title: Modes of failure of a threaded acetabular cup : a radiographic study with EBRA of 42 revised cups.
abstract: A radiographic study of a singular type of threaded cup, revised due to aseptic loosening, was performed with Einzel-Bild-Roentgen-Analyse (EBRA) to detect eventual risk factors and patterns of loosening. Fifty-three cups of 50 patients were revised. Forty-two cups could be measured with EBRA. No cup had obvious osteolysis, 33 cups demonstrated early migration, and all cups had migrated at the time of revision. Twenty-eight of the cups had a change of inclination and 21 of anteversion, respectively. The mean migration was 1.9 mm in the medial and 7.9 mm in the cranial direction; the mean wear rate was 0.2 mm/year. Cups with early migration had a higher migration rate. All male patients had early migration; medially placed cups had less migration than the other cups. Wear was not significantly affected by the migration of the implant. No cup had a complete radiolucent line, and the only radiographic sign for loosening was the change of position of the cup. Medial placement showed less migration in case of loosening. Regular radiographic follow-up is recommended for the examined implant, and the cup should not be used in the future.
authors.affiliation: Kantonsspital Liestal, Liestal, Switzerland. thomas.ilchmann@ksli.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Ilchmann
authors.forename: Severin
authors.initials: S
authors.lastname: Neher
authors.forename: Franz
authors.initials: F
authors.lastname: Maurer
authors.forename: Kuno
authors.initials: K
authors.lastname: Weise
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011475:Prosthesis Failure; D012086:Reoperation; D013997:Time Factors