Reactions and complications after the implantation of Endobon including morphological examination of explants

In the study described here, the integration of hydroxyapatite (HA) ceramic implants (Endobon) was investigated. These implants have an interconnectin g system of pores and are free from foreign protein. The material is not to xic, genotoxic, nor zytotoxic, and it is biocompatible. The progress of int egration was investigated by means of clinical and radiological check-ups. From 10 patients, it was possible to obtain samples for histological analys is during a second operation (e.g., metal explantation). Microscopic examin ation showed bony integration with newly formed bone in direct contact with the HA ceramic; it also showed osteoblasts and osteoid seams. No second op eration took place earlier than 4 months after the first operation, yet eve n after this relatively short period, bony integration was already evident. Clinical observation (based on X-rays, reports of pain, signs of inflammat ion) showed that in most cases healing was taking place without complicatio ns. More general operational complications such as thrombosis or nerve inju ry were observed in 4 patients. If the implant is not sufficiently protecte d from mechanical stress, bony integation will not take place, and the impl ant may fracture. HA ceramic, with a porosity between 30% and 80%, is not c omparable to cortical bone but only to spongy bone. This factor must be tak en into account when deciding whether a HA ceramic implant is indicated.