This device is intended to reduce or relieve pain and restore function and motion to the knee joint. Total knee replacement is indicated for patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee can be satisfactorily balanced and stabilized at the time of surgery.

The LPS-Flex Fixed Bearing Knee provides increased flexion capability for patients who have both the flexibility and desire to increase their flexion range. The LPS-Flex femoral, when used with LPS-Flex articular surfaces, is designed for use with both cruciate ligaments excised and when load bearing range of motion (ROM) is expected to be less than or equal to 155 degrees. This device is intended for cemented use only.

Device Description

The LPS-Flex Fixed Bearing Knee is a semiconstrained, condylar system for use without the cruciate ligaments when additional stability is required to prevent anterior subluxation of the femur relative to the tibia in flexion. The LPS-Flex Fixed Bearing Knee consists of an LPS-Flex femoral and an LPS-Flex articular surface.

AI/ML Overview

This is a 510(k) premarket notification for a medical device (NexGen® Complete Knee Solution Legacy® Posterior Stabilized (LPS); LPS-Flex Fixed Bearing Femoral and Articular Surface Components), not an AI/ML device. Therefore, the requested information about acceptance criteria, study details, and AI/ML-specific performance metrics (e.g., sample sizes for test/training sets, expert ground truth, MRMC studies) is not applicable or available in the provided document.

The document focuses on demonstrating substantial equivalence to a predicate device (NexGen® Complete Knee Solution Legacy® LPS Knee) through non-clinical performance evaluations and comparisons of design, materials, and mechanical performance.

Here's an analysis of the provided information, focusing on what is available:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not present a formal table of quantitative acceptance criteria with corresponding performance values in the way you might expect for an AI/ML device. Instead, it compares the proposed device to a predicate device across several parameters and concludes that they are "Similar" or "Identical."

Parameter	Acceptance Criteria (Implicit from Predicate Comparison)	Reported Device Performance (LPS-Flex)
Constraint (ASTM F1223)	Not significantly different from predicate device.	"negligible displacement variances between the LPS-Flex and the predicate device. Constraint was not significantly different."
Contact Area	Increased conformity compared to predicate.	"showed an increase in conformity for the device as compared to the predicate."
Tibial Baseplate Interlock Mechanism	Same as predicate device, with enhanced fixation for high flexion in some cases.	"the same as the predicate device. A screw is added to some LPS-Flex articular surfaces to enhance fixation during high flexion."
Fatigue Strength (Tibial Baseplate)	Same as predicate device.	"No additional fatigue strength data was needed because the device uses the predicate tibial baseplate." "The LPS-Flex knee uses the predicate tibial baseplate and has the same fatigue strength."
Design (Sagittal Plane Conformity)	Modified for increased conformity during walking gait angles and extended flexion range compared to predicate.	"The LPS-Flex femoral has a modified sagittal plane as compared to the predicate. This gives the LPS-Flex increased conformity during walking gait angles of flexion and accommodates the extended flexion range."
Design (Cam/Spine Geometry)	Modified to improve resistance to subluxation, correct rollback, kinematics, and reduce bending load on the spine compared to predicate.	"the shape of the femoral cam was modified and the clearance posterior to the polyethylene spine was deepened. This improves resistance to subluxation beyond the predicate and provides for the correct rollback and kinematics of the LPS-Flex joint. The cam and spine geometries of the LPS-Flex were also designed to provide a low cam/spine contact which reduces the bending load on the spine during high load flexion activities, such as squatting."
Materials	Same as predicate, with an additional Tivanium insert for LPS-Flex.	"Femoral component is Zimaloy® Cobalt-Chromium-Molybdenum Alloy for both the predicate and LPS-Flex. Articular surface is UHMWPE for both the predicate and LPS-Flex. A Tivanium insert is added to the LPS-Flex."
Patellofemoral Joint Stability	Same as predicate.	"The patellar groove design and stability of the LPS-Flex femoral component is the same as the predicate."
Wear Data (Polyethylene Thickness)	Minimum polyethylene thickness of 6.5 mm; design maintains conformity to minimize wear.	"The LPS-Flex has a minimum polyethylene thickness of 6.5 mm. Even though the LPS-Flex increases the maximum active flexion angle to 155 degrees, the design has maintained the conformity necessary to minimize or eliminate any new movement mechanisms that could affect wear."
Sterility	Identical to predicate; terminally sterilized by gamma radiation to SAL of 10^-6 or better.	"Both are terminally sterilized by gamma radiation...validated dosimetric release program designed to provide a sterility assurance level (SAL) of 10^-6 or better."
Biocompatibility	Meets or exceeds ASTM standards; materials common to orthopedic products.	"Material specifications for both the predicate and LPS-Flex meet or exceed ASTM standards, are common to orthopaedic products today and do not require additional biocompatibility testing."
Pyrogenicity	Not labeled as nonpyrogenic, as per USP XXIII, NF18 (1995 edition) for orthopedic products.	"Neither the predicate or the LPS-Flex are labeled as nonpyrogenic. Per USP XXIII, NF18 (1995 edition), page 1719, "These requirements do not apply to orthopaedic products.""

