Background
Injectable biologics are increasingly used in the management of knee osteoarthritis. However, there is ongoing debate regarding the quality and reliability of the research used to justify clinical use. The purpose of this study was to evaluate the level 1 evidence investigating the efficacy of injectable biologic solutions for knee osteoarthritis and assess the relationship between clinical outcomes, the risk of bias and citation factor of the journal.
Methods
A search of Pubmed and Medline was performed in January 2022 in line with the 2009 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Broad search terms were included to capture the maximum number of articles in the literature and included; 'osteoarthritis’, 'orthobiologics’, ‘biologics’ and 'Platelet rich plasma'. The criterion for inclusion was any published, randomised controlled trial studying injectable orthobiologics and osteoarthritis. Studies were assessed for bias using the Cochrane risk-of-bias 2 tool.
Results
995 articles were identified in the initial search of databases and reference lists. After removal of duplicates and initial screening of titles and abstracts, 77 articles met the inclusion criteria for review. On full text screening, a further 11 studies were removed with 66 remaining for final inclusion. The year of publication ranged from 2009 to 2022. The average citation factor of the published journals was 4.9 (SD 6.6). There were 18 studies deemed a ‘high risk’ of bias, 20 were reported as having ‘some concerns’ and 28 were ‘low risk’. All studies concluded improvement in platelet rich plasma (PRP) over baseline and 26 studies (62%) showed superiority over the control group. There were a limited number of studies for all other injectables to draw conclusions. There was no difference in impact factor between those studies which were at risk of bias and those which were not (p=0.093). Nor was there a difference in risk of bias for those studies which showed biologics to be superior to controls and those that did not (p=0.815). A subgroup analysis of studies analysing PRP outcomes specifically also did not demonstrate differences in risk of bias (p=0.850) or citation factor (p=0.214).
Conclusion
There were 66 level one studies assessing the efficacy of injectable biologics. All studies concluded clinical improvement in PRP over baseline and 26 studies (62%) showed superiority over control group. No relationship was found between favourable outcomes in injectable biologic therapy and the risk of bias of the study or the impact factor of the journal it was published in.