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102 Cards in this Set
- Front
- Back
- 3rd side (hint)
What are the 2 macroscopic bone types?
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1) Cortical bone= compact bone
2) Cancellous bone= trabecullar bone |
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What bone is cortical (compact) bone?
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In the shaft of the long bones
"cortex" - outer dense layer |
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Cortical bone is made up of _____ bone.
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Lamellar bone - bone is layed down layer by layer, can remodel in a dramatic fashion when force is applied
-cancellous is lamellar too |
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Where is cancellous bone located?
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-In center and ends of long bones
-flat bones |
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What are 2 microscopic types of bones?
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1) Woven
2) Lamellar |
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When is woven bone laid down?
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Occurs during rapid growth, rapid bone repair process, insertions of tendons/ligaments
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What is woven bone?
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Connective tissue stiffened by incorporation of mineral
-bundles of collagen fibers arranged similar to other CTs |
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Compare the mechanical properties of woven and lamellar bone.
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Woven bone is inferior to lamellar bone
-woven bone is usually remodeled to become lamellar bone (long bones, fractures) |
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______ is the major portion of cortical and cancellous bone.
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Lamellar
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What is the rate of lamellar bone growth on a per day basis in optimal conditions?
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****Osteoblats form1-2 um of lamellar bone per day
-slower rate of formation -deposited layer by layer |
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Osteoblasts lay down lamellar bone then remodel to form ______.
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Tunnels w/in bone- haversian systems/ secondary osteons
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What is the outer fibrous layer covering bones (other than where bone is covered by articular cartilage?
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Periosteum
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What layer of bone is responsible for remodeling/ regeneration?
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Periosteum- its the inner osteogenic layer
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What provides blood supply to bone? (3) What does the blood flow in?
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1) Branches from periosteum
2) Branches from endosteum 3) Nutrient foramen (long bones) -In: Medullary cavity, haversian canals, Volkmann's canals |
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What 3 cell types are present in bone?
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Osteocytes
Osteoblasts Osteoclasts |
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What are the 4 components of bone?
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1) Cells
2) Organic matrix (21% of wet weight) 3) Inorganic part of matrix (71% of wet weight) 4) Water (8% wet wt.) |
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What is the organic matrix comprised of?
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Osteoid: 90% type I collagen, 10% non-collagens (osteonectin, osteocalcin, proteoglycans)
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What makes the organic matrix of bone? What degrades it?
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Osteoblasts make it
Osteoclasts degrade it |
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What is the organic matrix of bone comprised of?
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Hydroxyapatite (Ca, P)
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What governs the inorganic matrix? degrades it?
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Governed by osteocytes
Degraded by osteoclasts |
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What are the 2 types of developmental bone formation?
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1) Membranous bone formation
2) Endochondral bone formation |
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What is membranous bone formation?
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Ossification by direct mineral deposition into organic matrix of mesenchymal CT
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What bone is formed by membranous bone formation?
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Skull, mandible, appositional growth of all bones
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What is endochondral bone formation?
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Cartilaginous template formed first, then transformed via calcification and replacement by bone
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What are 2 types of bone growth that utilizes endochondral bone formation?
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1) Longitudinal growth of long bones (growth plates)
2) Centrifugal growth of epiphyses |
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What are 3 types of growth cartilage?
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1) Discoid growth plate
-longidtudinal growth 2) Spherical growth plate -centrifugal growth 3) Apophysis -traction epiphysis |
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Where are discoid growth plates located?
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End of long bones (metaphyseal growth plate)
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Where are spherical growth plates located?
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-Cuboidal bones of carpus, tarsus
-epiphysis |
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What are 3 locations of apophyses?
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olecranon process, calcaneal tuber, tibial tuberosity
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What are the 5 zones of growth cartilage?
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1) Resting or reserve
2) Proliferative 3) Hypertrophic 4) Calcified cartilage 5) Primary spongiosa of bone (replaces calcified cartilage) |
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What is Wolff's Law?
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Bone adapts to the loads that are placed on it
-bone mass is increased where more bone is needed |
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What is the yield load of a load deformation curve?
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Place where the load placed on the bone suddenly results in a lot more deformation- where levels off on graphs, bad thing
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When examining a load deformation curve, what part is the stiffness?
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Slope of the straight portion of the graph
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What are the 3 factors that can be interpreted from a load deformation curve?
