Stryker

MAKO TKA System Surgical Guide Rev 00 Jan 2016

Surgical Guide

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Surgical Guide

Mako TKA Surgical Guide

TABLE OF CONTENTS INTRODUCTION... 1 SYSTEM OVERVIEW ... 3 A. MAKO TKA SYSTEM ... 3 B. TKA IMPLANT SYSTEMS... 4 INDICATIONS FOR USE ... 4 PATIENT SELECTION ... 4 MAKO TKA IMPLEMENTATION... 5 A. CT SCAN ... 5 B. INSTRUMENTATION ... 5 C. MAKO TKA TERMINOLOGY ... 5 D. SURGEON PREFERENCES ... 6 PRE-OPERATIVE PLANNING... 7 A. CT LANDMARKS REVIEW ... 7 B. RESECTION LANDMARKS REVIEW ... 8 C. IMPLANT PLANNING (PRE-OPERATIVE) ... 8 MAKO TKA SURGICAL TECHNIQUE ... 17 A. PATIENT POSITIONING ... 17 B. MAKO SYSTEM SETUP ... 17 C. EXPOSURE ... 22 D. BONE ARRAY PLACEMENT ... 24 E. BONE REGISTRATION ... 27 F. INTRA-OPERATIVE PLANNING ... 30 G. RIO SETUP - OPTIMIZE POSITION... 42 H. BONE PREPARATION ... 44 I. TRIAL REDUCTION AND JOINT ASSESSMENT... 53 J. POST-RESECTION IMPLANT ADJUSTMENTS ... 54 K. FINAL COMPONENT PREPARATION ... 55 L. PATELLAR PREPARATION ... 55 M. FINAL COMPONENT IMPLANTATION ... 55 N. CASE COMPLETION ... 56 iii

Mako TKA Surgical Guide

INTRODUCTION User Manual Terms of Use This manual is provided by MAKO Surgical Corp. (Stryker) and may be used for informational purposes only. Terms and Conditions related to the use of the Stryker Robotic Arm System (Mako) can be found in the placement agreement with the system user. About This Manual This manual describes the Mako Total Knee Arthroplasty (TKA) surgical technique assisted by the Stryker Robotic Arm System (Mako). The procedure will be identified as Mako (MAKOplasty) TKA in this manual. Manufacturer Support/Feedback MAKO Surgical Corp. 2555 Davie Rd. Ft. Lauderdale, FL 33317 USA Customer Service +1 (855) 303-6256 makosurgical.com Medical and Product Information This manual is informational only and is not intended as medical advice or a substitute for medical advice. As the manufacturer of medical devices in the field of orthopedics, Stryker does not practice medicine and does not recommend the surgical techniques referenced or discussed in this manual or any other surgical techniques for use on a particular patient. Stryker is not responsible for selection of the appropriate surgical technique to be utilized for an individual patient. Patents Reference: U.S. Patents http://patents.makosurgical.com/15 Indications for Use The Stryker Robotic Arm System (Mako) is intended to assist the surgeon in providing software defined spatial boundaries for orientation and reference information to anatomical structures during orthopedic procedures. The Mako is indicated for use in surgical knee procedures in which the use of stereotactic surgery may be appropriate, and where reference to rigid anatomical bony structures can be identified relative to a CT based model of the anatomy. These procedures include: •

Total Knee Arthroplasty (TKA).

The implant systems compatible with this system: • •

Triathlon Total Knee System (CR/CS/PS Cemented Primary) KINETIS Total Knee System (CR/UC).

Copyrights and Trademarks The content of this manual is protected under applicable copyright and trademark laws. You agree that you will not copy, distribute, republish, display, post, transmit or modify any content in this manual without Stryker’s prior permission. Any images displayed in this manual are the property of their respective copyright owners. Any reproduction, replication, modification or distribution of any art images in this manual is prohibited. The third-party trademarks in this manual are proprietary to their respective owners. These companies or their agents have granted Stryker the right to use their trademarks.

Mako TKA Surgical Guide Governing Law Any legal action or proceeding related to this manual or the information contained in it shall be brought exclusively in a court in Bergen County, New Jersey, and shall be governed by the laws of the State of New Jersey, without regard to conflicts of laws principles. Software Version TKA 1.0

There are no user serviceable parts in the Mako System, refer to your Stryker authorized personnel for service.

