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12 year old child with broken humerus and ulna with lactose intolerance…
12 year old child with broken humerus and ulna with lactose intolerance
Direct: fall impact
Indirect: Imbalance of protein and calcium consumption in diet
Both protein and calcium contribute to bone health
protein makes up bone matrix
makes bone flexible
calcium causes bone to be more dense
resists stress from weight of body
Downstream
fractures:
compound and communited fracture to humerus
part of humerus exposed to the outside world
immediately needs anitbiotics
surgery to irrigate the bone
during surgery; bone set and plated
longer repair time
clean and remove damaged tissue
runs risk of infection
communited bone reabsorbed by marcrophages
loss of physical bone density
bone materials reabsorbed into blood and distributed elsewhere
eventually bone remodeled
Child is still developing
presence of epiphyseal plate
if fracture occured at epiphyseal plate
Chondrocytes trapped in fibrocartilaginous matrix
bone and cartilage created to stabilize break
results in cartilage being replaced by bone
bone doesn't continue growing in length
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poor diet
junk foods lack nutritional value
protein
collagen fibers
make up bone matrix
osteoid
minerals
hydroxyapetite
calcium
bone density
phosphate
bone density
Background
Long bone
cells
osteoclast
located in trabecula
shave down bone
located in periosteum or endosteum
osteoblasts
build up bone
osteocytes
mature osteoblast
located in lacuna of osteon
control ostoblast and osteoclast
located in matrix of trabecula
osteogenic
stem cells
mature to be osteoblast
located in periosteum and marrow
osteon
parallel to to diaphysis
Central (Haversian Canal)
1 artery
1 vein
nerve
Lamella
rings of osteon
collagen fibers; single direction
multiple rings; different directions
resist torsional stress
Osteocytes
located in small spaces of lamella
lacunae
monitors the bone matrix
mineral composition
calcium and phosphate stores
canaliculi
connect from lamella to central canal
connect to the osteocytes
provide:
blood supply
nutrients from blood
exchange of waste
minerals
Perforating (Volkman) Canal
perpendicular to central canal
osteon to osteon
blood supple
nerves
Spongy Bone
trabeculae
along lines of stress
network makes bone lighter
for muscle contraction
no lacunae for osteocytes to connect to
dispersed capillaries provide blood supply
red marrow in these spaces
Medullary caviaty
center of diaphysis
hollow cavity
formed by ostocalsts
in children:
filled with red marrow
in adults:
filled with yellow marrow
Ossification
Intramembranous ossification
1) Ossification centers develop
mesenchymal cells
osteogenic cells
osteoblast
osteoblast cluster together
ossification center
2) Secretion of osteoid
osteoblasts secrete osteoid
osteoid calcifies
some osteoblasts trapped
osteoblast --> osteocytes
3) spongy bone and periostieum forms
osteoid layed around capillaries
trabeculae formed
mesenchyme condenses to form periosteum
4) Compact bone replaces immature spongy bone
deep immature spongy bone remodeled to compact bone
the spongy bone deeper is matured through remodeling
capillaries disperse into red bone marrow
Endochondral Ossification
1) Cartilage model
blueprint for future bony skeleton
hyaline cartilage makes of diaphysis of bone
epiphysis and diaphysis are separate
perichondrium forms
2) Formation of the Primary ossification center
capillaries penetrate perichondrium
periosteum forms from periochondrium
cartilage
3) Cartilage continues growth at ends of bone
Chondrocytes rapidly multiply
bone length increases
POC located in diaphysis
4) Secondary Ossification center develops
at epiphysis side; cartilage grows
at diaphysis side; bone grows
Epiphyseal plate zones
Proliferative zone
mitosis
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Hypertrophic zone
chondrocytes mature
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Calcification zone
mostly dead chondrocytes
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Ossification zone
osteoblast secrete bone tissue on cartilage
function of epiphyseal plate
longitudinal growth
SOC located at epiphysis
5) the epiphysis hardens
chondrocytes in epiphyseal plate get trapped by osteoblast
bone is finished growing
all that is left is an epiphyseal line
Fractures
Compound
pierce through epithelial layers
longer healing time
Simple
fragments stay within body cavity
Pathological
bone weakened by disease
Stress
mechanical stress
increased physical activity
Types of fractures
Complete
through and through
Incomplete
not broken through
Comminuted
broken in more than 2 pieces
Greenstick
splintering
Fissured
incomplete longitudinal break
Spiral
break from twisting action
Bone fracture repair
1)Fracture Hematoma
hematoma formation
torn blood vessels
the blood clots
2) Fibrocartilaginous callus
callus formation
chondrocytes of periosteum and endosteum
secrete fibrocartilaginous matrix
create hyaline cartilage and bone around break
stabilize break
3)Cartilage replaced
osteoclast resorb dead bone
osteogenic cells activated
divide to become osteoblast
adjacent osteoblast produce trabeculae
commence endochondral ossification
4) Remodeling
trabecular bone replaced
compact bone takes place
Bone Composition
Organic
Collagen fibers
make up 90% of bone matrix
gives bone tensile strength
provides surface for inorganic crystals
is a protein
Inorganic
Hydroxyapatite
salt crystals
Calcium
makes bone denser
Vitamin D is needed to absorb calcium
Phosphate
bone density
<---Compact bone