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Stiffness
Yield load Ultimate failure load |
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Stress is approximately equal to -_______.
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Load
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Strain is approximately equal to _______.
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Deformation
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What are the 2 regions of a stress-strain curve?
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Elastic region: lots of stress w/ little increase in strain
Plastic region: Increase in strain with little stress |
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What are the 5 normal loads placed on a bone?
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1) bending
2) Torsion 3) shear 4) Tension 5) compression |
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What are the 5 loading modes of bone?
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1) Tensile
2) compressive 3) bending 4) torsion 5) shear |
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Stress is approximately equal to -_______.
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Load
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Strain is approximately equal to _______.
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Deformation
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What are the 2 regions of a stress-strain curve?
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Elastic region: lots of stress w/ little increase in strain
Plastic region: Increase in strain with little stress |
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What are the 5 normal loads placed on a bone?
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1) bending
2) Torsion 3) shear 4) Tension 5) compression |
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What are the 5 loading modes of bone?
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1) Tensile
2) compressive 3) bending 4) torsion 5) shear |
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What are 2 ways fractures can result?
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Single ultimate failure load
Repeated cyclic loading |
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What are 3 ways repeated cyclic loading can cause fractures?
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1) Fatigue fracture
2) Site specific 2) Histologic evidence: microdamage |
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What are 2 specific sites that are prone to fracture?
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Dorsal cortical metacarpal fracture
Distal metacarpal condylar fracture |
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What are the 2 types of bone healing?
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1) Primary/ direct fracture healing
2) Secondary/ indirect fracture healing |
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What fractures will heal by primary/ direct fracture healing?
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Rigid internal fixation, adequate reduction, sufficient blood supply
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When bone heals via primary healing the fracture ends unite via ________.
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Haversiain remodeling
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When does secondary/ indirect fracture healing occur?
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Small movement in fracture gaps
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When bone heals via primary healing the fracture ends unite via ________.
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Haversiain remodeling
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What is secondary/ indirect fracture healing?
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Fracture heals via periosteal, intercortical and endosteal callus formation= endochondral ossification
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When does secondary/ indirect fracture healing occur?
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Small movement in fracture gaps
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What are the 7 events that occur during secondary/ indirect fracture healing?
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1) hematoma-->
2) granulation tissue---> 3) Fibrous tissue---> 4) Fibrocartilage--> 5) Mineralized---> 6) Woven bone---> 7) Lamellar bone |
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What is secondary/ indirect fracture healing?
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Fracture heals via periosteal, intercortical and endosteal callus formation= endochondral ossification
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What are the 7 events that occur during secondary/ indirect fracture healing?
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1) hematoma-->
2) granulation tissue---> 3) Fibrous tissue---> 4) Fibrocartilage--> 5) Mineralized---> 6) Woven bone---> 7) Lamellar bone |
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What are the 2 types of interfragmentary strain?
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1) Elongation
2) Bending |
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How much elongation can granulation tolerate? Cartilage? bone?
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Granulation tissue: 100%
Cartilage: 10-15% Bone: 2% - can't tolerate much elongation before it fails |
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What degree of bending can granulation tissue tolerate? Cartilage? Bone?
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Granulation tissue: 40 degrees
Cartilage: 5 degrees Bone: 0.5 degrees *Little tolerance to bending when healing |
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What are the 3 phases of bone healing?
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1) Inflammatory phase
2) Reparative phase 3) Remodeling phase |
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What happens during the inflammatory phase of bone healing?
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- vasodilation, leukocyte migration, chemotaxis
-mesenchymal cell proliferation, angiogenesis |
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When does the inflammatory phase of bone healing occur?
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2-3 weeks post injury
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What happens during the reparative phase of bone healing?
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-Repair tissue highly vulnerable to interfragmentary motion
-periosteal & endosteal callus formation by endochondral and membranous ossification |
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How long is the reparative phase of bone healing?
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2-12 months
-overlaps with inflammatory phase |
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What occurs during the remodeling phase of bone healing?
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Osteonal remodeling
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The remodeling phase overlaps with the ______ phase.
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Reparative phase
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When is it normal for the fracture gap to widen, as determined via radiographs?
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2-3 weeks post injury
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How can you determine the amount of interfragmentary motion of a bone via radiographs?
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Size of callus
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True or false. The size of the callus may predict the degree of fracture stability.
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False, size of callus may NOT predict degree of fracture stability
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How does complete healing of bone appear on a radiograph?
