The review had a clear objective, which was supported by adequate eligibility criteria. However, a very basic search (using one database) was conducted, and it was unclear if any language restrictions were imposed. No search appeared to have been made to specifically identify unpublished studies. In light of these limitations, it was likely that relevant studies may have been missed. The authors did not report on whether methods (e.g. independent duplicate processes) were used to reduce the risk of reviewer error and bias during the review selection and data extraction stages.
Although a few aspects relating to trial quality were sometimes reported and discussed, no systematic assessment of trial quality was made, so it was difficult to asses the reliability of the primary trials. Sufficient trial details were provided. A narrative synthesis was presented. However, definitions of what constituted clinically significant improvements were not provided or discussed.
The review's numerous methodological limitations suggest that the authors' conclusions should be interpreted with caution.
Both authors disclosed conflicts of interest with Genozyme Biosurgery (manufacturers of hylan G-F 20 evaluated in the review).