Comparison of the effects of alendronate sodium and calcitonin on bone-prosthesis osseointegration in osteoporotic rats

Alendronate (ALO) and calcitonin (CT), as commonly used antiosteoporosis drugs in current clinical practice, have been experimentally confirmed to produce the effectiveness of promoting osseointegration at the interface between prosthesis and host bone and enhancing the long-term stability of the prosthesis. Our current study compared these two drugs' effects on the osseointegration of prosthesis and found that both of them could promote bone attachment between prosthesis and host bone; moreover, ALO produced more pronounced effectiveness. A series of findings confirmed that ALO and CT improved bone attachment of implant in animals. However, which one shows stronger effectiveness has not yet been reported by previous researches. Our study compared the effects of the two commonly used antiosteoporosis drugs on the bone-prosthesis osseointegration so as to provide valuable reference for current clinical options of medication. Forty female SD rats aged 5 months were randomly set into A, B, C, and D groups. Except for group A, the others were ovariectomized to establish osteoporosis model (lumbar bone mineral density (BMD) decreased by 20% 4 weeks after ovariectomy). All the rats received prosthesis implantation at their tibial plateau. Then, the rats in groups C and D were given ALO (7 mg/kg/w) orally and CT (5 IU/kg/day) subcutaneously for 12 weeks, respectively. Prior to the execution, application of tetracycline hydrochloride for staining in vivo was done. After harvesting and embedding, the tibia with implants were cut into thin slides, then the bone histomorphometry was measured to observe the new bone around prosthesis and to calculate the osseointegration rate of the implants. By comparison, the effect of the two drugs on osseointegration was evaluated. (1) Both ALO and CT can effectively enhance the volume of bone mass surrounding the hydroxyapatite (HA) prosthesis and also significantly lever up osseointegration rate to 63.7% and 45.7%, respectively (p < 0.05). However, ALO produced more periprosthesis osseointegration rate than CT, with difference of 18% (p < 0.05). (2) The rats' lumber BMD increased in both ALO and CT groups, from 0.081 +/- 0.009 and 0.078 +/- 0.009 to 0.116 +/- 0.008 and 0.109 +/- 0.010 g/cm(2), respectively. Moreover, the effect of ALO was observed more pronounced than that of CT. In osteoporotic conditions, both administration of ALO orally and CT subcutaneously can enhance periprosthesis bone mass and the effects on osseointegration between host bone and prosthesis. Compared with CT, the effect of ALO is more pronounced.