Mako TKA Surgical Guide

SYSTEM OVERVIEW A. MAKO TKA SYSTEM The Mako TKA System is used to consistently and reproducibly plan and execute a primary Total Knee Arthroplasty (TKA). Using patient specific information from a pre-operative CT scan, the surgeon has the ability to pre-operatively and intra-operatively adjust the plan to achieve proper biomechanical reconstruction of the knee for patients who satisfy the criteria for indications for use. The Mako TKA System is comprised of the following components: •

• •

•

The Mako System • Robotic Arm • Camera Stand • Guidance Module Mako (MAKOplasty) TKA Application software Mako Knee Instrumentation • Mako Knee Array/Balancing Kit • Mako Power System and Attachment Kit (Cutting System) • Leg Positioner Kit Sterile Disposables

Figure 1. Mako TKA System

Mako TKA Surgical Guide

B. TKA IMPLANT SYSTEMS The Mako TKA System is used to plan and execute Triathlon and KINETIS implant systems. For detailed implant information for the selected implant, refer to the appropriate Instructions for Use and Surgical Technique of the selected implant system. • • • •

Triathlon Instructions for Use (PN QIN 4376) Mako TKA with Triathlon Surgical Protocol (PN TRIATH-SP-21) KINETIS Instructions for Use (PN PI-004) Mako TKA with KINETIS Surgical Technique (PN 210468).

INDICATIONS FOR USE For indications and contraindications for the selected implant system, please reference the implant specific Instructions for Use. • •

Triathlon Instructions for Use (PN QIN 4376) KINETIS Instructions for Use (PN PI-004).

Familiarity with and attention to appropriate surgical technique for total knee replacement is essential for success of the procedure. Only surgeons who have reviewed the literature regarding total knee replacement surgery and have had training in the technique using the Mako should perform this procedure. For additional details relating to Warnings and Precautions, Possible Adverse Effects and Packaging/ Sterilization (if applicable), refer to the Instructions for Use of the selected implant system. • •

Triathlon Instructions for Use (PN QIN 4376) KINETIS Instructions for Use (PN PI-004).

PATIENT SELECTION Patient selection for Mako TKA depends on the judgment of the surgeon with regard to the requirements of the patient. Prior to Mako TKA, the surgeon should consider the following: • • • • • • •

Articulation of the hip joint is necessary to complete bone registration. Metal in the operative or non-operative leg can lead to the creation of accuracy reducing artifacts in the CT scan which can adversely affect the operative plan. The presence of infection (including history of infection), acute or chronic, local or systemic should be ruled out. Poor bone quality may affect the stability of the implant. Patient size may complicate the resection procedure. Body Mass Index should be considered. Poor integrity and/or lack of ligament structures may prevent the restoration of a stable joint. The type and significance of the deformity (hyperextension, flexion contracture, or fixed varus/ valgus) must be considered. The surgeon has final decision authority in choosing patients for the Mako TKA procedure. The effectiveness of all knee implants can be reduced by poor patient selection.

Mako TKA Surgical Guide

MAKO TKA IMPLEMENTATION A. CT SCAN Each patient requires a pre-operative CT scan for the Mako TKA procedure. This scan must follow the protocol in the Mako Knee CT Scanning Protocol (PN 200004).

B. INSTRUMENTATION The Mako TKA Instrumentation and Disposables: •

•

Mako Knee Instrumentation • Mako Knee Array/Balancing Kit • Mako Power System and Attachment Kit • Leg Positioner Kit Sterile Disposables: • Mako Drape Kit • Leg Positioner Disposable Kit • Silicone Retractor Cords • VIZADISC Knee Procedure Tracking Kit • Checkpoints • Bone Pins • MICS Saw Blades (Standard or Narrow) Implant System Instrumentation • For specific implant system instrumentation required, refer to the Instructions for Use and Surgical Technique of the selected implant system. • Mako TKA with Triathlon Surgical Protocol (PN TRIATH-SP-21) • Manual TKA Surgical Technique for KINETIS (PN 210468).

