Durability of the cemented femoral stem in patients 60 to 80 years old.

The importance of surface roughness and durability of fixation of the cemented femoral stem were examined. Three cohorts of patients approximately 60 to 80 years old, had cemented total hip replacements: Charnley (1978-1983) with first-generation cement technique consisting of canal-plugging and digital packing; Omnifit (1986-1991), and Ranawat-Burstein (R-B) Interlok (1992-1994) with modified third-generation cement technique. Kaplan-Meier survivorships, using failure for all causes (best case) were 90% +/- 5.1% at 20 years for the Charnley 95.1%+/- 3.4% at 15 years for the Omnifit and 99.5% +/- 0.5% at 9 years for the R-B Interlok prosthesis. Log rank test with paired data showed no significant differences between the groups for mechanical failure as an end point. Comparisons of survivorship curves for failure from all causes showed significant differences between the Charnley compared with the Omnifit and Interlok series respectively, with no significant differences between the Omnifit and R-B Interlok series. The cemented femoral stem, with a good cement mantle and surface roughness ranging from 30 to 150 microinches, did not show any significant differences in mechanical failure. Other variables such as stem centralization and low polyethylene wear need additional evaluation in survivorship of cemented total hip replacements.