title: Early migration characteristics of a 180° porous-coated cup with 1-mm press fit.
abstract: BACKGROUND
  Evaluation of early cup movement is an important diagnostic tool to predict the likelihood of long-term implant loosening and clinical failure. The investigated cementless cup is clinically proven over 10 years, but there is a paucity of information that accurately describes the migration characteristics of this component.
  
  
  METHODS
  We retrospectively analysed the clinical outcome and migration behaviour of 60 Pinnacle 100 shells after an average 3.8-year follow-up (range 2.1-5.4 years). For migration measurement, EBRA (Einzel-Bild-Röntgen-Analyse) digital software was applied. Clinical assessment was performed using the HHS, the UCLA score and the SF-36 health survey.
  
  
  RESULTS
  The clinical outcome showed excellent results with a mean HHS of 95.4 (SD 7.1) and mean UCLA of 6.9 (SD 1.3). All implants were radiologically stable within the observation period and none of the cups was at risk for aseptical loosening. EBRA analysis revealed a mean total migration of 1.4 mm (SD 0.9) (95 % CI 1.1-1.6) at 3 years. Eight cups migrated more than 1 mm within the first three postoperative months, thereafter the migration curves flattened down.
  
  
  CONCLUSIONS
  Surgeons may expect to find a variable amount of early migration when using the Pinnacle cup. To our knowledge, these are the first results, which show an early "impaction" of a cementless cup, followed by subsequent osseointegration. We believe that an appropriate long-term outcome of the investigated cup is ensured. The data of the present investigation will provide clinicians with useful baseline information with which to compare new cup designs.
authors.affiliation: Department of Orthopaedic Surgery, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, Austria. christoph.stihsen@meduniwien.ac.at
authors.forename: Christoph
authors.initials: C
authors.lastname: Stihsen
authors.forename: Christopher
authors.initials: C
authors.lastname: Rath
authors.forename: Roman
authors.initials: R
authors.lastname: Radl
authors.forename: Ali A
authors.initials: AA
authors.lastname: Saalabian
authors.forename: Wilfried
authors.initials: W
authors.lastname: Materna
authors.forename: Peter
authors.initials: P
authors.lastname: Rehak
authors.forename: Reinhard
authors.initials: R
authors.lastname: Windhager
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007592:Joint Diseases / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016348:Osseointegration; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012189:Retrospective Studies