C. MAKO TKA TERMINOLOGY •

•

Approach Zone A volume in space around the knee joint where surgeon enabled motorized alignment to the stereotactic boundary cutting plane is permitted when the MICS Handpiece trigger is depressed. Approach Mode Approach Mode assists the user in guiding the cutting system to the stereotactic boundary for bone resection. Bone Registration The process of collecting points on the bony anatomy to enable the system to track patient anatomy in real-time. Checkpoint Bone: A metal divot inserted into the femur or tibia to confirm that the respective bone array has not shifted since bone registration. Cutting tool: A feature in the saw blade to confirm that the Robotic Arm Base Array has not shifted since RIO Registration. Cutting Mode Cutting Mode enables power to the cutting system while constraining the cutting system to the stereotactic boundary for bone resection. Engage Line The Engage Line is where the MICS Handpiece cutting tool is moved to during surgeon enabled motorized alignment. It is a mediolateral line segment located approximately 20 mm from the bone.

Mako TKA Surgical Guide •

•

• • • •

•

Free Mode Free Mode (Unlock) disables Approach Mode and Cutting Mode. If pressed while in Cutting Mode, power to the MICS Handpiece is disabled and then the stereotactic control is disabled. MICS: MAKO Integrated Cutting System The MAKO Integrated Cutting System consists of a MICS Handpiece, Right Angle Saw Attachment, Sagittal Saw Attachment, Standard Saw Blade, and Narrow Saw Blade. MPS: Mako Product Specialist The Mako Product Specialist, or the Stryker Representative helps operate the Mako (MAKOplasty) TKA Application software during the surgical procedure. PCA Posterior Condylar Axis is defined by a line connecting the two most posterior points of the medial and lateral condyles. Mako Centerline The mid-plane that bisects the Robotic Arm base into symmetrical halves (parallel to the long side panels on either side of the Mako). Stereotactic Recovery Stereotactic Recovery re-engages stereotactic control if it has been disabled while cutting. TEA Transepicondylar Axis is defined by a line connecting the surgical medial and lateral epicondyles. Whiteside’s Line Anterior-posterior axis of the femur as defined by a line through the deepest groove of the trochlea. Velocity Limit While in Cutting Mode, if an array moves (e.g., array is loose or patient leg moves) with excessive velocity, power is shut off to the cutting system, an audio warning is sounded, and stereotactic control is disabled until the leg stabilizes. VIZADISC Reflective markers that attach to the tracking arrays, allowing the camera to track their location in real-time.

D. SURGEON PREFERENCES The surgeon can customize the Mako (MAKOplasty) TKA Application in Surgeon Preferences. The preferences listed below are important in selecting the desired workflow: •

•

• •

‘Measured Resection’ or ‘Ligament Balancing’ workflow. ‘Measured Resection’ workflow utilizes resection depths to finalize the implant plan, whereas ‘Ligament Balancing’ workflow utilizes gap balancing to finalize the implant plan. ‘Distal/Tibia Cut First’ or ‘Pre-Resection Balancing’. If ‘Ligament Balancing’ workflow is selected, ‘Distal/Tibia Cut First’ enables bone resection to set the extension gap before balancing the flexion gap, whereas ‘Pre-Resection Balancing’ allows the surgeon to balance gaps before any bone resections are made. ‘Perform RIO Setup and RIO Registration before Bone Preparation’. Selecting this preference moves these steps from their default position of after ‘Probe Check’ to before ‘Bone Preparation’. ‘Bone Resection’ or ‘Estimated Cartilage’. ‘Bone Resection’ displays resection depth based on bone landmarks, whereas ‘Estimated Cartilage’ displays resection depth based on estimated cartilage thickness (Bone Resection + 2 mm). ‘Display Total Combined Resection Depth’. Displays the addition of the femur and tibia resections depths for each compartment in extension and flexion. ‘TKA Cutting Sequence’. Sets the order of the cutting steps for the femur and tibia.

Mako TKA Surgical Guide

PRE-OPERATIVE PLANNING The Mako (MAKOplasty) TKA Application enables the user to perform pre-operative implant planning using a patient-specific CT-based bone model and virtual implant templates. The primary purpose of pre-operative planning is to size, align, and position the implant to bony anatomy. Fine tuning of the implant plan using additional clinical information such as patient specific kinematics, fixed deformities, and soft tissue tension will be completed during Intra-operative Planning.

