Osteon remodeling dynamics in Macaca mulatta: normal variation with regard to age, sex, and skeletal maturity.

As research into bone maintenance and turnover is accelerated and expanded due to public health concerns about osteoporosis and other age-related changes and pathologies of bone, nonhuman animal models are becoming increasingly important as they allow for enhanced experimental manipulation and environmental control relative to humans. Old World Monkeys, such as the rhesus macaque, share physiological and developmental characteristics that make these primates particularly well suited to such studies. The purpose of this study was to characterize normal age and sex variation in osteon remodeling dynamics in skeletally immature and mature rhesus macaques. Femoral cross-sections from 75 Macaca mulatta were examined to evaluate the effect of age, sex, and skeletal maturity on osteon remodeling dynamics in this popular research primate. Results indicate that sex has a significant effect on osteon area (On.Ar), but generally is not an important contributor to normal variation in intracortical remodeling dynamics. Age and skeletal maturity, however, contribute significantly to variation in osteon population density (OPD), activation frequency (Ac.f), and bone formation rate (BFR), as is the case in humans. This study is the first to characterize normal age and sex variation in osteon remodeling in growing and adult rhesus macaques and its results support the use of this animal as a model for age-related changes and pathologies in the human skeleton.