Parathyroid hormone (1-34) increases the density of rat cancellous bone in a bone chamber - A dose-response study

Intermittent treatment with parathyroid hormone (PTH) has has an anabolic effect on bath intact cancellous and cortical bone. Very little is known about the effect of the administration off PTH on the healing of fractures or the incorporation of orthopaedic implants. We have investigated the spontaneous ingrowth of callus and the formation of bone in a titanium chamber implanted at the medioproximal aspect of the tibial metaphysis of the rat. Four groups of ten male rats weighing approximately 350 g were injected with human PTH (1-34) in a dosage of 0, 15, 60 or 240 mu g/kg/day, respectively, for 42 days from the day of implantation of the chamber. During the observation period the chamber became only partly filled with callus and bone and no difference in ingrowth distance into the chamber was found between the groups, The cancellous density was increased by 90%, 132% and 173% in the groups given PTR in a dosage of 15, 60 or 240 mu g/kg/day, respectively. There clp as a linear correlation between bone density and the log PTH doses (r(2) = 0.6), Our findings suggest that treatment with PTH may have a potential for enhancement of the incorporation of orthopaedic implants as well as a beneficial effect on the healing of Fractures when it is given in low dosages.