Fracture of the Bone

BONE FRACTURE





 Definition.
Bone fracture means the bone has been craked or broken. It is the most common bone lesion and is defined as a break in the continuity of bone or a part of its mineralized structure




 Etiology.



• Traumatic physical force e.g. excessive impact, rotation, bending or any other mechanical force acting on previously normal bone


• Secondarily as a consequence of an unnoticed or trivial injury of previously diseased bone (pathologic or spontaneous fracture).





 Types of fractures
A fracture is classified as basing on the direction of the fracture line and the extent of damage




 Simple (closed) fracture.




The broken parts are still in normal anatomical position, surrounding tissue damage is minimal (skin is not pierced).The overlying tissues are intact



• Compound (open) fracture.





The broken end of the bone has moved and it pierces the skin. There may be extensive damage to surrounding blood vessels, nerves and muscles. Here pathogenic microorganisms have a route from the surface to the bone



• Incomplete fracture.





The fracture line does not pass the entire bone i.e. the bone is not broken in to two pieces.



• Complete fracture.





Fracture line crosses the entire bone and produces two bone fragments.



• Greenstick fracture.





The bone splits longitudinally (break along the long axis of the bone).Occurs mot commonly in children because their bones are not as brittle as adults due to collagen content.



• Transverse fracture.





Fracture line runs perpendicularly at right angle to the long axis of the bone.



• Oblique fracture.





Fracture line runs diagonally to a long axis of the bone.



• Spiral fracture.





 A fracture where at least one part of the bone has been twisted.



• Comminuted fracture.





The bone is broken into several pieces/fragments.



• Impacted/Compacted fracture.





The broken ends of a bone are forced into one another; many bone fragments may be created.



• Compression fracture.





A fracture that happens only in the vertebrae, usually due to pathological conditions such as osteoporosis which results in spine collapse.



• Depressed fracture.





A fracture of the skull where a cranial bone break (or a portion of skull bone is crushed) with depression of the bone in towards the brain.



• Avulsion fracture.





      Is a fracture where the tendon tears away a piece of bone.




Naming/Describing a fracture:
In describing a bone fracture, it is important to at least mention the following things



• The involved bone e.g. humerus.


• Location/part of the bone involved e.g. proximal, diaphyseal or distal.


• The type of the fracture e.g. simple, compound etc.


• Direction of the fracture line e.g. transverse,spiral,oblique





 For example “simple transverse proximal humeral fracture”




 Bone fracture healing.




Fracture healing process takes up to 18 months. The healing of a fracture is a proliferative physiological process in which the body facilitates repair of bone fracture.




 Phases of fracture healing.
There are three major phases of fracture healing: Reactive phase, Reparative phase and Remodeling phase.




 Reactive phase.



• Immediately after fracture the blood from ruptured blood vessels accumulates in the site between the fractures bone segments. The accumulated blood is called hematoma.


• Platelets and fibrin present in hematoma forms a blood clot.


• All cells (Except fibroblasts) within the blood clot degenerate and die.


• Within few days new blood vessels from the fractured ends of the bone grow into the site i.e. into the blood clot.


• These new blood vessels bring White blood cells (inflammatory cells) to the site/are. WBCs remove all non viable deal material from the site.


• Fibroblasts multiply and produce collagen fibres.





To this step collagen matrix replaces the blood clot and the reactive phase virtually ends here.




 Reparative phase.



• Osteoprogenitor cells in the periosteum, medullary cavity and surrounding soft tissue are activated.


• Activated osteoprogenitor cells stimulate osteoclatic and osteoblastic activities.


• Periosteal cells proximal to the fracture gap develop into chondroblast and produce hyaline cartilage.


• Periosteal cells distal to the fracture gap develop into osteoblasts and produce a woven bone (unmineralized bone) called callus.


• The formed hyaline cartilage and woven bone (callus) bridges the entire fracture gap, hence restoring some of it original strength.


• Endochondral ossification occurs in hyaline cartilage, and woven bone (callus) is mineralized to form a trabecular bone.





To this step trabecular bone replaces hyaline cartilage and a woven bone (callus) and the reparative phase virtually ends here.




 Remodeling phase.



• Osteoclasts reabsorb the trabecular bone, creating a shallow resorption pit known as Howship’s lacuna.


• Simultaneously osteoblasts deposit compact bone within the resorption pits.





To this step compact bone replaces trabecualr bone, this restores the normal strength of the fractured site.




 Factors affecting fracture healing.




Some of the factors that delay fracture healing include the following:




Fracture healing will depend on many factors



• Severity of the injury.


• Type of fracture.


• Vascular damage.


• Method and efficient of treatment.


• Presence of infection.


• Age of the patient.

Complications of fracture healing.