Preservation™Knee System surgical technique

™
Preservation™ Knee System surgical technique
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Contents
Ci™ System Connections
2
Borders of the Condyles
29
Ci™ System Set-up
4
Femoral Cortex Modelling
30
Start-up Procedure
5
Femoral Model Calculation and Verification
31
Ci™ Menu Buttons
6
Tibial Slope
32
Ci™ Procedure Set-up
8
Cartilage Defect Planning
33
Tibial & Femoral Array Positioning
10
Leg Extension
34
Tibial & Femoral Array Fixation
11
Desired Post-Operative Leg Alignment
34
Camera Side
11
Leg Flexion
35
Camera Alignment
12
Femoral Implant Planning
35
Incision & Exposure
13
Tibial Implant Planning
37
Registration
14
Motion Analysis
39
Calculating the Femoral Head Centre
15
Tibial Pin Insertion
40
Pointer Tips
16
Tibial Resection Navigation
41
Definition of the Malleoli
17
Tibial Resection
43
Definition of the Tibial Mechanical Axis
18
Tibial Resection Verification
44
Tibial Sizing
19
Check Extension Gap
45
Tibial A/P Direction
20
Check Flexion Gap
46
Tibial Modelling
21
Extension / Flexion Gap Adjustments
47
Tibial Plateau Modelling
22
Distal Femoral Resection
48
Tibial Model Calculation and Verification
23
Distal Femoral Resection Verification
50
Femoral Mechanical Axis
24
Tibial Template Navigation
51
Registration of Epicondyles
25
Tibial Template Preparation
52
Registration of the Anterior Cortex
26
Femoral Preparation
53
Epicondylar Axis
27
Tibial Component Trial and Verification
57
Femoral Condyle Modelling
28
Femoral Component Trial and Verification
58
1
Ci™ System Connections
3
2
5
1
4
Ci™ Unit Connections
Connecting the Ci™ System
1. Power switch (on / off)
2. Power lead connection
3. Currency switch
All cables are connected to a panel at the
The power switch is positioned below the
The standard 3 pin power lead connects
The red ‘H-shape’ switch adjusts the
rear of the Ci™ unit. All power cables and
power socket. A green light indicates when
to the power socket.
power supply between 110 volts and 220
connectors are supplied with the system.
the unit is switched on.
volts. Make sure that the correct voltage is
selected before switching on the system.
2
Power lead
Camera cable
Camera unit cable 1
Camera unit cable 2
Earth connection
4. Earth lead connection
5. Camera unit connection
Important: The camera must be switched
Please refer to the System User Guide
The earth socket is identified by the
The orange coloured camera cable plugs
on at least 20 minutes prior to the start of
(Art-No: 52543-03EN) for detailed
standard yellow and green earth colours.
into the camera unit socket (also marked
the procedure.
set-up instructions.
The system must be earthed using the
in orange). The cable pins are aligned
cable supplied before switching on the
before inserting the cable. The cable is
system.
removed by pulling smoothly and slowly to
Connections on the camera unit should
also be checked at this stage.
avoid damaging the pins.
3
Ci™ System Set-up
Ci™ Unit
Surgeon
Assistant
Surgeon
Assistant
O.R. Nurse
O.R. Nurse
Ci™ Unit
Camera Unit
Camera Unit
Option 2: Ci™ System next to surgeon
Option 1: Ci™ System opposite surgeon
Positioning the Ci™ System in the O.R.
Ideally the infra-red camera unit has an
If the Ci™ unit is positioned within the
Please refer to the System User Guide
The Ci™ unit should be positioned so that
uninterrupted view of the tibial and femoral
sterile field it must be covered using the
(Art-No: 52543-03EN) for detailed
the surgeon has a clear view of the screen.
marker arrays throughout a full range of
drape supplied.
set-up instructions.
The touch-screen should be within easy
motion (flexion, extension and pivoting of
reach of the surgeon or theatre assistant.
the hip joint). The camera unit should be
Unstable stands or tables should not be
used for placement of the Ci™ unit. (see
positioned between 1.5 and 2 metres
ordering information for Ci™ unit trolley)
away from the surgical site.
4
Start-up Procedure
Figure 1
Figure 2
Figure 3
All cables must be fully connected before
Once the power supply has been switched
If the camera unit is not properly
The start-up screens allow the user to
switching on the system.
on, the Ci™ software will automatically
connected, no ‘beeps’ will be heard and
configure network and video settings
initialise (Figure 1).
an error message will appear asking you
if required (Figure 3).
to restart the system (Figure 2).
Two ‘beeps’ indicate that the camera unit
A blank CD-R (not CD-RW) should be
is properly connected.
inserted into the Ci™ unit to allow any
patient data to be stored.
