The purpose of this study was to assess the efficacy of intra-articular PRP injection in knee osteoarthritis as compared with hyaluronic acid injection and to determine whether the clinical efficacy of PRP is associated with its biological characteristics.
: A total of 110 patients with symptomatic knee osteoarthritis received a single injection of leukocyte-rich PRP (1 commercial kit) or HA. Clinical data were assessed at baseline and at 6 weeks and 3 and 6 months after injection. The primary endpoint was an improvement in the International Knee Documentation Committee (IKDC) subjective score at 6 months, and the secondary endpoints were improvements in scores based on the Patient Global Assessment, the visual analog scale (VAS) for pain, the Western Ontario and McMaster Universities Osteoarthritis Index, and the Samsung Medical Center patellofemoral score. Cell counts and concentrations of growth factors and cytokines in the injected PRP were assessed to determine their association with clinical outcomes.
PRP showed significant improvement in IKDC subjective scores at 6 months (11.5 in the PRP group vs 6.3 in the HA
group; P = 0.029). There were no significant differences between groups in other clinical outcomes. The Patient Global Assessment
score at 6 months was better in the PRP group (P =0.035). The proportion of patients who scored above the minimal clinically
important difference (MCID) for VAS at 6 months was significantly higher in the PRP group (P = 0.044). Within the PRP group,
the concentrations of platelet-derived growth factors were high in patients with a score above the MCID for VAS at 6 months.
The incidence of adverse events did not differ between the groups (P>0.05).
PRP had better clinical efficacy than HA. High concentrations of growth factors were observed in patients who scored above the MCID in PRP group. These findings indicate that the concentration of growth factors needs to be considered for future investigations.