 skeleton – bone and cartilage  embryos: hyaline cartilage  young children: most replaced by bone  bridge of nose, parts of ribs, joints = still cartilage  ossification – bone formation  lose hyaline cartilage  keep articular cartilage

 allows for normal proportions and strength during long bone growth  response to  calcium levels in blood  removal or deposit of calcium in/from bones  pull on bones from gravity and muscles  build bone strength through stress  atrophy – loss due to lack of stress  rickets – bones of children fail to calcify

 Young bones break from trauma.  Older bones break due to thinning and weakening.

 simple  clean break  no skin penetration

 compound  broken ends protrude through soft tissue and skin  also called open fracture  big risk of infection

 comminuted  many small pieces  common in elderly  compression  crushed bone  pressed inward (skull fracture)

 impacted  broken ends forced onto each other (hip or wrist)

 spiral  twisting break (sports)  greenstick  incomplete break

 reduction = realignment of broken ends  closed reduction= rejoined without surgery  open reduction = surgery using pins and wires  immobilized for 6 to 8 weeks

 hematoma  fibrocartilage callus  granulation tissue – cartilage, matrix, collagen  closes gap in bone  bony callus  replaces fibrocartilage callus  remodeled due to stress on fracture site  “Patches” fracture over several months.