Zimmer Biomet ORTHOsoft Knee 2.4 Universal User Manual Dec 2016.pdf
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ORTHOsoft®
Knee 2.4 Universal
User Manual
Page 3
Table of Contents
System Overview.................................................................................................1
Indication for Use/Intended Use........................................................................... 1
Training................................................................................................................ 1
Implant Indications............................................................................................... 1
Contraindications................................................................................................. 1
Complications ...................................................................................................... 1
Preoperative Guide..............................................................................................2
Application Launch............................................................................................... 2
OR Setup.............................................................................................................. 3
Intraoperative Guide................................................................................................. 3
Tracking System’s Volume..................................................................................... 3
Remote Control in the Sterile Field........................................................................ 5
Assembling Markers............................................................................................. 5
Surgery Task Bar, Snapshot and Menu Buttons..................................................... 6
Surgeon Profile..................................................................................................... 6
General Preferences............................................................................................. 7
Workflow.............................................................................................................. 8
Femur Preferences................................................................................................ 8
Tibia Preferences.................................................................................................. 9
Targets................................................................................................................. 9
Patient Information............................................................................................... 9
Calibration of the Navigated Instruments ............................................................. 9
Positioning of the Bone References .................................................................... 11
Digitization of the Bony Landmarks .................................................................... 11
Surgical Technique: Distal Cut First..................................................................... 14
Surgical Technique: Anterior Cut First
with Insall Gap Balancing Technique................................................................... 24
Postoperative Guide................................................................................................29
Exiting the Application........................................................................................ 29
Case Data Manager............................................................................................ 29
Updating the System.......................................................................................... 29
Update According to Regulatory Region............................................................. 29
Shut Down the Sesamoid Plasty Computer......................................................... 30
Ordering and Instrument Cleaning/Sterilization Information............................. 31
Instrument Inventory and Sterilization/Cleaning Methods.................................. 31
Sterilization Parameters...................................................................................... 32
APPENDICES
Appendix A - CAS Same Incision Trackers............................................................... 43
Appendix B - Posterior Referencing Instrumentation............................................. 45
Appendix C - CAS Femoral Cut Alignment Guide used in Anterior Cut First.......... 48
Appendix D- CAS Independent Adjustment Mechanism Technique...................... 50
Appendix E - Universal Positioning Block Technique ............................................. 53
Appendix F - Distal Cut Navigation with Natural-Knee II System........................... 57
Appendix G - Implant “Universal” - Anterior Cut First
with Insall Gap Balancing Technique ...................................................................... 58
General Information...................................................................................Back Cover
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1 | ORTHOsoft Knee 2.4 Universal User Manual
System Overview
Indication for Use/Intended Use
Contraindications
The ORTHOsoft Knee Universal System is indicated
for use as a stereotaxic instrument to assist in the
positioning of total knee replacement components
intraoperatively.
Clinical
It is a computer controlled image-guidance system
equipped with a three-dimensional tracking sub-system.
It is intended to assist the surgeon in determining
reference alignment axes in relation to anatomical
landmarks, and in precisely positioning the alignment
instruments relative to these axes by displaying their
locations.
1. In the case of a hip pathology severely limiting
its range of motion (e.g. arthrodesis, severe
contractures, chronic severe dislocation);
Training
Prior to use of the system, surgeons must follow a
training given by Zimmer CAS or the application
distributor.
Warning: Zimmer CAS Surgical Navigation Systems
should only be used by trained surgeons.
Implant Indications
The knee implants installed with the system must be
used in accordance with their package insert labeling.
The operation should be performed in accordance with
the corresponding surgical technique published by the
manufacturer for the specific implant.
The ORTHOsoft Knee Universal System is compatible
with the femoral distal cut first and anterior cut first
surgical techniques.
Warning: The system should only be used with
the instruments provided by Zimmer CAS or
by the distributor for the given application.
Zimmer CAS Surgical Navigation System should not be
used:
2. In the case of a hip joint pathology or knee pathology
with significant bone loss (e.g. evascular necrosis of
the femoral head with collapse, severe dysplasia of
the femoral head or the acetabulum, femoral condyle
collapse); and
3. For any other contraindicated case, as given by the
implant manufacturer.
General
Zimmer CAS Surgical Navigation System should not be
used:
1. In the presence of strong infrared sources or infrared
reflectors in the vicinity of the optical markers. This
could cause interference with the Zimmer CAS
Optical System and alter its performance; or
2. To perform surgery other than those specified in the
surgical technique and the user guide.
Complications
Possible complications associated with the use of the
Zimmer CAS Surgical Navigation System may include,
but are not limited to, the following:
1. Infection; and
2. Misplacement of the implants potentially leading to
dislocation, impingement or leg length discrepancy.
The occurrence of one of these complications may affect
the patient’s mobility.
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Preoperative Guide
Application Launch
Step 1: After turning on the Sesamoid Plasty Computer,
press “ORTHOsoft TKA” and the Patient ID dialog box
will launch.
Step 2: To launch the application:
a. Enter the desired information in the Patient ID dialog
box and then click the “Continue” button;
or
b. Click on the “Skip” button.
Warning: To comply with the US HIPAA regulation,
this field should not contain any information
that could identify the patient.
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Preoperative Guide (cont.)
Intraoperative Guide
OR Setup
Tracking System’s Volume
Given that the field of the optical tracking system is
limited, appropriate positioning of the optical tracking
equipment is crucial. A specific camera location must be
selected to allow an unobstructed camera view of the
operation field.
The ORTHOsoft Knee Universal Application supports
three different types of the optical system volumes. An
automatic detection is performed when the application
is launched. The appropriate Volume viewer is selected
according to the camera’s configuration, i.e. available
tracking volumes and installed firmware.
An appropriate camera placement should allow for
the calibration of instruments and the navigation to be
carried out with a single rotation of the camera. This will
facilitate handling during surgery.
The shape and dimensions of the three kinds of volumes,
“Pyramid”, “Arc” and “Silo”, are shown in Figures 4.2
through 4.4.
The OR setup must be determined according to the
side of the operated knee (left or right knee), the
specifications of the optical system and the standard
instrument setup. Special care should be taken to
ensure that the femoral reference is seen during the
entire kinematics process (for more details about the
kinematics, refer to the Femoral Landmarks section
(p. 12).
