A comparison of meta-analyses on articular treatments for knee osteoarthritis-related pain

To identify meta-analyses (MAs) evaluating local treatments for knee osteoarthritis (KOA)-related pain, assess registration practices, and compare overlapping MAs to evaluate consistency, reproducibility, and potential redundancy.

MEDLINE (via PubMed®) was searched from inception to March 2025 for MAs that were grouped according to treatment. Pairwise comparisons were performed between MAs investigating the same intervention, evaluating registration status, databases searched, search strategies, included studies, and pain outcome results.

Eighty-one MAs were included, generating 566 pairwise comparisons across 15 treatment themes. Twenty-seven MAs were registered, including 26 in PROSPERO. Registration frequency increased significantly over time, reaching 65.4% among MAs published between 2022 and 2025 (P<0.001). The search strategy was unavailable in 18.2% of pairwise comparisons and identical in only two cases (0.4%). Database searches were identical in 6.9% of comparisons. Of the 113 possible comparisons of pain outcomes, only 32 (28.3%) yielded identical results, while 36 (31.9%) were completely different. Registration status, methodological quality, journal impact factor, and publication year were not associated with greater concordance between MAs.

Substantial discrepancies exist between overlapping MAs evaluating local treatments for KOA-related pain. These discrepancies appear largely related to differences in search strategies, study selection, outcome definitions, and reporting practices. Although PROSPERO registration has increased over time, it remains underused and does not ensure greater concordance between MAs. PROSPERO consultation before starting SR, prospective registration of SR, transparent reporting of search strategies, and greater standardization of outcome reporting may improve the reproducibility and usefulness of evidence synthesis.