Are Injections of Platelet-Rich Plasma Overused in Knee Osteoarthritis Despite Their Unproven Effectiveness?

Abstract

Objective: To clarify whether intra-articular injections of platelet-rich plama (PRP) are really effective for pain management in knee osteoarthritis. Methods: In this article, we have performed a narrative review of recent literature (2018-2019) to clarify whether intra-articular injections of PRP are truly effective. Results: A study with an evidence level of 1 that compared the long-term (5 years) clinical results of intra-articular injections of PRP versus hyaluronic acid (HA) in knee osteoarthritis showed that both treatments were effective in improving the knee’s functional status. PRP did not provide superior clinical improvement over HA in terms of the duration of the effect or symptom-functional improvement at various points during the follow-up. The mean duration of the patient’s subjective perception of pain relief was 9 months with HA and 12 months with PRP (no significant difference). Another trial with an evidence level of 1 compared the efficacy of intra-articular injections of leukocyte-poor PRP, HA and normal saline solution (sham control group) in mild-moderate knee osteoarthritis. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and the International Knee Documentation Committee (IKDC) subjective score were obtained at the start of the study and at 1, 2, 6 and 12 months after treatment. The 3 groups showed statistically significant improvements in the outcome measures at 1 month; however, only the PRP group maintained significant improvement in both the WOMAC score and the IKDC score at 12 months. Conclusions: Although promising initial results from the use of PRP have been published, most of the studies with an evidence level of 1 have had numerous problems, including small sample sizes, potentially inappropriate control cohorts and short follow-ups. Despite these limitations, there is still evidence to justify the use of PRP in treating knee osteoarthritis. However, further high-level human studies using standardized protocols are needed.