A. CT LANDMARKS REVIEW Surgeon/Mako Product Specialist Accurate and precise definition of bony landmarks is critical as they define the femur and tibia mechanical axes, anteroposterior (AP) axes, and mediolateral (ML) axes. Implant alignment is displayed with respect to these axes. These landmarks are collected by the MPS and reviewed by the surgeon pre-operatively. For a complete description of landmark definition, refer to the Mako TKA Application User Guide (PN 210467). Femur Axes Definition 1. Femur Mechanical Axis: The Femur Mechanical Axis is defined by a line connecting the ‘Hip Center’ to the ’Femur Knee Center’. a. ‘Hip Center’ is defined as the center point of a circle fit to the femoral head in the coronal,sagittal, and transverse planes. b. ‘Femur Knee Center’ is defined at the most distal point of the trochlear groove in the coronal and sagittal views. 2. Transepicondylar Axis (TEA): The mediolateral TEA is defined by a line connecting the ’Medial Epicondyle’ to the ’Lateral Epicondyle’. The Femur Mediolateral (ML) Axis is parallel to the TEA in the transverse plane. a. ‘Medial Epicondyle’ is defined by a point in the bony sulcus, which is called the surgical medial epicondyle. It is not the clinical medial epicondyle, which is the most proud (or prominent) bony protuberance that can be palpated clinically. b. 'Lateral Epicondyle’ is defined by the most proud (or prominent) point on the lateral bony protuberance. 3. Femur Anteroposterior (AP) Axis: The ‘Femur AP Axis’ is naturally perpendicular to the ‘Femur ML Axis’. The ‘Femur AP Axis’ is approximately parallel to Whiteside’s line, which is the line through the deepest groove of the trochlea. Tibia Axes Definition 1. Tibia Mechanical Axis: The Tibia Mechanical Axis is defined by a line connecting the ’Tibia Knee Center’ to the ‘Ankle Center’. a. ’Tibia Knee Center’ is defined as the proximal exit location of the anatomic tibial shaft in both the coronal and sagittal views. b. ‘Ankle Center’ is computed from the collection of the medial and lateral malleoli landmarks. The line connecting the two malleoli will appear externally rotated (approximately 20°) from the Tibia Mediolateral (ML) Axis. The malleoli landmarks are located on the outermost bony protuberances, halfway from the most anterior and most posterior edges when viewed by an externally rotated plane. The ‘Ankle Center’ is computed as 44% from the medial malleolus and 56% from the lateral malleolus. 2. Tibia Anteroposterior (AP) Axis: The ’Tibia AP Axis’ is set using the ‘Rotational Landmark’ and is defined by a line connecting the ‘PCL Center’ to the medial 1/3 of the tibial tubercle. a. ‘PCL Center’ is defined as the center of the PCL insertion region, which is characterized by a bright dense region of bone in the transverse view. Place the center of the blue rotation bar (ML 7

Mako TKA Surgical Guide axis) there. The PCL insertion can be best visualized in the transverse view by setting the crosshair below the lowest compartment in the coronal view be it medial or lateral. b. Medial 1/3 of the tubercle is defined as the approximate anterior-medial corner of the tubercle as visualized by a transverse cross-section at the level of the tibial tubercle. Rotate the green arrow bar (AP axis) until it intersects the medial 1/3 of the tibial tubercle. 3. Tibia Mediolateral (ML) Axis: The ‘Tibia ML Axis’ is naturally perpendicular to the ‘Tibia AP Axis’. The malleoli landmarks should match the location as palpated during the bone registration process using the ‘Patient Landmark’ page. Because the malleoli landmarks do not lie in a plane parallel to the coronal plane, they should not be located as the outermost protuberance in the coronal plane.

B. RESECTION LANDMARKS REVIEW Surgeon/Mako Product Specialist The resection landmarks are used to compute the medial and lateral resection thicknesses of the distal femur, posterior femur, and proximal tibia. These initial points are automatically calculated based on a software algorithm. Ensure that the resection landmarks are not located on osteophytes and are located where a caliper would normally be used to measure condyle resection thickness. If the default resection landmarks appear incorrect, they can be modified on this page by manually selecting the correct point.

