The weight-average molecular weight (MW(w)) of a cement and the method used to mix its
powder and liquid monomer constituents have been identified in the literature as key variables that affect mechanical properties of the fully polymerized cement that are relevant to its performance as a grouting agent in cemented
arthroplasties. The goal of the present work was to identify which of these two variables exerts the greater effect in the case of fully reversed tension-compression
fatigue performance. A judicious choice of cement brands, Surgical
Simplex P and Osteopal, and the use of hand versus vacuum mixing, permitted this identification to be achieved. Three key observations were made in this work. First, for a given cement, the
fatigue performance of vacuum-mixed specimens is far superior to that of hand-mixed ones, which may be a consequence of the substantially lower percentage areal porosity of the former specimens. Second, regardless of the mixing method, the
fatigue performance of Osteopal outstrips that of
Simplex P, a result that is attributed to the much higher MW(w) of the former cement. Third, hand-mixed Osteopal outperforms vacuum-mixed
Simplex P (especially at low alternating stress levels), indicating that MW(w) of a
bone cement is more influential than mixing method on its
fatigue performance.