The current literature supports the efficacy of PRP in the treatment of knee osteoarthritis (OA). Nevertheless, it is not clear if the subchondral bone edema, also called “bone marrow edema” (BME), can influence the response to PRP intra-articular treatment. The aim of this study was to investigate the influence of BME (assessed with magnetic resonance imaging - MRI) in the clinical outcome of patients with knee OA who underwent intra-articular PRP injection.
A total of 204 patients (138 men and 66 women) treated with knee intra-articular PRP injections (1 to 3 consecutive injections) was included in this study. A clinical evaluation with the IKDC subjective score was performed at baseline and at 2,6, 12 months of follow-up. Moreover, patients were evaluated at baseline with an MRI to assess the presence of BME which was classified according to the WORMS score. Based on MRI analysis, patients were divided in two groups for a comparison: BME group (n=82) and no-BME group (n=122). In the BME group, further analysis was performed based on BME degree and BME location.
Both groups reported a significant improvement for the IKDC subjective score from baseline to all follow-ups. In particular, the BME group improved from 49.2±16.5 to 64.7±17.2 at 12 months (p>0.0005), while the no-BME group improved from 48.9±15.7 to 62.6±19.8 at 12 months (p>0.0005). No significant differences in terms of IKDC subjective score were reported between the two groups in terms of clinical improvement. The sub-analyses performed on BME degree (WORMS 1, 2, 3) and BME location (femur, tibia, patella) did not show any significant differences in terms of IKDC score improvement.
This study showed that intra-articular PRP injections provided a significant clinical improvement up to 12 months in patients with knee OA, and BME did not significantly influence the effect of PRP and clinical outcome.