title: High long-term loosening rate of conical screw cups.
abstract: BACKGROUND
  Acetabular screw cups seem to give high primary stability. We analyzed the migration and loosening behavior of a first-generation screw cup in a longterm follow-up.
  
  
  METHODS
  We examined 92 uncemented titanium alloy conical screw cups prospectively. Implant migration was assessed with a digital high-precision method (EBRA) with an accuracy of 1.0 mm.
  
  
  RESULTS
  After mean 11 (0.5-18) years, 87 patients were available for examination and 5 patients had died. 32 implants had been revised and 7 cases showed radiographic evidence of loosening. The 10-year survival rate was 71%. Migration of more than 1 mm occurred in 53 hips. Implant survival was strongly associated with an annual migration of greater than 0.2 mm.
  
  
  CONCLUSIONS
  The long-term behavior of this cup is not satisfactory. In spite of extraordinarily high primary implant stability, secondary osseointegration of this cup often fails. The annual migration rate represents a valid parameter for prediction of implant survival.
authors.affiliation: Department of Orthopaedics, Werneck, Germany. christian.hendrich@kh-schloss-werneck.de
authors.forename: Christian
authors.initials: C
authors.lastname: Hendrich
authors.forename: Ulf
authors.initials: U
authors.lastname: Sauer
authors.forename: Stephan
authors.initials: S
authors.lastname: Kirschner
authors.forename: Helge
authors.initials: H
authors.lastname: Schmitz
authors.forename: John M
authors.initials: JM
authors.lastname: Martell
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation; D001863:Bone Screws / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D014025:Titanium
chemical_list: D014025:Titanium