Download Surgical Technique patella addendum

99.26.12Patella rev.0
GMK SURGICAL TECHNIQUE - PATELLA ADDENDUM
INTRODUCTION
The following surgical technique is an Addendum to the GMK Primary Surgical Technique.
It describes the patella preparation by means of the new Medacta Clamp, to be used both with
resurfacing and inset patella versions.
For the other steps of the surgical technique, please refer to the official GMK Primary Surgical
Technique.
RESURFACING PATELLA
Ref.no. 02.07S.721RES - Resurfacing
patella tray
2
1.
2.
3.
4.
5.
4
1
Medacta clamp
Adjustable cup
Patella clamp base
Spacer for patella clamp
Micrometric resection guide
3
5
Clip the adjustable cup on the upper jaw of
the Medacta clamp and the patella clamp
base on the lower jaw of the Medacta
clamp.
A
CAUTION: The upper surface of the patella
clamp base is endowed with 4 spikes. Handle
with care.
Open completely the adjustable cup by
rotating the screw A.
Insert the blue spacer (red arrow).
B
CAUTION: To ensure the correct fixation, align
the hole on the spacer to the hole on the
adjustable cup before inserting the spacer
(B).
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99.26.12Patella rev.0
Assemble the micrometric resection
guide on the patella clamp base.
CAUTION: The lever A must be at this
step fully released.
C
B
1. Center the slot C located on the
resection guide on the square
knob B located on the patella
clamp base
2. Slide down the resection guide
(1,2) until the same level is
reached (3)
3. Lock the lever A to fix the
connection.
A
1
2
3
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99.26.12Patella rev.0
Position the assembly on the patella,
making sure to be aligned to the
lateral shield of the patella.
CAUTION: Resection jaws must be at
this step fully open.
Close the clamp until contact
between the superior adjustable
cup and the patella is reached.
Then fix the position by moving the
lever ahead.
Read the patella thickness on the
scale located at the top of the
clamp (22 mm in the example).
Thickness values range from 18 mm
to 34 mm.
CAUTION: The read value is only an
indication and can differ from the
real patella thickness. This value
represents the distance between
the top of the patella base clamp
and the bottom of the adjustable
cup and may differ from the real
bone thickness.
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99.26.12Patella rev.0
Read the residual bone stock after
resection on the scale located at
the side of the clamp (16 mm in the
example).
Bone stock values range from 12
mm to 24 mm.
CAUTION: The read value is only an
indication. This value represents the
difference between the measured
patella thickness and the distance
between the bottom of the
adjustable cup and the resection
slot and may differ from the real
bone thickness
Residual bone stock = patella
measured thickness – resection
thickness.
A
To reproduce the same thickness of
the natural patella, the bone stock
scale has to be set (A) on the value
corresponding to:
patella measured thickness – 10 mm.
CAUTION: The minimum bone stock
allowed by the instrument is 12 mm.
WARNING: An insufficient residual
bone stock may cause patella
fracture.
When the resection level is
deemed satisfactory, lock the jaws
by rotating the corresponding
screw.
Perform the patellar cut by using
an oscillating saw.
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99.26.12Patella rev.0
Open the clamp by driving the
two handles slightly down and
simultaneously move back the
lever.
Unscrew
the
knob
of
the
micrometric resection guides to
open its jaws. Remove the whole
assembly from the joint and
disassemble
the
micrometric
resection
guides
from
the
Medacta clamp.
Size the resurfacing patellar
implant by using the dedicated
templates.
Disassemble the adjustable cup
from the Medacta clamp and clip
the drilling guide (LAT marked)
OPTION: In case a Keblish
approach is used, a dedicated
drilling guide is available on
request (MED marked)
As a general rule, the 2 peg holes
(red circle) must be on the medial
side of the patella once reduced.
Lateral
Facet
Medial
Facet
Medial
Facet
Lateral
Facet
PATELLA IN PLACE
EVERTED PATELLA
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99.26.12Patella rev.0
Close the clamp until contact
between the drilling guide and
the resection is made.
Then fix the clamp position by
using the upper lever.
Perform the 3 peg holes by using
the dedicated drill.
Remove the clamp from the joint.
Rest the trial resurfacing patella on
the bone, centering it on the 3
holes.
Reduce the patella and test the
knee joint through its full range of
motion.
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99.26.12Patella rev.0
Remove the trial patella.
Assemble the patellar
cup on the clamp.
cement
The bone cement must be
prepared
according
to
the
related
instructions
for
use,
provided
by
the
cement
manufacturer. Once the cement
has the right viscosity, it should be
applied to the internal surface of
the patellar implant. Lock the
patella, by closing the Medacta
clamp. Hold the implant in the
final position and clear the
extruded
cement
from
the
patella, ensuring that no cement
remains on the articular surface.
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99.26.12Patella rev.0
INSET PATELLA
Ref.no. 02.07S.721INS - Inset patella
tray
Size the inset patellar implant by
using the dedicated templates or,
alternatively, the reamer guides.
