title: Mueller reinforcement rings in acetabular revision: outcome in 164 hips followed for 2-17 years.
abstract: BACKGROUND
  In revision hip arthroplasty, cages are commonly used for acetabular reconstruction in cases with loss of bone stock. It is important to follow this patient group closely, in order to better understand failure mechanisms and the chance of long-term success.
  
  
  METHODS
  We followed our first 164 acetabular revisions with the Mueller reinforcement ring (ARR) in 164 patients, with an average follow-up period of 6 (2-17) years. Mean age at surgery was 69 (29-92) years. 39 patients died (39 hips) during follow-up, but only 3 patients (3 hips) were lost to follow-up.
  
  
  RESULTS
  In the observation period, 13 of the hips had to undergo acetabular re-revision for aseptic and septic loosening. Overall survival at 5 years was 95% (CI: 89%-98%) and 90% (CI: 76%-95%) at 8 years using acetabular re-revision or implant removal for all reasons as endpoint. In addition, mechanical and clinical failure was seen in 2 cases. The mean Harris hip score was 70 points, whilst the Merle d'Aubigné score averaged 7 points. Radiolucent lines according to DeLee and Charnley were observed twice in zone I, 6 times in zone II and 14 times in zone III.
  
  
  CONCLUSIONS
  We found that mid- to long-term survival of the ARR is acceptable. However, failure of the implant due to allograft collapse/resorption or deep infection, and also poor clinical outcome, remain major concerns in acetabular revision arthroplasty. This should be recognized when advising patients.
authors.affiliation: Department of Orthopaedic Surgery, University of Heidelberg, Germany.
authors.forename: Ulf J
authors.initials: UJ
authors.lastname: Schlegel
authors.forename: Rudi G
authors.initials: RG
authors.lastname: Bitsch
authors.forename: Maria
authors.initials: M
authors.lastname: Pritsch
authors.forename: Martin
authors.initials: M
authors.lastname: Clauss
authors.forename: Hans
authors.initials: H
authors.lastname: Mau
authors.forename: Steffen J
authors.initials: SJ
authors.lastname: Breusch
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D016025:Bone Transplantation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D016896:Treatment Outcome