Histomorphological and biomechanical characterization of calcium phosphates in the osseous environment

The standardization of characterization techniques is becoming increasingly important for bone replacement materials as it becomes apparent that, for the field to advance, testing must be developed to allow the biocompatibility or bioactivity of a new material to be assessed and directly compared with existing materials. Currently there are many forms of biocompatibility test for materials destined for the osseous environment, ranging from immersion in simulated body fluid to implantation into living bone. However, the variety of ways in which the data from these tests may be acquired and interpreted, as a result of changes in parameters such as surgical technique and mechanical test conditions, means that much of the published data within the field is not comparable. This paper will introduce the concept of biocompatibility by considering calcium phosphate bioceramics, and discusses some aspects of in vivo experimental design, including simple histomorphometry techniques, in addition to considering practical methods for the assessment of the biomechanical characteristics of an osseointegrated implant.