Warning: Control of the line of sight is essential to
the proper use of the optical tracking system.
Refer to the Figure 4.1 for the correct camera placement.
The exact camera position depends on the OR setup,
the surgeon preferences and the position of the tracked
instruments relative to the patient.
Figure 4.1
Environment and OR Setup
Figure 4.2
Tracking Area of the “Pyramid” Volume
1. Top View
2. Front View
3. Tracking Area
Figure 4.3
Tracking Area of the “Arc” Volume
1. Top View
2. Front View
3. Tracking Area
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1.
Figure 4.4
Tracking Area of the “Silo” Volume
1. Top View
2. Front View
3. Tracking Area
The optimal visibility of the optical markers can be
controlled with the Volume viewer. Be careful not to have
two instruments with the same marker in the camera’s
field of view. All foreign objects should be removed from
the path between the camera and the markers.
The Volume viewer helps to aim the camera and to
verify that all tracked instruments are inside the camera
field before any calibration/navigation steps. The
markers that are seen by the optical tracking system are
displayed in the graphical representation of the camera
field. The application displays an icon marked with the
“No” symbol each time that an instrument needed to
complete the task is outside of the camera volume.
Two views of the Volume viewer are shown in Figure 4.5.
The top view is used for the horizontal adjustment of
the camera and the frontal view is used for the vertical
adjustment. The grey area outlined in both views
represents the optimal volume of the camera.
It is recommended to position the markers within the
grey area for the calibration of instruments.
Warning: It is preferable to calibrate or navigate
instruments in the central region of the volume
(identified in grey in every Volume viewer),
rather than on the outside edges of the volume.
2.
Figure 4.5
Volume Viewer
1. Pyramid Volume Viewer
2. Arc Volume Viewer
3. Silo Volume Viewer
3.
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Intraoperative Guide
Remote Control in the Sterile Field
The system can be also controlled with the help of the
CAS Registration Pointer, to activate the “Next” and
“Previous” buttons. This feature allows navigation
through the intraoperative procedure without user
interaction with the screen or the mouse. The pointer
tip placed on the femoral reference switches the “Next”
button. The pointer tip placed on the tibial reference
switches the “Previous” button.
The implant size can be modified by touching the bone
reference with the CAS Universal Offset Paddle. The tip
of the CAS Universal Offset Paddle placed on the femoral
reference switches the “Size Increment” button, whereas
the CAS Universal Offset Paddle placed on the tibial
reference switches the “Size Decrement” button.
Through all navigation panels (except in Femoral and
Tibial Landmarks panels), the snapshot can be triggered
using the CAS Registration Pointer from the sterile field,
by orienting the pointer’s tip upwards and respecting
the stability criterion. In any landmarking task, orienting
the pointer’s tip upwards and respecting the stability
criterion will trigger activation of the Remote menu
(Figure 4.7) for landmark reacquisition.
This menu will provide the ability to choose any available
landmark to reactivate. By tilting the pointer on one side
or the other, as shown with the feedback needle in Figure
4.7, the focus of the selector will change accordingly.
Once the focus is on the desired landmark to reactivate,
holding the pointer upwards and stable, in the OK
section, will trigger selection of the item.
Figure 4.7
Remote Menu
Assembling Markers
The NavitrackER Markers must be installed on each
instrument used for navigation. Push the marker onto the
mounting studs until it is firmly seated (CAS NavitrackER
Pliers can be used to facilitate the installation of the
markers on the instruments). It is important to verify that
the NavitrackER Markers remain clean throughout the
surgery.
Warning: Always minimize handling of the
NavitrackER Markers, since errors may result from
the non-uniform reflection of their surface.
Warning: Always use unblemished markers.
Warning: Always ensure that reflective NavitrackER
Markers are firmly seated.
Warning: The use of optical markers other than those
provided by Zimmer CAS may lead to inaccuracies.
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Surgery Task Bar, Snapshot and
Menu Buttons
The Surgery Task bar shown in Figure 4.8 allows direct
access to a specific panel. Icons featuring a thick white
color frame and blue background color indicate the
currently active panel. Icons featuring a thin blue color
frame and black background color indicate that the
surgery task is directly accessible. Greyed out icons
indicate that the surgery task is inactive.
Inactive surgery tasks become accessible once all
preceeding surgery tasks have been completed. The
number and order of the displayed surgery tasks depend
on the chosen Surgeon Profile settings.
Figure 4.8
Surgery Task Bar
The “Snapshot” button allows to capture the screen
display and save it to a file.
The “Menu” button gives access to a menu which
includes: a “Volume Viewer” button to verify the
instruments tracked by the optical tracking system, a
“Help” button that displays contextual help, an “Audio
Volume” button to set the volume, a “Language”
sub-menu to select the language of the user interface
and a “Quit Application” button to exit the application.
Surgeon Profile
The system uses the concept of profiles to store
particular surgical preferences. Once a profile is created,
it can be used to perform a surgery without specifying
the preferences again.
A list of the existing profiles is located on the left side of
the Surgeon Profile panel. Three buttons are available to
create (Create Profile), edit (Edit Profile) or permanently
remove (Delete Profile) a selected profile. Each selected
profile contains a list of preferences that are classified
into the following categories: General, Workflow, Femur,
Tibia and Targets.
Figure 4.9
Surgeon Profile
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Intraoperative Guide
General Preferences
Implant
This preference allows the surgeon to select the implant
used in the total knee replacement surgery. The
“Universal” choice can be selected to navigate only the
distal femoral and proximal tibial cuts (orientation and
resection levels) without navigating the femoral implant
size selection, the axial rotation or the A/P position.
Pointer Type
This preference allows the surgeon to select the type
of the CAS Registration Pointer that will be used for
navigation. The US pointer is the pointer manufactured
by Zimmer CAS with part number 20-8000-070-01.
The EU pointer is a pointer manufactured by Zimmer
Biomet with part number 05.00017.310.
Show 30°–60° in ROM (Range of Motion)
This option enables the 30 and 60 degrees of flexion
indicators in the ROM panel in addition to the 0 and
90 Degrees of flexion indicators.
Positioning Instrument
This preference allows the surgeon to select between
two instruments for adjusting varus/valgus, flexion/
extension or tibial slope using femoral distal and tibial
cutting guides.