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Bridging of bone & remodeling of the callus
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What are the 4 ultimate goals of bone healing?
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1) Reconstruction of original cortices
2) Early return of total limb function 3) Rapid bone union 4) Prevention of fracture disease |
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What are 6 ways that bone healing can predispose the bone to fracture disease?
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1) Soft tissue contracture
2) Loss of muscle 3) Osteopenia 4) Loss of joint function- prevent OA 5) Contralateral limb disease -breakdown or laminitis 6) Malunion / nonunion |
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What type of bone healing is most desirable?
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Primary fracture healing by Haversian remodeling rather than secondary healing by callus formation
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What are 3 ways to try and provide the right circumstances for primary healing?
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1) Rigid fixation
2) Adequate reduction 3) Preservation of blood supply |
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What are 4 advantages of the biologic effect of plating?
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1) Direct bone union if fracture compression
2) Stress protection 3) Rigid fixation 4) Adequate reduction |
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What is the disadvantage of the biologic effects of plating?
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Disrupt periosteum & fracture hematoma to apply
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What are the 3 types of bone plating techniques?
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1) Compression
2) Neutralization 3) Buttress |
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**What are the properties of compression bone plates?
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-tension band (on tension surface of bone)
-Pre-stressing (overbending) -Load sharing |
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**What are the properties of neutralizing bone plates?
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- protect the repair
- medial buttress intact |
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**What are the properties of buttress bone plates?
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- no load sharing
-Acts as a splint or bridge to maintain length of limb - no holes in bridge |
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What are the 2 ways to preserve blood supply?
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1) Preserve Periosteum
2) Preserve soft tissue attachments |
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What are the 2 components of biologic osteosynthesis?
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Closed reduction & external fixator
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What are 3 advantages to biologic osteosynthesis?
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1) Encourage early callus growth (indirect union) to move load from implant to bone
2) Emphasize preservation of blood supply over anatomic reconstruction- "spatial alignment" 3) Provide for early dynamization to stimulate callus growth |
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Why is biologic osteosynthesis difficult in horses?
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Large biomechanical often dictates fixation technique (i.e. plating)
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Dynamization is only possible in _____ animals.
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Smaller animals
-Often happening inadvertently in horses |
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What is dynamization?
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Strategic reduction in rigidity of fixation to allow for MICROmotion of fracture ends
-stimulates vascular and callus growth by interfragmentary micromotion -has ability to adjust degree of fixation to enable dynamization |
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________ allows for stages removal when using dynamization therapy.
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External skeletal fixator
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What are the 3 main functions of bone grafts & replacements?
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1) Osteogenesis
- by fresh osteoblasts 2) Osteoinduction -growth factors, cytokines 3) Osteoconduction -matrix scaffold |
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What are the 4 types of bone grafts and replacements?
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1) Autogenous fresh cancellous bone grafts
-tuber coxae, sternum 2) Cortical bone (less common) 3) Bone replacements (osteoconductive only) -Hydroxyapatite, tricalcium phosphate 4) Growth factors -bone morphogenetic protein-2 (BMP-2) |
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What is a type I open fracture?
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Small skin laceration without bone exposure, no gross contamination
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What is a type II open fracture?
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Skin laceration w/ little tissue loss, minimally exposed bone, minimal gross contamination
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What is a type III open fracture?
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Extensive laceration, significant tissue loss, extensive gross contamination
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What are the different configurations for fractures?
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-fissure/hairline/greenstick
-transverse, oblique, spiral, comminuted/compound, avulsion |
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Give some examples of a fracture location?
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Diaphyseal, metaphyseal, physeal, epiphyseal
-intra-articular |
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What are the 5 components to fracture classification?
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1) Complete vs incomplete
2) Displaced vs non-displaced 3) Open vs closed 4) Configuration 5) Location |
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What is a type I salter harris fracture?
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Complete separation of the physis
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What is a type II salter harris fracture?
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Physeal fractures breaks out in metaphysis
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what is a type III salter harris fracture?
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Intra-articular fracture through epiphysis and physis
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What is a type IV salter harris fracture?
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Intra-articular fracture extending through epiphysis, physis, and metaphysis
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What is a type V salter harris fracture?
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Crushing injury leading to closure of physis in limited area
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What is a type VI salter harris fracture?
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periosteal bridge between metaphysis and epiphysis slows growth on affected side?
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