A medical device company asked Exponent to assist with testing of their bone cement to be used for treatment of vertebral compression fractures for FDA submission. In this study, static tensile and compressive testing, as well as fully reversed fatigue testing, was performed on three PMMA-based bone cements. Cements tested were SimplexsP with 10% barium sulfate (Stryker Orthopedics, Mahwah, NJ) which served as a control; SimplexsP with 36% barium sulfate prepared according to the clinical recommendation of Theodorou et al.; and KyphX HV-R with 30% barium sulfate (Kyphon Inc., Sunnyvale, CA). Static tensile and compressive testing was performed in accordance with ASTM F451-99a. Fatigue testing was conducted in accordance with ASTM standard F2118-01a under fully reversed, ±10-, ±15-, and ±20-MPa stress ranges. Survival analysis was performed using 3-parameter Weibull modeling techniques. KyphX HV-R was found to have comparable static mechanical properties and significantly greater fatigue life than either of the two control materials evaluated in the present study. The static tensile (Figure 1) and compressive strengths (Figure 2) for all three PMMA-based bone cements were found to be an order of magnitude greater than the expected stress levels within a treated vertebral body (Figure 1). The static and fatigue testing data collected in this study indicate that bone cement can be designed with barium sulfate levels sufficiently high to permit fluoroscopic visualization while retaining the overall mechanical profile of a conventional bone cement under typical in vivo loading conditions. This study was published in the journal
Biomaterials in 2005.*
Figure 1. Tensile stress-strain curves for Simplex, KyphX HV-R, and Clinical formulations tested in room temperature air
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Figure 2. Tensile stress-strain curves for Simplex, KyphX HV-R, and Clinical formulations - testing was conducted in room temperature air
*Kurtz S, Villarraga M, Zhao K, Edidin A. Static and fatigue mechanical behavior of bone cement with elevated barium sulfate content for treatment of vertebral compression fractures. Biomaterials 2005; 26:3699–3712.