principles of bone healing Flashcards
what are the three phases of bone healing?
- inflammatory
- restorative
- remodeling
when damage to a bone occurs what happens to induce the first stage of bone healing?
when damage to bone occurs there is lysis of osteocytes and dead soft tissue cells give off substaces that attract inflammotory celss (incl macrophages) which start to clear away the necrotic tissue - inflammatory stage starts
what is the fisrt step of the inflammatory phase when a frature occurs?
formation of a blood clot at the frature site, occurs within a couple of hours
what cells do the cleaing of the fracture site during the inflammatory phase?
phagocytes and macrophages
what is the importance of the clot formed during the inflammatory phase when a fracture occurs?
has a role in the process of neovascularisation to the fracture site
where can the clot that is formed at a fracture during the inflamatory phase be located?
within the periosteum or broken through the periosteum and around the surrounding tissues if the periosteum is broken
what is
compartment syndrome relating to the clot formed during the inflammatory phase of frature repair and what issue does it cause?
if the periosteum is broken when the clot forms it can invade the surrounding tissues and this can cause a large bleed in the muscle belly spaces which can go unoticed leading to blood loss and hypovolemic shock
what are the subdivisions of the restorative phase?
soft callus formation and hard callus formation
what is the structure of the soft callus like?
hypercellular fibrocartilaginous tissue
what is the function of the soft callus in the restorative phase?
it is elastic, but it starts to stabilise the fracture
how long does the soft callus restorative phase last?
4 day to 3 weeks
what results in the formation of a hard callus?
As the fracture is stabilised and blood supply is restored, the newly formed cartilage is progressively substituted by bone tissue by means of a process endochondral ossification (osteoblasts)
when does the formation of the hard callus begin and end?
begins 2 weeks after fracture and ends 6-12th week
what can interupt the ossification of the callus
movement of the fracture site
what occurs in the remodeling phase?
At the end of the restorative phase the ends of the bones are envoloped by a fusiform mass - callus (like a skin scar). this callus will start to remodel depending on the function of the limb and the way the facture has set (this affects the forces accross the limb)