11 - bone injuries

long bone anatomy

diaphysis, epiphysis, metaphysis

growth plate

medullary canal

what is a fracture

break in the structural continuity of bone

types of bone

cortical

cancellous

why do bones fail

high energy transfer in normal bones

repetitive stress in normal bones - stress fracture

low energy transfer in abnormal bones - osteoporosis, osteomalacia, other bone disorders

what are fractures - failure of bone

mechanical and structural failure of bone

what are the 4 stages of fracture healing

inflammation

soft callus

hard callus

bone remodelling

inflammation stage 1 of fracture healing

begins immediately

- haematoma and fibrin clot

- platelets, PMN's, neutrophils, monocytes and macrophages

- by-products of cell death - lysosomal enzymes

- fibroblasts

- mesenchyymal and osteprogenitor cells - transformed endothelial cells

- angiogenesis - macrophages

soft callus stage 2 of fracture healing

begins when pain and swelling subsides

lasts until bony fragments are united by cartilage or fibrous tissue

a giant ion can still occur

replace cartilage with DMB matrix

stage 3 hard callus of fracture healing

conversion of cartilage to woven bone

typically long bone fracture

increased rigidity - obvious callus on imaging

bone remodelling stage 4 of fracture healing

conversion of woven bone to lamellar bone

medullary canal reconstituted

bone responds to loading characteristics Wolffs law

what cases delayed union

high energy injury

distraction - increased osteogenic jumping

instability

infection

steroids

immunosuppressant

NSAIDs

warfarin

ciprofloxacin

smoking

what causes non-union

failure to heal

failure of calcification fibrocartilage

instability - excessive osteoclasts

abundant callus formation

pain + tenderness

persistent fracture line

sclerosis

if there is delayed bone healing what do you need to do

consider alternative management

- different fixation

- dynamisation

- bone graft