Effect of alendronate amount on the static mechanical properties of bone cement

Objective: To determine the effect of alendronate amount on the static mechanical properties of bone cement before elution and 4 weeks after elution, and determine suitable amount of alendronate in cement from the perspective of biomechanics. Methods: Samples of compression strength and bending strength (modulus) were prepared with bone cement adding 0,10, SO, 100, S00 and 1000 mg alendronate in SO g Cemex'XL bone cement powders respectively (named as G ₀-G₅ groups). The compression strength, bending strength, and bending modulus of bone cement were examinated by INSTRON 8032 tester before the elution and 4 weeks after the elution. Some broken samples of 4-point bending test were examinated by scanning electronic microscopy (SEM), and some other samples of bending strength (modulus) tests by micro-CT. Results: No significant difference was found in the compression strength before the elution, 4 weeks after elution in the 6 groups, and before and after the elution in the respective groups (P>0.05). Compared with G₀ group, G ₁-G₄ groups had no obvious difference in the bending strength before the elution and 4 weeks after the elution (P>0.05), while G_s group had difference (P<0.05). There was no significant difference in the bending strength before and after the elution in the respective groups (P>0.05). Taken G₀ group as the control group, G₁-G₄ groups had no visible effects on the bending modulus 4 weeks after the elution (P>0.05), while G₅ group decreased it significantly (P<0.05). Bending modulus before the elution in the 6 groups didn't show obvious difference (P>0.05), while bending modulus before and after the elution in the respective groups displayed a marked difference (P<0.05). Conclusion: Less than 500 mg alendronate added in Cemex XL 50 g bone cement powder does not decrease the compressive strength, flexural strength and flexural modulus before the elution and 4 weeks after the elution.