5
Ci™ Menu Buttons
1. Status Field – red / orange / green
Green: Normal tracking mode
Yellow: Ci™ instrument not visible to camera
Red: Ci™ instrument and / or navigation array not visible to camera for more than 3 seconds
Pressing on this button brings up the camera field of view screen. This will show the position
of all visible navigated instruments in the field of view.
2. Information Button
Provides information on the application, version number, phone ’hotline’ numbers
and www.iorthopaedics.com website
3. Zoom In
Zooms in on the morphed bone model
4. Zoom Out
Zooms out of the morphed bone model
5. Ligament Balancing
Can be used at any time after the registration
procedure is complete
6
6. 3D Model
Allows the user to switch between hiding or displaying the 3D model, leaving only the
‘cloud’ of acquired points visible on screen.
7. Implant information
Provides details on the implants and sizes. This may be used to confirm the selected
implants after the implant planning stage.
8. Verification Button
If, at any time the reference arrays are moved or knocked out of position, you can re-verify
the accuracy of the bone model using the pointer. If the bone model is no longer
accurate, the registration process will need to be repeated. (if only one array has been
moved, the registration will only need to be repeated for that array). Use the next / back
buttons to return to the appropriate point in the procedure.
9. Screenshot Button
This allows the user to take manual screenshots at any stage of the procedure.
Screenshots are stored within the system and can be written to a CD. The system will also
take automatic screenshots at key stages during the procedure.
10. Close Button
This closes the application. All information can then be stored on disk before continuing
with a new procedure. The patient’s name and ID are stored as an HTML file with all
information gathered during the procedure.
7
Ci™ Procedure Set-up
On screen there are next and back buttons.
In this surgical technique we use arrows to
indicate movement to the next step.
Arrow Key:
Press ‘next’ to continue
Press ‘back’ to return to the previous step
Figure 4
Figure 5
The procedure is started by entering the
The appropriate knee system software is
patient’s name and ID, using the touch-
selected from the choices displayed -
screen keyboard (Figure 4).
LCS® / P.F.C.® Sigma™ / P.F.C.® Sigma™ RP /
This information will appear on the screen
Preservation™ (Figure 5).
and on each screenshot taken during the
operation.
8
Figure 6
Figure 7
A choice of metal backed fixed bearing,
The appropriate leg and the affected condyle
all polyethylene fixed bearing or mobile
are selected for the operation (Figure 7).
bearing implants is displayed on screen
(Figure 6). The desired implant is selected
(as defined pre-operatively). Press ‘change’
to alter the selections on screen.
9
Tibial & Femoral Array Positioning
Position of standard
Ci™ tibial jig
Schantz pin
position
Intended femoral
array position
Schantz pin
position
Intended tibial
array position
Figure 8
Figure 9
The arrays must be placed away from the
Note: The position of the reference arrays
Positioning of the tibial jig
Positioning of the femoral array
intended positions of both the femoral and
must not be moved during the operation,
The tibial jig / system handle assembly is
The femoral array should be positioned
tibial instruments to avoid any contact
as this will lead to inaccurate information
held in an approximate position on the
away from the intended incision and
during bone resection and drilling. It is
being displayed, and possible cancellation
tibial while a a mark is made to identify the
should not influence soft tissue and
important that the navigated system
of the procedure. Please refer to the
schantz pin position.Care should be taken
ligament movement in extension and
handle is attached to the tibial jig prior to
Clinical User Guide (Art-No: 60901-11EN)
to position the array clear of the tibial jig
flexion (Figure 9).
array fixation and that its position is noted.
for further information on positioning and
and any navigated instrument (Figure 8).
fixation of the reference arrays.
10
Tibial & Femoral Array Fixation
Camera Side
Screw
connector
Flexible
joint
Fixation
knob
Cortical
bone spikes
Figure 10
Figure 11
A schantz pin is inserted into the drill and
The tibial array is lowered onto the pin until
The screw connector is tightened by hand
The position of the camera in relation to
introduced bicortically to the tibia. A soft
it touches the surface of the leg and the
until the array is stable. A wrench is used
the patient is defined on the system
tissue cover should be used on the
spikes on the bottom of the array engage
to fully secure the final position and angle
(Figure 11).
schantz screw to avoid any tissue
with cortical bone. The array is angled so
of the array.
disruption. The reflective marker spheres
that it does not interfere with the positioning
Care should be taken if the patient has
should now be attached to the tibial
of the tibial jig and the navigated system
osteoporotic bone, as over tightening of
(T-shape) array.
handle (Figure 10).
the array may loosen the schantz pin.
