Effect of different mixing modes of enoxaparin sodium on biomechanics of bone cement

Abstract

Objective To observe the biomechanical effects of enoxaparin sodium added to bone in different mixing modes. Methods The enoxaparin sodium for injection was mixed with polymethylmethacrylate (PMMA) bone according to different dosages and different mixing methods. Group A was used as blank control group without enoxaparin sodium. Groups B (8 000 AxaIU), C (16 000 AxaIU) and D (24 000 AxaIU) served as control groups in a powder mixture. Groups E (8 000 AxaIU), F (16 000 AxaIU) and G (24 000 AxaIU) served as experimental groups. The enoxaparin sodium for injection was dissolved and added to the PMMA bone cement. Under the environment of sterility, temperature (23±1) ℃, relative humidity higher than 40% (operating room environment), according to the international standard ISO5833: 2002 Implants for surgery-Acrylic resin cement regulations, bone cylinder specimens and cuboid specimens were prepared. After measurement and X-ray irradiation, 5 specimens of each group were selected, and the compressive strength, flexural strength and flexural modulus were measured on an electronic material universal testing machine. Results The compressive strength, flexural strength and flexural modulus in groups E, F and G were significantly lower than those in the control groups (t=12.731, 41.646, 3.128, P<0.05). The lowest values were (57.17±1.15) MPa, (67.93± 0.55) MPa, and (19.2± 0.114) GPa respectively. Conclusion The addition of enoxaparin sodium to PMMA bone in a liquid mixture can significantly reduce the biomechanical properties of bone cement. Key words: Polymethylmethacrylate bone cement; Enoxaparin sodium; Biomechanics