Sodium fluoride sustained-release bone cement: an experimental study in vitro and in vivo

A new "low temperature" bone cement, consisting of polymethylmethacrylate (PMMA) and 6% sodium fluoride, was developed for use in orthopedics. Fluoride is a well-known agent that may stimulate osteoblast activity and differentiation in vitro and in vivo; for this reason fluoride has been used for 30 years in the treatment of osteoporotic diseases of the bone. A local effect obtained with a slow release of fluoride from bone cement at the interface between bone and prosthetic implants could potentially enhance new bone formation around the prosthesis. This material was investigated both "in vitro", by establishing the kinetics of fluoride release from the acrylic bone cement and its maximal compressive strength, and "in vivo", by fitting 24 rabbits, which were then killed after 4, 12 and 16 weeks, with femoral implants, following labelling with fluorescent stains to allow the histologic evaluation of bone remodelling. The "in vitro" study revealed the release kinetics of fluoride from bone cement and the compressive strength of PMMA, that is not affected by the addition of fluoride. The "in vivo" investigation showed considerable healing ability after surgical and heat trauma, and new bone formation that appears larger on the surface in contact with fluoridated cement.