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66 Cards in this Set
- Front
- Back
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What type of bone is this?
- randomly oriented collagen fibers - weak bone - appears in fetus, site of fracute, and pathological conditions |
woven bone
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What type of bone is this?
- collagen arranged in parallel layers - strong bone - appears in adults |
lamellar bone
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Name the two types of lamellar bone.
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- cortical (compact)
- cancellous (spongy) |
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Which of the following occurs at site of fracture?
- cutting cones - intramembranous bone formation - endochondral bone formation - all the above |
- all the above
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Which type of cells are at the front of a cutting cone, which type of cells follows during bone repair?
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- in the front: osteoclasts removing bone
- follows: osteoblasts laying down new bone |
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What are the prerequites for bone healing?
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1. adequate blood supply
- nutrient artery (intramedullary) - periosteal vessels - metaphyseal vessels 2. adequate mechanical stability |
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Which blood vessels supply long bones?
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- nutrient artery (intramedullary): supply diaphyseal cortex
- periosteal vessels: supply outer cortex, important souce of blood supply in fracured bone. - metaphyseal vessels |
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Which is the parental vessel of the capillary buds that forms during bone repair?
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periosteal vessels
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Why do orthopedic surgeons reluctant to strip the periosteum layer during fracture surgeries?
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Try to reserve as much periosteum as possible because periosteal vessels are the major blood supply during bone repair.
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When does blood flow peak in fracture repari?
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at 2 wks after fracture
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T/F: Fracture stimulates the release of growth hormone that promote angiogenesis and vasodilation.
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T.
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T/F: Patients should limit activity for a long time after fracture to provide mechanical stability to promote bone repair.
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F.
- True for the first month - after that, loading and motion stimulate healing. |
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What happens if there is inadequate mechanical stability after bone fracture?
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Hypertrophic nonunion: excessive deformation at fracture site interrupting tissue differentiation to bone
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What happens if there is over-stabilition after bone fracture?
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Atrophic nonunion
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Atrophic nonunion is caused by ___ whereas hypertrophic nonunion is caused by ___.
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Atrophic nonunion is caused by overstabilizaiton/infection whereas hypertrophic nonunion is caused by inadequate stabilization.
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What are the three stages of fracture healing?
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1. inflammation
2. repair 3. remodeling |
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Stages of fracture healing: inflammation
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- hematoma under periosteum between bone ends: provide fibrin scafold for migration of repair cells
- local vessel thrombose -> bony necrosis - increase capillary permeability -> swollen - growth factors stimulate proliferation and differentiation of mesenchymal cells from periostium and peripheral blood. |
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Stages of fracture healing: repair
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fibroblasts and chondrocytes produce callus (matrix)
- periosteal(hard) callus: intramembranous ossification - intramedullary(soft) callus: endochondral ossification |
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Stages of fracture healing: repair
Which type of callus is formed by intramembranous ossificatiion? |
periosteal(hard) callus
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Stages of fracture healing: repair
Which type of callus is formed by endochondral ossificatiion? |
intramedullary(soft) callus
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When is a fractured patient considered clinically healed?
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When patient has no pain at the fracture site
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Stages of fracture healing: remodeling
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- woven bone converted to lamellar bone
- unneeded callus removed - reconstiturte medullary cavity - bone reconstructed in response to stress (convex surface is electropositive and has osteoclast activity, concave surface is electronegative and has osteoblast activity) and strain (Wolff's law). |
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What is Wolff's law?
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Bone in a healthy person will adapt to the loads it is placed under. If loading on a particular bone increases, the bone will remodel itself over time to become stronger.The external cortical portion of the bone becomes thicker as a result.
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Convex or concave surface?
electropositive |
convex
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Convex or concave surface?
electronegative |
concave
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Convex or concave surface?
osteoclast activity |
convex
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Convex or concave surface?
osteoblast activity |
concave
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Which mechanism of bone healing is this?
- no motion at the frature site: rigid internal fixation - do not form fracture callus - cutting cone formed at fracture site - osteoblast lay down lamellar bone forming secondary osteon - slow process |
direct bone healing
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Which mechanism of bone healing is this?
- contact healing - gap healing (<200-500 microns) |
direct bone healing
- contact healing: lamellar bone formed directly - gap healing (<200-500 microns): woven bone first then remodeled to lamellar bone. |
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Which mechanism of bone healing is this?
- gap healing (large gaps) |
indirect bone healing:
- bridging periosteal callus - medullary callus - endochndral osification - rapid |
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Which mechanism of bone healing is this?
- bridging periosteal callus - medullary callus - endochndral osification - rapid |
indirect bone healing
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Describe indirect bone healing.
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- bridging periosteal callus
- medullary callus - endochndral osification - rapid |
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Bone healing is locally regulated by which 4 types of molecules?
