title: Porous-coated cups fixed with screws: a 12-year clinical and radiostereometric follow-up study of 50 hips.
abstract: BACKGROUND
  Excellent mid-term results have stimulated the use of hemispherical porous-coated cups in hip replacement. With longer follow-up, there have been problems related to polyethylene wear and liner fixation, and osteolysis has been documented in reports of selected cases. We evaluated the clinical and radiographic results of 50 patients followed for 12 years.
  
  
  METHODS
  58 consecutive patients (58 hips), mean age 55 years, were operated with Harris-Galante (HG) I or II cups using line-to-line fit and additional screw fixation. Polyethylene linersgamma-sterilized in air and 32-mm ceramic heads were used. 8 patients died within 12 years, leaving 50 patients with a complete 12 year follow-up. 23 of the cups were also evaluated with radiostereometry (RSA) for migration, liner stability, and wear.
  
  
  RESULTS
  All metal shells were still in situ after 12 years. 4 hips had been revised due to femoral loosening. In these revisions, the liner had been exchanged due to wear and/or instability, resulting in a cup survival rate of 89%. 28 cups displayed osteolytic lesions, mainly in relation to screws. RSA revealed minimum translations, but in many cases there were pronounced liner rotations suggesting unstable liners within the metal shell. The annual proximal wear was 0.09 mm and the three-dimensional wear was 0.16 mm.
  
  
  CONCLUSIONS
  RSA can predict the long-term performance of cup fixation. Low migration during the initial years after implantation indicates excellent long-term results regarding fixation of the metal shell. The main problem with this design appears to be liner instability and osteolysis, factors that are probably interrelated. Because these phenomena are clinically silent, we recommend regular follow-up of patients with HG cups to avoid sudden loosening and complicated revisions.
authors.affiliation: Department of Orthopaedic Surgery, Flinders University and Flinders Medical Centre, Adelaide, Australia. s.m.rohrl@medisin.uio.no
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Röhrl
authors.forename: Bo
authors.initials: B
authors.lastname: Nivbrant
authors.forename: Finnur
authors.initials: F
authors.lastname: Snorrason
authors.forename: Johan
authors.initials: J
authors.lastname: Kärrholm
authors.forename: Kjell G
authors.initials: KG
authors.lastname: Nilsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D001863:Bone Screws; D020099:Coated Materials, Biocompatible; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D016062:Porosity; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D013499:Surface Properties; D016896:Treatment Outcome
chemical_list: D020099:Coated Materials, Biocompatible