C. IMPLANT PLANNING (PRE-OPERATIVE) Surgeon/Mako Product Specialist The Mako (MAKOplasty) TKA Application allows the surgeon flexibility regarding the sequence of planning steps and selected anatomic reference points. The sequence of planning steps below represents one such sequence designed to achieve the desired deformity correction, ligamentous balance, and knee kinematics.

Figure 2. ‘Implant Planning’ Page

Mako TKA Surgical Guide Table 1 , Table 2 , and Table 3 provide the recommended implant planning guidelines. The default compartment reference is the least diseased side because the bone and cartilage are expected to have less wear (i.e., to be a more reliable reference) than the diseased side. • •

Varus knee: lateral compartment (least diseased) Valgus knee: medial compartment (least diseased)

To predict if the knee is in varus or valgus, set both the femoral and tibial component varus rotations to 0°, compute the total combined coronal (extension) resections for medial and lateral compartments, and identify which compartment has the least resection. The compartment with the least combined resection is expected to have more wear and disease. • •

Varus knee: total medial resection depth < total lateral resection depth (i.e. medial wear) Valgus knee: total lateral resection depth < total medial resection depth (i.e. lateral wear)

The surgeon has the ability to deviate from the default references and positioning values based on the clinical needs of the patient. All varus/valgus and flexion/extension values are displayed with respect to the mechanical axis of the applicable bone while internal/external rotation values are displayed with respect to the AP/ML axes of the applicable bone.

Femoral Component 1. Establish Coronal Rotation In the coronal plane, the femur anatomic axis is approximately 5-7° valgus with respect to the femur mechanical axis. The Mako (MAKOplasty) TKA Application displays coronal rotation values with respect to the femur mechanical axis. Set the coronal rotation to the desired value. 2. Establish Axial Rotation In the transverse plane, the transepicondylar axis (TEA) is approximately 3° externally rotated from the posterior condylar axis (PCA). The Mako (MAKOplasty) TKA Application displays axial rotation values with respect to the TEA. The rotation angle of the component with respect to the PCA can be toggled on in the side bar, if desired. Set axial rotation to the desired value. 3. Establish Sagittal Rotation In the sagittal plane, the femur typically exhibits a natural anterior bow. During conventional surgical procedures, the femoral intramedullary rod approximates the distal 1/3 of the femur, which due to the sagittal bow of the femur creates approximately 4° of flexion with respect to the femur mechanical axis in the sagittal plane. The Mako (MAKOplasty) TKA Application displays sagittal rotation values with respect to the femur mechanical axis. To replicate referencing with an IM rod, the femoral component should be rotated ≥0° flexion. Set component flexion to the desired value.

Sagittal rotation of the femoral component can be adjusted to fine tune the size, avoid anterior overhang, and avoid anterior notching.

Mako TKA Surgical Guide 4. Establish Resection Depth The Mako (MAKOplasty) TKA Application displays resection depth as the distance from the planar cut to the selected resection depth landmark. Set the resection depth to the desired value. The surgeon can select from multiple resection depth options in Surgeon Preferences: • ‘Bone Resection’ represents the measured resection thickness of the bone only. It does not include the thickness of the cartilage (if present). • ‘Estimated Cartilage’ adds an estimated 2 mm of cartilage to the bone resection value. This may more closely represent the resection thickness on the non-diseased side as would be measured by a caliper. For both varus and valgus knees, note the depth of the distal trochlear groove. If desired, distal condyle resection depth can be modified from the default plan to resect to the level of the native depth of the trochlear groove. Distal femur resection at the depth of the trochlear groove will create what is commonly referred to as a “butterfly” cut. For a typical knee, the medial condyle extends more distally and posteriorly than the lateral condyle. The default plan will usually resect more medial condyle than lateral condyle.

Verify that the minimum resection depth on the diseased side is greater than or equal to the values recommended in Table 1 . Make adjustments as necessary.

5. Establish Size & Position The optimal femoral component size is the largest component that does not overhang the anterior femur, does not notch the anterior femur, does not overhang the medial and lateral resected bone edges, and does not overstuff the patellofemoral compartment. Rotate any 3D View or use ‘Slicer View’ to check for overhang and overstuffing. Set the component to the desired size and center the component between the resected medial and lateral cortical edges.

