Abstract
Recent improvements in HA-coating technique make it possible to apply HA by different methods. The most promising is the precipitation technique. A thin Ca-P of 10 – 30 microns thickness can be applied using precipitation in fluid. The process takes place at room temperature in stead of at temperatures of many thousends of degrees centigrade. Still providing an HA-coating of similar type as the plasma-spray technique, there are several advantages associated with its use. To start with, the coating is of a micro-crystalline type in stead of macro-crystalline. This provides enhanced bioactivity because the exposed surface area of a micro-crystralline surface is much greater. At second it is possible to coat irregular surfaces, including porous materials that can not be coated using conventional techniques because the pores would be closed down. At third it is possible to include biological factors in the coating such as growth factors, bone-morphogenetic proteins or antibiotics at the time of manufacturing because the process takes place at room temperature. The high temperatures used with plasma-sprayed HA-coatings would preclude this. Experiments confirm these improvements. They show much enhanced bone apposition. Also the combination with antibiotics, growth factors or BMP’s is attractive because it may lead to a reduction in the need for bone graft materials or infection especially in revision surgery. This will greatly influence the possibilities of bone repair especially in revision surgery. Several experimental and clinical studies are currently ongoing and it is expected that these new enhanced coatings will expand the use of HA-coatings on more implant surface structures.
The abstracts were prepared by Ms Grazia Gliozzi. Correspondence should be addressed to her at the Italian Orthopaedic Research Society, Laboratory for Pathophysiology, Instituti Ortopedici Rizzoli, University of Bologna, Bologna, Italy.