1. CAS Universal Positioning Block
(calibration is required)
Warning: The spring of the CAS Universal Positioning
Block should not be bent with pliers. Doing so could
damage the instrument.
• If a 1.27 mm or thicker cutting block slot thickness
(closed cutting block) is used to perform the cuts,
the CAS Universal Offset Paddle 1.27 mm (P/N
108.116) should be used to navigate the cutting
planes. In the Surgeon Profile settings, the selection
for the Cutting Slot Thickness preference must be
equal to the thickness of the saw slot used to perform
the cuts even if thicker than 1.27 mm.
• If the cutting blocks have no integrated cutting slots
(open cutting block), the CAS Universal Magnetic
Offset Paddle (P/N 108.117) could be used to
navigate the cutting planes. In the Surgeon Profile
settings, “No Cutting Slot” must be selected as the
Cutting Slot Thickness.
Warning: Make sure the appropriate Cutting Slot
Thickness is selected for the saw slot of the cutting
block.
Warning: The CAS Universal Magnetic Offset Paddle
must not be used with cutting guide having a saw
capture (closed cutting block).
Warning: Whenever using a CAS Universal Offset
Paddle or the CAS Universal Positioning Block,
ensure the blade is fully inserted in the slot to be
navigated.
Cutting Slot Thickness
Warning: The MIS Innex A/P Cutting Guide* should
be used with the CAS Universal Magnetic Offset
Paddle placed against the lower portion of the
cutting saw slot. The 1.00 or 1.27 mm CAS Universal
Offset Paddles should not be used with the MIS
Innex A/P Cutting Guide* and its saw capture which
presents offsets.
This preference allows the surgeon to select the
appropriate slot thickness. If the cutting blocks have saw
guide slots, the surgeon must choose between the 1.00,
1.27, 1.35 or 1.45 mm thickness in accordance with the
thickness of the slot used for the tibial and femoral cuts.
Warning: The standard Innex A/P Cutting Guide*
should be used only with the 1.00 or 1.27 mm CAS
Universal Offset Paddles because the shoulder is too
narrow for it to provide stable support for the CAS
Universal Magnetic Offset Paddle.
• If a 1.00 mm cutting block slot thickness (closed
cutting block) is used to perform the cuts, the CAS
Universal Offset Paddle 1.00 mm (P/N 108.115)
should be used to navigate the cutting planes. In the
Surgeon Profile settings, 1.00 mm must be selected
as the Cutting Slot Thickness.
Warning: For the insertion of the CAS Universal
Offset Paddle (1.00 mm or 1.27 mm) in the slot of
the cutting block, avoid recessed holes since the
instrument could remain trapped.
2. CAS Universal Offset Paddle
(calibration is not required)
*Innex Implant not available in the US
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Workflow
Femur Preferences
First Cut
Compute Distal Resection Level
This preference allows the surgeon to select the
preferred surgical technique starting with the anterior
cut first (AC 1st) or distal cut first (DC 1st).
This preference enables navigation of the distal
resection level that requires digitization of the femoral
distal condyles.
Surgical Flow
Compute Posterior Resection Level
This preference allows the surgeon to select the surgical
flow for the surgery. The femur can be navigated first or
the tibia.
This preference enables navigation of the posterior
resection level on the Femur Rotation Navigation panel
or the Anterior Cut Navigation panel.
Perform Initial ROM
Distal Condyles Acquisition Method
This option enables the preoperative Range of Motion
(ROM) panel. It can be used to help evaluate the flexion
contracture and the varus/valgus deformity at different
flexion angles.
This preference allows the surgeon to select the
preferred method for digitization of the distal femoral
condyles.
The product supports two methods: acquisition of
multiple points or digitization with the CAS Universal
Validation Tool.
Enable Femur Rotation Panel (DC 1st)
This option enables the Femoral Rotation panel in the
distal cut first sequence. This panel allows selecting the
implant size, set the Anterior/Posterior position and the
axial rotation of the implant.
Gap Balancing Technique
This option allows the selection of the preferred ligament
balancing technique. The supported techniques are
Insall Gap Balancing and Soft Tissue Balancing. Insall
Gap Balancing is only available when the Femoral
Rotation panel is enabled.
Navigate CAS Tensor
This preference allows the surgeon to use the CAS
Tensor for ligament balancing and placement of the
femoral component. The CAS Tensor is only available
when performing Insall Gap Balancing.
Enable Varus/Valgus Panel (AC 1st)
This option enables the Varus/Valgus Adjustment panel
that is used to set the desired varus/valgus of the cutting
block.
Compute A/P Axis of Rotation
This preference triggers the application to display the
femoral rotation angle with respect to Whiteside’s line
on the distal femur, as digitized by the user. If enabled,
the A/P axis and rotation angle based on the Whiteside’s
line will be displayed in the Femur Rotation Navigation
panel or the Anterior Cut Navigation panel.
Compute Epicondylar Axis Rotation
This preference triggers the acquisition of two
landmarks on the medial and lateral femoral
epicondyles. If enabled, the femoral rotation angle,
based on the line between the two epicondyles, will be
displayed in the Femur Rotation Navigation panel or the
Anterior Cut Navigation panel.
Compute M/L Size
This option enables computation of the M/L sizing.
The suggested M/L size of the implant will be displayed
in the Femur Rotation Navigation panel and Anterior Cut
Navigation panel.
For Gender Solutions® Implant families, the M/L sizing
suggestion will provide information on the appropriate
implant type (male or female) among the selected
implant size. An M/L sizing suggestion displayed in
red means that the smallest implant size is too wide in
comparison to the digitized femur.
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Intraoperative Guide
Tibia Preferences
Patient Information
Compute Resection Level
The Patient Information panel allows selection of the
operative side. Click the “L” icon for a left knee or the “R”
icon for a right knee (Figure 4.11). The selected operative
side is highlighted in blue.
This preference enables the navigation of the resection
level that requires the acquisition of two points on the
tibial condyles.
Axial Acquisition Method
This preference allows the surgeon to select the
preferred method for axial acquisition. The product
supports two methods: acquisition of PCL-tubercle or
acquisition of the relative position of the femur and tibia
when the knee is flexed at 90 degrees (refer to the Tibial
Landmarks section (p.13) for more details).
Warning: Make sure that the correct patient side is
selected before starting the navigation.
Show Natural Varus/Valgus
This preference triggers the calculation of the natural
varus/valgus angle. If enabled, the natural varus/valgus
angle will be displayed in the Tibia Navigation panel.
The natural varus/valgus angle is the varus/valgus
orientation of the intact tibial plateau as defined by the
medial and lateral points digitized on the tibia.
Show Rotational Angles
This preference enables the display of the axial rotation
angles in the Tibia Navigation panel.
Compute Post. Plateau Rotation
This preference triggers the calculation of the rotation
angle with respect to the points acquired on the medial
and lateral posterior plateau of the tibia. If enabled, the
posterior plateau rotation angle will be displayed in the
Tibia Navigation panel.
Targets
Distal Resection Level
This preference sets the targeted resection level of the
distal cut in the Femur Navigation panel.
Implant Distal Cut Angle
This preference is available only when the “Universal”
implant is navigated in the Anterior Cut First sequence.
This option is required to pre-set the targeted implant
distal cut angle (flexion/extension).
Tibia Posterior Slope
This preference sets the targeted posterior slope of the
tibial cut in the Tibia Navigation panel.
Tibia Resection Level
This preference sets the targeted resection level of the
tibia cut in the Tibia Navigation panel.
Figure 4.11
Patient Information
Calibration of the Navigated
Instruments
Note: The following instruments can be calibrated
while the patient is being prepared in order to
minimize the time of the surgery:
Warning: Verify that the tools are in good condition
to perform the operation. If you notice any signs of
bending, fatigue or deterioration, do not use the
application and contact technical support.
Warning: Avoid placement of markers on both sides
of the CAS Universal Validation Tool Body.
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US and EU CAS Registration Pointer
CAS Universal Positioning Block
The instructions related to the pointer calibration
procedure are illustrated in Figure 4.12.
The instructions related to the CAS Universal Positioning
Block Calibration procedure are illustrated in Figure 4.13.
Figure 4.12
CAS Registration Pointer Calibration
Figure 4.13
CAS Universal Positioning Block Calibration
1. Attach the size 4 NavitrackER Marker on the side of the CAS
Universal Validation Tool Body that will face the camera.
1. Attach NavitrackER Markers, sizes 2 and 9, to the CAS
Universal Positioning Block.
2. Attach the CAS Short Posterior Condyles Digitizer (with the
applicable drill guide) or the CAS Posterior/Distal Condyles
Digitizer to the CAS Universal Validation Tool Body and
secure the locking mechanism.
2. Insert the CAS Universal Positioning Block into the
CAS Universal Validation Tool Body. Make sure it is
fully entered into the slot to the shoulder limit.
3. Place the assembly on the CAS Calibration Star Holder.
3. Orient optical markers towards the camera and
secure the rotational tracker (if applicable).
4. Insert the CAS Registration Pointer in the CAS Universal
Validation Tool Body and tighten the wing screw.
4. Position the assembly in the optimal part of the
camera volume (grey zone).
5. Make sure that the tip of CAS Registration Pointer is in
contact with the base of the pointer hole.
5. Successful calibration will be confirmed by a check
mark and a sound.
Warning: Make sure that the tip of the CAS Registration
Pointer is in contact with the base of the pointer hole. If
not, calibration of the pointer may be inaccurate and lead
to inaccurate positioning of the implant.
6. Position the assembly in the optimal part of the camera
volume (grey zone).
7. Successful calibration will be confirmed by a check mark
and a sound.
Warning: Whenever using the CAS Universal Offset
Paddle or the CAS Universal Positioning Block,
ensure the blade is fully inserted in the slot to be
navigated with the blade’s shoulder against the edge
of the slot.
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Intraoperative Guide
Positioning of the Bone References
Digitization of the Bony Landmarks
The bone references are used to track the patient’s
femur and tibia and show the navigated instruments in
relation to their respective positions.
Digitization of the bony landmarks is required to display
the relevant information in the navigation panels.
This system allows automatic registration of points
using a stability criterion with the pointer. An initial
movement of the instrument is first required to initialize
the registration of the points. Confirmation sounds are
played to advise the user that a point has been acquired
successfully or unsuccessfully.
Warning: Bone references MUST be firmly attached
to the bone and MUST NOT move at any moment
during surgery. In the case of a bone reference has
moved, the landmarks digitized on that bone must be
digitized again.
Warning: Beware that muscle fibers may apply
bending forces on the pins.
Warning: Make sure that the pins are not positioned
close to the bone cuts. Placing the pins close to the
bone cuts location will increase the risk of breaking
the pins with the cutting tools.
Femoral Reference
In order to install the femoral reference, use two CAS
Fix Pin Fluted or pins of equivalent type (Steinmann).
The pins can be inserted percutaneously through the
vastus medialis in the femur, as proximal as possible, to
stay clear of the working area. The pins should be set
bicortically in the bone to ensure maximum stability.
However, when an intramedullary rod is used, place the
pins in the distal part of the femur to avoid interference
between the pins and the rod.
Warning: Be alert to the risk of causing damage to
the saphenous artery and vein, femoral artery and
vein, or the popliteal artery and vein while installing
the bone reference.
Tibial Reference
Two CAS Fix Pin Fluted are used to install the tibial
reference. To obtain a non-obstructed working area, the
pins are inserted percutaneously into the medial surface
of the tibial diaphysis at approximately mid-tibia. They
should be set bi-cortically to ensure maximal stability in
the bone. In cases where an intramedullary rod is used,
place the pins in the proximal part of the tibia to avoid
interference between the pins and the rod.
If a keeled implant is used and the pins are placed more
proximally, ensure that the pins are not placed in an area
of interference with the keel. Impact with the keel or its
broaching instruments can cause breakage of the pins as
well as movement of the reference, which could result in
inaccuracies.
Furthermore, two points may not be digitized at the
same location. Therefore a minimal displacement of 5
mm is required between two points.
