Bone Healing Flashcards by Charlotte Doyle

Field and Ruthenbeck, VCOT, 2018:
Pattern of optical density measures during fracture healing?
Correlation between optical density measures and the qualitative measure of bridging callus and the radiographic union score for tibial fractures (RUST)?

Field and Ruthenbeck, VCOT, 2018:
Optical density measures decreased through 4 weeks post-op (resorptive phase) and then gradually and consistently increased at 8-16 weeks post-op
Optical density measures showed strong correlation with measures of bridging callus and RUST

How well did you know this?

Not at all

Perfectly

Yeh JAVMA 2021

Time to fixator removal in cats

Factors associated with PO complications

Time to fixator removal in cats
-8 weeks

Factors associated with PO complications
-BW
-tibial fracture
-use of type 2 fix
-use of destabilization

How well did you know this?

Not at all

Perfectly

Guidelines for using locking plates

Spanning long segments of bone (3x the length of fractured segments)
Limiting screw-to-hole ratio to less than 0.5
Limiting distance between plate and bone to 2 mm
Leaving 2-3 screw holes empty over the fracture

How well did you know this?

Not at all

Perfectly

How to make a plate construct stiffer

Larger plate
Shortening working length (placing screws closer to fracture ends)
Adding implants (IM pin, second plate)

How well did you know this?

Not at all

Perfectly

Construct stiffness is maximized if screws are placed where?

At the end of the plate and near the fracture

How well did you know this?

Not at all

Perfectly

There is little mechanical advantage to placing more than _____ screws per fracture segment with respect to _________

Axial stiffness

How well did you know this?

Not at all

Perfectly

Placing a ______ screw per fragment increases ____________

4th

Torsional rigidity

How well did you know this?

Not at all

Perfectly

Screws should be omitted from holes closest to fracture gap in what size gap

1mm

How well did you know this?

Not at all

Perfectly

Star drives allows for how much greater torque than hex heads

65%

How well did you know this?

Not at all

Perfectly

a) SOP

b) ALPS

c) Fixin

d) PAX

How well did you know this?

Not at all

Perfectly

Bridging plate

Plate span ratio
-comminuted
-simple fractures

Screw density

Plan span ratio
-comminuted 2-3
-simple fractures 8-10

Screw density
0.5 to 0.4

How well did you know this?

Not at all

Perfectly

The addition of an IM pin to a bridging plate effect

Reduces strain = Fatigue life of plate increased

Improves overall stiffness = risk of plastic deformation decreases

How well did you know this?

Not at all

Perfectly

Minimal screw for plate rod

One bicortical
One monocortical

How well did you know this?

Not at all

Perfectly

Disadvantages of Ex Fix

-Increase risk for infection
-external and eccentric placement of fixation = large bending moment on fixation pins

How well did you know this?

Not at all

Perfectly

Type: Ia
Pins: Half
Connecting Bars: 1
Pin Geometry:
-Unilateral uniplanar

How well did you know this?

Not at all

Perfectly

Type: Ib
Pins: Half
Connecting Bars: 2
Pin Geometry:
-unilateral biplanar

How well did you know this?

Not at all

Perfectly

Type: I-II
Pins: Half and 1 full
Connecting Bars: 2
Pin Geometry:
-bilateral uniplanar

Type: II modified
Pins: Half and 2 full
Connecting Bars: 2
Pin Geometry:
-Bilateral uniplanar

Type: II
Pins: Full
Connecting Bars: 2
Pin Geometry:
-Bilateral uniplanar

Type: III modified
Pins: Half and full
Connecting Bars: 3
Pin Geometry:
-Bilateral biplanar

Forces stabilized by Ex Fix

Compression
Shear
Torsion

Ex Fix Configuration for Radius

I
Ib
Acrylic
I-II hybrid
II

Ex Fix Configuration for Tibia

I
Ib
Acrylic
I-II hybrid
II
III
Circular
Arches
Combined Nail ESF

Strategies to Preserve the Pin-Bone Interface of ESF

1) Increase the strength of the pin-bone interface junction and pin-pull out strength

2) Decrease the load and bending forces per pin

Pin placement configuration for ESF application

Far pins first -nearest joints -3/4 bone diameter away Near pins second -closest to fracture -1/2 bone diameter away

Increase the strength of the pin-bone interface junction and pin pull-out strength of ESF

Pin type: -threaded over smooth Pin size: -threaded portion 20-30% bone diameter Pin placement: -Central placement through widest part of bone Insertion techniques: -Predrill w/ bit 0.1 mag smaller than pin shaft -Insertion speed < 300 rpm -Proper insertion force

Decrease the load and bending forces per pin in ESF

Adequate pin number: -3-4 pins per fragment Decrease the pin working length: -Place clamp with bolt toward patient, no more than 1 cm from surface of skin Pin configuration and frame stiffness: -Far-near-near-far pin placement -Consider multiplanar frame -Consider augmentations (articulations, diagonals, IM pin)

Interlocking Nails resists

Bending Rotation Axial load

Indications for locking Nail

Closed comminuted diaphyseal fracture long bones

Fracture pattern Type of mechanical loading