We read with great interest the comments by Alberto Gregori and Graeme Holt
regarding our meta-analysis. We believe all of the issues they raise were
clearly addressed in the printed article and the electronic appendix, but we
will be happy to respond to their letter in a point-by-point fashion.
First, we do not agree that the conclusion of the abstract conflicts with
current best evidence. Most trials focused on alignment and not on function,
quality of life, or cost. We believe that all would agree that higher
precision in restoring the physiological limb axis is an advantage of
navigated total knee replacement over conventional total knee replacement, but
patient-centered and health-economic values have more weight in clinical and
political decision-making. In the Discussion, we stressed the need for
high-quality trials aimed at investigating clinically relevant outcomes.
Second, meta-analyses (especially in orthopaedics) are often criticized for
including only randomized controlled trials, thereby limiting the external
validity of the results. We are very much aware of the discrepancy between
methodological and clinical demands. In the Materials and Methods section, we
clearly pointed out that we conducted a metaregression analysis to account for
different study designs. There was no meaningful difference in effect
estimates between randomized controlled trials and other study settings.
Third, all key features of our search strategy were mentioned in the
Materials and Methods section. Specifically, we (1) reported all databases
searched, (2) tried diligently to avoid a Tower of Babel bias by including
studies in all languages, (3) performed a manual search, (4) reported the
study selection in a QUOROM flowchart, (5) assessed methodological features by
two or more independent raters, and (6) tested for publication bias and
statistical heterogeneity. If we missed any important quality criterion of a
valid meta-analysis (or a relevant paper that contradicts our findings), we
would be pleased to be informed by Mr. Gregori and Mr. Holt.
Fourth, in the Discussion section, we admitted the limits of the chosen end
points; however, as indicated by Mr. Gregori and Mr. Holt in their letter,
this shortcoming was related not to the quantitative summary but rather to the
lack of reporting of other end points in the original manuscripts.
Mr. Gregori and Mr. Holt conclude that navigated total knee arthroplasty
improves implant alignment but consequent improved implant survival remains
unproven. We are happy about this conclusion as it perfectly agrees with the
findings of our meta-analysis.