11
Camera Alignment
Red dots: Tibial array
Yellow dots: Femoral array
Purple dots: Ci™ pointer
Blue dots: Additional Ci tools
Grey dots: Unknown marker
The status field
lights indicate that
all instruments
are visible
The camera field of view
Green:
Normal tracking mode
Yellow:
Ci™ instrument not visible to camera
is indicated by the blue cone
Red:
Red circles: Tibial array
Ci™ instrument and / or navigation array
not visible to camera for more than 3 seconds
Yellow circles: Femoral array
Purple circles: Ci™ pointer
Grey:
Blue circles: Additional Ci tools
Camera communication error during start-up
Re-start the system
Grey circles: Unknown marker
Figure 12
The camera alignment window highlights
Coloured dots represent the positions
The status field lights indicate the visibility
movement of the reference arrays and
of the femoral and tibial reference arrays,
of the arrays and instruments.
instruments. These are displayed as
and the Ci™ pointer.
The camera displays can be accessed at
different coloured dots and circles
The circles show the position of the
any time during the procedure by touching
instruments in relation to the camera unit’s
the status field lights.
on-screen (Figures 12).
field of view.
12
Incision & Exposure
Figure 13
Figure 14
Depending on the location of the
2 cm distal to the joint line (Figure 13). The
The deep menisco-tibial layer of the
pad may also be excised to improve vision
osteoarthrosis, an antero-medial or antero-
joint capsule is entered with a parapatellar
medial or lateral capsule should be
and allow inspection of the opposite
lateral skin incision is performed. The
incision (Figure 14). Once the joint is
carefully reflected to provide good access
compartment. Two large rake retractors are
incision should begin 1 cm proximal to the
exposed a final assessment can be made
to any tibial osteophytes and allow
then introduced to maintain access at all
superior border of the patella. It should
of the extent of arthritic damage and the
accurate wound closure. Any excess deep
stages of the procedure.
extend 6 - 10 cm distally along the edge of
suitability of the joint for this procedure.
synovium is excised to provide clear sight
No ligament releases should be
the patella and patella tendon, and end
of the joint. If required, all or part of the fat
performed as part of this procedure.
13
Registration
It is vital that all osteophytes are
removed from the entire medial or
lateral edges of the femur and tibia
Anatomic axis
Mechanical axis
Valgus angle
Joint line
Figure 15
Figure 16
In order to achieve medial / lateral (M/L)
A retractor is used on the patella rim to
Registration defines the mechanical axis
existing 3D model created from an
alignment and joint stability, it is vital that
draw the patella into a central position.
and important anatomical landmarks
extensive database of healthy and arthritic
all osteophytes are removed from the
Any significant osteophytes on the edge of
(Figure 16). This allows accurate
knees. Tibial registration is performed first,
entire medial or lateral edges of the femur
the patella should also be excised.
positioning and sizing of the intended
followed by femoral registration. Each
and tibia before registration takes place
implants. A 3D model of the patient’s bone
screen offers the option to re-perform the
(Figure 15).
anatomy is created and mapped onto an
step if required.
14
Calculating the Femoral Head Centre
An assistant may hold the
pelvis in position during this
step to ensure that an accurate
calculation is made.
Figure 17
Figure 18
Registration defines the mechanical axis
Calculating the rotational centre of the
The femur is pivoted using circular
The system calculates the centre of the
and important anatomical landmarks. This
femoral head defines the proximal point of
motions (Figure 17). The system
femoral head to within 3 mm. This relates
allows accurate positioning and sizing of
the mechanical axis. It is important to
calculates a series of points to determine
to no more than a 0.5˚ deviation on the
the intended implants. A customised 3D
make sure that the patient’s pelvis is not
the rotational centre and will automatically
mechanical axis. If the centre of the
model of the patient’s bone anatomy is
moved excessively during registration
proceed when the rotational centre has
femoral head is not calculated correctly,
created. Each screen offers the option to
as this will lead to miscalculation by
been calculated (Figure 18).
a warning box will appear and the step
re-perform the step if required.
the system.
is re-performed.
15
Pointer Tips
The pointer is pivoted prior
to a point being acquired
Figure 19
1. To acquire points accurately, it is helpful
Figure 20
2. To avoid acquiring unnecessary points
3. Make sure all three marker spheres on
to refer to the screen as each point
to hold the tip of the pointer with one
before the pointer is positioned, it may
the pointer are directed towards the
is acquired. If the camera cannot see
hand while pivoting the pointer with the
be helpful to cover one of the marker
camera unit when acquiring a point.
the pointer, a deep sounding ‘beep’ will
other. This will ensure that all of the
spheres with a hand. This will effectively
be heard,
4. When a point has been successfully
points are registered on the bone, not
‘eliminate’ the pointer from the field
away from the patient (Figure 19).
of view (Figure 20).
acquired, the system will emit an
audible ‘beep’. This removes the need
5. If at any stage during the procedure the
marker spheres become contaminated
with blood or tissue, they may be gently
16
cleaned using lint-free cloth.
