title: A randomized study on migration of the Spectron EF and the Charnley flanged 40 cemented femoral components using radiostereometric analysis at 2 years.
abstract: OBJECTIVE
  We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation.
  
  
  METHODS
  150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration.
  
  
  RESULTS
  At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5).
  
  
  CONCLUSIONS
  The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants.
authors: Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway. tkad@helse-bergen.no
authors: Thomas
authors: T
authors: Kadar
authors: Geir
authors: G
authors: Hallan
authors: Arild
authors: A
authors: Aamodt
authors: Kari
authors: K
authors: Indrekvam
authors: Mona
authors: M
authors: Badawy
authors: Leif Ivar
authors: LI
authors: Havelin
authors: Terje
authors: T
authors: Stokke
authors: Kristin
authors: K
authors: Haugan
authors: Birgitte
authors: B
authors: Espehaug
authors: Ove
authors: O
authors: Furnes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation; D002484:Cementation; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011475:Prosthesis Failure / Q000209:etiology*; D059869:Radiostereometric Analysis; D012086:Reoperation; D016037:Single-Blind Method; D016896:Treatment Outcome