Exceptions
1. The posterior tibia and healthy plateau points on the
same M/L side can be digitized at the same position,
as well as the distal femoral condylar points and the
M/L landmarks. Also, no proximity criterion is applied
between the mechanical tibial entry point and the
PCL entry point.
2. The minimum distance between the femur
mechanical entry point and the A/P trochlear groove
points is 3 mm.
3. A minimal distance of 20 mm must be observed
between two points used to create an axis (e.g.
epicondylar axis, tibial tubercle-PCL axis, etc.).
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Femoral Landmarks
Successful digitization of the femoral landmarks enables
the Femur Navigation panels.
Femoral Head
Detection of the femoral head center is performed
by recording 14 static positions of the leg. For each
acquired point, the leg should be stabilized until a
confirmation sound is played. The points should be
taken in a large conical pattern with respect to the
femoral reference.
If a non-recommended pattern such as two unique
positions in flexion/extension or a small cone is
performed, the center of rotation algorithm will reject
the result. As a result, a pop-up will appear asking the
user to redo the acquisition (Figure 4.14). If a center was
already acquired and accepted, the user will be asked to
retry or keep the previous accepted center of the femoral
head.
Warning: To ensure an accurate detection of the
center of the femoral head, cover a wide circle with
the leg when completing the process.
Mechanical Axis Entry Point
The entry point of the mechanical axis is defined as the
deepest point of the intercondylar notch.1
It is recommended to determine the desired entry point
on a preoperative radiograph and compare it with the
intraoperative location in situ.
Together with the femoral head, the entry point forms
the femoral mechanical axis that is used as the main axis
of the femoral coordinate system. The varus/valgus,
flexion/extension and rotation values are computed
relative to the mechanical axis.
Anterior Cortex Points
These points are digitized on the anterior cortex and
are then used for the sizing of the femur and to gage
notching. Three points have to be acquired along the
femoral mechanical axis. The length between each of the
three points should be 2–2.5 cm, totaling approximately
4–5 cm between the first and last point.
Warning: If the digitization of the anterior cortex
is done on the extension of the lateral condyle, the
implant sizing suggestion will be over-estimated.
Epicondylar Axis (Optional)
The epicondylar axis is used for the femoral rotational
alignment. It is determined according to the digitization
of the medial and lateral epicondyles.
Figure 4.14
Failure of the Center of Rotation Algorithm
The pelvis and the optical camera must remain stable
during the whole process to obtain a good level of
accuracy. The minimum distance between each position
is 20 mm. The algorithm automatically validates the
kinematics.
Femoral head detection is a crucial process that
will influence the end result of the surgery. The
contraindications for the femoral head detection are
hip pathologies severely limiting its range of motion
(e.g. arthritis and hip dysplasia). In order to verify the
contraindications, place the femur in internal rotation
and verify that the hip does not move during the
kinematics procedure.
Warning: The pelvis and the optical camera must
remain immobile during the whole femoral head
digitization process to ensure system accuracy.
M/L (Optional)
The two points are digitized on the medial and lateral
edges of the femoral distal condyles. Then the M/L
sizing of the femoral component is suggested based on
the digitized points.
A/P Axis (Optional)
The A/P axis is also used for the femoral rotational
alignment. It is determined according to the digitization
of a point right above the femoral notch and a second
one in the deepest section of the trochlea.
References
1. Oswald MH et al. (1993). Radiological analysis of normal axial
alignment of femur and tibia in view of total knee arthroplasty.
J Arthroplasty. Aug;8(4): 419-26.
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Intraoperative Guide
Femoral Landmarks (cont.)
Distal Condyles
Posterior Condyles
These points are digitized on the distal femoral
condyles. They are used to compute the distal resection
level that is displayed in the Distal Cut Navigation panel.
The most posterior points of the femoral condyles are
digitized using the CAS Universal Validation Tool Body
with the CAS Posterior Condyles Digitizer. Depending
on the curvature of the distal femur in sagittal view, a
slight flexion should be set before digitization of the
points. During acquisition, verify that the CAS Posterior
Condyles Digitizer is in contact with both posterior
condyles. If proper contact is not achieved, sizing
problems and rotational misalignment might occur.
Multiple Points Method
One of the methods to digitize the distal femoral
condyles is to acquire multiple points (six points) with
the CAS Registration Pointer.
Warning: Care must be taken not to penetrate
through the cartilage with the pointer tip.
Warning: Final results depend on the accurate
acquisition of landmarks. For accurate depth results,
ensure that distal condyles are digitized most distally
with respect to the distal cut, taking into account the
flexion of the cut.
CAS Universal Validation Tool Body Method
The distal femoral condyles can also be acquired with
the CAS Universal Validation Tool Body. Refer to Figure
4.15 for the detailed instruction.
Tibial Landmarks
Successful digitization of the tibial landmarks enables
the Tibia Navigation panel.
Mechanical Axis Entry Point
The entry point is identified as the entrance point of
the intramedullary canal. This point should be centered
along medial/lateral axis. A/P positioning should fall
between the middle and one-third of the anterior edge
of the tibial plateau.
Healthy Plateau Points (Optional)
The resection level displayed in the Tibia Cut Navigation
panel is computed with two points digitized on healthy
areas of the medial and lateral plateau of the tibia.
Warning: Care must be taken not to penetrate
through the cartilage with the pointer tip. Avoid
damaged areas.
Warning: Whenever the digitization of a healthy
plateau is not possible, either due to spatial limitation
in the incision or due to specific anatomical issues,
register the inaccessible plateau on the anterior distal
tibia. The resection level from that side will not be
displayed, which will prevent confusion in the tibial
resection levels.
Figure 4.15
Acquisition of the Distal Femoral Condyles
with CAS Universal Validation Tool Body
1. Position the CAS Universal Validation Tool Body such
that the edge of the instrument is in contact with the
referenced (e.g. healthy) distal condyle.
2. Adjust flexion/extension and varus/valgus angles
of the instrument to the target angles of the distal
femoral cut.
3. Stabilize the instrument.
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Tibial Landmarks (cont.)