Definition of the Malleoli
Figure 21
Figure 22
The medial and lateral malleolus are
Place the tip of the pointer to the medial
Acquiring the malleoli defines the distal
It is important that these points are
defined using the Ci™ pointer.
malleolus and pivot the pointer (Figure 21).
point of the mechanical axis.
acquired as accurately as possible as
implant position and alignment are
It is important not to move the tip of the
The malleoli can usually be located by
All single registration points for
referenced to the hip / ankle axis and
pointer from the bone. Once the system
hand before acquiring the points. It is
anatomical landmarks are acquired in
the mechanical axis.
has registered the medial malleolus, the
important that draping or bandaging is
the same way.
lateral malleolus can be registered in the
reduced to a minimum to enable the
same way (Figure 22).
malleoli to be located.
17
Definition of the Tibial Mechanical Axis
Figure 23
Figure 24
The mechanical axis is defined by
It is important that the point acquired
The definition of the mechanical axis is the
acquiring the posterior aspect of the ACL
defines the mechanical axis, and not the
basis for all further calculations and should
tibial attachment point (Figure 23).
tibial eminence.
be acquired as accurately as possible.
This is indicated by the arrow on screen
(Figure 24).
18
Tibial Sizing
Figure 25
Figure 26
The most medial or lateral point of the
The points should be acquired at the
The posterior point is required to assess
A visual check should also be performed
proximal tibia is acquired using the pointer,
approximate level of resection.
tibial component sizing. This point should
during the tray navigation step.
followed by the most anterior and posterior
be acquired as accurately as possible.
point on the affected compartment
(Figures 25 & 26).
19
Tibial A/P Direction
Figure 27
Figure 28
The pointer is placed on the tibia to
The pointer is held in place for 2 seconds
Note: incorrect registration of the tibial
determine the A/P direction of the tibial
to allow the system to calculate the
A/P direction may lead to compound
slope (Figure 27). If access to the centre of
direction (Figure 28).
slope phenomenon.
the tibia is limited, the pointer can be
placed to one side.
20
Tibial Modelling
Points should be acquired
around the rim, and as
posteriorly as possible
Figure 29
Figure 30
A fixed number of points along the anterior
The pointer is placed on the tibia and
The tip of the pointer should ‘paint’ the
The sequence ends when enough points
and medial or lateral tibia are acquired
pivoted to begin the procedure. A ‘beep’
surface of the tibia. Points should be
have been acquired.
using the Ci pointer. These are used to
will indicate when to begin moving the
acquired mainly around the rim and extend
define the bone model (Figure 29).
pointer (Figure 30).
as posteriorly as possible. Acquisitions
further down the tibia are less important,
but will add shape to the model.
21
Tibial Plateau Modelling
Place the tip of the
pointer in the centre
of the plateau
Figure 31
Figure 32
The Ci™ pointer should be placed in the
The tip is moved in a circular motion across
It may be helpful to apply varus or valgus
The sequence ends when enough points
centre of the medial or lateral tibial plateau
the surface of the plateau (Figure 32).
stress to the knee joint to allow greater
have been acquired.
(Figure 31).
access to the tibial plateau.
22
Tibial Model Calculation and Verification
The white areas
The deviation from the tip
represent acquired points
of the pointer to the bone
is represented in mm
Figure 33
Following registration, the system adapts
the tibial model (Figure 33).
• White areas are parts of the model with
Figure 34
• Brown areas are parts of the model
where no points have been acquired.
The maximum acceptable deviation is less
Note: implant sizing is based on aquired
than 2 mm. Acquired points will normally
points only. The accuracy of the model
show a deviation of less than 1 mm
should be checked on the areas
Verification of the model will only be
responsible for implant sizing and
accurate in white areas where points have
position (medial or lateral boundary,
been acquired (Figure 34).
medial or lateral plateau).
The accuracy of the model is checked by
deviations no greater than 2 mm from
holding the Ci™ pointer to the tibia. The
the actual bone structure.
exact deviation from the tip of the pointer
to the model is displayed on the screen.
23
Femoral Mechanical Axis
Figure 35
Figure 36
The registration of the femur is
The pointer should be placed at the
It is important that the mechanical axis
automatically activated once the tibial
anterior aspect of the femoral notch point
point is acquired as accurately as possible.
registration has been completed.
as indicated on screen (Figures 35 & 36).
24
Registration of Epicondyles
Figure 37
Figure 38
Acquisition of the most medial and lateral
These points are required for the model
epicondylar points may be made either
morphing process and are not used in
through the incision or on top of the skin
implant alignment.
(Figures 37 & 38).
25
Registration of the Anterior Cortex
Figure 42
The anterior cortex is acquired using the
This point helps to shape the final bone
pointer. Ideally, the pointer should be
model (Figures 39 & 40).
Figure 43
placed on the deepest point on the
anterior femoral cortex just above the
superior border of the femero-patella
articular surface.
26
Epicondylar Axis
Figure 41
Figure 42
The pointer is placed on the distal
The pointer can be positioned through the
Note: this line does not have an
condyles (below the patella) and held still
incision and can be checked by feeling
influence on the rotational alignment
to allow the system to calculate the
through the skin for contact.
of the femoral component.
epicondylar axis (Figures 41 & 42).
