The effects of acetabular cup temperature and duration of cement pressurization on cement porosity in a canine total hip replacement model

Objective - To determine the effect of acetabular cup temperature and duration of cement pressurization on porosity of the acetabular cement mantel. Study design - In vitro study. Methods - Twenty-four polyurethane foam blocks prepared for acetabular prosthetic implantation were implanted with polyethylene acetabular cups using four combinations and variations of temperature and pressure: (1) high temperature/short-term pressurization; (2) high temperature/long-term pressurization; (3) low temperature/long-term pressurization; and (4) low temperature short-term pressurization. Five 1-mm-thick slices were taken from the center of each block using a tissue processing system. The slices were scanned into a personal computer using a photo slide scanner. Imaging software was used to determine cement surface area and size, number, and distribution of pores. The quality of the cement-implant interface was subjectively evaluated. Statistical analysis of relative cement porosity was performed by a Kruskal-Wallis analysis of variance comparing the four groups individually and combining the short-term pressurization groups versus the long-term pressurization groups. Results - There were no significant differences in cement porosity between the four test groups (P = .11). There were no significant differences in porosity between the combined groups (P = .48). Conclusions - There is no benefit in prewarming acetabular cups before implantation. There are no deleterious effects of short-term pressurization of the cement during implantation.