Surgical Technique: Distal Cut First
Axial Acquisition Method
Tubercle - PCL
This technique can be applied to NexGen Complete Knee
Solution, Persona® Knee Implants, Vanguard® Complete
Knee System* or Natural-Knee System Implants. The
workflow for cutting the distal femur first is as follows:
The neutral rotation is defined by a point in the middle
of the PCL insertion area on the tibial plateau and one on
the medial third of the tibial tuberosity. This axis should
lie perpendicular to the posterior edges of the proximal
tibia.
Flexion Acquisition
In digitizing the A/P axis of the tibia, an acquisition in
flexion can be used to transfer the alignment of the
femoral mechanical axis to the tibial coordinate system.
It must be noted that an initial movement of the leg is
first required to initialize the acquisition in flexion. On
average, this rotational axis option is aligned with the
posterior aspect of the tibial plateau, which could differ
from the tubercule-PCL alignment.
1. Initial Range of Motion
2. Tibial Cut Navigation
3. Distal Cut Navigation
4. Femoral Rotation Navigation (anterior cut)
5. Postoperative Range of Motion
The sequence of tibia or femur first is user selectable in
the Surgeon Profile panel settings.
Warning: During ligament balancing procedure
do not apply excessive stress to the knee joint
compartments in order to avoid permanent damage
to the ligaments.
Initial Range of Motion (ROM)
The initial Range of Motion panel can be used to evaluate
the preoperative flexion contracture and the varus/
valgus (V/V) deformity. The panel is shown in
Figure 4.17.
Figure 4.16
Flexion Acquisition
Warning: Care should be taken to avoid any torsion
of the tibia during acquisition with the leg in flexion,
i.e. aligning the unstressed foot forward (neutral
rotation).
Posterior Plateau (Optional)
The posterior plane rotation angle displayed in the
Tibia Navigation panel is based on these two points.
They must be digitized on the posterior limit of both the
medial and lateral plateaus.
Figure 4.17
ROM Panel
Ankle points
In order to recreate the mechanical axis of the tibia,
two points are digitized on the medial and the lateral
malleolus. The varus/valgus, flexion/extension and
rotation values are computed relative to the mechanical
axis.
*Vanguard XP not supported
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Intraoperative Guide
Initial Range of Motion (cont.)
The varus/valgus (HKA) angle is displayed under the
Left viewer that displays the lower limb alignment in an
A/P view. The flexion angle is displayed under the Right
viewer, which displays a sagittal view of the lower limb
alignment.
An initial movement of the leg is required first to initialize
the procedure. Then, evaluate the varus/valgus stability
in full extension (0 degrees of flexion) by applying
medial and lateral stresses to the knee joint to assess the
amount of passive correction obtainable.
The amount of varus/valgus can be also assessed at
30 degrees, 60 degrees and 90 degrees of flexion.
The maximum varus/valgus angle values are recorded
in the indicators for each of the four angles of flexion
(0 degrees, 30 degrees, 60 degrees and 90 degrees).
During the ROM procedure, the application will switch
automatically from one indicator to another as the user
goes to each flexion angle. In addition, the “Clear All”
button is available to reset the indicators and restart the
ROM procedure.
Figure 4.18
Installation and use of the CAS Universal Offset Paddle
1. Place the standard extramedullary jig on the tibia.
2. Fix the jig on the tibial plateau.
3. Slide the CAS Universal Offset Paddle and navigate
the tibial cut.
4. Insert pins through the cutting guide to the bone.
Tibial Cut Navigation
The purpose of the Tibia Navigation panel is to assist
the surgeon to perform the desired tibial proximal
resection. This panel allows the positioning of the tibial
cutting guide with respect to the tibial mechanical axis
and adjustment of the resection level. The panel consists
of three subtasks: Navigate Bone Fixation (only for
CAS Universal Positioning Block Instrumentation, refer
to Appendix E on page 53 for more details), Navigate
Cutting Block, and Tibial Cut Validation.
Warning: Make sure to use the appropriate CAS
Universal Offset Paddle for the Cutting Block
Navigation. The paddle used should be the selected
from one of the preferences. Use of the wrong CAS
Universal Offset Paddle could lead to resection level
inaccuracies.
Warning: The CAS Universal Offset Paddle is
compatible with standard cutting blocks that have
cutting slots or planar surfaces for cut alignment.
The use of a CAS Universal Offset Paddle with
any incompatible cutting block could lead to
inaccuracies.
5. Remove the extramedullary jig to perform the tibial
cut.
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Tibial Cut Navigation (cont.)
Navigate Cutting Block
Tibial Cut Validation
The intent of the Navigate Cutting Block subtask is to
set the appropriate orientation of the standard tibial
cutting guide with respect to the mechanical tibial axis.
In the panel, the medial and lateral Resection Level
indicators are displayed under the Frontal viewer. Note
that if a plateau was inaccessible and registered on
the recommended anterior distal tibia, the resection
level from that side will not be shown. The Posterior
Slope indicator is displayed under the Lateral viewer.
In addition, the varus/valgus and axial rotation angles
of the navigated cutting guide are located in between
the two viewers. In order to navigate and position the
tibial cutting guide, refer to Figure 4.19 for the detailed
instructions.
The purpose of the tibial cut validation is to verify if the
tibial resection was achieved as desired. It is mainly
used to inspect the orientation and, if needed, introduce
the necessary corrections to the tibial cut. In order to
validate the tibial resection, refer to Figure 4.20 for the
detailed instructions.
Figure 4.20
Tibial Cut Validation
1. Attach the CAS Short Posterior Condyles Digitizer
(with the applicable drill guide) or the CAS Posterior
and Distal Condyles Digitizer to the CAS Universal
Validation Tool Body.
Figure 4.19
Navigate Cutting Block
1. Use the extramedullary instruments (from the
standard instrumentation system) to adjust varus/
valgus, posterior slope and the resection level.
2. Secure the position of the tibial cutting guide with the
drive pins.
3. Remove the extramedullary assembly.
4. Perform the tibial resection with the help of the
positioned tibial cutting guide.
Warning: The CAS Universal Offset Paddle should
not be used as a lever arm to correct the cutting
block orientation. Doing so could bend the tip of the
instrument and result in inaccurate measurements
for all subsequent navigated surgeries.
2. Place the CAS Universal Validation Tool Body on the
tibial cut.