Alternatively, it can be held on top of the
incision and positioned against the
condyles.
27
Femoral Condyle Modelling
Points should be acquired
as posteriorly as possible
on the affected condyle
Figure 43
Figure 44
A fixed number of points along the surface
The tip of the pointer should ‘paint’ the
If insufficient posterior points are acquired
of the medial or lateral condyle are acquired
surface of the condyles. Points should be
the system will ask for the step to be re-
using the Ci™ pointer (Figures 43 & 44).
acquired as posteriorly as possible and
performed.
Acquisition should begin at the most
along the distal part of the affected condyle.
distal point.
This allows the system to accurately
calculate both the size and position of the
intended implant.
28
Borders of the Condyles
Figure 45
Figure 46
A fixed number of points along the border
These points will act as a guide to help
of the affected condyle are acquired using
define the M/L and rotational alignment of
the Ci™ pointer. It should move along the
the implant.
outer and inner edge of the condyle in one
movement (Figures 45 & 46).
29
Femoral Cortex Modelling
Figure 47
Figure 48
Multiple points on the affected side of the
anterior femoral cortex are acquired using
the Ci™ pointer (Figures 47 & 48).
30
Femoral Model Calculation and Verification
The white areas
The deviation from the tip
represent acquired points
of the pointer to the bone
is represented in mm
Figure 49
Following registration, the system adapts
the femoral model (Figure 49).
• White areas are parts of the model with
Figure 50
• Brown areas are parts of the model
where no points have been acquired.
The maximum acceptable deviation is less
Note: femoral implant sizing is based on
than 2 mm. Acquired points will normally
aquired points only. The accuracy of the
show a deviation of less than 1 mm
model should be checked on the areas
Verification of the model will only be
responsible for implant sizing and position.
The accuracy of the model is checked by
deviations no greater than 2 mm from
holding the Ci™ pointer to the tibia. The
the actual bone structure.
exact deviation from the tip of the pointer
accurate in white areas where points have
been acquired (Figure 50).
to the model is displayed on the screen.
31
Tibial Slope
Figure 51
Figure 52
The navigated plane is attached to the
After removal of the meniscus and with the
After a couple of seconds or by pressing
It may be helpful to remove the 3D model
navigated tibial handle with the flat side
leg in flexion, the instrument is placed on
‘next’ the system will measure the tibial
and use the acquired points only as a
facing down toward the tibia.
the tibial plateau as posteriorly as
slope angle and display this on screen
reference to adjusting the slope manually.
possible. The leg is placed in extension to
(Figure 52). The tibial slope angle can be
enable the instrument to be secured
re-adjusted manually if required. Pressing
between the tibia and femur (Figure 51).
‘next’ will accept the tibial slope angle.
32
Cartilage Defect Planning
Figure 53
Figure 54
The next few steps allow the surgeon to
The amount of cartilage to be removed
Important: Care should be taken when
Large cartilage defect assumptions
assess the pre-disease leg alignment.
should be assessed visually. The defect
assessing the cartilage defect. The larger
may produce a small distal resection
amount (in mm) is entered into the system.
the cartilage defect, the thinner the distal
face. This may cause problems with
Average defects range between 1 - 2 mm
bone resection. Choosing a 2 mm or
fixation of the femoral cutting block
and in severe cases up to 3 mm (Figures
3 mm cartilage defect may cause
later in the procedure.
53 & 54).
problems in patient’s with sclerotic bone.
33
Leg Extension
Desired Post-Operative Leg Alignment
Figure 55
Figure 56
The leg is placed in full extension and held
This is used to gauge the patient’s
The leg is then placed in approximately
When natural alignment is achieved
in position to allow the system to register
maximum extension range for the femoral
4 - 7 degrees of flexion. Varus / valgus
(balanced medial and lateral tension)
the maximum extension angle (Figure 55).
planning steps.
movement is applied to the joint and
the position is stored on the system.
ligament stress is assessed (Figure 56).
34
Leg Flexion
Femoral Implant Planning
Figure 57
Figure 58
The leg is placed in approximately
The femoral implant size and position is
Dark blue lines – proposed cutting plane
Green line - Most anterior point of the tibia,
85˚ to 95˚ of flexion. A neutral position of
displayed on screen (Figures 58-61).
of the femur
projected parallel to the mechanical axis of
Button functions and screen information:
Orange line - HKA line.
the tibia should be achieved. No external
femur. The anterior point of the femoral
A/P or rotational force should be applied.
component should always remain behind
The position is stored on the system
Blue arrows – allow repositioning of the
Yellow line – proposed cutting plane of
(Figure 57).
femoral component
the tibia
35
this line.