CAUTION: The reamer guide is
endowed with 3 spikes. Handle
with care.
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99.26.12Patella rev.0
Clip the adjustable cup on the upper
jaw of the Medacta clamp and the
patella clamp base on the lower jaw of
the Medacta clamp.
A
CAUTION: The upper surface of the
patella clamp base is endowed with 4
spikes. Handle with care.
Open completely the adjustable cup by
rotating the screw A.
Insert the blue spacer (red arrow).
B
CAUTION: To ensure the correct fixation,
align the hole on the spacer to the hole
on the adjustable cup before inserting
the spacer (B).
Close the clamp on the patella, fix its
position by using the upper lever and
read the bone thickness on the upper
scale (red circle).
Then unlock the lever to open the
clamp and disassemble the adjustable
cup.
CAUTION: The read value is only an
indication and can differ from the real
patella thickness. This value represents
the distance between the top of the
patella base clamp and the bottom of
the adjustable cup and may differ form
from the real bone thickness.
Clip the reamer guide of the correct size
on the clamp, making sure that the
three spikes are facing the patella.
Close the clamp until contact between
the reamer guide and the patella is
made.
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99.26.12Patella rev.0
To assemble the reamer of the
suitable size to the reamer holder,
insert the reamer on the tip of the
reamer holder (1), turn it 90° (2) until it
is fixed to the reamer holder.
2
1
Before drilling, check that the depth
gauge A is in neutral position. If
necessary the reaming depth can
be modified by screwing the depth
gauge (1 turn = 1 mm).
A
Fix the depth gauge by turning the
fixation screw B.
NOTICE: When the depth gauge is in
the neutral position, the drilling
depth corresponds to the patella
implant thickness of the validated
side.
B
NEUTRAL
POSITION
DEEPER HOLE
MORE SHALLOW
HOLE
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99.26.12Patella rev.0
Release the lever and remove the
clamp from the joint.
insert the trial inset patella on the
bone, centering it on the central
hole.
Reduce the patella and test the
knee joint through its full range of
motion.
Remove the trial patella.
Assemble the patellar
cup on the clamp.
cement
The bone cement must be
prepared
according
to
the
related
instructions
for
use,
provided
by
the
cement
manufacturer. Once the cement
has the right viscosity, it should be
applied to the internal surface of
the patellar implant. Lock the
patella, by closing the Medacta
clamp. Hold the implant in the
final position and clear the
extruded
cement
from
the
patella, ensuring that no cement
remains on the articular surface.
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99.26.12Patella rev.0
Instrumentation nomenclature
Ref. No.
Description
Picture
Q.ty
02.07.10.1075
Medacta clamp
1
02.07.10.1141
Patella clamp base
1
02.07.10.1148
Patella cement cup
1
02.07.10.1148
Micrometric resection guide
1
02.07.10.1093
Patella drilling guide
1
02.07.10.0428*
Patella drilling guide (Keblish approach)
1
02.07.10.0425
Spacer for patella clamp adjustable cup
1
02.07.10.1154
Patella clamp adjustable cup
1
02.02.10.0404
Patella peg drill (Ø4.5 L 155) Hudson coupling
1
02.07.10.1159
Trial resurfacing patella # 1
1
02.07.10.1064
Trial resurfacing patella # 2
1
02.07.10.1160
Trial resurfacing patella # 3
1
02.07.10.1169**
Patella template Ø20
1
02.07.10.1166*
Patella template # 1 Ø24
1
02.07.10.1167*
Patella template # 2 Ø28
1
02.07.10.1168*
Patella template # 2 Ø32
1
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99.26.12Patella rev.0
Ref. No.
Description
Picture
Q.ty
02.07.10.1161**
Trial inset patella ø20
1
02.07.10.1162
Trial inset patella ø24
1
02.07.10.1163
Trial inset patella ø28
1
02.07.10.1164
Trial inset patella ø32
1
02.07.10.1142**
Reamer Guide Ø20
1
02.07.10.1143
Reamer Guide Ø24
1
02.07.10.1144
Reamer Guide Ø28
1
02.07.10.1165
Reamer Guide Ø32
1
Reamer Holder
1
T12893**
Reamer Ø20
1
T12894
Reamer Ø24
1
T12895
Reamer Ø28
1
T13716
Reamer Ø32
1
T12896
Legend:
*on demand
**on demand (not for US market)
Part numbers subject to change.
Note for sterilization: The instrumentation is not sterile upon delivery. It must be cleaned before use and
sterilized in an autoclave respecting the regulations of the country EU, directives where applicable and
following the instruction for use of the autoclave manufacturer.
For detailed instructions please refer to the document “Recommendations for cleaning decontamination and
sterilization of Medacta® International reusable orthopedic devices” available at www.medacta.com.
GMK®, Medacta® are registered trademarks of Medacta International SA, Castel San Pietro, Switzerland.
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