Experimental study of the mechanical properties of Palacos bone cements

Background. Currently, bone cements are widely used in orthopedics. The range of prescriptions for bone cement use is very large, and requires different qualities depending on the purpose. Therefore, researchers are forced to conduct their own invetigations to study the mechanical properties of bone cements. The purpose was to determine in the experiment the value of an elastic modulus and ultimate strength of Palacos bone cements for further use in mathematical models of osteosynthesis and arthroplasty. Materials and methods. Samples of two brands of cement, Palacos R and Palacos fast, were examined. Samples with a diameter of 5 mm and a length of 10 mm were made from each type of cement. The study was carried out 2 hours and 2 days after polymerization. At each stage, 10 cement samples of each type were tested for compression. Results. After 2 hours of polymerization, the Palacos fast samples had a statistically significant advantage in terms of the tensile strength, which was 105.77 ± 3.19 MPa, over the Palacos R — 87.24 ± 3.70 MPa. The higher elastic modulus for Palacos fast samples — 2,942.50 ± 99.67 MPa compared to Palacos R — 82,542.40 ± 65.55 MPa turned out to be statistically significant. Two days after fabrication, the strength characteristics of bone cements changed upward. Thus, the ultimate strength of Palacos fast samples was determined within 116.39 ± 2.85 MPa, which is statistically significant higher than for Palacos R samples for which this indicator was within 95.58 ± 4.53 MPa. Similar tendencies were characteristic of an elastic modulus, which amounted to 3,048.93 ± 108.70 MPa for Palacos fast and 2,642.90 ± 22.93 MPa — for Palacos R samples. The value of the elastic modulus for both brands of bone cement has a statistically significant tendency to increase. On average, an elastic modulus for Palacos R cement increased by 4.0 ± 2.6 %, for Palacos fast samples — by 3.5 ± 1.4 %. Conclusions. Palacos R bone cement by the end of the polymerization process has an elastic modulus of 2,542.40 ± 65.55 MPa and a tensile strength of 87.24 ± 3.70 MPa, which is statistically significant lower (p = 0.001) than thereof Palacos fast cement (2,942.50 ± ± 99.67 MPa and 105.77 ± 3.19 MPa, respectively). The indicators of the tensile strength and elastic modulus of the samples of bone cement of both studied brands have a statistically significant (p = 0.001) tendency to increase within 2 days, on average by 9.6 ± 10.1 % and 3.5 ± 4.0 %, respectively. The obtained elastic modulus and ultimate strength of Palacos R and Palacos fast bone cements can be used for mathematical modeling of various types of arthroplasty.