Term
| What is the function of a pin in an external skeletal fixaiton system? |
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Definition
| -engages the bone to provide stabilization of fracture repair |
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Term
| What do clamps do in an external skeletal fixation system? |
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Definition
| -secure the pins to the connecting bar |
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Term
| What does the connecting bar do in an external skeletal fixation system? |
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Definition
| -connect the clamps to the pins |
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Term
| What are the two classifications of fixaiton pins based on thread location? |
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Definition
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Term
| Describe a smooth fixation pin. |
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Definition
-dec pullout strength
-inc suscpeptibility to cyclic loading and premature loosening |
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Term
| What is a threaded fixation pin with a positive profile? |
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Definition
-threads rolled onto pin shaft
-stronger |
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Term
| What is a threaded fxaiton pin with a negative profie? |
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Definition
-threads cut into pin shaft
-weaker but a tapered end gives improved strength |
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Term
| What are the different materials that connecting bars are made of? |
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Definition
-stainless steel
-carbon fiver
-aluminum
-titanium
-acrylic |
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Term
| What is a type 1A linear EST fixation? |
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Definition
| -unilateral and uniplanar |
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Term
| What is a type IB ESF type? |
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Definition
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Term
| What is a type II ESF type? |
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Definition
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Term
| What is a type III ESF type? |
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Definition
| -bilateral, biplanar Type I + Type II |
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Term
| How does frame strength relate to frame complexity regarding ESF types? |
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Definition
| -strength inc as frame complexity inc |
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Term
| For what kind of fracture would we use a hybrid ESF? |
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Definition
| -fracture that has a small fragment of bone |
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Term
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Definition
| -half pins and a ring with small fixation wires (wires replace fixation pins) |
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Term
| What is a circular ESF type? |
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Definition
| -system includes small Kirschner wires connected to rings and connecting bars |
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Term
| What kind of injuries do we use circular ESFs for? |
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Definition
-severely comminuted fractures
-angular limb dformities |
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Term
| What are the general rules for ESF placement? |
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Definition
-use threaded pins
-use largest pin size allowed by bone geometry
-use 3-4 pins per main fragment
-space pins evenly throughout the fragments
-place pins perpendicular to the long axis of bone |
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Term
| What is the concern regarding pin-bone interface? How do you maximize strength? |
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Definition
-high stress = premature loosening
-predrill the hole with slightly smaller drill bit, reduce thermal necrosis while placing pins, produce radial preload |
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Term
| Rank the pins of ESF based on pin pullout strength. |
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Definition
| -neg profile, taperes > pos profile > neg profile > regular > smooth |
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Term
| How does pin diameter relate to its biomechanical principles for ESF? |
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Definition
-stiffness is proportional to radius ^ 4
-pin is too big = bone fracture
-pin diameter should be 25% of bone diameter |
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Term
| What is the maximum number of pins that can be used per each main fracture segment? What is the logic behind paying attention to this number? |
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Definition
-maximum of 4 pins per main fracture segment
-ideal number of pins = inc stiffness and dec cyclic stress on each individual pin |
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Term
| Describe the ideal pin position for ESF. |
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Definition
-placed evenly along working segment of bone
-initial pin placed 1-2cm from joint
-pins should be no closer than pin diameter from fracture ends |
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Term
| With which bones can ESF be sued? |
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Definition
| -distal bones: radius/ulna and tibia/fibula |
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Term
| Why should ESF methods only be used on distal bones? |
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Definition
-ESF placement has safe corridors
-pin morbidity
-inc working length for pin = hihger risk of failure |
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Term
| Where is the safe corridor on the tibia for ESF? |
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Definition
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Term
| Where is the safe corridor on the femur for ESF? |
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Definition
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Term
| What is the ideal distance b/n clamp and skin? Why? |
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Definition
-1-2cm
-fixation pin stiffness dec as the distance from skin to the connecting bar increases |
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Term
| Where should ESF clamps be positioned in relation to the connecting bar? Why? |
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Definition
-inside the connecting var
-dec working length of the pin and inc stiffness |
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Term
| ESF frame stiffness inc with more complex frame type. What are the advantages of a simpler frame design? |
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Definition
-less expense
-less cumbersome frame
-more latitude for pin placement
-less operative time
-fewer frustrations for the surgeon
-fewer pin tracts = reduced morbidity |
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Term
| What are the indications for ESF? |
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Definition
-long bone fractures
-arthrodesis
-spinal solumn fixation
-mandibular fractures
-distraction osteogenesis |
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Term
| What are some of the possible complications of eSF? |
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Definition
-pin tract infection
-neurovascular injury
-pin breakage/loosening
-loss of fracture reduction
0pressure necrosis of the skin
-delayed union
-iatrogenic fracture |
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