Reference point indentation

Fracture is the clinical event in osteoporosis that induces morbidity and mortality. Bone strength depends on three basic components: amount of mineral; architecture; and tissue characteristics. However, a minimally invasive technique called reference point indentation (RPI) has been developed as a novel, feasible measurement of the mechanical properties of bone at the tissue level. The two RPI techniques, cyclic reference point indentation (cRPI) and impact reference point indentation (iRPI), differ in their loading rates and patterns and use of test probes that have slightly different diameters. Several preclinical studies have been performed using cRPI in various animal models, including mice, rats, pigs, and dogs. Clearly, additional preclinical studies are needed to establish optimal protocols for preclinical testing and to determine whether cRPI is a reliable technology for assessing in vivo bone material properties in various animal models.