A2: Fracture repair and implants Flashcards
Which fractures are suitable for cage rest?
Cancellous, non load-bearing bones which are minimally displaced e.g. pelvis, mandible, spine, scapula
What is external co-aptation?
Splint, bandage, cast etc
Which fractures are suitable for external coaptation?
Below elbow or stifle, young, minimal displacement, stable fracture, only one bone if a two-bone area
When are IM pins usually used?
Auxiliary - not alone
How much do IM pins cost?
Cheap
What are two methods of inserting IM pins?
Normograde or retrograde
Which method of IM pin insertion is preferred?
Normograde, as disturbs fracture site less
How much stability does an IM pin provide?
Not much - minimal torsion or axial support
When is IM pin contra-indicated?
In radius, as no entry point that doesn’t damage the joint
What three methods do you usually use IM pins in combination with?
With a unilateral ESF, or along with a bone plate, or along with an interlocking nail
How can you tell how far you have inserted a pin?
Compare another pin of the same size to the outside
What’s the advantage of using an interlocking nail?
Prevents rotation and axial collapse (better torsional and axial stability)
What’s another name for an IM pin below 2mm?
K wire
What is a long oblique fracture?
fracture 2.5x diameter of bone
When applying cerclage wire to a long oblique fracture, how many cerclages should you apply?
2
What is the principle of the tension band wire?
Active distracting forces are counteracted and converted into compressive forces
What can bone screws be combined with?
Plate, interlocking nail, ESF or IM pin
Which bone type can you use plates on?
Cancellous
When should you never use bone screws in isolation?
Diaphyseal fractures
What is the pitch of a screw?
The angle of the threads
Where can you use cortical screws?
Diaphyseal bone
What does a cortical screw look like?
Fully threaded, shallow threads, flat pitch
Why are cortical screws strong?
Wide core diameter
Where can you use cancellous screws?
Epiphyseal or metaphyseal fracture
What do cancellous screws look like?
Partially or fully threaded, fewer threads per unit length, deep threads
Why are cancellous screws weak?
Narrow core diameter
When do you use locking screws?
With locking plates
What does a locking screws look like?
Threaded head, narrowest pitch
What do lag screws do?
Join and compress two pieces of bone e.g. in articular fractures
What are three functions bone plates can perform?
Compression, neutralisation, bridging
Which plate can perform which function?
Any can do any
Which fractures would you put a compressive plate on?
Transverse, short oblique below 45 degrees, or osteotomies
What are three advantages gained by using a compressive plate?
Friction increases stability, primary bone healing, load sharing between bone and implant
How do plates compress?
By closing fracture gap as screws are tightened
Which is the tension side of the femur?
Lateral
Which is the tension side of the tibia?
Cranial or medial
Which is the tension side of the humerus?
Cranial or lateral
Which is the tension side of the radius
Craniomedial or cranial
Which force side do you apply the plate to?
The tension side to convert this into compression (dynamic compression)
What is neutralisation?
Reconstructing a bone to anatomical shape by lag screws or wire
What is “bridging”?
Joining up the fragments of an unreconstructable fracture
Which forces can IM pins withstand?
Bending a little
Which forces can an IN nail withstand?
All, mainly torsion and compression
Which forces can ESF withstand?
All, mainly bending
Which forces can plate withstand?
All, but bending least
What is a DCP?
Dynamic compression plate
What kind of compression can you do with a DCP?
Static
What is an LCP?
Locking compression plate
What do you use an LCP with standard screws for?
Interfragmental or axial compression
What do you use an LCP with locking screws for?
stable plate-screw connection without loss of
reduction, regardless of plate modelling
What do you use reconstruction plates for?
To contour in three planes e.g. pelvic or mandibular fracture
What’s the disadvantage of reconstruction plates?
Weak
What are veterinary cuttable plates for?
Long bones of cats, MTs, MCs
What are cuttable plates NOT for?
Compression of fracture
