NATURAL-KNEE II UNICOMPARTMENTALKNEE SYSTEM

K955778 · Intermedics Orthopedics · HRY · Mar 8, 1996 · Orthopedic

Device Facts

• Record ID: K955778
• Device Name: NATURAL-KNEE II UNICOMPARTMENTALKNEE SYSTEM
• Applicant: Intermedics Orthopedics
• Product Code: HRY · Orthopedic
• Decision Date: Mar 8, 1996
• Decision: SN
• Submission Type: Traditional
• Regulation: 21 CFR 888.3530
• Device Class: Class 2
• Attributes: Therapeutic

Intended Use

The Natural-Knee II - Unicompartmental Knee Prosthesis is intended for resurfacing of one side of the knee joint.

Device Story

System provides unicompartmental knee resurfacing; consists of femoral component, tibial baseplate, and tibial insert. Femoral component (cast CoCrMo) features central cruciate stem and posterior runner for rotational stability; available in 7 sizes. Tibial baseplate (wrought Ti-6Al-4V) features three pegs for rotational stabilization and optional screw fixation; available in 6 sizes. UHMWPE tibial insert snaps into baseplate via capture features; available in 3 thicknesses and 3 sizes. Both metallic components available in nonporous or CSTi porous-coated versions. Used by orthopedic surgeons in clinical settings to replace damaged joint surfaces, restoring joint function and reducing pain.

Clinical Evidence

Bench testing only. Evaluated contact area, constraint, and baseplate-insert locking mechanism push-out strength; results demonstrated performance comparable to other legally marketed devices.

Technological Characteristics

Materials: Cast CoCrMo (femoral), wrought Ti-6Al-4V (tibial baseplate), UHMWPE (ASTM F648, insert). Design: Symmetrical, semi-constrained, modular. Features: Central cruciate stem, posterior runner, rotational stabilization pegs, optional screw fixation, snap-fit locking mechanism. Available in nonporous or CSTi porous-coated versions.

Indications for Use

Indicated for patients requiring resurfacing of one side of the knee joint (unicompartmental) due to degenerative or traumatic joint disease.

Regulatory Classification

Identification

A knee joint femorotibial metal/polymer semi-constrained cemented prosthesis is a device intended to be implanted to replace part of 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 consist of a femoral component made of alloys, such as cobalt-chromium-molybdenum, and a tibial component made of ultra-high molecular weight polyethylene and is limited to those prostheses intended for use with bone cement (§ 888.3027).

Reference Devices

• Howmedica PCA Unicompartmental Knee System
• DePuy Synatomic Unicondylar Knee
• Wright Medical Whiteside Ortholoc II Unicondylar Knee System
• Osteonics Omnifit SCR Knee System
• Zimmer Miller/Galante Unicompartmental Knee System
• Kirschner Performance Unicompartmental Knee
• Smith & Nephew Richards Genesis Unicompartmental Knee
• Johnson & Johnson PFC Unicompartmental Knee System

Submission Summary (Full Text)

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510(k) SUMMARY

K 955778

M - 8

December 14, 1995

In accordance with the Food and Drug Administration Interim Rule to implement provisions of the Safe Medical Devices Act of 1990 and in conformance with 21CFR 807, this is to serve as a 510(k) Summary for the Intermedics Orthopedics, Inc. Natural-Knee® II - Unicompartmental Knee System.

Submitter: Intermedics Orthopedics, Inc.
9900 Spectrum Drive
Austin, TX 78717
[phone]

Contact Person: Jacquelyn Hughes
Manager, Regulatory Affairs

Classification Name: Knee joint femorotibial metal/polymer semi-constrained cemented prosthesis, 21 CFR 888.3530.

Common/Usual Name: Unicondylar knee prosthesis, partially constrained

Trade/Proprietary: Natural-Knee® II - Unicompartmental Knee Prosthesis

Product Description/Substantial Equivalence:

The Natural-Knee II - Unicompartmental Knee Prosthesis is intended for resurfacing of one side of the knee joint. The system consists of metallic femoral and tibial components as well as a polyethylene tibial insert.

The femoral component is a symmetrically designed component, eliminating the need for left/right orientations. The femoral component is manufactured from cast cobalt chromium/molybdenum (CoCrMo) and features a central cruciate stem which aids in stabilization. A central posterior runner is incorporated into the inner surface to provide further rotational stability. Contact area is maximized by the "sweeping" condylar geometry. Both a nonporous and CSTi porous coated version are available. The femoral component is available in 7 sizes (1-7).

The tibial component is a symmetrically designed component, eliminating the need for left/right orientations. The tibial component is manufactured from wrought titanium alloy (Ti-6Al-4V). The baseplate features three pegs on the underside which aid in rotational stabilization. A screw hole has been placed in the center of the baseplate for optional screw fixation. The baseplate is designed with capture features which permit the UHMWPE tibial insert to be snapped into place. Both a nonporous and CSTi porous coated version are available. The baseplate is available in 6 sizes (1-6).

The tibial insert is a symmetrically designed component manufactured from Ultra-High Molecular Weight Polyethylene (ASTM F648). The insert articulating geometry is semi-constrained and is captured in the baseplate by the mating capture features. The insert is available in 3 thicknesses (9, 11, and 13 mm) and 3 sizes (1-2, 3-4, and 5-6).

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Contact area and constraint testing on the femoral and tibial components showed the Natural-Knee II Unicompartmental Knee Prosthesis to be comparable to other legally marketed devices.

Testing on the baseplate-insert locking mechanism indicated that the push-out strength was comparable to other legally marketed devices.

The Natural-Knee II Unicompartmental Knee Prosthesis is also similar to the Howmedica PCA Unicompartmental Knee System, the DePuy Synatomic Unicondylar Knee, the Wright Medical Whiteside Ortholoc II Unicondylar Knee System, the Osteonics Omnifit SCR Knee System, the Zimmer Miller/Galante Unicompartmental Knee System, the Kirschner Performance Unicompartmental Knee, the Smith & Nephew Richards Genesis Unicompartmental Knee, and the Johnson & Johnson PFC Unicompartmental Knee System.

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