Sagittal rotation of the femoral component can be adjusted to fine tune the size, avoid anterior overhang, and avoid anterior notching. Both anterior and posterior referencing is supported via the drop down menu on the side panel. Posterior referencing will maintain the location of the posterior cut when upsizing/downsizing. Anterior referencing will maintain the location of the anterior flange cut when upsizing/downsizing. The patellofemoral compartment can be best visualized in ‘Slicer View’ by moving the sagittal slice to the lowest depth of the trochlear groove. The implant plan displays the desired component position. Mediolateral position of the femoral component is ultimately determined post-resection by the surgeon with the femoral trial during manual femoral peg preparation. The Sharp Probe (Blue) or Blunt Probe (Green) can be placed on the medial and lateral edges of the trial and compared to the planned placement to help guide final mediolateral component position. The Mako (MAKOplasty) TKA Application will only allow the user to plan femoral and tibial component size combinations that are compatible with each other.

Mako TKA Surgical Guide

If anterior femur notching is expected, a warning will be displayed in the Information Box. The Mako (MAKOplasty) TKA Application predicts anterior femur notching by identifying if any part of the superior edge of the anterior cut stereotactic boundary is inside the bone. If the CT scan or femur segmentation is too short to include this region, then notching cannot be predicted. Edit the femur segmentation or obtain another CT scan that includes femur bone at least 20 mm above the superior femoral component flange tip. Osteophytes can give the appearance of a wider bone. Avoid centering the component using ‘Resected View’ only. The medial and lateral cortical bone edges at the planned resection depth are best visualized in ‘Slicer View’ by scrolling through the coronal and transverse views.

Mako TKA Surgical Guide Table 1. Recommended femoral component planning guidelines Femoral Component Positioning

Reference

Default / Range

KINETIS

Triathlon

Rotational Alignment Varus / Valgus Rotation

Mechanical Axis

External Rotation

Transepicondylar Axis (TEA)

Flexion Rotation

Mechanical Axis

Default

0° varus

Range

2° varus - 2° valgus

Default

0° external

Range

PCA < 3° from TEA: • 0-3° external from TEA PCA > 3° from TEA: • Min 3° external from PCA • Max 3° external from TEA

PCA < 3° from TEA: • 0-3° external from TEA PCA > 3° from TEA: • Min 3° external from PCA (for neutral tibia cut)* • Max 3° external from TEA

Default

4° flexed

2° flexed

Range

2-6° flexed

0-5° flexed

Default

7 mm bone (9 mm estimated cartilage)

6 mm bone (8 mm estimated cartilage)

Range

5-9 mm bone (7-11 mm estimated cartilage)

4-8 mm bone (6-10 mm estimated cartilage)

Min

4 mm bone (6 mm estimated cartilage)

Default

9 mm bone (11 mm estimated cartilage)

8 mm bone (10 mm estimated cartilage)

Range

7-11 mm bone (9-13 mm estimated cartilage)

6-10 mm bone (8-12 mm estimated cartilage)

Min

4 mm bone (6 mm estimated cartilage)

Largest size that does not: • Overhang anterior femur • Notch anterior femur • Overhang ML bone edges • Overstuff the PF joint Center between ML cortical bone edges

Resection Depths

Varus Knee

Distal and posterior lateral Distal and posterior medial

Valgus Knee

Distal and posterior medial Distal and posterior lateral

Size and Position

Size

Posterior Referencing

Default

Largest size that does not: • Overhang anterior femur • Notch anterior femur • Overhang ML bone edges • Overstuff the PF joint

Position

ML Cortical Bone Edges

Default

Center between ML cortical bone edges

* If the tibial cut is placed in varus, then < 3° external rotation of the femur can be considered. ** The surgeon has the ability to deviate from the default references and positioning values based on the clinical needs of the patient.

