Bones Flashcards
Cortical bone
-mostly in the shaft (diaphysis)
-dense
-stiff
Cancellous bone
-aka trabecular or spongey bone
-shock absorbing
-can compress
-mostly in the epiphysis of the bone
Osteocytes
mature bone cells
-sensing and signaling
Osteoblasts
bone builders
-secrete osteoid, collagen-based bone matrix
Osteoclasts
bone dissolvers
-cause release of calcium
Bones are…
dynamic
-mineralization and demineralization are continual
Osteoporosis
“brittle bones”
-demineralization exceeds mineralization
-common at old age
Osteomyelitis
infection in a bone
Periostitis
new bone growth (deposition) associated with irritation, trauma to an area of the periosteum
Common locations of periostitis
-between the splint bones and cannon (“splints”)
-at the insertion of tendons or ligaments (most common in lower leg/pastern)
-can also occur in response to trauma to an area
Splints
a form of periostitis
-more common on front limbs (the medial aspect)
-can be sore when it first happens
-more common in young horses
Ring bone
a form of periostitis
-new bone proliferation at the insertion of the extensor tendon
-usually on the short pastern
-common in horses that work on hard surfaces or horses that have a lot of animation
-can cause lameness if it bridges over the pastern
Types of fractures:
-open or closed
-complete or incomplete
-comminuted
-displaced or non-displaced
Open fracture
skin in broken and the bone is exposed,
increased risk of infection
Closed fracture
bone is fractured but did not break skin, much better than an open fracture
Complete fracture
in two pieces
Incomplete fracture
only cracked (not completely broken in two)
Comminuted fracture
a type of complete fracture
-bone is in many pieces or shattered
Displaced fracture
the bone fragment has moved from its original site
-the fragment can puncture the skin or damage the neurovascular bundle (if in the legs) and cause more damage
Non-displaced fracture
bone is aligned as it should be, just fractured. Better than a displaced fracture
The three phases of bone healing:
-inflammatory phase
-reparative phase
-remodeling phase
Inflammatory phase of bone healing
- hemorrhaging, clot, inflammatory cells arrive (heat, pain, swelling)
- increase blood flow
- osteoclasts arrive and will clean up bone debris in the area
Reparative phase of bone healing:
- chondrocytes and fibroblasts arrive, deposit collage to begin the formation of a soft callus (over the fracture site) – 1-2 weeks
- osteoblasts arrive and deposit osteoids, osteoids form the matrix that will be mineralized
- mineralization of osteoid begins formation of the hard callus, bone formation may occur outside the boundary of the original bone – 2-4 months
Remodeling phase of bone healing:
- may overlap with reparative phase
- osteoclasts remove excess bone mass at fracture site…returns bone to original shape (can take several months)
- bone strength can return to normal
What affects bone healing rate?
-extent and location of damage
-type of fracture (open comminuted/displaced is the worst)
-age of animal (young faster than old)
-ability to stabilize (prevent further damage and the proximity of pieces to each other)
-amount of associated soft tissue damage
Internal fixation
a type of fracture repair
-putting in screws to stabilize the bone
-sometimes screws are left in, sometimes they are taken out
What is the main goal of fracture first aid?
to prevent closed, incomplete fractures from becoming:
-open
-complete
-comminuted
-displaced