Internal Fracture Fixation: Bone Plates + Screws Flashcards
what are the 2 requirements for fracture healing
BIOLOGY/VIABILITY AND MECHANICS/STABILITY
T/F: bone plate & screws combat all forces except torsion
FALSE- it combats all fracture forces!
what forces can bone plate + screws combat?
all!
what types of plating can be done?
- compression plating
- neutralization plating
- buttress plating
for a simple transverse fracture with ideal load sharing, what type of plating would you use?
compression
for a oblique fracture with partial load sharing, what type of plating would you use?
neutralization
for a butterfly/comminuted fracture with no load sharing, what type of plating would you use?
buttress plating
what are dynamic compression plates? (DCP)
specially designed plate holes, you tighten the eccentrically placed screw to slide the plate along the bone, which compresses the fracture
if you placed it directly into the fracture it would just neutralize it and hold it into place, but if you do screws on either side then you are compressing it together
when are buttress/bridging plates used?
- non-reconstructive approach: biologically friendly
- plate spans a gap to prevent collapse of fracture: holding bone “out to length” for correct spatial alignment
- all weight bearing forces are transmitted through the plate and screws; doing a lot of work
what are neutralization plates?
- oblique fracture
- anatomic reconstruction of fracture: cerclage wire or screws
- plate neither compresses nor distracts but holds everything in its current place
- axial load shared by implants AND bony column
what can you add in with a plate?
IM pin; can extend lifespan of buttress plate 10x
larger pin = longer fatigue life, but also competes more with screws for bone space
usually downsize size of pin to 40% instead of 60-70%
what are the advantages of locking screw/plate systems?
- rigid link between locking screw & bone plate: the screws have threading that matches threading in the hole in the plate
- fixed screw angle: don’t need perfect match of plate to contour of bone now
- bone plate functions as “internal fixator”
locked in place so load doesn’t toggle/loosen the screws!
what are the steps of bone plate application?
- choose anatomic reconstruction or spatial re-alignment of fracture site
- contour plate to match bone
- aim for 6 cortices of screw purchase on each side of fracture zone: (screw going through 2 cortices = bicortical)
how many screw cortices should be on each side of the fracture zone?
6 cortices: so ideally 3 bicortical screws on each side of fracture zone
bone plate advantages
- suitable for reconstruction or bridging
- highly stable and durable fixation
- allows early return to comfortable limb use
- low post-op maintenance vs coaptation or ESF
bone plate disadvantages
- expensive and extensive inventory
- technically challenging! additional training required
when can screws be used on their own?
more commonly in a lag screw fashion: drill holes specifically to cause compression
most common for joint fracture: want perfect reconstruction of joint surface for perfect function
use screw across the condyle in lag fashion, and use plate and screws above the joint
want the articular surface to be perfectly reconstructed!!
