Background: Proponents of navigated knee arthroplasty stress its
potential to increase the precision of component placement. We conducted a
systematic review and meta-analysis to substantiate the validity and relevance
of this contention.
Methods: We searched major medical and publishers' databases for
randomized trials and any other studies comparing navigated with conventional
knee arthroplasty. Major periodicals were searched manually. We made no
restrictions for types of studies or language. Methodological features were
rated independently by two reviewers. After testing for publication bias and
heterogeneity was done, the data were aggregated by random-effects modeling.
We estimated the weighted mean differences of mechanical limb axes and
functional scales and the risk ratios of deviations from the straight axis
with 95% confidence intervals.
Results: We included thirty-three studies (eleven randomized trials)
of varying methodological quality involving 3423 patients with a mean age (and
standard deviation) of 67.3 ± 4.1 years (62.6% were women, and 83.7%
had primary osteoarthritis). The mean preoperative deviation from the
mechanical axis was 2.3° ± 5.1°. There was no evidence of
publication bias, but there was strong statistical heterogeneity. The
alignment of the mechanical axes did not differ between the navigated and
conventional surgery group (weighted mean difference, 0.2°; 95% confidence
interval, -0.2° to 0.5°). Patients managed with navigated surgery had
a lower risk of malalignment at critical thresholds of >3° (risk ratio,
0.79; 95% confidence interval, 0.71 to 0.87) and >2° (risk ratio, 0.76;
95% confidence interval, 0.71 to 0.82). No conclusive inferences could be
drawn on functional outcomes or complication rates. Navigation lengthened the
mean duration of surgery by 23%.
Conclusions: Navigated knee replacement provides few advantages over
conventional surgery on the basis of radiographic end points. Its clinical
benefits are unclear and remain to be defined on a larger scale.
Level of Evidence: Therapeutic Level III. See
Instructions to Authors for a complete description of levels of evidence.