Mako TKA Surgical Guide Tibial Component 1. Establish Coronal Rotation In the coronal plane, the tibia anatomic and mechanical axes are nearly collinear. The Mako (MAKOplasty) TKA Application displays coronal rotation values with respect to the Tibia Mechanical Axis. Set the coronal rotation to the desired value. 2. Establish Axial Rotation In the transverse plane, the Mako (MAKOplasty) TKA Application displays axial rotation values with respect to the ‘Tibia AP Axis’. Set axial rotation to the desired value. Symmetric tibial components will typically leave uncovered bone in the posterior-medial region. Avoid attempting to maximize posterior-medial coverage because this could lead to excessive internal rotation of the tibial component.

3. Establish Tibial Slope In the sagittal plane, the Mako (MAKOplasty) TKA Application displays slope values with respect to the Tibia Mechanical Axis. Set posterior slope to the desired value.

Native medial and lateral compartment slopes can be best visualized in ‘Slicer View’ by moving the sagittal slice to the medial and lateral resection landmarks, respectively.

4. Establish Resection Depth The Mako (MAKOplasty) TKA Application displays resection depth as the distance from the planar cut to the selected resection depth landmark. The surgeon can select from multiple resection depth options in Surgeon Preferences. • ‘Bone Resection’ represents the measured resection thickness of the bone only. It does not include the thickness of the cartilage (if present). • ‘Estimated Cartilage’ adds an estimated 2 mm of cartilage to the bone resection value. This may more closely represent the resection thickness on the non-diseased side as would be measured by a caliper. For a varus knee, the lateral plateau is typically more prominent relative to the diseased medial plateau; therefore, the default plan will likely resect more bone from the lateral plateau. For a valgus knee, the typically more prominent lateral plateau is diseased; therefore, the default plan might resect approximately equal amounts of bone on the lateral and medial plateaus. Verify that the minimum resection depth on the diseased side is greater than or equal to the values recommended in Table 2 . Make adjustments as necessary.

5. Establish Size & Position The optimal tibial component size is the largest component that does not overhang the perimeter of the tibial plateau. Rotate any 3D View or use ‘Slicer View’ to check for overhang. Set the component to the desired size. Center the component between the resected medial and lateral cortical edges. Center the component between the resected anterior and posterior cortical edges on the lateral side.

Mako TKA Surgical Guide The implant plan displays the desired component position. Anteroposterior (AP) and Mediolateral (ML) position and axial rotation of the tibial component is ultimately determined post-resection by the surgeon with the baseplate trial during manual tibial keel preparation. The Sharp Probe or Blunt Probe can be placed on the medial, lateral, and anterior edges of the trial and compared to the planned placement to help guide final component position. Use the thinnest tibial insert thickness when pre-operatively planning. If necessary, additional bone can be resected.

The Mako (MAKOplasty) TKA Application will only allow the user to plan femoral and tibial component size combinations that are compatible with each other. Symmetric tibial components will typically leave uncovered bone in the posterior-medial region. Avoid attempting to maximize posterior-medial coverage because this could lead to excessive internal rotation of the tibial component. Osteophytes can give the appearance of a larger tibial plateau. Avoid centering the component using ‘Resected View’ only. The cortical bone edges at the planned resection depth are best visualized in ‘Slicer View’ by scrolling through the coronal, transverse, and sagittal views.

Mako TKA Surgical Guide Table 2. Recommended tibial component planning guidelines

Tibial Component Positioning

Reference

Default / Range

KINETIS

Triathlon

Rotational Alignment Varus / Valgus Rotation

Mechanical Axis

External Rotation

Tibia AP Axis

Posterior Slope

Default

0° varus

Range

2° varus - 2° valgus

Default

0° external

Range

0-5° external

Default

CR: 5° posterior slope UC: 5° posterior slope

CR: 3° posterior slope CS (PCL retaining): 3° posterior slope CS (PCL sacrificing): 0° posterior slope PS: 0° posterior slope

Range

CR: 2-8° posterior slope UC: 2-8° posterior slope

CR: 0-3° posterior slope CS: 0-3° posterior slope PS: 0-1° posterior slope

Default

7 mm bone (9 mm estimated cartilage)

Range

5-9 mm bone (7-11 mm estimated cartilage)

Min

2 mm bone (4 mm estimated cartilage)

Default

5 mm bone (7 mm estimated cartilage)

Range

3-7 mm bone (5-9 mm estimated cartilage)

Min

2 mm bone (4 mm estimated cartilage)

Mechanical Axis

Resection Depths

Lateral Varus Knee Medial

Medial Valgus Knee Lateral

Size and Position Size

Best Coverage

Default

Largest size that does not overhang AP and ML

Position

AP and ML Cortical Bone Edges

Default

Center between AP and ML cortical bone edges

** The surgeon has the ability to deviate from the default references and positioning values based on the clinical needs of the patient.

