title: Navigated cup implantation in hip arthroplasty.
abstract: OBJECTIVE
  Many studies have suggested that navigation-based implantation can improve cup positioning in total hip arthroplasty (THA). We conducted a systematic review and meta-analysis to compile the best available evidence, and to overcome potential shortcomings because of small sample sizes in individual studies.
  
  
  METHODS
  The search strategy covered the major medical databases from January 1976 through August 2007, as well as various publishers' databases. The internal validity of individual studies was evaluated independently by 3 reviewers. We used random-effects modeling to obtain mean differences in cup angulation and relative risk (RR) of cup positioning outside Lewinnek's safe zone.
  
  
  RESULTS
  Of 363 citations originally identified, 5 trials of moderate methodology enrolling a total of 400 patients were included in the analysis. Mean cup inclination and anteversion were not statistically significantly different between the conventional groups and the navigated groups. Navigation reduced the variability in cup positioning and the risk of placing the acetabular component beyond the safe zone (RR = 0.21, CI: 0.13-0.32).
  
  
  CONCLUSIONS
  Based on the current literature, navigation is a reliable tool to optimize cup placement, and to minimize outliers. However, long-term outcomes and cost utility analyses are needed before conclusive statements can be drawn about the value of routine navigation in THA.
authors.affiliation: Department of Orthopedic Surgery, University of Regensburg, Bad Abbach, Germany. j.beckmann@asklepios.com
authors.forename: Johannes
authors.initials: J
authors.lastname: Beckmann
authors.forename: Dirk
authors.initials: D
authors.lastname: Stengel
authors.forename: Markus
authors.initials: M
authors.lastname: Tingart
authors.forename: Jürgen
authors.initials: J
authors.lastname: Götz
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Christian
authors.initials: C
authors.lastname: Lüring
mesh_terms: D000077:Acetabulum / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D006622:Hip Prosthesis; D006801:Humans; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted; D016896:Treatment Outcome