EARLY ASEPTIC LOOSENING OF UNCEMENTED FEMORAL COMPONENTS IN PRIMARY TOTAL HIP-REPLACEMENT - A REVIEW BASED ON THE NORWEGIAN ARTHROPLASTY REGISTER

The Norwegian Arthroplasty Register recorded 24 408 primary total hip replacements from 1987 to 1993; 2907 of them (13%) were performed with uncemented femoral components. We have compared the results of eight different designs, each used in more than 100 patients. Survivorship o f the components was estimated by the Kaplan-Meier method using revisi on for aseptic loosening of the femoral component as the end-point. At 4.5 years, the estimated probability of revision for aseptic loosenin g for all implants was 4.5%, for the Bio-Fit stem 18.6% (n = 210) and for the Femora stem 13.6% (n = 173). The PM-Prosthesis and the Harris/ Galante stem prostheses needed revision in 5.6% and 3.6%, respectively . The clockwise threaded stem of the Femora implant needed revision in 20% of right hips, but in only 4% of left hips. The short-term result s of the four best uncemented femoral components (Corail, LMT, Profile and Zweimuller) were similar to those for cemented stems, with revisi on for loosening in less than 1% at 4.5 years. The importance of the c ontrol of innovative designs and the registration of early results is discussed.