Zimmer Biomet ORTHOsoft Knee 2.4 Universal User Manual Dec 2016

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ORTHOsoft®

Knee 2.4 Universal

User Manual

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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.