TOMOGRAPHIC (PQCT) AND BIOMECHANICAL EFFECTS OF HPTH(1-38) ON CHRONICALLY IMMOBILIZED OR OVERLOADED RAT FEMURS

Six-month old rats chronically submitted to right hindlimb immobilizat ion (IM) with mechanical overload (OL) of the left leg were treated 1 month later with 200 ug/kg/d of hPTH(1-38) for 15 or 75 days. Peripher al quantitative computed tomography (pQCT) scans and bending tests sho wed that hPTH increased cortical mass and volumetric BMD (vCtBMD) in b oth legs. However, elastic modulus of cortical bone and diaphyseal loa d-bearing capacity were improved only in OL bones. Improvement of diap hyseal strength was attributable to that of cortical bone quality, yet a stronger mechanostatic response of cortical modeling to bone materi al quality was also observed in treated OL bones. Data support hPTH(1- 38) use for improving cortical bone mass and strength and point out a physical activity interaction with therapeutic results.