2. Sample Size Used for the Test Set and Data Provenance

Not applicable. This is a medical device clearance based on substantial equivalence, primarily using non-clinical (mechanical/material) testing and comparison to an existing predicate device. There is no "test set" in the context of an AI/ML study. The studies mentioned (e.g., ASTM F1223) refer to standard test methods for mechanical properties.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and the Qualifications of Those Experts

Not applicable. There is no clinical "test set" requiring expert ground truth in the context of an AI/ML study. The evaluation relies on engineering principles, material science, and established ASTM standards.

4. Adjudication Method for the Test Set

Not applicable. There is no "test set" in the AI/ML sense, and thus no adjudication method for ground truth.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

Not applicable. This is not an AI/ML device, and no MRMC study was conducted or is relevant to its clearance.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Not applicable. This is not an AI/ML device.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)

Not applicable in the AI/ML sense. The "ground truth" for this device's performance is established by:

Mechanical Testing Results: Adherence to established ASTM standards (e.g., F1223 for constraint).
Design Specifications: Comparison of design features to the predicate device and engineering rationale.
Material Specifications: Compliance with ASTM standards for materials.
Sterility Validation: Adherence to ISO standards (e.g., ANSI/AAMI/ISO 11137-1994) for sterility assurance level (SAL).

8. The Sample Size for the Training Set

Not applicable. This is not an AI/ML device.

9. How the Ground Truth for the Training Set was Established

Not applicable. This is not an AI/ML device.

Summary of the Device's Approval and Basis:

The Zimmer NexGen® Complete Knee Solution Legacy® Posterior Stabilized (LPS); LPS-Flex Fixed Bearing Femoral and Articular Surface Components received 510(k) clearance based on its substantial equivalence to the predicate device, NexGen® Complete Knee Solution Legacy® LPS Knee.

The study that "proves" the device meets acceptance criteria primarily consists of:

Non-clinical performance evaluations:
- Constraint analysis per ASTM F1223, showing negligible displacement variances compared to the predicate.
- Contact area determination, showing increased conformity compared to the predicate.
- Confirmation that the tibial baseplate interlock mechanism and fatigue strength are equivalent to or improved over the predicate.
Detailed technological comparison: Demonstrating similarities and differences in design, materials, and other performance aspects, with explanations for modifications (e.g., modified sagittal plane, cam, and spine geometries for increased flexion and stability) and why these changes do not raise new questions of safety or effectiveness.
Adherence to recognized standards: For sterility (gamma radiation to SAL 10^-6 per ANSI/AAMI/ISO 11137-1994) and biocompatibility (materials meeting ASTM standards).

The conclusion was that "Clinical data and conclusions were not needed for this device" because the non-clinical data sufficiently demonstrated substantial equivalence to a legally marketed predicate device.

Summary

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K99,581

Image /page/0/Picture/1 description: The image shows the logo for Zimmer. The logo consists of a large, bold letter "Z" enclosed in a circle. Below the circle, the word "zimmer" is written in lowercase letters. The number 30 is in the upper left corner of the image.

