No difference in migration or wear between cemented low-profile cups and standard cups : a randomized radiostereographic study of 53 patients over 3 years.
BACKGROUND
Minor design changes may cause major changes in implant performance. Thus, as part of a stepwise introduction of a new low-profile cup, we performed a randomized trial comparing it to a well-documented standard cup.


METHODS
60 patients, stratified according to sex, weight, and age, underwent cemented total hip arthroplasty using a Lubinus SP2 stem with ceramic head and were randomized to either the new low-profile Lubinus Flanged Anti-Luxation cup (FAL) or the Lubinus Standard Eccentric cup (Standard). 7 patients were excluded and 53 (28 FAL) were evaluated at 3, 6, 12, and 36 months postoperatively. Primary outcome variables, cup migration (MTPM), and wear (total 3-dimensional femoral head penetration) were measured with radiostereometry (RSA). Clinical outcome was evaluated with the western Ontario and McMaster osteoarthritis index (Womac) and the visual analog pain score (VAS).


RESULTS
We found no difference in migration between the FAL and Standard cups. There was no difference in wear between the two cups and there was no correlation between wear and migration. 3 cups (2 FAL and 1 Standard) showed continuous migration of a magnitude that indicated an increased risk of early loosening. Clinical outcome was excellent, without any difference between the 2 groups.
Palm
Lars
L
Department of Orthopaedic Surgery, University Hospital Linköping, Sweden. lars.palm@lio.se
Olofsson
Jörgen
J
Aström
Stig-Eric
SE
Ivarsson
Ingemar
I
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D002484:Cementation; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010780:Photogrammetry; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016896:Treatment Outcome