Background

Viscosupplementation for knee osteoarthritis (OA) may raise concerns regarding conflicts of interest (COI). Evidence of inconclusive study results and publication bias in previous studies has led to concern that financial COI have influenced viscosupplementation outcomes. It is critical to ensure that clinical practice is guided by informed decision making and evidence-based medicine. Methods

A systematic review was conducted following PRISMA guidelines. PubMed, MEDLINE, and Web of Science databases were searched for articles pertaining to hyaluronic acid (or similarly derived) injections to native knees with primary OA only. Bibliometric data, financial COI, and study outcomes were assessed. Results

67 studies met inclusion criteria for analysis, 53 of which (79.1%) presented Level I evidence, and 21 of which (31.3%) reported at least one author with COI. All studies reporting COI also disclosed industry funding. There were no relationships between reported COI and study outcomes (Χ2 = 0.31, P = 0.577), levels of evidence (Χ2 = 3.48, P = 0.176), or relative citation ratio (RCR) (S = 743, P = 0.591). Studies reporting COIs/industry funding tended to be published in journals with significantly higher impact factors (IF) (reporting COI: IF = 3.5 ± 2.0; no COI: IF = 1.8 ± 1.1; S = 950, P < 0.001). Study outcomes were not related to the probability of being published in an open access journal (Χ2 = 0.01, P = 0.960), nor to level of evidence (Χ2 = 2.67, P = 0.263), RCR (S = 618, P = 0.835), or IF (S = 563, P = 0.655). Conclusions

Investigator COIs (and commercial funding of studies) have not significantly influenced the frequency of favorable outcomes or study level of evidence regarding contemporary viscosupplementation for the treatment of knee OA. Studies reporting COIs/industry funding tended to be published in journals with significantly higher impact factors. Results overwhelmingly supported using viscosupplementation to treat knee OA. Level of evidence

Level V Systematic Review.