The 36-Month Survival Analysis of Conservative Treatment Using Platelet-Rich Plasma Enhanced With Injectable Platelet-Rich Fibrin in Patients With Knee Osteoarthritis.

Introduction: Knee osteoarthritis (KOA) is a musculoskeletal disease that leads to pain, stiffness, and deformity of the load-bearing knee joints. Biologic products including platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) are now in the spotlight for the treatment of KOA owing to their role of disease-modifying potential effect. There are still limited studies on the survival rate of KOA treated with biological intervention. We conducted this study to evaluate the primary outcome as the survival rate of KOA treated with PRP enhanced with injectable PRF that helps avoid unnecessary surgical intervention.

Methods: There were 368 participants who met the inclusion and exclusion criteria. Participants were informed about this prospective cohort study protocol and signed written consent forms. Each participant received one injection of 4 ml of PRP and 4 ml of injectable PRF (iPRF), the so-called "PRP enhanced with iPRF". Clinical assessment was evaluated with the visual analog scale (VAS) at the second, fourth, sixth, 12th, 18th, 24th, 30th, and 36th-month post-treatment. If the VAS pain score improved by more than 80% compared to the previous treatment, there was no need for a repeated dose. If the pain scores improved by 50% to 80% compared to the previous treatment, the participants were advised a repeated dose. However, if the pain scores improved by less than 50% compared to the previous treatment, the participants were advised to undergo surgical intervention instead of a repeated dose. The primary outcome was recorded as any surgical treatment (either arthroscopic knee surgery, unicondylar arthroplasty, or total knee arthroplasty) at any time point post-treatment. The secondary outcome was recorded as the interval (months) between first-to-second, second-to-third, and third-to-fourth injections.

Results: The overall survival rate of knees that did not require surgical intervention during the 36-month follow-up was 80.18%. The mean number of injections was 2.52±0.07 times for overall participants. The mean interval time was 5.42±0.36, 8.92±0.47, and 9.58±0.55 months for the first-to-second, second-to-third, and third-to-fourth injections.

Conclusion: This study supports the usage of PRP enhanced with iPRF as a biologic modality for the treatment of KOA. This treatment modality provides a satisfactory survival rate at the 36-month follow-up. The longer interval between each injection supports the disease-modifying effect of PRP enhanced with iPRF.