Mechanical strength of antibiotic-impregnated bone cement on Day 0 and Day 15: a biomechanical study with Surgical Simplex P and teicoplanin

Abstract

OBJECTIVES: To determine the maximum amount of a specific antibiotic added to 40 g acrylic bone cement in terms of the effect on mechanical properties of the bone cement on Day 0 and after antibiotic release on Day 15. METHODS: In an experimental design, eight teicoplanin doses (0, 400 mg, 800 mg, 1200 mg, 1600 mg, 2000 mg, 3200 mg and 4000 mg) were added to bone cement (Surgical Simplex P). Specimens were prepared using the third generation cementing technique to determine the compressive strength and four-point bending strength according to ASTM and ISO standards, respectively. For each concentration, 10 samples were prepared for Day 0 and Day 15. Mechanical tests were performed on Day 0 and after antibiotic leaching in water at 37 degrees C on Day 15. 0 mg specimens served as controls and mechanical strengths for each antibiotic concentration on Day 0 and Day 15 were compared. RESULTS: In compression tests, Day 0 samples showed no significant differences, whereas Day 15 samples starting with 800 mg exhibited significant decreases in compressive strength. However, the compressive strengths were above the minimum standard of 70 MPa set by ASTM at all concentrations and in all groups. Four-point bending tests demonstrated significant decreases in strength starting with 1200 mg in Day 0 samples, and with 400 mg in Day 15 samples. Four-point bending strengths of 2000 mg, 3200 mg, and 4000 mg samples decreased below, or approximated closely the minimum standard of 50 MPa set by ISO on Day 15. CONCLUSION: Our results suggest that the maximum amount of teicoplanin dose to be safely added to 40 g of Surgical Simplex P is 1600 mg when third generation cement mixing and application techniques are employed.