Thermal aspects of the use of polymethylmethacrylate in large metaphyseal defects in bone. A clinical review and laboratory study.

The potential necrotizing effects of the heat produced by the exothermic polymerization process has raised questions regarding the use of polymethylmethacrylate (PMMA) in orthopedic surgery. An experimental model was used to: (1) analyze the amplitude and distribution of heat in bone taken from autopsy specimens when large metaphyseal defects (simulating tumor excision) were filled with curing PMMA and (2) to observe any significant necrotizing temperatures. The experimental design included two experimental groups of five distal femora into which either a small- or large-bore defect was made in the lateral epicondylar region. These defects were filled with either one or two packs of PMMA cement, and temperature probes were used to record temperature elevations at the cement core, the bone-cement interface, and the surrounding 1-, 2-, 3-, and 5-mm bone intervals. To simulate physiologic temperature and fluid environment, the experiment was conducted in a 37 degrees normal saline bath. There is clinical evidence suggesting that the large amounts of PMMA used in tumor reconstructive surgery (often two packs or more) may lead to thermal necrosis of remaining tumor cells in the curetted cavity. This may explain, at least in part, the decrease in recurrence of giant-cell bone tumor after curettage and PMMA cementation.