Mako TKA Surgical Guide Confirm Plans 1. Overall Limb Alignment Confirm that the sum of the femoral and tibial component coronal rotations are less than or equal to the values recommended in Table 3 . Make adjustments as necessary. Same rotation labels add together, whereas opposite rotation labels subtract from each other. For example, if the femoral component is in 1° of varus and the tibial component is also in 1° of varus, the overall limb alignment will be 2° of varus. On the other hand, if the femoral component is in 1° of valgus and the tibial component is in 2° of varus, the overall limb alignment will be 1° of varus.

2. Combined Sagittal Rotation Confirm that the sum of the femoral and tibial component sagittal rotations are less than or equal to the values recommended in Table 3 . Make adjustments as necessary.

If the combined sagittal rotation is over the maximum threshold per Table 3 , a warning will be displayed in the Information Box.

3. Total Combined Resection Confirm that the sum of the femur and tibia resections on the least diseased side are equal to the sum of the femoral and tibial component condyle thicknesses as recommended in Table 3 . Make adjustments as necessary. Table 3. Recommended combined implant planning guidelines.

Combined Positioning Positioning

Reference

Default / Range

KINETIS

Triathlon

Default

0° varus

Range

3° varus - 3° valgus

Femoral flexion + Tibial slope

Max

14° combined rotation

8° combined rotation

Femur + Tibia resection depth (least diseased compartment)

Minimum

14 mm bone (18 mm estimated cartilage)

13 mm bone (17 mm estimated cartilage)

Overall Limb Alignment

Femoral + Tibial coronal rotation

Combined Tibiofemoral Hyperextension Combined Tibiofemoral Resection

** The surgeon has the ability to deviate from the default references and positioning values based on the clinical needs of the patient.

Mako TKA Surgical Guide

MAKO TKA SURGICAL TECHNIQUE The work flow described in this section can be implemented by a standard OR team (Surgeon, Physician Assistant, Surgical Technologist and Circulating Nurse) with the addition of a Mako Product Specialist (MPS). The Mako (MAKOplasty) Total Knee Application software is designed to be operated from the Guidance Module by the MPS under the direction of the operative surgeon.

A. PATIENT POSITIONING Sterile Staff Member It is possible for the surgical staff to complete all steps of Patient Positioning and Mako System Setup without the surgeon. This can greatly improve the efficiency of the Mako TKA procedure. 1. Patient position: Orient the patient in the supine position on the surgical table and align the patient with the long axis of the surgical table. Ensure that the operative leg can be maximally flexed when the heel is aligned with the end of the table. Confirm that the non-operative knee can freely drop off the end of the table when flexed to 90°. Use a stirrup or alternate device to protect the non-operative leg from soft tissue damage due to the weight of the overhanging leg during the case. 2. Drape the patient. For best results, bias the medial/lateral patient position such that the hip, knee and ankle on the operative side are close to the edge of the surgical table.

3. Leg Positioner setup: Stryker provides a Leg Positioner for the Mako TKA procedure. Secure the patient’s foot and proximal tibia into the leg holder boot. Securing the tibia tightly in the boot will help to stabilize the knee during bone resection (refer to the Leg Positioner User Guide (PN 210470) for detailed instructions)

B. MAKO SYSTEM SETUP This section briefly describes how to setup the Mako System for use in the operating room. Reference the Mako TKA Application User Guide (PN 210467) and the Mako System User Guide (PN 210711) for detailed information. 1. OR layout Sterile Staff Member Setup the Mako System for a right or left leg, as depicted in Figure 3. Based on surgeon preference, the surgeon may stand on the operative side or at the end of the surgical table, between the patient’s legs. 2. Start the Mako (MAKOplasty) TKA Application Mako Product Specialist To start the application, click ‘TKA’ from the ‘Startup’ page of the Mako (MAKOplasty) TKA Application.

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