Abstract
Aim: Mean radiographic polyethylene wear can not distinghish between so-called Òbedding-inÒ and true wear in porous-coated cups (Sychterz 1999). Wear performance of two different generations of the same cement-less porous-coated cup are compared. Material and Methods: 83 Harris-Galante I (HGI) (32mm femoral head) and 93 Harris-Galante II (HGII) (28mm) cups are analyzed. The average follow-up was 11.5 yrs for HGPI and 6.7 years for HGPII cups. Anteroposterior pelvic radiographs (at 3 and 6 months and annually thereafter) were scanned digitally and linear wear was estimated using a software package with the Sychterz method. All radiographs were made following the same protocol. Results. Postoperative bedding-in was: 0.15±0.04 mm for HGI and 0.11±0.02 for HGII cups (p< 0.001). Femoral head penetration at the end of follow-up was: 1.50±0.28 mm for HGI and 0.85±0.01 for HGII. Mean wear excluding bedding-in was: 0.13±0.23 mm/year for HGI and 0.11±0.09 for HGII (p=0.740). The femoral head penetration rate was highest in the þrst two years and then decreased with the time and was similar in both groups. Conclusions: The digitized Sychterzñ method allows us to determine bedding-in and true polyethylene wear. The second generation cups show a decrease in the bedding-in process, but do not have a lower wear rate.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
