Boneloc bone-cement - Experience in hip arthroplasty during a 3-year period

Polymethyl methacrylate (PMMA) bone-cement was introduced in the 1960s for fixation of total hip arthroplasty replacement components. Long-term results of cement fixation for hip and knee arthroplasty have been extremely good. Although the use of PMMA bone-cement has enabled long-term survival of joint arthroplasty implants, there has been concern about aseptic loosening. This concern led to the introduction of Boneloc bone-cement (Biomet, Warsaw, IN) in the early 1990s. It was hoped that with the improved physical and chemical characteristics of Boneloc, there would be less aseptic loosening in the long-term. A clinical trial was conducted to evaluate Boneloc bone-cement in cementing the femoral component of the Bimetric total hip arthroplasty prosthesis in 33 hips in 32 patients. On follow-up, 7 stems (24%) developed definite loosening, and 3 stems (10%) were possibly loose. Of the 7 definite loose stems, 5 (17%) were revised because of increasing pain or progressive loosening. Despite the biologic advantages of Boneloc, this study suggests that the chemicals substituted in Boneloc bone-cement led to an alteration in its mechanical properties. These properties proved to be inferior to conventional PMMA bone-cement. There is possible time-dependent deterioration of mechanical properties leading to early aseptic loosening. The conventional PMMA bone-cement has stood the test of time. Research and experimental studies should continue to improve the mechanical properties of Boneloc before further human trials. Key words: Boneloc, cement, hip arthroplasty, early loosening, cement failure.