Frontal / flexed view (top left)
Lateral view (top right)
Projected
anterior point
of the tibia
Anterior / posterior
Anterior / posterior
translation
translation
Internal / external
M/L
Internal / external
Flexion / extension
Superior / inferior
Flexion / extension
rotation
rranslation
rotation
rotation
translation
rotation
Figure 59
Figure 60
The image can be zoomed in or out for
Adjustment is limited to 10 degrees internal /
better viewing using the Zoom function on
external rotation, while changes to superior /
the menu bar.
inferior adjustment will automatically
change the bone loss assumption.
36
Tibial Implant Planning
Planning information (bottom right)
The implant size function is
used to change the size of the
femoral component. After
changing the size, the distal
cut will be re-calculated, and
the flexion gap adjusted.
The system will only allow
compatible sized components
to be selected.
The ‘freesize’ option can be
used to manually change the
implant size. However, if
inappropriate implants are
selected, the system will
display a warning message
relating to implant
compatibility. The ‘proceed’
option will be removed at this
stage to force the user to
select compatible implants.
Figure 61
Figure 62
When using the fine tune functions, the
Tibial implant planning is conducted in the
Frontal / flexed view (top left screen)
acquired points are the main reference
same manner as the femoral implant
Superior / inferior and in varus / valgus
for planning and implant placement.
planning. Adjustments can be made to
adjustments can be made to the tibial
The 3D model only provides additional
both the proposed femoral and tibial
implant. If the tibial insert thickness is
information and 3D orientation.
implants at this stage (Figures 62 -66).
increased, the resection level is automatically
adjusted to ensure that leg alignment is
not influenced.
37
Frontal / flexed view (top left)
Lateral view (top right)
Figure 63
Figure 64
Axial view (bottom left)
Figure 65
Medial / lateral and rotational adjustments
Axial view (bottom left screen)
The yellow dot represents the centre of the
The tibial position and the femoral position
may also be made to the femoral
The tibial implant position can be adjusted
tibial component
(top left screen) are optimised to allow the
component at this stage.
in A/P, M/L and internal / external rotation.
contact point of the femoral component to
The red dot represents the contact point of
lay central on the tibial component.
The image shows the virtual tracking of the
Lateral view (top right screen)
the femoral component in extension
The orientation (red line) of the femur is
femoral component on the tibia in extension.
The posterior slope can be adjusted using
The red line represents the internal / external
approximately aligned to the direction of
direction of the femoral implant in extension.
the tibial component.
the blue arrows.
38
Motion Analysis
Planning Information (bottom right)
The ‘implant size’ and ‘implant
size’ buttons change the size
of the tibial component and /
or the insert. The tibial cut is
re-calculated and the gaps
adjusted accordingly. The
system only allows compatible
sized implants to be selected.
The ‘freesize’ option can be
used to change this manually.
However, the system will only
allow you to change the tibial
component and insert size if a
compatible femoral implant is
also selected at the same time.
Resets all
Returns to the
Accepts all
adjustments
previous step
adjustments
Figure 66
Figure 67
The planning screen displays the final tibial
The virtual contact points are shown on
The yellow dot represents the centre of the
implant data.
screen in real time through a full range of
tibial implant. The large red dot represents
motions (Figure 67). If adjustments need
the current contact point of the femoral
to be made to the plan shown on screen,
implant. The smaller red dots show the
the previous implant planning steps can
recorded contact points between the
be repeated.
femoral and tibial components.
39
Tibial Pin Insertion
Figure 68
Figure 69
The navigated system handle is attached
If the shape of the tibia does not allow
A slotted or non-slotted cutting option is
Note: If the pin is moved too far from the
to the tibial jig (Figure 68). The suggested
fixation in the M/L position shown on
selected on screen, depending on
suggested screen position, M/L
fixation position of the pin is shown on
screen, the closest possible position
preference (Figure 69).
adjustment may be difficult.
screen (Figure 69). The system handle
should be used.
When navigation is complete, the tibial jig
allows the tibial jig and pre-fixation pin to
is pinned in place.
be accurately positioned on screen.
40
Tibial Resection Navigation
Navigated L-cut block
Tibial slope adjustment screw
Figure 70
Figure 71
With the tibial jig pinned in place, the
Make sure the tibial jig is placed against
Step 1: The L-cut block is rotated until the
Step 2: The tibial slope is adjusted by
navigated handle is removed. The navigated
the tibia throughout the following steps to
navigated L-cut line (blue) is parallel to the
turning the slope screw until the planned
tibial jig array / L-cut block is attached to
maintain a consistent reference for the fine
planned L-cut line (yellow) (Figure 71).
and actual resection planes are parallel
the top of the tibial jig (Figure 70).
adjustments on screen.
Once in position, the screw is tightened to
in the sagittal view. The slope may be
ensure stable fixation.
increased by up to 2˚ after pinning the
jig to the bone. The slope cannot be
decreased at this stage.
