Site and sex specific bone mineral content, and density trajectories from adolescence through to 15 years post peak bone mass.

Background: Relatively, little is known about bone parameter trajectories after attainment of peak bone mass (PBM).

Aim: To investigate the individual and mean trajectories of bone mineral content (BMC) and areal bone mineral density (aBMD) after the attainment of PBM at four anatomical sites (Total Body (TB), Lumbar Spine (LS), Total Hip (TH), Femoral Neck (FN)).

Subjects and methods: SITAR models were fitted to 162 individual's (70 males and 92 females) longitudinally collected bone parameters.

Results: It was found from PBM to 15-years post PBM, that males TB, TH and LS increased by 4-7% in BMC and by 10% in TB aBMD, and a 1.3% decrease in FN BMC and a 2-4% decrease in LS, TH and FN aBMD. In comparison, females TB, LS TH and FN increased by 1-7% in BMC and increased in TB and LS aBMD by 3-15% and decreased by 1-3% in TH and FN aBMD, 15 years after the attainment of PBM.

Conclusion: Comparing the change to the precision of the instrument it was found that males and females showed real change in BMC at the TB, LS and TH but no real change at the FN from PBM to 15 years post PBM. In aBMD a real increase was found in TB and decrease in FN. Future studies should explore the roles of other factors, such as changes in lifestyle, related to bone mineral change after PBM attainment on bone trajectories.