Bone regeneration. Flashcards
what are the stages of fracture healing in cortical bone ?
stage of hematoma
stage of granulation tissue
stage of callus
stage of remodelling
stage of modelling
how long does stage of hematoma last up to ?
lasts up to 7 days
how long does stage of stage of granulation take ?
2-3 weeks
what is the granulation stage ?
angiogensisi , proliferation of fibroblasts forming granulation tissue in the space between the fracture
how long does stage of callus take ?
4-12 weeks
what is callus stage ?
the granulation tissue triggers mesenchymal stem cells to proliferate - from periosteum , medullary canal
differentiation and proliferation to osteoblasts and chondroblasts .
the osteoblasts lay down the intercellular matrix which are the collagen fibres making woven bone arranged in an irregular pattern
granulation tissue is replaced with fibrous connective and cartilage tissue
and osteoclasts starts clearing away dead bone
the intercellular matrix which soon gets imbedded with calcium salts
the stiffer the immobilisation the lesser the callus
flexible fixation will cause endochondral ossification - hypertrophic nonunion
callus formation is slower in what accounts ?
slower in adults then children
and cortical bone than cancellous bone
what is stage of remodelling ?
the callus is replaced by mature bone with typical lamellar structure
how long does stage of remodelling take ?
anything from 1 -4 years
what is the stage of modelling
the bone is gradually strengthened
shaping of the cortices
can take many years
this is driven by weight bearing stress and muscle forces
what is primary bone healing ?
where the fracture hematoma has been disturbed through intraoperative measures
the bone heals without callus formation such as compression plate
intramembranous healing- the direct laying down of bone tissue or collagen 1 tissue
what is secondary bone healing ?
fracture hematomais not disturbed the healing is with callus formation
seen in or IM , external fixation , bridging plate , cast immobilisation
enchondral healing - involves cartilage as a precursor
factors affecting fracture healing ?
age
type of bone - flat and cancellous bone heal quicker than tubular and cortical bone
fracture pattern - spiral unites faster
oblique
the transverse
open and comminuted fracture more case of delayed union and non union
interposition of tissue - where fracture ends pierce through soft tissue causing it to be in-between
vascularity to the bone
bone to bone contact with reduction
immobilisation
compression of fracture site
