Effect of age and osteoarthritis on bone mineral in rhesus monkey vertebrae.

We have used vertebrae of free-ranging rhesus macaques to study the effect of age and osteoarthritis on bone mineralization and bone density and to relate these findings to weight, sex, parity, and mineral chemistry. Bone mineralization was determined using the density fractionation technique and bone density using dual-photon absorptiometry. Arthritis was determined osteologically. We found a relationship between mineralization, age, and osteophytes, such that mineralization rose with age in nonarthritics and decreased with age in arthritics. This could also be seen when the females were examined separately. In males, only an increase in mineralization with age could be seen. In females mineralization decreases with parity. Also in females, DPA density decreases with age and increases with parity. No relationships with DPA density could be seen using males and females together or males alone. In conclusion, we have shown that normal skeletal aging in rhesus monkeys is accompanied by an increase in mineralization similar to that in other species, but this is not true in the presence of osteoarthritis. In the females parity has an important effect because it seems to build up bone mass even though the bone present may be undermineralized.