A reduced-modulus acrylic bone cement: preliminary results.

Excessive local contact stress is implicated as an important factor in the initiation of the loosening process after total joint arthroplasties. A reduced-modulus acrylic bone cement, which decreases the bone-cement interface stresses, was developed to test this hypothesis. The formulation consists of butylmethacrylate beads, having a glass transition temperature of 27 degrees C, in a methylmethacrylate matrix. This cement, polybutylmethylmethacrylate (PBMMA), has an elastic modulus one-eighth that of standard PMMA bone cement, 0.27 vs. 2.1 GPa, at body temperature. In vivo use in a pilot study using the sheep total hip arthroplasty model shows a reduction in the rate of loosening of femoral components when compared both radiographically and mechanically with PMMA controls.