Abstract
The effects of the intermittent administration of parathyroid hormone (PTH) were studied in a rabbit callus distraction model. We made callus distraction model in Japanese white rabbits (2.2 to 2.6 kg), and underwent continuous distraction on the osteotomized-tibia for 10.5 mm. Concomitantly with the commencement of distraction, in 5 rabbits, 10μg/kg (group P10) or 30μg/kg (group P30) of PTH were injected subcutaneously every other day for 4 weeks. The 5 omophagous rabbits were identified as the group N. Eight weeks after surgery, the bones of the hind legs were extracted, a plain X-ray image, bone density, pQCT and μCT measurements, and mechanical testing were performed. The P30 group showed advanced remodeling of the callus to a greater extent in the plain X-ray image, significant sectional enlargement in the callus in pQCT study, and the largest bone trabeculae of the callus microarchitecture in μCT than the other two groups. In mechanical testing, the work to failure in the group P30 was significantly larger than that in the other two groups. In conclusion, intermittent administration of PTH promotes osteogenesis of calluses in a rabbit callus distraction model.
