Add to ORKGThe composition and viscosity of an acrylic bone cement have both been identified in the literature as being parameters that affect the mechanical properties of the material and, by extension, the in vivo longevity of cemented arthroplasties. The objective of the present study was to determine the relative influence of these parameters on a key cement mechanical property; namely, its fracture toughness. Two sets of cements were selected purposefully to allow the study objective to be achieved. Thus, one set comprised two cements with very similar compositions but very different viscosities (Cemex(TM) RX, a medium-viscosity brand, and Cemex Isoplastic, a high-viscosity brand) while the other set comprised two cements with similar viscosities...