A simple method of determining the modulus of orthopedic bone cement

Abstract

Accurate determination of the elastic modulus of surgical bone cements is of primary importance, when evaluating the stresses within the cement mantle in Total Joint Arthroplasty. This article presents a new method of determining the modulus of surgical bone cements from the biaxial flexural test. The biaxial flexural test is not currently employed in mainstream orthopedic mechanical testing, which is surprising because most loading in orthopedic applications is biaxial in nature. Nor has this method been utilized for dental materials, even though the biaxial flexure test has been used for many years in this field. It has been demonstrated that the modulus of surgical bone cements can be determined from the biaxial flexural test, and these results are in agreement with results from compressive and bending tests.

Biaxial flexural modulus of antibiotic‐impregnated orthopedic bone cement

“…These tests in isolation may not be representative of bone cement's true load-bearing capacity in total joint arthroplasty. Accordingly, Higgs et al 25 developed a biaxial flexural testing protocol where the testing specimen is evaluated under combined loading conditions (hoop, axial, and flexural loading). It was shown 26 that under biaxial loading, maximum bending stresses occur at the center of test sample away from the edges and are independent of the angular orientation and the number of supports.…”

“…Kirstein and Woolley 26 substantiated the biaxial theory by reporting a good agreement between a number of experimental results and the theoretical predictions of tangential strains along the concentric support circle. Furthermore, finite element analysis 25 has been used to further validate the accuracy of the biaxial test theory for cement loading applications in TJR. The \biaxial modulus" can be determined using this protocol, which involves supporting a testing specimen (configured in the shape of a plate) on three or more points near its periphery and equidistant from the center portion of the specimen.…”

“…26,27 The utility of this testing method with bone cement has been previously evaluated and found to be in agreement with results from compressive and bending tests. 25 Although this testing method has been previously described, to our knowledge it has not specifically been used to analyze and compare the effects of adding different antibiotics to polymethylmethacrylate bone cement (Simplex 1 P, Stryker Orthopedics, 325 Corporate Drive, Mahwah, NJ 07430). This application will enable more accurate and consistent reporting of critical parameters that may guide the orthopedic surgeon in deciding, which antibiotics to use with bone cement for selective cases in total joint arthroplasty.…”

Calcium polyphosphate as an additive to zinc-silicate glass ionomer cements

“…Discs were placed on a threepoint support ring and a point load was applied at the centre. Biaxial flexural tensile strength was calculated using the equation developed for cement discs by Timoshenko and Woinowsky-Krieger 37 and tensile modulus was calculated following Higgs et al 38 (mean AE SD, n ! 5).…”

Effect of surface modification of polymer beads on the mechanical properties of acrylic bone cement

“…This is the measure of the ability of the bone cement to act as an elastic buffer between the prosthesis and the bone [24]. The porosity of the composite usually decreases E. The micro-pores in the cement should be partially removed via vacuum mixing.…”