Exam 1: Lecture 3 - Principles of Orthopedic Surgery II Flashcards
What type of issues can you use external skeletal fixators for
long bone fxs, correct osteotomies, joint arthrodesis, temporary joint immobilizations
when should we not/rarely use external skeletal fixators?
for articular fractures (not), pelvic and spinal fractures (rarely)
T/F: External fixators can be adjusted during and after surgery to improve fracture alignment
true!
what is the functional period for external fixators
it is related to the onset of pin loosening but varies depending on frame constructed
how are linear ex-fix frames classified
by number of planes occupied by frame and number of sides of limb from where fixator protrudes
what are the 4 types of common linear ex-fix frames
- unilateral-uniplanar (type Ia)
- unilateral-biplanar (type Ib)
- bilateral-uniplanar (type II)
- bilateral-biplanar (type III)
out of the 4 common linear ex-fix, what is the strongest, stiffest, and least used
bilateral-biplanar (type III)
what type of ex-fix
unilateral-uniplanar (type Ia)
what type of ex-fix
unilateral-biplanar (type Ib)
what type of ex-fix
bilateral-uniplanar (type II) maximal type
what type of ex-fix
bilateral-uniplanar (type II) minimal type
what are the 2 subtypes of bilateral-uniplanar ex-fix
maximal type II frames filled with full pins
minimal type II frames constructed with minimum of two full pins
what type of ex fix
type III bilateral-biplanar
what type of ex-fix
type III
what the heck is going AWN
external fixator that is bandaged
what are the 2 types of pins used for ex-fix
half pins and full pins
what are half pins for ex-fix
penetrate both cortices but only one skin surface
what are full pins for ex-fix
penetrate both cortices and skin surfaces
what type of ex-fix pins
half pins
what type of ex-fix pins
full pins
what are the types of pins from top to bottom
- centrally threaded cortical pin
- centrally threaded cancellous pin
- end-threaded cortical pin
- end-threaded cancellous pin
- mandibular fixation pin
what are connecting bars for ex-fix made out of
stainless steel, titanium, alloy, and carbon fiber
what is the strongest type of connecting bar? Weakest?
strongest - carbon fiber
weakest - titanium
what are these
linkage devices/clamps to join fixation pins
what are the 8 ways we can increase strength and stiffness for ex-fix
- pre-drill before inserting positive profile threaded pins
- increase pin numbers (up to 4 per bone)
- increase pin size (up to 25% of bone diameter)
- locate pins near joints and near fracture
- decrease distance between bone and pin-clamp interface
- increase connecting bar size
- increase number and planes of connecting bars
- tie IM pin into fixator frame
what are the steps to inserting fixation pins
- expose pin insertion site
- center pin in bone
- pre-dill pin hole
- insert pin with LOW RPM power
- release incision around pin to prevent skin tension
- pin drilled into bone at point of greatest cross-sectional diameter
what are circular external fixators used for
stabilize fractures, compress nonunions or distract fractures, transport bone segments, or dynamically correct bone angular and length deformities
what are ring fixators unique for
controlled distraction of bone segments by creating new bone formation in trailing pathways
what type of ex-fix
circular external fixators
what are the types of intramedullary fixation
- intramedullary pins
- kirschner wires (k wire)
- interlocking nails
what type of intramedullary fixation
IM pin
what type of intramedullary fixation
kirschner wires (K wire)
what type of intramedullary fixation
interlocking nails
when are IM pins used
for diaphyseal fractures of humerus, femur, tibia, ulna, metacarpal, and metatarsal bones
when are IM pins CONTRAINDICATED
for the radius!! JUST SAY NO
what are the biomechanical advantage of IM pins
resistance to applied bending loads
what are the biomechanical disadvantages of IM pins
- poor resistance to axial (compressive) loads
- poor resistance to rotations loads
- lack of fixation (interlocking) with bone
T/F: You can use just an IM pin and no other type of implant is necessary
false! IM pins REQUIRE supplementation with other implants (like cerclage wire, ex-fix, or plate)
what type of IM pin is on the left and what is on the right
left - chisel
right - trocar
what do we need to remember for applying IM pins with cerclage wire
select pin sized 60-70% of medullary canal width
what do we need to remember for applying IM pins with ex-fix
select pin sized 50-60% of medullar canal width
what do we need to remember for applying IM pins with bine plate
select pin sized 40-50% of medullary canal width
T/F: we use retrograde or normograde pin insertion in the humerus and femus
TRUE
T/F: we ONLY use normograde pin insertion in tibia
true
what type of IM pin placement is this
normograde placement
what type of IM pin placement is this
retrograde placement
what is steinmann pins or kirschner wires
crossed pins/wires placed in triangulated pattern
what is the purpose of interlocking nails
to stabilize simple and comminuted mid-diaphyseal femoral fxs
what do interlocking nails provide resistance to
- bending
- rotational
- axial loading forces
T/F: Interlocking nails are an effective IM fixation for non-reducible fractures
true!!
why are IM pins secured by proximal and distal transfixing screws
to engage bone to nail and provide axial, bending, and torsional stability
what is this
interlocking nails
what are the 6 key concepts for applying interlocking nails
- use largest nail that fits in bone
- span length of bone with nail
- ream medullary canal with steinmann pin or reamers
- insert nail in normograde fashion
- position nail screw holes 2cm away from sx
- secure nail w 4 screws or fixation bolts
T/F: Orthopedic wire MUST be used in combination with other ortho implants
true! Supplemental for axial, rotational, and bending support of fractures
how is cerclage wire placed
around circumference of bone
how is hemicerclage wire or interfragmentary wire placed
through pre-drilled holes in bone
T/F: cerclage wire combined with k-wire prevents slipping where the bone diameter changes
true!
