The effects of combined human parathyroid hormone (1-34) and simvastatin treatment on osseous integration of hydroxyapatite-coated titanium implants in the femur of ovariectomized rats.

The effect of human parathyroid hormone 1-34 (PTH) and simvastatin (SIM) alone could promote bone healing in osteoporotic osseous integration of the implant, but there are no reports about the combined use of PTH and SIM for promotion of bone healing around implant in osteoporotic settings still limited. This study aims to investigate effects of PTH+SIM on osseous integration of the implant in OVX rats. Female Sprague-Dawley rats were used for this study. Twelve weeks after bilateral ovariectomy, all animals were randomly divided into four groups: group control; group SIM; group PTH and group PTH+SIM. Afterwards, all OVX rats received hydroxyapatite (HA)-coated titanium rods (external diameter and length are 1.5mm and 20mm) in the femoral medullary canal. Subsequently, the animals from group SIM, group PTH and group PTH+SIM received human parathyroid hormone 1-34 (60μg/kg, three times a week), SIM (5mg/kg daily), or both for 12 weeks. Implants were inserted bilaterally in all animals until death at 12 weeks. The bilateral femurs of rats were harvested for evaluation. All groups increased new bone formation around the surface of titanium rods and push-out force; group PTH+SIM showed the strongest effects on new bone formation and biomechanical strength. Additionally, these are significant difference observed in bone formation and push-out force between groups SIM and PTH. This finding suggests that intermittent administration of PTH or SIM alone has an effect to increase new bone formation on the surface of HA-coated implants in the osteoporotic condition, and the additive effects of combination PTH and SIM on osseous integration of the implant in OVX rats.