3. Stabilize the instrument to acquire the varus/valgus,
posterior slope and resection level of the cut.
4. Verify the values and introduce the corrections if
needed.
5. To restart the Tibial Cut Validation subtask move the
CAS Universal Validation Tool Body in the camera
volume.
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Intraoperative Guide
Distal Cut Navigation
The intent of the Distal Cut Navigation panel is to assist
the surgeon to perform the desired femoral distal
resection. This panel is designed to allow accurate
positioning of the distal cutting guide with respect to the
femoral mechanical axis, adjustment the resection level
of the cut, and estimation of the implant size. The panel
consists of three subtasks: Navigate Bone Fixation (only
for CAS Universal Positioning Block Instrumentation;
refer to page 53 of Appendix E for more details),
Navigate Cutting Block, and Distal Cut Validation.
2. It is recommended to add some extension during
insertion of the spike to counter the common
tendency of inserting with excess flexion. Only gross
spike alignment is necessary since the adjustment
mechanism allows for a fine adjustment of 30 degrees
in extension and 15 degrees in flexion.
Instrument Setup
In distal cut first, follow these steps to align the cutting
guide as desired.
1. Assemble the CAS Distal First Spike with the CAS
Extractor Adaptor, making sure the rotation limiting
pin is properly aligned, as shown in Figure 4.21.
Pierce the cortex at the mechanical axis entry point
with a cortex breaker or a 3.2 mm drill bit (only a
few millimeters in depth). Align the CAS Extractor
Adaptor Arm in the anterior direction (along the
Whiteside’s line). Impact the spike into the distal
femur, as shown in Figure 4.21. Do not impact deeper
than the end of the four blades on the spike.
Figure 4.22
Insertion of the Spike in Proper Flexion
Warning: Make sure the spike is stable before
performing manipulations relative to the next steps.
3. In order to save time and ease intraoperative
manipulations, the scrub nurse should align the
varus/valgus (green screw) and the flexion/extension
(AO fitting) at zero degrees as a starting point.
Loosening the rotation locking lever (yellow) prior to
installation will ease manipulations. See Figure 4.23.
Figure 4.21
Installation of the CAS Distal First Spike
Figure 4.23
Adjust the CAS Femoral Cut Alignment Guide.
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Distal Cut Navigation (cont.)
4. Assemble the CAS Mini Cutting Block 1.27 mm to
the CAS Distal Cutting Block Platform using the CAS
Cutting Block Screw and slide the assembly in the
main alignment guide, as shown in Figure 4.24. The
cutting guide can be positioned in three locations
(medial, lateral, or centered). It is suggested to use
the center position, but particular circumstances
and patient conditions may require using another
position per surgeon preference.
Navigate Cutting Block
The intent of the Navigate Cutting Block subtask is to
set the appropriate orientation of the cutting guide with
respect to the femoral mechanical axis. In the panel,
the angles of varus/valgus and flexion/extension of the
navigated cutting block are displayed under the Frontal
and Lateral viewers. In addition, the resection level and
the suggested size of the implant are displayed in the
indicators that are located between the two viewers. In
order to navigate and position the distal femoral cutting
guide, refer to Figures 4.26, 4.27 and 4.28 for the
detailed instructions.
6. After releasing the T-handle, adjust the flexion/
extension angle and lock it in desired position by
tightening that same T-handle.
Figure 4.24
Assembly of the CAS Mini Cutting Block 1.27 mm with the CAS
Distal Cutting Block Platform.
5. Slide the complete assembly on the inserted spike.
Figure 4.26
Locking the Flexion/Extension Adjustment
7. Adjust varus/valgus angle by pressing on the “V-V”
fork and releasing it in the desired position, as shown
in Figure 4.28. Using the green screws, on both
medial and lateral sides, finely adjust the varus/
valgus angle either by hand or using a screwdriver.
8. Adjust distal resection to the desired value by
rotating the blue wheel on the distal platform, as
shown in Figure 4.28.
Figure 4.25
Assembly Fixed on the Femur
Warning: Using the CAS Universal Offset Paddle 1.0
mm in the CAS Mini Cutting Block 1.27 mm can be
permitted if the thumb screw is tightened slightly
more than usually to remove the free-play in the
cutting slot.
Warning: The CAS Mini Cutting Block 1.27 mm can
be disassembled from the CAS Distal Cutting Block
Platform if the user unscrews the CAS Cutting Block
Screw (108.089.06) too much.
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Intraoperative Guide
Distal Cut Navigation (cont.)
10. Once the distal cutting guide is firmly positioned
on the bone, unscrew the knob holding the cutting
guide, and remove the assembly, leaving the cutting
block in place as shown in Figure 4.30 below.
Figure 4.27
Distal Cut Screen
Figure 4.30
Remove the Assembly, Leaving the Cutting Block in Place
11. If the resection level is not satisfactory after removing
the assembly, alternate holes (-2 mm, +2 mm, +4 mm,
+6 mm) can be used to achieve the desired bone
resection level.
Figure 4.31
Move Block to Other Pinholes as Necessary
Figure 4.28
Adjustment of the Varus/Valgus and Resection Level with the
Femoral Cutting Guide Alignment
9. Ensure that the alignment guide mates with at least
one distal condyle and place pins in the 0 mm holes
of the cutting guide.
12. Extracting the CAS distal first spike:
• NexGen Complete Knee Solution: Directly use the
NexGen slap hammer on the spike.
• Natural-Knee II System, Persona Knee Implants and
Innex Total Knee System*: Use the CAS Extractor
Adaptor by pulling the sleeve and assembling it on
the spike. Then, use the Natural-Knee II, Persona
Knee or Innex* slap hammer for removal.
• Vanguard Complete Knee System**: Directly use the
NexGen Slap Hammer on the spike.
• Other: Use slap hammer by assembling it on the
CAS Extractor Adaptor and, then, pulling the sleeve
to assemble it on the spike. Finally, use the NaturalKnee II Slap Hammer for removal.
Figure 4.29
Position Pins in the “0 mm” Holes
*Not available in the US
** Vanguard XP not supported
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Distal Cut Navigation (cont.)
