Bones Flashcards
What are the two bone membranes
Periosteum (outer membrane)
Endosteum (inner membrane )
Both contain fibroblasts in a collagen matrix which is a source of bone cell for growth and repair
What is the outer and inner layer of bone called
Outer - lamellar bone (compact)
Inner- trabecular bone (spongey)
What are the 3 bones cells and what do they do
Osteoblasts (immature cells)- lay down bone by producing osteoid (type 1 collagen) which is then mineralised
Osteocytes ( mature cells) needed for maintenance and calcium homeostasis
Osteoclasts - related to macrophages and dissolve bone
Theory behind Wolfs Law
Bone is a crystal which when bent quickly it generates a current. Osteocytes detect this and lay down new bone where it is compressed and removed bone where it is under tension.
During fracture healing slight cyclic loading should be carried out to allow the bone to get stronger
What are the 4 key factors needed for good fracture healing
Good Blood flow
Intact nerve supply
Stability of bone
Slight movement (wolfs law)
What is inflammation of the bone called
Osteitis
Describe the process of bone growth in 5 steps
Cartilage cells in the epiphysis multiply and form long columns
Chondrocytes gradually accumulate calcium
Surrounding matrix calcifies the chondrocytes die
Osteoblasts come along, some remain in the periosteal to line the bone whilst others transition into osteocytes
Osteoclasts absorb the bone which is already laid down leaving pits which allow the osteocytes to reconstruct new bone
Why is over work stress negative thing during fracture healing
Bone removal is quicker than bone deposition
Meaning bone strength declines and stress fractures wiill occur
What is it called when only the periosteum is damaged
Periostitis
Name 5 bone shapes
Long -limbs
Flat - skull
Cuboid - tarsus
Irregular - vertebrae
Sesamoid - patella
What are the 4 main bloody supply to bones
Epiphyses arteries
Metaphyseal arteries
Nutrient artery
Periosteal arteries
What is sequestrum
Bone fragments which loose blood supply and die
Why is over work stress a negative thing during fracture healing
Bone removal is quicker than bone deposition meaning bone strength declines and stress fractures will occur if further pressure is put on the bone
What are the 3 phases id fracture healing
Reactive
- damaged blood vessels bleed and form a clot
- osteocytes along the fracture line due
-fibroblasts multiply and infiltrate the clot and produce collagen
Repair phase
- fibroblasts change into chindroblasts and start to product hyaline cartilage (type 2 collagen) to bridge the gap
- osteoblasts mineralise the cartilage to form a callus
Remodelling phase
- hyaline cartolage is removed as normal patron grow into the callus
- first proper bone is woven and gradually replaced by lamellar in the cortex and trabecular in the medulla
List of fracture types (9)
Greenstick
Simple
Oblique
Spiral
Comminuted
Compressed
Longitudinal
Multiply
Articulate