______ is one of the most used implant but also most often MISUSED implant
cerclage wire
T/F: Misuse of cerclage wire causes a significant % of postop complications
true
How does cerclage wire work as a stabilizer
prevents fragments from moving/collapsing under weight bearing loads
what are the 3 criteria for cerclage wire
- length of fx 2-3 times diameter of marrow cavity
- maximum of 2 fracture lines
- fracture is anatomically reduced
what implant should we NEVER use alone in ortho procedures
cerclage wire!!
T/F: If >2 or 3 bone segments are present or if fracture lines are not significant length then cerclage wire is ONLY used to hold fragments in place
true
what is the most common cause of cerclage wire fail
when you try to gain stability with cerclage wire in multi-fragmented fractures
what are some probable outcomes when cerclage wire fails
collapse of fx, loss of stability, and wire loosening to delay healing
what are the 5 concepts of applying cerclage wire
- only anatomically reconstructed long oblique or spiral fxs
- place 2-3 cerclage wires per fracture line
- place wires perpendicular to long axis of bone
- space the wires 1/2 to 1 bone diameter apart and at least 0.5cm from fx
- support cerclage wire with another implant!
what is the importance of this picture
it is showing the application of cerclage wire
when do we use hemicerclage wire
when the fx length is LESS THAN 2X of bone diameter
when do we use tension bands
avulsion fractures
what is an avulsion fracture
when there is a contraction of muscle group that generates tension pulling the bony prominence or origin from anatomic location
what is the main purpose of tension band
convert distractive tensile forces into compressive forces
what is being shown here
tension band wiring
what are the 5 steps to apply tension band wires
- use 2 k-wires or small steinmann pins
- place wires parallel to each other and perpendicular to fx
- seat wires in opposite cortex
- place hole for wire same distance below fx as pins are above fx
- tighten wire in direct contact w bone
when are bone plates or screws ideal
when there is complex or stable fractures or when there is anticipated prolonged healing
what are the 3 ways plates are used
- compression plate
- neutralization plate
- bridging plate with or w/o IM pin
when do we use compression plates
for transverse fxs
when do we use neutralization plates
to support long oblique fractures reconstructed w/ lag screws
when do we use bridging plates
combined with an IM pin to span non-reducible fx
what type of plate
compression plate
what type of plate
neutralization plate
what type of plate
bridging plate combined w IM pin
what are the screws from left to right
- cortical
- fully threaded cancellous
- partially threaded cancellous
what is the function of neutralization plate
protects reconstructed bone from torsional, bending, and shearing forces
what is the function of bridging plate
serves as a splint for spatial alignment of bone during healing
what is the function of buttress plate
functions to prevent collapse of adjacent articular surface
what is the function of locking plate (screws secured in bone and plate
it will hold the bone in position
what type of plate
locking plate
what are the 5 concepts for applying bone plates
- select appropriate plate size
- select plate that spans bone length
- accurately contour plate
- place min of 3 screws or 6 secure cortices above and below fx
- use longer and stronger plate for bridging plates
what are lag screws
screws put in to compress fx line between 2 bony fragments
what is the optimal position of a lag screw
perpendicular to fracture line
what is a glide hole
hole equal in diameter to outside diameter of thread diameter of screw (aka can take the screw and slide it through the hole with no resistance)
what is a thread hole
hole in equal diameter to inner core diameter or shaft of screw (aka smaller hole so the threads push into bone and compress it)
what steps of placing a lag screw are being shown here
- drill glide hole
- insert sleeve through glide hole
what steps of placing lag screws are shown here
- use counter sink to cut bevel in cortical bone at entrance of glide hole to increase contact area
- determine length of screw inserted w/ depth gauge
what steps of placing lag screws are being shown
- use tap to cut threads for screw in far bone segment
- insert screw and tighten to create inter-fragmentary compression so there is no gap between fragments
what are the 5 key concepts for applying lag screws
- reduce and secure fx before lag screw
- optimal compression = place screw perpendicular to fx
- drill near cortex equal to screw thread diameter (glide hole)
- drill far cortex equal to screw core diameter (thread hole)
- with partially threaded screws threads should NOT cross fx
how do we insert partially threaded cancellous bone screw
- drill near and far cortices as threaded holes
- measure depth
- tap holes
- insert screw to compress fx
what is important to remember when we insert screws for partially threaded screws
for compression to occur, threads should NOT CROSS fx line
