BONE FRACTURES AND DISLOCATIONS

General Principles of Fractures and Dislocations

Outlines

• Introduction
• Definitions
• Types of fractures
• Approach to orthopedic injury
• Investigations in orthotrauma
• Management of fractures
• Open fractures
• Approach in compound fractures
• Approach to a polytrauma case
• Dislocations

INTRODUCTION

It is not surprising if a bone breaks but what is surprising is the fact that bone does not break more often considering the amount of forces it is subjected to everyday by the muscle action, load transmission,etc. Bone has devised its own mechanism to ward off the unnatural forces and keep itself intact. But only when the force is too large and occurs suddenly
(as in road traffic accidents (RTA), fall, etc.), or when a force is chronic and repetitive (e.g. prolonged standing as in a policeman, nurse, etc.) or when the natural resistance of the bone is eroded by a disease process (e.g. tumor, infection, etc.), that a bone
succumbs to the insult and breaks.
When it breaks, it is bound to injure the surrounding soft tissues like
muscles, ligaments, etc.

DEFINITIONS

Fracture is a break in the surface of a bone, either across its cortex or through its articular surface.
Dislocation is a complete and persistent displacement of a joint.
Subluxation is partial dislocation of a joint.
Sprain is a temporary subluxation of a joint due to ligament injury and the articular surfaces return to normal alignment.
Strain is a tear in the muscle.

The bone can break within its soft tissue envelope and may not communicate to the exterior (simple or closed fractures) or it may rip through its soft tissues or the soft tissue itself may be damaged by the
external forces, exposing the bone to the external atmosphere (compound or open fractures). If the former event is bad, the latter event is catastrophic. In both the situations depending on whether the force is direct (as in direct impact in RTA) or indirect (e.g. through the muscle action), and depending on the amount of force applied, the direction of force, age and other factors, different fracture patterns are produced and each one poses a problem peculiar to its own.

Remember

Forces required to break a bone could be:
• Repetitive (e.g. a stress fracture).
• Trivial (e.g. pathological fractures).

• Large and sudden (e.g. RTA).

TYPES OF FRACTURES

• Simple or compound—this has been already explained fracture
• Based on the extent of fracture line:
– Incomplete fractures—it involves only one surface or cortex of the bone.
– Complete fracture—here the fracture involves both the cortices and the entire bone. A complete fracture could be undisplaced or displaced.

Causes for displacement

• Muscle forces.
• Gravity.
• Obliquity of the fracture line.
• Improper handling of the fracture

• Based on fracture patterns (orthopedic trauma association classification)

Linear fractures: 
 
These could be transverse, oblique or spiral. Any fracture that forms an angle less than 30° with the horizontal line is called transverse. Angle equal to or more than 30° is termed oblique.

Comminuted fractures:

Here the fracture fragments are more than two in number. They are further sub-classified into ≥ 50 percent comminution or more than 50% comminution.

 Butterfly-shaped fractures are also included in this group and could be less than 50 percent or equal to or more than 50 percent.

Segmental fractures: 

A fracture can break into segments and the segment could be two-level, three-level, and a longitudinal split or
comminuted.

Bone loss:

This could be a < 50 percent bone loss, more than 50 percent bone loss, or a complete bone loss.

Atypical Fractures 

a. Greenstick fractures: 

It is seen exclusively in children. Here the bone is elastic and usually bends due to buckling or breaking of one cortex when a force is applied. This is called a greenstick fracture.

b. Impacted fractures:

 Here the fracture fragments are impacted into each other and are not separated and displaced.

c. Stress or fatigue fractures: 

It is usually an incomplete fracture commonly seen in athletes and in bones subjected to chronic and repetitive stress (e.g.third metatarsal fracture, fracture tibia, etc.).

d. Pathological fractures: 

It occurs in a diseased bone and is usually spontaneous. The force required to bring about a pathological fracture is trivial.

e. Hairline or crack fracture: 

It is a very fine break in the bone that is difficult to diagnose clinically.
Radiology usually helps or still better is CT scan.

f. Torus fracture: 

This is just a buckling of the outer cortex.

Remember

• Greenstick #:occurs in children.
• Stress #: common in athletes.
• Fatigue#:in occupations like police, nurse,etc.
• Pathological #: usually seen in elderly people.
• Hairline or crack #:is a special variety of incomplete fracture.

DISPLACEMENT OF FRACTURES

A complete fracture usually gets displaced due to various factors already mentioned. Depending on
the direction of force, mode of injury, pull of the muscles, a fracture can show any one of the following
displacements or angulation:

• Anterior angulation or displacement• Posterior angulation or displacement• Varus or medial angulation or displacement• Valgus or lateral displace or angulation
• Shortening.• Translational