Navigated cup implantation in hip arthroplasty.
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.
Beckmann
Johannes
J
Department of Orthopedic Surgery, University of Regensburg, Bad Abbach, Germany. j.beckmann@asklepios.com
Stengel
Dirk
D
Tingart
Markus
M
Götz
Jürgen
J
Grifka
Joachim
J
Lüring
Christian
C
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