Flashcards in Bone Pathology Deck (39):
What goes inside a Haversian Canal?
and Connective Tissues
What is the mature form of woven bone called and how are they different?
-->Collagen runs in the same direction
Where is the house of the osteocytes?
Lacunae in between lamellae of bone in the Haversian Canal
How are the osteocytes communicated with each other?
Via the canaliculae
one of the main functions of osteocytes is?
Mechanic Transduction and remodelling of bone depending on where the stress is coming from
Which bone cell has a perinuclear hof?
in order for the monocyte/granulocyte cell lineage to differentiate into osteoclasts what 2 molecules are needed?
what is the function of osteoprotegrin? what secretes it?
binding to RANKL in order to inhibit it from binding onto RANK on the osteoclast
Produced by osteoblast
how does PTH increases osteoclast activity?
binds to the osteoblast to induce RANKL and decrease release of osteoprotegrin
besides the osteoid what else does osteoblast produce?
Vesicles containing Alkaline Phosphatase (takes phosphate groups from anything nearby causing deposition)
What is Stronger Hydroxyapatite or Fluoroapatite
Disruptions in the integrity of living bone
What are the 2 main types of fractures?
(displaced, open=compound, closed=simple, comminuted)
Incomplete --> Greenstick (more common in children)
What is a comminuted fracture?
where there are more than 2 fragments after the fracture
What is a Colles Fracture?
Displaced Fracture when there is a fall onto an outstretched hand (FOOSH [fall onto out-stretched hand])
Spiral Fractures are fast to heal because...
there are several points of contact
Butterfly Fractures --> 2 sites of fracture in V shape close to each other
what is a mounted fracture?
colloquial term --> Displaced, comminuted & compound fractures
Stress Fractures are...
fractures caused by repeated low force injury to normal bone (can happen when a fatty goes running for the first time)
Pathological fractures are...
fractures caused by a reasonable amount of force breaking abnormal bone
What are the 4 phases of fracture healing?
Reparative Phase (/ into Soft Callus and Hard Callus)
Describe the inflammatory phase of bone healing
haematoma and formation of blood clot (fibrin mesh creates a framework). Release of pro inflammatory cytokines. Some necrosis
Formation of Granulation Tissue
Happens during the first few days
Describe the soft callus phase of bone healing
there is formation of chondrocytes from migration of osteoprogenitor cells from the endosteum and periosteum
periosteum starts repairing itself and new vessels start invading the tissue
(Repairing from the outside in, days to weeks)
Describe the hard callus phase of bone healing
osteoid deposition after endochondral ossification thanks to the osteoblasts releasing alkaline phosphatase
FORMATION OF WOVEN BONE
--> thicker than the original but not as strong
weeks to months
Describe the remodelling phase of bone healing
woven bone is transformed into lamellar bone along the lines of stress
formation of Haversian Systems
years to happen
if the ends of the fractured bone are closer together, healing will be faster because there is no need for the formation of a Soft Callus T/F. Instead of that what type of ossification occurs
What is the goal of clinical treatment of a fracture?
Reduction and Fixation
R= put closer together
F= hold them still
Open Fractures with Poor Blood Supply include intracapsular fractures T/F
T no periosteum
What is known as a NON-UNION?
fracture that does not heal with persisting primary management
a pathologic condition in which failure of callus formation following pathologic fracture through an area of deossification in a weight-bearing long bone results in formation of a false joint. cells similar to synoviocytes appear at the site
What is a delayed union?
Fracture that is taking longer than expected to heal
upper limb 6-8 week
lower limb double that
Add 25% if femur or non-spiral
What is Mal-Union?
Healing of a bone in an unacceptable position
What is osteonecrosis?
Death of bone due to disruption of blood supply.
Can happen with the head of the femur if the fracture is above the neck (this is where the blood supply comes into the bone)
From what age does bone reabsorption overcomes deposition?
What is osteoporosis?
loss of trabecular bone
Paget's Disease/Osteitis Deformans is caused because there is
Large, overactive osteoclasts with osteoblasts producing more bone
(Formation of giant osteoclasts up to 100s of nuclei, followed by osteoblasts)
Cement lines a diagnostic factor (boundary between osteons)
What do rickets and osteomalacia have in common?
lack of vitamin D causes impaired mineralisation with increased osteiod production
Bone reabsorption by increased expression of RANKL and decreased production of osteoprotegerin (OPG)
(note intermittent doses of PTH induce osteoblasts only)
bony mets affect bone in which ways?
production of molecules that interact with bone cells.
Cytokines and growth factors