. (1))

P.O. Box 708 Warsaw, IN 46581-0708 219 267-6131

510(k) Summary of Safety and Effectiveness NexGen® Complete Knee Solution Legacy® Posterior Stabilized (LPS); LPS-Flex Fixed Bearing Femoral and Articular Surface Components

Submitted by: I.
Zimmer, Inc. P.O. Box 708 Warsaw, Indiana 46581-0708
II. Contact Person:
Stephen H. McKelvey Senior Regulatory Affairs Associate Regulatory Affairs Telephone: (219) 372-4944 Facsimile: (219) 372-4605
Ш. Date Prepared:
May 6, 1999
IV. Name of Device:

A.	Trade Name:	Femoral and Articular Surface Knee Components
B.	Proprietary Name:	NexGen® Complete Knee Solution Legacy® PosteriorStabilized (LPS); LPS-Flex Fixed Bearing Femoral andArticular Surface Components
C.	Common Name:	LPS-Flex Fixed Bearing Knee
D.	Classification Nameand Reference:	Knee joint patellofemorotibialpolyethylene/metal/polyethylene semiconstrained cementedtotal knee prosthesis - 21 CFR 888.3560

Image /page/0/Picture/12 description: The image shows a geometric design. The design is composed of six identical triangular shapes arranged around a central point. Each triangle is further divided into three smaller triangles, creating a star-like pattern within each larger triangle. The overall design has a symmetrical and radial appearance.

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E. Predicate Device:

NexGen® Complete Knee Solution Legacy® LPS Knee

F. Device Description:
The LPS-Flex Fixed Bearing Knee is a semiconstrained, condylar system for use without the cruciate ligaments when additional stability is required to prevent anterior subluxation of the femur relative to the tibia in flexion. The LPS-Flex Fixed Bearing Knee consists of an LPS-Flex femoral and an LPS-Flex articular surface.
G. Intended Use:
This device is intended to reduce or relieve pain and restore function and motion to the knee joint. Total knee replacement is indicated for patients with severe knee pain and disability due to rheumatoid arthritis, osteoarthritis, primary and secondary traumatic arthritis, polyarthritis, collagen disorders, avascular necrosis of the femoral condyle or pseudogout, posttraumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy, moderate valgus, varus, or flexion deformities. This device may also be indicated in the salvage of previously failed surgical attempts if the knee can be satisfactorily balanced and stabilized at the time of surgery.

The LPS-Flex Fixed Bearing Knee provides increased flexion capability for patients who have both the flexibility and desire to increase their flexion range. This device is intended for cemented use only.

H. Comparison to Predicate Device:
See attached table.
I. Non-clinical Performance and Conclusions:
- 1. The level of constraint for the proposed device was analyzed per ASTM F1223. The femoral-to-articular surface motion is resisted by the articulating surface geometry, the polyethylene spine and the close conformity between the two components. The simulation exhibited negligible displacement variances between the LPS-Flex and the predicate device. Constraint was not significantly different.
- 1. The contact area was also determined and showed an increase in conformity for the device as compared to the predicate.

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1. The tibial baseplate interlock mechanism for the device is the same as the predicate device. A screw is added to some LPS-Flex articular surfaces to enhance fixation during high flexion.
1. No additional fatigue strength data was needed because the device uses the predicate tibial baseplate.
J. Clinical Performance and Conclusions:

Clinical data and conclusions were not needed for this device.

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Technological Comparison to Predicate Device

