fracture process and healing Flashcards
what are the 2 ways bone can heal
primary healing (first intention) or secondary healing (second intention)
primary bone healing
this process occurs when there is a minimal fracture gal (less than 1mm) and the bone simply bridges the gap with new osteoblasts
which fractures can heal by primary bone healing
hairline fracture and when the fractures are healed with compression screws and plates
what do most fractures heal by
secondary bone healing
secondary bone healing
involves an inflammatory response with recruitment of pluropotential stem cells which can the differentiate
process of secondary bone healing
- haematoma occurs with inflammation from damaged tissue
- macrophages and osteoclasts remove debris and resorbs bone ends
- granulation tissue format from fibroblast and new blood vessels
- chondroblasts form cartilage (soft callus)
- osteoblasts lay down bone matrix (type 1 collagen) by enchondral ossification
- calcium mineralisation produces immature woven bone (hard callus)
- remodelling occurs with organisation along the lines of stress into lamellar bone
when is soft and hard callus usually formed
soft callus forms by about 2-3 weeks, hard callus takes around 6-12 weeks
requirements for secondary bone healing
- needs a good blood supply for oxygen, nutrition and stem cells
- requires a little movement or stress (compression or traction)
what can cause atrophic non-union
lack of blood supply, no movement, too big a fracture gap or tissue trapped in the fracture gap
what impairs fracture healing
smoking due to vasospasm and vascular disease, chronic disease and malnutrition
what can cause hyper-trophic non-unions
due to excessive movement at the fracture site with abundant hard callus forming but excessive movement results in there not being enough time to bridge the fracture gap
