Early migration predicts late aseptic failure of hip sockets.
We report a prospective, stratified study of 60 PCA-cups and 60 RM-polyethylene cups which have been followed for a median time of 90 months, with annual radiography. The radiological migration of cups was measured by the computer-assisted EBRA method. A number of threshold migration rates from 1 mm in the first year to 1 mm in five years have been assessed and related to clinically determined revision rates. A total of 28 cups showed a total migration of 1 mm or more within the first two years; 13 of these cups have required revision and been exchanged. The survival curves of cups which had previously shown early migration were considerably different from those without early migration. For cups with a migration of less than 1 mm within the first two years the mean survival at 96 months was 0.96 +/- 0.02; for migrating cups, it was 0.63 +/- 0.11 (log-rank test, p=0.0001; chi-square value=39.4). Early migration is a good predictor for late loosening of hip sockets.
Krismer
M
M
University Orthopaedic Hospital, Innsbruck, Austria.
Stöckl
B
B
Fischer
M
M
Bauer
R
R
Mayrhofer
P
P
Ogon
M
M
D000368:Aged; D016009:Chi-Square Distribution; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects* / Q000145:classification; D006801:Humans; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011857:Radiographic Image Interpretation, Computer-Assisted; D012086:Reoperation; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors