Fractures

Osteocytes

mature bone cells

Osteoblasts

cells that rebuild bone

osteoclasts

cells that tear down bone

Wolff's law

Bones grow or remodel due to mechanical stress
1.Handedness causes increased bone thickness
2.Curved bones are thickest where most likely to buckle
3.Spongy bones remodel quickly among lines of stress
4.Projections occur where active muscles attach

Classification of Fractures

1. 1.Position bone ends after fracture
2. Completeness of the break
3. Orientation relative to long axis
4. Penetration of the skin
5. Nature of the break

Position bone ends after fracture

-Non Displaced - retain normal position
-Displaced - out of alignment

Completeness of the break

-Complete - broken through
-Incomplete - partially broken

Orientation relative to long axis

-Linear - broken parallel to long axis
-Transverse - broken perpendicular to long axis

Penetration of the skin

-Open (Compound)
-Closed (Simple)

Nature of the break

-comminuted
-compression
-depressed
-epiphyseal
-greenstick
-spiral

comminuted

bone fragments into 3 or more pieces; common in the elderly

compression

bone is crushed; common in porous bones

depressed

broken bone portion is pressed inward, typical of skull fracture

epiphyseal

epiphyseal plate tears, seperating epiphysis from diaphysis

greenstick

bone breaks incompletely, much in the way a green twig breaks. one side of the shaft splits, the other side bends

spiral

ragged break occurs when excessive twisting forces are applied to a bone
long break

hyaline cartilage

Most common type of cartilage; it is found on the ends of long bones, ribs, and nose

elastic cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage
-external ear

Fibrocartilage

Pads between vertebrae that are shock absorbers