41
Final pin position
M/L adjustment screw
Resection height adjustment screw
Second pin position
Figure 72
Figure 73
Step 3: The tibial jig is rotated around the
Step 4: The M/L-position of the L-cut is
Step 5: Once the M/L, varus / valgus and
Step 6: The height of the tibial cut is now
initial pin to adjust the varus / valgus angle.
adjusted by turning the M/L adjustment
tibial slope are aligned, the tibial jig is
adjusted by turning the vertical screw in
screw. It is important that the varus / valgus
secured in place below the cutting block
the centre of the tibial jig. Adjustments to
angle remains unchanged during M/L
using one or two pins (Figure 72).
the varus / valgus angle and tibial slope
adjustment.
can be made if required. The jig is secured
in place with a final pin prior to resection
(Figure 73).
42
Tibial Resection
Figure 75
Figure 74
The L-cut is initiated along the L-cut guide.
The transverse cut must be performed
Care must be taken to avoid over
avoid cutting into the unaffected condyle.
The L-cut can be completed after removing
according to the cutting option selected
resecting the bone or weakening the
The L-cut must not proceed past the
the L-cut block (Figure 74).
earlier (either slotted or non-slotted)
ACL. During the transverse cut, the saw
transverse cut as this may cause
(Figure 75).
blade must be kept as level as possible,
tibial fracture.
and the L-cut guide must be used to
43
Tibial Resection Verification
Figure 76
The tibial resection is verified using the
The resection may be repeated at this
navigated plane, attached to the navigated
stage if required.
Figure 77
handle (Figures 76 & 77).
44
Check Extension Gap
Figure 78
Figure 79
Figure 80
The distal femoral cutting block is attached
The system will indicate which tibial and
The cutting block is inserted into the
to the non-navigated handle (Figure 78).
femoral spacer blocks to attach to the
extension gap and the joint is assessed for
cutting block (Figure 79).
stability and alignment is checked on
screen (Figures 79 & 80).
45
Check Flexion Gap
Figure 81
The cutting block is removed and the knee
Note: Make sure the knee is stable in
is placed in approximately 90˚ of flexion.
extension. The flexion position allows for
The femoral spacer is removed, and the
slightly more laxity, which may help in
cutting block is inserted into the flexion
high flexion.
Figure 82
gap. The joint is assessed for stability
(Figures 81 & 82).
46
Extension / Flexion Gap Adjustments
Tight in Extension / Flexion OK:
• If the tibial slope is OK a small shave
Loose in Extension / Flexion OK:
of bone may be taken from the
• Check the tibial slope and re-cut
• Check the tibial slope and re-cut
posterior condyle.
if necessary.
if necessary.
• Alternatively, choose a thinner tibial insert
• Reduce the bone loss assumption
• Choose a thicker tibial insert and shave
or re-cut the tibia, and increase the bone
(i.e. a thinner bone loss shim may be
a little off the posterior condyle to adjust
loss assumption (i.e. a thicker bone loss
used to move the femoral component
the flexion gap.
shim may be used to move the femoral
slightly proximal)
component slightly distal).
• Alternatively, increase the bone loss
assumption (i.e. a thicker bone loss
Tight in Extension and Flexion:
shim may be used to move the femoral
Loose in Flexion / Extension OK:
component slightly distal).
• A thinner insert should be selected.
• Check the tibial slope and re-cut
• If a thinner insert is not available, re-cut
if necessary.
Loose in Extension and Flexion:
the tibia and update the tibial cut with
• Choose a thicker tibial insert and reduce
• Use a thicker tibial insert.
the navigated plane
bone loss assumption. Reduce the bone
loss assumption (i.e. a thinner bone loss
Tight in Flexion / Extension OK:
• Check the tibial slope and re-cut
• Note: Be careful with using larger bone
shim may be used to move the femoral
loss shims to correct a loose extension
component slightly proximal. The knee
position as this could lead to a very thin
should not be tight in flexion).
resection level on the distal femur. If this
if necessary.
resection level is very thin, fixation of the
femoral cutting block may be
problematic later in the procedure.
47
Distal Femoral Resection
Figure 83
Figure 84
The non-navigated system handle is
The block and spacers are introduced into
Two pins are used to fix the cutting block
Important: There should be no gap
attached to the distal femoral cutting
the joint and the leg flexed to the angle as
in place.
between the distal cutting block and the
block. The appropriate tibial and femoral
indicated on the screen (2 planes parallel).
surface of the femur. If a gap exists, the
spacers are added to the cutting block as
This ensures that the distal cut matches
resection will not match the planned
indicated on screen (Figure 84).
the planned flexion / extension angle of the
resection on the system.
femoral component (Figures 83 & 84).
48
Figure 85
Figure 86
The system handle is removed and the
To avoid capsular damage posteriorly, this
Once the resected distal bone is removed,
distal resection performed (Figure 85).
cut should be completed with the distal
any remaining soft tissue is cleared from
femoral cutting block removed (Figure 86).
the meniscal rim and posterior of the tibia.
