Effect of temperature changes in acrylic cement on prosthetic implant surgery. An investigation into the relationship between quantity and temperature changes at different levels on loosening of the implant.

Loosening of the prosthetic stem is one of the most frequent problems in arthroprosthetic replacement. Fixation at the bone/cement interface is therefore of crucial importance. This can be affected by several factors, one of which is the heat generated in the acrylic cement, which may exceed the level at which tissue viability is affected. The authors therefore investigated this phenomenon in theoretical models. These were related to the level and duration of temperature changes at four levels - inside the cement and at the interfaces between cement, implant, spongy bone and cortical bone. Graphs showing temperature peaks and duration are constructed in all the varying conditions and their implications discussed. These concern the viability of osteocytes and vascular tissue, and the mechanical strength of the cement. The implications on design and surgical technique are obvious and point to the need to use the thinnest layer of cement compatible with firm fixation.