Transcript Locked Plating

Locked Plating
Thomas F. Higgins, MD; Sean E. Nork, MD;
James P. Stannard, MD; and Philip J. Kregor, MD
Locked Plating
Definition
Locked plating, for the purposes of this talk,
is a screw and plate construct for the
purposes of osteosynthesis, in which the
screw engages the plate with a mechanism
which secures a fixed angle between the
two.
History
Locked plating, improvised in various ways
for years, and in development for many
years, came into widespread commercial
availability and clinical use in the United
States between 1998 and 2002.
Five stages of new
Medical Technology
1.
Experimentation
2.
Skepticism
3.
Fevered enthusiasm / overuse
4.
Complications and despair
5.
Judicious use
Like much new medical technology, the
employment of locked plating was
complicated by a lack of a thorough
understanding of indications and
mechanism of action
The ideal recipe for implant and construct
stiffness is still not fully understood.
Where maximizing construct stiffness was
once the ultimate goal, locked plating has
likely created some situations where
constructs have, in fact, become TOO stiff.
The correct employment of locked plating
techniques necessitates understanding the
following:
1.
2.
3.
4.
Mechanism of action of locked plating
Differences from non-locked plating
Indications for locked plating
Contra-indications / misuses of locked
plating
Recommended Reading
Gauthier et al, Injury 2003,
Vol 34 Supplement 2, pp. B63-76
Mechanics of locked plating
 Traditional
(non-locking) plates rely on
friction between the plate and the bone
achieved by terminally tightening of
screws passed through the plate to the
bone.
 Locked
plating does not require that the
plate be compressed to the bone, as the
interface between the plate and screw is
secured without this plate-bone
compression
 With
non-locking fixation, failure of
fixation may initiate with toggle between
the screw and plate, subsequent loss of
compression between the plate and bone
Correct and incorrect sequencing
in the application of locked
plating
Surgical Technique
 Reduce
 LAG
the joint (if applicable)
First (Lag, then Lock)
 Re-confirm
alignment
 Lock
 After
the second locked screw, no change
can be made
The next twelve slides should be viewed as a
“slide show”. The screws with green
“x”’s represent locking screws, and the
screws without “x”’s are non-locking.
Lab Exercise
Metaphyseal
Fixation
Lab Exercise
Metaphyseal
Fixation
Lab Exercise
Metaphyseal
Fixation
Lab Exercise
Metaphyseal
Fixation
Reduction of Shaft
Lab Exercise
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Metaphyseal
Fixation
Reduction of Shaft
Locked Plating Advantages
 Increased
rigidity
 Decreased
 Potential
toggle
use as a reduction tool
 May
permit fixation with less stripping of
soft tissues
 May
be helpful in osteoporotic bone
Locked Plating Disadvantages
 Very
expensive
 Constructs may be too rigid
 Some percutaneous applications be selfdrilling
– That must be unicortical or strips near cortex
 No
tactile feedback on bone purchase
 They “allow you to stop thinking”
– Reduction must still be achieved, it is not
magically achieved by locking implant
List of
Indications for Locking
(Framework)
Indications for Locking

Biological Fixation
– Spanning Comminution (bridging)
– Percutaneous Techniques in selected indications

Implant as reduction tool

Metaphyseal / Bicondylar Articular Fractures
– Short Articular Segment
– Periprosthetic Fractures

Osteoporosis
Biological Fixation
Without necessitating compression of the
plate to the bone to achieve fixation, locked
plating may be applied percutaneously, or
with less damage to the vascularized tissue
immediately adjacent the bone.
Obese 33 yo female with bilateral
open femur fractures
I&D, Spanning external fixation
 Locking
plate is secured to the periarticular segment, the metaphyseal is not
disturbed or dissected, and then the plate is
secured to the diaphysis.