Femur Rotation Navigation
(only available when an implant is
selected)
The purpose of this panel is to select the proper implant
size, set the A/P position and the axial rotation of the
implant. In addition, the medial and lateral posterior
condyles resection level can be navigated. The Femur
Rotation Navigation panel is shown in Figure 4.34 and
the detailed instructions are shown in Figures 4.35, 4.36
and 4.37.
Figure 4.32
Extraction of the CAS Distal First Spike
Distal Cut Validation
The purpose of the Distal Cut Validation is to verify if
the distal femoral resection was achieved as desired. It
is mainly used to inspect the orientation and if needed
introduce the necessary corrections to the distal femoral
cut. In order to validate the distal femoral resection, refer
to Figure 4.33 for the detailed instructions.
Implant Sizing, Anterior/Posterior Placement,
and Posterior Resection Level
Depending on the implant type, this task is completed
with the CAS Universal Validation Tool Body assembled
with the corresponding drill guide, or the CAS Universal
Offset Paddle inserted in the anterior cutting slot of the
appropriate A/P cutting block (4-in-1 type).
A 3D phantom model of the femoral distal lateral plane is
displayed with transparency. The posterior condyles and
anterior cortex points are superimposed on the model.
The anterior plane, distal plane and posterior plane of
the selected implant size are also superimposed on the
model. The sizing of the implant can be performed while
the instrument is positioned on the distal cut surface. It
can be performed according to the green anterior cortex
line attached to the bone, in the lateral view or with the
pointer tip, if it is positioned on the anterior cortex.
Figure 4.33
Distal Cut Validation
1. Remove the CAS Posterior Condyle Digitizer from the
CAS Universal Validation Tool Body.
2. Place the CAS Universal Validation Tool Body on the
distal femoral cut.
3. Stabilize the instrument to acquire the varus/valgus,
flexion/extension and resection level of the cut.
4. Verify the values and introduce the corrections if
needed.
5. To restart the Distal Cut Validation subtask move the
CAS Universal Validation Tool Body in the camera
volume.
Figure 4.34
Femur Rotation Navigation
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Intraoperative Guide
Femur Rotation Navigation
(only available when an implant is
selected) (cont.)
For distal cut first procedures, the optimal A/P size is
calculated based on the current distal cut and shown
in the sizing indicator (ruler in the Figure 4.33 for
instance). This optimal A/P size is converted into a sizing
suggestion in the femoral rotation panel.
If the optimal A/P size lies between two implant sizes,
the system suggests the largest of both implants in
order to avoid notching. If the optimal A/P size cannot
be computed (for instance, if the distal cut was not
validated, or if the largest implant in the family would still
cause notching), no A/P sizing suggestion is made in the
Femur Rotation Navigation panel.
Warning: Do not use the pictorial representation of the
bones for component positioning purposes. They are
provided solely to visualize axis orientation and do not
represent the actual bone anatomy.
Warning: If standard cutting guides are used, make
sure that the size of the cutting guide that you are using
corresponds to the size displayed by the system.
Refer to Figure 4.36 for the detailed instructions about the
posterior resection level.
The implant selector is initialized with the suggested
A/P size, shown next to the selector. If the suggested
A/P size is unavailable, the selector is initialized with the
suggested M/L size, if enabled, or the smallest implant
in the family. In all cases, the surgeon should validate
this suggestion based on the information provided in the
Lateral viewer and the Sizing indicator.
Refer to Figure 4.35 for the detailed instructions about
implant sizing and A/P placement.
Figure 4.36
Posterior Resection Level (Optional)
1. Adjust the A/P position of the implant to navigate
the medial and lateral resection level of the posterior
condyles (shown on the posterior condyles in grey).
Figure 4.35
Implant Sizing and A/P Placement
1. Position the navigation instrument on the distal
femoral cut.
2. Adjust the A/P position of the instrument such that
the bottom horizontal line is aligned with the green
marker (posterior condyles).
3. To avoid notching, select the size of the implant such
that the implant flange line is positioned above the
anterior cortex line.
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Femur Rotation Navigation
(only available when an implant is
selected) (cont.)
Adjustment of the Axial Rotation
Three rotational parameters are displayed below the
Axial viewer according to the femoral landmarks that
were digitized (A/P rotation, epicondylar rotation,
posterior condylar rotation). The rotation angles should
be used to determine the desired orientation. Refer to
Figure 4.37 for the detailed instructions on the implant
axial rotation adjustment
Figure 4.38
Acquire Posterior Plane
Figure 4.37
Axial Rotation Parameters
1. When the navigation instrument is positioned on
the distal femoral cut, perform implant axial rotation
adjustment. The A/P, epicondylar and posterior
axis indicators can be used as a reference to set the
desired rotation of the implant.
1. Position CAS Universal Validation Tool Body with the
CAS Posterior Condyle Digitizer against the distal
and posterior cut surfaces.
2. Stabilize the instrument.
3. Acquire the posterior femoral cut plane.
2. Secure the navigated block on the femur with the
drive pins.
3. Drill the peg holes.
Soft Tissue Balancing (option only
available if an implant is selected)
This panel is intended for ligament balancing when
the femoral and tibial cuts are finished. To obtain a
defined stress, spacer blocks or a spreader with a forcemeasuring tool can be used. Refer to Figures 4.38, 4.39
and 4.40 for the detailed instructions on the soft tissue
balancing procedure.
Figure 4.39
Flexion Gap
1. Bring the leg into flexion.
2. Position spacer block or spreader device between the
tibial cut and femoral posterior cut.
3. Perform laxity test and ligament adjustment if
necessary.
4. Position the pointer in the area of the knee joint to
record the flexion gap value or directly click on the
“Record Gap” button.
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Intraoperative Guide
Soft Tissue Balancing (option only
available if an implant is selected) (cont.)
Figure 4.40
Extension Gap
1. Bring the leg into extension.
2. Position spacer block or spreader device between the
tibial cut and femoral distal cut.
3. Perform laxity test and ligament adjustment if
necessary.
4. Position the pointer in the area of the knee joint to
record the extension gap value or directly click on the
“Record Gap” button.
Postoperative Range of Motion
The postoperative range of motion is similar to the Initial
Range of Motion task. Refer to the Initial Range of Motion
section (p. 14) of the present document.