Bone cement and the implications for anaesthesia

Abstract

Poly(methyl methacrylate) (PMMA) was developed in 1928 and was first marketed under the name of ‘Plexiglas’. Since then, PMMA has been used in a huge number of applications, including transparent glass substitutes in windows, semiconductor research, and for the bodies of electric guitars. PMMA has a good degree of biocompatibility, which has made it an important component of replacement intraocular lenses, dentures, and dental filling composite materials. In orthopaedic surgery, PMMA bone cement is used to affix implants and to remodel lost bone. The medical orthopaedic use of PMMA is universally credited to Sir John Charnley, who was inspired by his dentist to use dental acrylic for prosthetic fixation in total hip replacement (THR) procedures in 1957. In 1965, he began to use bone cement (CMW Bone Cement TM ) that was developed specifically for THRs rather than dental acrylic. Bone cement is now routinely used in a variety of orthopaedic procedures. The microscopic structure of bone cement comprises two substances glued together. The so-called ‘pearls’ in bone cement consist of small particles of pre-polymerized PMMA, which are present as white powder. The second substance is a liquid monomer of methyl methacrylate (MMA). Both substances are mixed together in theatre after the addition of a catalyst that initiates the polymerization of the monomer fluid. When the bone cement hardens, the individual pearls are entrapped and glued within the net of the polymerized monomer, but no chemical binding occurs between the pearls and the polymerized