Both the nailed and
plated fractures heal
with callus
Percutaneous Techniques
are a form of “biological
plating”
(in selected indications)
15 y.o. male
This is a functions like a nail:
Secondary healing, Relative stability
Percutaneous / Submuscular Plating
Metaphyseal / Bicondylar
Articular Fracture
36 y.o. male skier
36 y.o. male skier
With bicondylar involvement, and very small
articular segment, locking fixation allows us
to secure the joint surface back to the
diaphysis in the correct orientation
4 months out
Long Standing 6 months
Use of Locked Plate as Reduction
Tool
1.
Lock plate to articular segment in correct
alignment
2.
Provisionally affix plate to diaphysis
3.
Confirm alignment
4.
Secure plate to the diaphysis with nonlocking or locking screws
Obese 47 y.o. female
Open Distal femur fracture
Reduce Joint
 Reduce
jointm then
set the correct
orientation of the
plate on the
articular fragment
(as with this jg)
 Make
sure it is not
flexed or extended
on the lateral view
(done in this case
with jig)
After joint reduction,
make sure that the plate
is correctly aligned to
the articular segment.
Then connect to
diaphysis.
Connect reduced joint to Diaphysis
Short Articular Segment
Open Femur Fracture
 27
y.o. male
 Motorcycle
 Open
vs. flatbed truck, then guard rail
L femur with segmental loss,
 Segmental
L tibia
Very small remaining articular segment
ORIF and cement spacer in metaphysis
Well healed after subsequent bone grafting
35 y.o. vs. tractor
Femoral neck fracture plus intertrochanteric
fracture equals short articular segment
Periprosthetic Fractures
(This is also a form of a short
articular segment)
Obese 64 y.o. female
72 y.o. male TAA
Periprosthetic Fracture
“Periprosthetic” = Short Articular Segment
Osteoporosis
74 y.o. diabetic female
Locking Plate Principles
 Locking
plate is an IMPLANT, not a
technique
 There
are unique techniques
 Beware
the siren call of M.I.S. (Malaligned Implant Surgery)
Locking Implants Still Require
Reduction
Unclear Indications/
Non-indication
Compression plating in healthy
diaphyseal bone
does not require locking
16 y.o. male, healthy bone, nonlocking fixation
18 y.o. female, diaphyseal injury.
Locking fixation not necessary
Partial Articular Fractures
“B-type fractures”
require buttress, not locking.
24 y.o. male
Snowboarder vs. Half-Pipe
Beware “too rigid” construct
72 y.o. Rheumatoid female on multiple cytotoxic
medications. Ground level fall. Repaired with this
locking construct
The experience over the last ten years with
locking fixation has demonstrated that we
now have the ability to make a construct “too
strong” or “too stiff”
Particularly in
1.Comminuted
2.Very
metaphyseal fractures, or
simple transverse or spiral patterns
rigid immobilization of the fracture may
obliterate all motion, and prevent the
formation of callus, leading to non-unions.
In these patterns, the correct answer may be a
wider spread of our fixation, allowing more
motion around the fragments, and the
formation of a more vigorous healing
response
Failed varus
nonunion revised to
this, allowing more
motion in the
metaphysis and a
callus response.
One other potential response to the problem of
excess stiffness in locking constructs has been so
called “far cortical locking”. This entails overdrilling the near cortex and then placing a screw that
engages the far cortex and locks in the plate (see
diagram, next slide).
This may theoretically allow more motion in the
construct, and reduce strain at the screw – plate
interface.
At the time of this publishing, this technology has
not been proven clinically, but may have some
promise in the future.
“Far cortical locking”
Locked Plating Mechanics
Summary
1.
Understand the biomechanical difference
from conventional plating
2.
Understand the limitations
3.
Reduce and lag before locking
Locked Plating Indications
Summary

Biological Fixation

Plate as a reduction tool

Metaphyseal / Articular Fractures

Short articular segments /
periprosthetics

Osteoporosis
Locked Plating
 Huge
advance in plating
 Must
understand biomechanics and what
the various constructs accomplish
 Need
to know and understand the new
“rules” of locked plating, as we understand
them, and not just apply locked plating
blindly
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