Parameter	Identical, Similaror Different?	Similarities and Differences
Design	Similar	Frontal plane conformity between the femoral and articular surface components is identical. The LPS-Flex femoral has a modified sagittal plane as compared to the predicate. This gives the LPS-Flex increased conformity during walking gait angles of flexion and accommodates the extended flexion range. Compatibility between predicate and LPS-Flex components is high (predicate femorals can be used with the LPS-Flex articular surface). The patellar groove design is identical for the predicate and LPS-Flex device. The same patella is used for both devices. One additional posterior femoral bone cut is required to accommodate the extended flexion range of the LPS- Flex, otherwise the box and patellar groove geometries are the same as the predicate and standard NexGen instrumentation may be used. To improve stability of the femoral component on the articular surface and to reduce the moment applied to the polyethylene spine, the shape of the femoral cam was modified and the clearance posterior to the polyethylene spine was deepened. This improves resistance to subluxation beyond the predicate and provides for the correct rollback and kinematics of the LPS-Flex joint. The cam and spine geometries of the LPS-Flex were also designed to provide a low cam/spine contact which reduces the bending load on the spine during high load flexion activities, such as squatting.
Materials	Similar	Femoral component is Zimaloy® Cobalt-Chromium-Molybdenum Alloy for both the predicate and LPS-Flex. Articular surface is UHMWPE for both the predicate and LPS-Flex. A Tivanium insert is added to the LPS- Flex. Surface characteristics are identical for both the predicate and LPS-Flex (Uncoated, PMMA coated and Co- nidium hardened).
Performance	Similar	Interlock mechanism - 17 and 20 mm thick LPS-Flex articular surfaces require a secondary screw fixation, in addition to the dovetail locking system already present in the predicate and LPS-Flex. This screw provides an additional safety factor to prevent anterior lift-off of the articular surface from the tibial baseplate. Tibial Baseplate Fatigue Strength - The LPS-Flex knee uses the predicate tibial baseplate and has the same fatigue strength. Lateral Stability of the Patellofemoral Joint - The patellar groove design and stability of the LPS-Flex femoral component is the same as the predicate. Both are used with all-polyethylene patellar components. Wear Data -The LPS-Flex has a minimum polyethylene thickness of 6.5 mm. Even though the LPS-Flex increases the maximum active flexion angle to 155 degrees, the design has maintained the conformity necessary to minimize or eliminate any new movement mechanisms that could affect wear.
Parameter	Identical, Similaror Different?	Similarities and Differences
Sterility	Identical	• There are no differences between the predicate and LPS-Flex sterility processes. Both are terminally sterilizedby gamma radiation. Gamma radiation processing and dose mapping are conducted according toANSI/AAMI/ISO 11137-1994. The products are accepted for release as sterile though a validated dosimetricrelease program designed to provide a sterility assurance level (SAL) of 10° or better (ANSI/AAMI/ISO11137-1994, ANSI/AAMI ST32-1991 and ISO/TR 13409-1996).
Biocompatibility	Identical	• Material specifications for both the predicate and LPS-Flex meet or exceed ASTM standards, are common toorthopaedic products today and do not require additional biocompatibility testing.
Pyrogenicity	Identical	• Neither the predicate or the LPS-Flex are labeled as nonpyrogenic. Per USP XXIII, NF18 (1995 edition),page 1719, "These requirements do not apply to orthopaedic products."

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Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

Jul 30 1999

Mr. Steven H. McKelvey Senior Regulatory Affairs Associate Zimmer Inc. P.O. Box 708 Warsaw, Indiana 46581-0708

K991581 Re:

Trade Name: NexGen Complete Knee Solution Legacy Posterior Stabilized (LPS)- Flex Fixed Bearing Femoral and Articular Surface Components Regulatory Class: II Product Code: JWH Dated: May 6, 1999 Received: May 7, 1999

Dear Mr. McKelvey:

We have reviewed your Section 510(k) notification of intent to market the device referenced above, and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act). You may, therefore, market the device, subject to the general control provisions of the Act. The general control provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the current Good Manufacturing Practice requirement, as set forth in the Quality System Regulation (QS) for Medical Devices: General Regulation (21 CFR Part 820), and that, through periodic (OS) inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.

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Page 2 -- Mr. Stephen H. McKelvey

This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4659. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its Internet address "http://www.fda.gov/cdrh/dsmamain.html".

Sincerely yours,

Celia M. Witten, Ph.D., M.D. Director Division of General and Restorative Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Indications for Use

Page of

510(k) Number (if known): 991581 ん

Device Name:

NexGen® Complete Knee Solution Legacy® Posterior Stabilized (LPS); LPS-Flex Fixed Bearing Femoral and Articular Surface Components

Indications for Use:

(Please do not write below this line - Continue on another page if needed)

Concurrence of CDRH, Office of Device Eyaluation (ODE)

(Division Sign-Off)
Division of General Restorative Devices
510(k) Number K991581

Prescription Use
(Per 21 CFR 801.109)
OR Over The-Counter Use
(Optional Format 1-2-96)

Regulation Number and Section

§ 888.3560 Knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis.

(a)
Identification. A knee joint patellofemorotibial polymer/metal/polymer semi-constrained cemented prosthesis is a device intended to be implanted to replace a knee joint. The device limits translation and rotation in one or more planes via the geometry of its articulating surfaces. It has no linkage across-the-joint. This generic type of device includes prostheses that have a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a tibial component or components and a retropatellar resurfacing component made of ultra-high molecular weight polyethylene. This generic type of device is limited to those prostheses intended for use with bone cement (§ 888.3027).(b)
Classification. Class II.