Hardware Flashcards
Buttress Plate: uses
wall that acts as a bridge between larger fragments with intervening small fragments leaning against the plate
-Usually used for peri/intra-articular fractures at the end of long bones
—- Distal tibia/pilon fractures
Buttress plate: forces prevented
Prevents shearing/bending forces
What side of injury is Buttress plate placed
on the tension side of an injury
Neutralization plate: fracture type used in
applied to fractures already reduced/compressed with lag screw placed outside of the plate
-Protects interfrag screw from torsional forces
What type of screws are used in a neutralization plate
all concentric screws
Compression plate: when used and MOA
- used when lag screw fixation not enough
- MOA: overbend the plate, tension device, screw insertion geometry
Important points about Static compression plate (3)
- compression achieved at the fracture
- Eccentric drilling of first two screws
- Rest of screws con be inserted concentrically
Important points about dynamic compression plate (2)
-Compression achieved at fracture and when implant is subject to physiological loads
- Follows concept of tension band fixation
- —plate is placed on tension side not compression side
What is a bridging plate
a neutralization plate without interfrag screws
Bridging plate: what does it achieve
maintains length and alignment of severely comminuted fractures
Wave plate: when is it used
for areas of delayed healing
-contoured away to allow bone graft and better ingrowth of vessels
What is a Hook plate and when is it used
could be fashioned from 1/3 tubular plate
used for small/comminuted medial malleolar fragments
Limited contact plate: design
grooves present on the underside of the plate that limit periosteal contact
Tension band: construct and when useful
- 2 parallel K-wires reverses tension and turns it into compression
- good for avulsion fracture, malleoli, small fragment, comminuted fracture
Stainless steel wire: when useful
for IPJ fusion
Stainless steel wire: pro’s and cons
Pro: osteoporotic bone, splintage
Con: no compression, tendons may become irritated
Axial or dynamic compression: 3 different modifications
1) neutralization mode: centered
2) compression mode: 1 mm eccentrically away from fracture line
3) Buttress mode- 1 mm eccentrically towards fracture line
Limited contact dynamic compression: construct and how is stress distributed
- Underside of plate contoured for compression in different directions
- better distribution of stress to plate, less hardware failure
Locking plate: how is force distributed
- Evenly distributes force across entire screw
- Screw and plate function as one unit instead of separate units.
Reconstruction plate: construct
notches allow for easier bending
Cortical screw: anatomy
threads are closer together than cancellous screw for better cortical bon contact
Cortical Screw: what does the core diameter affect
Large core diameter increases strength
Shaft screw: anatomy and when used
- Partially treaded
- For interfrag compression
Cancellous screw anatomy
Threads are further apart for better cancellous bone contact.
-When used as lag screw the entire length of the thread should be in fracture fragment
Cancellous screw: threads
deep and widely spaced apart
Cancellous screw: self tapping
yes
Cancellous screw: used
as lag screws for metaphyseal fractures
Cortical screws: threads
shallow and closely spaced
Cortical screw: self tapping
NO
Describe Malleolar screws
partially threaded self cutting cortical screw
Describe Herbert screw
- Headless screw.
- proximal and distal threads are separated by smooth shaft
- Leading threads have greater pitch. Allow for some compression
Lag screw: optimal screw placement
one screw perpendicular to long axis of bone and the rest perpendicular to fracture line
Lag screw: perpendicular to fracture
max interfrag compression but minimal axial stability
Lag screw: perpendicular to long axis of bone
max axial stability,can cause dislocation of fragments as it is tightened
Drill bit sizes: mini frag set
- 1 (U)—> 1.5 (O)
- 5(U)—> 2.0 (O)
- 0 (U)—> 2.7 (O)
Drill bit sizes: small frag set
- 5 (U)—> 3.5 (O)
2. 5 (U)—> 4.0 (O)
Drill bit sizes: large frag size
- 2 (U)—> 4.5 (O)
3. 2(U)—> 6.5 (O)
Steps to AO screw fixation (6)
- Underdrill
- Overdrill
- Countersink
- Measure
- Tap
- Insert
1st screw placed in Lapidus procedure
- size
- orientation
-3.5 screw or 4.0 screw
“home run screw”
-from dorsal Met to plantar medial medial cuneiform
Size of screw for Lisfranc arthrodesis
3.5 or 4.0 screw
Triple arthrodesis size of screw
6.5 or 7.0 cannulated screws
