QCT measurement of cortical bone repair in osteopenic ovariectomized rats treated with PTH

A longitudinal QCT model was developed to quantify the osteogenic efficacy of parathyroid hormone (PTH) to enhance fracture repair in rats. Holes were drilled into both femora of aged, osteopenic, ovariectomized (OVX) rats. hPTH-(l-38) was administered subcutaneously, and longitudinal QCT scans were taken weekly from baseline for five weeks. 3D volumes of each midshaft were realigned using a rigid body registration method, and oblique sections were analyzed parallel to the cortical bone surfaces. Image intensities were measured in the defect areas along cortical surfaces to ascertain the rate and extent of cortical bone regeneration with PTH. PTH significantly enhanced cortical bone repair relative to vehicle controls and displayed a unique bone regeneration pattern.