The first Ceramic knee implant in a human patient was used by Dr. G. Langer of the Orthopedic Clinic at the University of Jena, Germany in 1972 [1]. In 1980, Drs. Oonishi and Hasegave began using a Alumina femoral component on a polyethylene tibial component [2]. These early attempts all involve the search for solutions to the wear and degradation problems. The application of ceramics was limited by the demand of thin components. In the present feasibility study the in vitro wear behavior of a knee concept with a novel Alumina Matrix Composite (AMC) Ceramic was examined [3,4].

The wear behavior of the Ceramic components for the knee system were tested in accordance to ISO/WD 14243-3 for 5*106 cycles. Six samples were tested. The lubricant was calf serum diluted with deionized water. All tests have been performed with components made of the novel AMC Ceramic.

The wear test performed showed an average gravimetric wear rate below 1 mg/1*106 cycles on each of the six components. A change of geometry was not measurable after 5 million cycles. No significant change of the surface structure was detectable with a conventional surface tracer. SEM and AFM pictures show traces of ultra mild abrasive wear at the surface. The performed investigation on the novel knee concept shows the following potential benefits for a Ceramic knee bearing:

approx. 500 times lower volumetric wear

The novel AMC Ceramic offers a solution to minimize the allergic and wear related problems of knee implants. New concepts on the basis of hard on hard combination are to be realized. The use of knee endo-prosthesis with Ceramic on Ceramic combination is an option for îzeroî wear bearings in the knee. These first results motivate to start further R& D on Ceramic on Ceramic bearings for total knee implants.

Introduction The first ceramic knee implant in a human patient was used by Dr. G. Langer of the Orthopaedic Clinic at the University of Jena, Germany in 1972. In 1980, Drs. Oonishi and Hasegave began using a alumina femoral component on a polyethylene tibial component. These early attempts all involve the search for solutions to the wear and degradation problems. The application of ceramics was limited by:

polyethylene wear and degradation

Excellent Scratch resistance AMC Ceramics is much harder than most surgical instruments. In comparison, metal components are easily scratched and damaged during surgery with the consequence of increasing wear.

Surface quality: Surface quality of the articulation surfaces components made from AMC Ceramics provide excellent articulation surfaces.

Low Friction: Knee Components made of AMC Ceramics show a low coefficient of friction. The resulting frictional forces on the prostheses are lower and offer the option for a reduction of aseptic loosening.

Low Allergic Potential: Ceramics are generally not considered as elicitors of allergic reactions. Hypersensitive reactions – especially to nickel – in total joint replacement are discussed as one possible reason for postoperative syndromes.

Surface Lubrication: AMC is a material with a very good surface lubrication capability. A low wetting angle is exhibited by the material.

Conclusion: Knee implants have become an area of great interest in the past years. For more than 10 years ceramic femoral components are used in Japan. Published follow-up data in scientifically journals are promising. Leading orthopaedic surgeons are interested in this option today to reduce the risk of pitting and delamination of Polyethylene. Material improvements are required for young active patients and nickel sensitive patients.

The novel AMC Ceramic offers a solution to minimise the allergic and wear related problems of knee implants. New concepts on the basis of hard on hard combination are technically already realised. The use of knee endoprosthesis with ceramic on ceramic combination is an option for ”zero” wear bearings in the knee.

The first Ceramic knee implant in a human patient was used by Dr. G. Langer of the Orthopedic Clinic at the University of Jena, Germany in 1972 [1]. In 1980, Drs. Oonishi and Hasegave began using an Alumina femoral component on a polyethylene tibial component [2]. These early attempts all involve the search for solutions to the wear and degradation problems. The application of ceramics was limited by the demand of thin components. In the present feasibility study the in vitro wear behavior of a knee concept with a novel Alumina Matrix Composite (AMC) Ceramic was examined [3,4].

The wear behaviour of the Ceramic components for the knee system were tested in accordance to ISO/WD 14243-3 for 5*106 cycles. Six samples were tested. The lubricant was calf serum diluted with deionized water. All tests have been performed with components made of the novel AMC Ceramic. The wear test performed showed an average gravimetric wear rate below 1 mg/1*106 cycles on each of the six components. A change of geometry was not measurable after 5 million cycles. No significant change of the surface structure was detectable with a conventional surface tracer. SEM and AFM pictures show traces of ultra mild abrasive wear at the surface.

The performed investigation on the novel knee concept shows the following potential benefits for a Ceramic knee bearing:

approx. 500 times lower volumetric wear

The novel AMC Ceramic offers a solution to minimize the allergic and wear related problems of knee implants. New concepts on the basis of hard on hard combination are to be realized. The use of knee endoprosthesis with Ceramic on Ceramic combination is an option for ”zero” wear bearings in the knee. These first results motivate to start further R& D on Ceramic on Ceramic bearings for total knee implants.