6: Delayed Union/Nonunion - Drown Flashcards Preview

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Flashcards in 6: Delayed Union/Nonunion - Drown Deck (19)
1

3 main blood supplies to adult long bone

- principal nutrient a (penetrates cortex direct to medullary canal, main supply to diaphysis)
- metaphyseal-epiphyseal a (penetrate corteca t both metaphyssi, anastomose with medullary aa)
- periosteal a (supply outer 1/4 to 1/3 boen)

2

inflammatory phase of secondary fracture healing

- immediately post injury
- hematoma forms
- mast cells, PMNs, macrophages, lysosomal enzymes present
- pain and swelling occurs to splint area and to immoilize fracture site
- 3-4 d

3

proliferative phase of secondary fracture healing

- fibrin scaffold provided durign inflammatory phase replaced with emsenchymal cells producing granulation tissue
- callus begins as islands of cartilage and osteoid in granulation tissue
- 7-10 d chondrocytes produce matrix spanning fx site allowing stabilization
- cartilage replaced by bone during enchondral ossification

4

remodeling phase of secondary fracture healing

- after fx bridged
- osteoclastic resorption of woven bone and replaced with lamellar bone

5

why phase is skipped with primary bone healing?

fibrocartilagnious callus phase
- heals through haversian remodeling and cutting cones (leading tips of osteoclasts tha phagocytose osteoid at end of haversian canals)

6

non-anatomical alignment at fracture stie

malunion

ex: angulation, shortening, rotation, translation
tx: none -> surgical itnervention

7

any fx not healed in reasonable period of time

delayed union

8

radiographic findings delayed union

- serial radiographs show unchanged irritation callus, persistance of fracture cleft
- also see persistent edema dn pain

9

tx delayed union

- NWB and immobilization
- electrical bone growth stimulation

10

nonunion = failure to achieve stable fx healing after ____ of tx

8-9 months

11

reasons for non-union

- distraction
- poor reduction
- soft tissue interposition
- infection
- vascular compromise
- excessive motion at fx site

12

3 types of viable non-unions

- hypertrophic "elephant foot"
- slightly hypertrophic "horses foot"
- oligotrophic (no callus formation, bone scan says vascular bone ends)

13

contraindications electrical bone stimulation

- gap greater than 1/2 diameter of bone involved
- pseudoarthritis
- isolated malunion
- isolated usage in pathological fx due to tumor or infection

14

4 types non-viable nonunion

- dystrophic (torsional wedge - only one side good)
- necrotic (comminuted fracture)
- defect (gap present)
- atrophic (end result)

all considered avascular

15

indications for bone grafting

- delayed union
- non-union
- pseudo arthroses
- osseous defect left after taruma, infection, tumor
- arthrodesis of jts
- congenital defect

16

osteogenesis v osteoconduction v osteoinduction of bone grafts

- formation of new bone by living cells in autografts
- structural framework
- ability to transfrom pluripotent stem cells in recipient bed into osteoblasts

17

coil applied over fracture site

inductive coupling and combined magnetic field EBGS

18

two electrode discs applied on oppostie sides of fx site

capacitive coupling

19

autograft
isograft
allograft/homograft
xenogragt

- you
- identical twin
- donor
- other species

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