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1. growth factors
- TGF - BMP:1,2,3,7 - FGF:1,2 - PDGF - IGF 2. cytokines - IL1,4,6,11: bone resorption - GM-CSF - TNF: bone resorption 3. PGEs/LTs 4. Hormones - estrogen - thyroid hormone - glucocorticoids |
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Describe the effect of this on bone healing.
TGF |
- promote proliferation and differentiation of mesenchymal precursors to osteoblasts and osteoclasts
- stimulate both intramembranous and endochondral bone formation |
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How does TGF stimulate endochondral bone formation?
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- induce synthesis of cartilage-specific proteoglycans and type II collagen
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How does TGF stimulate intramembranous bone formation?
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- stimulate collagen synthesis by osteoblasts
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Which of the following BMP induce cell differentiation?
- BMP1 - BMP2 - BMP3 - BMP7 |
- BMP3: not clinically used yet
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Which of the following BMP promote endochondral ossification?
- BMP1 - BMP2 - BMP3 - BMP7 |
- BMP2
- BMP7 |
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Which of the following BMP regulate ECM production?
- BMP1 - BMP2 - BMP3 - BMP7 |
- BMP1: cleaves procollagens I, II, III
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Which of the following BMP cleaves procollagens I, II, III?
- BMP1 - BMP2 - BMP3 - BMP7 |
- BMP1
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T/F: BMP can be issolated from demineralized bone matrix.
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T.
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What are some effects of FGF on bone healing?
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- increase proliferation of chondrocytes and osteoblasts
- enhance callus formation - FGF2 stimulate angiogenesis |
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Which FGF induces angiogenesis?
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FGF2
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What is this factor that regulates bone healing?
- increase proliferation of chondrocytes and osteoblasts - enhance callus formation |
FGF
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What are the role of PDGF in bone healing?
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- stimulate bone cell growth
- increase type I collagen synthesis by osteoblasts - PDGF-BB stimulate bone resorption by osteoclasts |
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What are the 2 predominant PDGF in circulation?
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- PDGF-AB
- PDGF-BB |
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What is this factor that regulates bone healing?
- proliferation and stimulation of osteoblasts, osteoclasts, and chondrocytes |
TGF
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What is this factor that regulates bone healing?
- proliferation and of osteoblasts and chondrocytes |
FGF
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What is this factor that regulates bone healing?
- proliferation of osteoblasts and osteoclasts. |
PDGF
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What are the effects of IGF on bone healing process?
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- stimulate collagen and matrix synthesis
- stimulate replication of osteoblasts - inhibits collagen degradation |
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What is this factor that regulates bone healing?
- proliferation of osteoclasts. - synthesis of collagen - inhibit collagen degradation |
IGF
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Which factor stimulate IGF1 production in the liver?
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GH
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Which cytokine is the most potent stimulator of bone resorption?
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IL1
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Which hormone suppresses IL1 and IL6 synthesis?
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estrogen
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What are the effects of PGE on bone healing process?
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- stimulate osteoblastic bone formation
- inhibit isolated osteoclasts' activity |
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What are the effects of LT on bone healing process?
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- stimulate osteoblastic bone formation
- enhance osteoclasts' capacity to form resorption pits |
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Which molecule stimulate osteoblast to form bone while inhibit osteoclasts activity?
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PGE
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How does estrogen stimulate fracture healing?
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- modulate release of specific IL-1 inhibitor
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Which thyroid hormones stimulate osteoclast bone resorption?
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Thyroxine (T4)
Triiodothyronine (T3) |
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What are the effects of glucocorticoids on bone healing?
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- inhibit Ca2+ absorption from gut -> increase PTH -> more bone resorption
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Some local factors that influence fracture healing. (4)
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- soft tissue injury
- interuption of local blood supply - interposed soft tissue at frature site - radiation, thermal/chemical burns, infection |
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Some systemic factors that influence fracture healing. (3)
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- malnutrition: reduced proliferation and activiy of osteochondroblasts, decreased callus formation
- smoking: inhibits osteoblasts, vasocontriction - diabetes mellitus: collagen defects ( decreased content, defective crosslinking, alterations in subtype ratios). |
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How does malnutrition affect fracture healing?
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- reduced proliferation and activiy of osteochondroblasts
- decreased callus formation |
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How does smoking affect fracture healing?
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- inhibits osteoblasts
- vasocontriction: loss of blood supply |
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How does DM(diabetes mellitus) affect fracture healing?
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collagen defects
- decreased content - defective crosslinking - alterations in subtype ratios). |
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Which FDA-approved precedure demonstrated benefit in stimulating healing of fresh fractures?
- decreased healing time (even in smokers) |
Low-intensity Ultrasound:
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