The Natural-Knee® Tibial Baseplates and the Natural-Knee® All Poly Patella are semi-constrained in design and both the medial and lateral collateral ligaments must be intact.
Device Story
Natural-Knee® system components include modified tibial baseplates and all-polyethylene patellar components. Tibial baseplates feature central screw holes for enhanced fixation, modified porous coating pockets, and increased thickness; inferior surface coated with Cancellous Structured Titanium (CSTi™). Patellar components are circular, available in 4 sizes (7mm and 10mm thicknesses), designed to articulate with Natural-Knee® Primary and Revision femoral components. Used by orthopedic surgeons in total knee arthroplasty procedures to restore joint function. Device provides mechanical stability and articulation surface for knee joint.
Clinical Evidence
Bench testing only. Analysis confirmed baseplate withstands acceptable cantilever fatigue loading. Patello-femoral contact area and lateral subluxation tests performed; results comparable to competitive all-poly patellar devices.
Technological Characteristics
Materials: Cancellous Structured Titanium (CSTi™) porous coating, polyethylene. Design: Semi-constrained, cruciate-retaining. Tibial baseplates feature central screw holes for fixation. Patellar components are circular, 7mm/10mm thickness. Energy source: None (mechanical). Connectivity: None. Sterilization: Not specified.
Indications for Use
Indicated for patients requiring total knee replacement who have intact medial and lateral collateral ligaments.
Regulatory Classification
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).
Predicate Devices
Kirschner™ Performance™ Knee
Biomet AGC Knee
Howmedica P.C.A.
Zimmer Miller-Galante Knee System
Richards® Genesis Knee All-Poly Patellae
Submission Summary (Full Text)
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K934695
510(k) SUMMARY OF SAFETY AND EFFECTIVENESS
MAY - 2 1996
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 Summary of Safety and Effectiveness for the Natural-Knee® Tibial Baseplates and the Natural-Knee® All Poly Patella.
Submitter: Intermedics Orthopedics®, Inc.
1300 East Anderson Lane
Austin, Texas 78752
(512) 835-1971
Date: September 29, 1993
Contact Person: JoAnn Ringer
Manager, Regulatory Affairs
Classification Name: Knee Joint Patellofemorotibial Polymer/Metal/Polymer Semi-Constrained Prostheses
Common/Usual Name: Total Knee Replacement, Tibial Articulating Surface
Trade/Proprietary: Natural-Knee® Tibial Baseplates
Natural-Knee® All Poly Patella
# PRODUCT DESCRIPTION/SUBSTANTIAL EQUIVALENCE:
## Tibial Components
The Natural-Knee® Tibial Baseplates involve modifications to the original Natural-Knee® Tibial Baseplates. The modifications to the tibial resurfacing and stemmed baseplates involve the addition of a centrally located screw hole for optional enhanced insert/baseplate fixation. Furthermore, changes to the configuration of the porous coating pockets and increase in overall baseplate thickness were made to the resurfacing baseplate. The Natural-Knee® Baseplates are semi-constrained in design and both the medial and lateral collateral ligaments must be intact. The tibial baseplates are part of the present Natural-Knee® System and mate with the same Natural-Knee® tibial inserts as the existing Natural-Knee® tibial baseplates. The inferior surface of the porous-coated baseplate is coated with Cancellous Structured Titanium (CSTi™).
The design is substantially equivalent to the tibial baseplates used in the Kirschner™ Performance™ Knee and the Biomet AGC Knee in that both of the baseplates have centrally located screw holes for tibial tray fixation. The tibial plateau is cruciate retaining as is the Howmedica P.C.A. and the Zimmer Miller-Galante Knee System.
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Results of an analysis indicated that the baseplate would withstand acceptable cantilever fatigue loading conditions.
## Patella
The Natural-Knee All Poly Patella is designed to articulate with the Natural-Knee® Primary and Revision femoral components. It has a circular shape and is provided in 4 sizes and thicknesses of 7 and 10mm. The design is similar to the Richards® Genesis Knee All-Poly Patellae.
Patello-femoral contact area and lateral subluxation tests were performed. The results of these tests are comparable to competitive all poly patellas.
