Joint Endoprosthetics Research Articles

Characteristic Properties of a New Dispersion Ceramic

The ceramic materials Al2O3 and ZrO2 proved successful in hip joint endoprosthetics for more than 20 years. The advantages of these materials are to be found in particular with the very good properties like biocompatibility and wear resistance; thus, they are clearly ahead of conventional materials like metal or PE. The increasing requirements regarding implants can only be realised by means of improvement of the used materials. That is why we surveyed utilisation of new dispersion ceramics consisting of Al2O3 and ZrO2. The first tests were aimed at characterisation of the material regarding material features and measurement of burst load at the hip joint heads. The results showed that both bending strength and burst load of the components could be significantly improved. Thus, the new ZTA dispersion ceramic is perfectly suitable for use with joint endoprosthetics.

Third-Body-Wear as a Risk Factor in Joint Endoprosthetics

It is well known, that wear of the articulation partners of hip joint prostheses affect the long-term durability of the implants in vivo. The wear is dramatically increased if particles in the artificial joint gap act as third body. Those particles can also occur after a fracture of a ceramic component. Until now there are some different guidelines which coupling (metal-polyethylene, ceramic-polyethylene, ceramic-ceramic) should be used for revision. We tested and compared the wear behaviour of a ceramic-PE-pairing and a ceramic-ceramic-pairing under third body wear conditions with alumina-particles in a hip joint simulator.

Development of an Alumina Ceramic with a Gradient of Concentration and Microstructure for the Application of Load Bearing Implants

Alumina and zirconia have played an important role in joint endoprosthetics for the use in tribologically loaded implant components like hip joint heads and cups for years. In our investigations we prepared an alumina ceramic with a gradient in concentration of zirconia. The zirconia content was realized by infiltration processes with different ZrO2 – precursors. The material was characterized concerning ZrO2-distribution, infiltration depth and microstructure.

Die operative Therapie der ankylosierenden Spondylitis

Surgery may bcome necessary in ankylosing spondylitis in a wide variety of organs, although such cases are extremely rare. This includes, in the region of the supporting and locomotor system, occasional invasive diagnostic measures or the morphological exclusion diagnosis of other diseases. Surgical treatment of extravertebral joint manifestations is mainly determined by the high standard of joint endoprosthetics. It is only rarely that patients suffering from Bechterew's disease require linear osteotomy to be performed - in which the tendency of complication is great - because promising conservative measures are now available. Although ankylosing spondylitis produces a great spontaneous stiffening tendency at the vertebral column, it may occasionally be necessary to perform stabilizing surgery due to atlanto-axial dislocation. In such cases, the pathogenic factors, clinical science and surgical technique are hardly different from the much more frequent atlanto-axial dislocation in rheumatoid arthritis. On the other hand, the present state of surgical technique does not lead us to expect theoretically meaningful, mobilizing surgery in the region of the vertebral column in the near future.