susceptible to fracturing.  These diseases can be metabolic, infectious, or neoplastic in nature and they effect a bone's structural integrity.  A break caused be such a disease is deemed a pathological fracture.

• A fracture that would normally occur when muscles are tensed, may not occur when the muscles are relaxed.  Bones have a certain degree of flexibility to them, but when their surrounding muscles are tense bones become rigid.

The physical properties of bones are not the only factors to consider when dealing with different types of fractures.  One also has to consider the direction and intensity of the force and the instrument used to deliver the force.  The most common forces involved in fractures are compression (compaction - ex. commonly seen after falls), tension (stretching - ex. medieval rack), rotation (twisting), shear (sliding), and bending (angulation) (Galloway 46).

COMMON FRACTURES

Fractures are named by a variety of means; they can be named for such things as the individual who first described them (ex. Colle's fracture), their appearance (ex. greenstick fracture), or the forces that cause them (ex. stress fracture, compression fracture).
 

Transverse Fracture - This is a fracture that occurs at right angles to the long axis of a bone.  There is tension on one side of the bone and compression on the other.  Bones are more resistant to compressive force, so the break begins on the side that is being effected by tension.
Oblique Fracture - This type of fracture is usually the result of angulation and compressive forces.  It starts out as a transverse fracture, but as the forces increase on the remaining bone, the fracture is forced downward.
Spiral Fracture - This type of fracture circles up the shaft of a bone and it is caused by rotational forces that are usually low velocity in nature.
Comminuted Fracture - This is any fracture in which the bone breaks into more than two fragments.  The break is classed by the severity of the fragmentation.
Butterfly Fracture - This fracture is caused by compression (represented by the arrow) and tension.  An example is getting hit by a car where the point of impact is compression as the bone bends around the car.  A butterfly fracture means that bone is bending; in
                                              juveniles this can lead to a greenstick fracture.
Diagram is a classification of complete fractures.  The arrows indicate the direction of the force involved.
Image courtesy of Galloway, p. 53

Other fractures include:


Diagram of possible fractures of the tibia (shin bone).  These fractures are classified according to the shape of the fracture line, the severity of the injury, and the number of broken parts involved.
Image courtesy of Galloway, p. 195

On the skull, there are four main types of fractures:

Linear Fractures - These fractures tend to occur from a low velocity force derived from a large mass.  They travel quickly across the cranial vault, usually going in the direction where there is least resistance.  Linear fractures are also common to see where a force has traveled through the body; for example a blow to the head may cause some energy to travel down the spinal column resulting in linear fractures elsewhere in the body.
Diastatic Fractures - These are simply any fractures that go into a suture line.
Depressed Fractures - These fractures can be caused by a high velocity force from a small mass, causing a "caving-in".  Linear fractures are commonly found around a depressed fracture.
Stellate Fractures - "Star-shaped" fractures that are made up of multiple linear fractures.  They
Diagram of cranial vault fractures.                               result from low velocity forces.
Image courtesy of Galloway, p. 69
 
 
 
 
 

* Images courtesy of Dirkmaat, various pages