49
Distal Femoral Resection Verification
Figure 87
The femoral resection is verified using the
The resection may be re-performed if
navigated plane (Figure 87).
required. The verified position is used to
Figure 88
update the plan on the system (Figure 88).
50
Tibial Template Navigation
Figure 89
The tibial template (as indicated on
If good bone coverage cannot be
screen) is attached to the navigated
achieved, a new position can be chosen
system handle and positioned on the
or the template size can be changed. The
Figure 90
• The yellow dot represents the centre of
the tibial component.
• The M/L and rotational position of
the femoral component can be
adjusted at this stage to improve
• The red dot represents the contact point
resected tibia using on screen navigation
template is held in position for 3 seconds
tracking alignment.
of the femoral component in extension.
(Figures 89 & 90).
to update the system. The axial view is
• The red line represents the internal /
used to assess the component tracking
external rotation of the femoral
on screen.
component in extension.
51
Tibial Template Preparation
Figure 91
Figure 92
With all on screen adjustments made,
A sagittal saw is used to pre-cut the keel
the navigated handle is removed and
slot. The tibial osteotome completes the
the template is fixed in place with a
keel preparation (Figure 92).
Specialist® II pin and the navigated handle
is removed (Figure 91).
52
Femoral Preparation
When the blue and yellow
dots are aligned, the M/L
and rotational position of
the block is correct.
Figure 93
Figure 94
The femoral finishing block is attached to
The block is placed flush to the distal
The screen indicates if the block is sitting
Rotational alignment and M/L position are
the navigated system handle.
femoral resection, with the foot held
flush on the distal cut (Figure 94).
navigated on screen.
against the posterior condyle. It may help
With correct alignment achieved, the block
to adjust the angle of the leg to reduce the
is pinned in place.
tension in on the patella while positioning
the block (Figure 93).
53
Figure 95
Figure 96
There are two pin holes on either side of
The system handle is removed and the
the block. The upper pin hole is angled,
posterior resection and posterior chamfer
and is used on the outer side of the
cut are made using a Preservation™ saw
condyle. The lower straight hole is used on
blade (Figure 96).
the side closest to the patella (Figure 95).
54
Figure 97
Figure 98
The femoral peg hole is made using the
The femoral slot is completed with a burr.
peg drill (Figure 97).
In cases where hard or sclerotic bone is
present the slot should be pre-cut with a
saw blade (Figure 98).
55
Figure 99
Figure 100
The 3/8th hibs gouge is used to mark the
The Preservation™ chisel is used to make
anterior profile of the femoral component
the anterior chamfer cut (Figure 100).
(Figure 99).
56
Component Trial & Verification
Figure 101
Figure 102
The trial components are used to ensure
The tibial prosthesis is trialed first and
The system will then display a report with
that the knee is placed in the appropriate
gently impacted into place using the
planned and achieved measures. The
position to facilitate implantation, prior to
C-arm impactor. The tray and keel should
appropriate tibial insert trial is inserted.
inserting the final components.
be fully seated on the tibia. The position of
For all poly and fixed bearing tibial
the three dimples in the trial are recorded
implants the same modular trials are used
with the pointer in the order as indicated
(Figure 103).
on screen (Figures 101 & 102).
57
Figure 103
Figure 104
Figure 105
The femoral prosthesis is attached to the
The system will then display a report
femoral introducer, introduced to the femur
with planned and achieved measures
and gently pushed into place using the
(Figure 106).
femoral impactor. The position of the three
dimples in the trial are recorded with the
pointer in the order indicated on screen
(Figures 104 & 105).
58
Figure 107
Figure 108
The joint is checked for alignment
The tracking of the components can also
Final femoral preparation should be
and stability in flexion and extension
be checked (Figure 108).
completed using current Preservation™
(Figure 107).
instruments.
59
Figure 109
A CD-ROM is inserted to allow all planning
The system will automatically save this
On the close application screen,
information, screenshots and therapy
information on shut-down. The system
press ‘finish’ to exit the Ci™ software
reports to be recorded.
shut-down begins after pressing the
(Figure 109).
‘close’ button on the final screen.
60
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This publication is not intended for distribution in the USA
The Ci™ logo and Ci™ are trademarks of DePuy International Ltd.
Preservation™ and Sigma™ are trademarks and LCS®, P.F.C.® and Specialist® are registered trademarks of DePuy Orthopaedics, Inc.
© 2004 DePuy International Limited. All rights reserved.
Cat No: 52527
BrainLAB AG
Ammerthalstraße 8
85551 Heimstetten
Germany
Tel: +49.89.991568-0
Fax: +49.89.991568-33
DePuy International Ltd
St Anthony’s Road
Leeds LS11 8DT
England
Tel: +44 (113) 270 0461
Fax: +44 (113) 272 4191