Clinical and Cellular Predictors of Outcomes in Autologous Conditioned Plasma Therapy for Knee Osteoarthritis: A Prospective Cohort Study

Introduction Autologous conditioned plasma (ACP) is a single-spin, leukocyte-poor platelet-rich plasma (PRP) that provides a plasma with a platelet concentration 2 to 3 times the blood platelet concentration. The objective of this study was to investigate the clinical effectiveness of ACP intra-articular injection in patients with knee osteoarthritis (OA) and to identify any demographic, disease-associated, or biological predictors of outcome.Methods A prospective cohort study was conducted between 2022 and 2023 in a single high-volume tertiary center, including 42 patients (54 knees) who consented to be enrolled. Patients underwent a series of 3 injections of ACP at weekly intervals, prepared using the Arthrex ACP Double-Syringe System. Lysholm scores were collected at baseline, 3-months, and 6-months post-injection.Results Forty patients (49 knees) completed the follow-up and were included in the final analysis. The mean age was 53.8 +/- 10.16 years (range 35-76 years), and the median body mass index (BMI) was 29 (interquartile range [IQR]: 27-34). There were 22 females and 18 males. Treatment failure occurred in 12 out of 49 cases (24.49%). The mean platelet concentration in the ACP was 588.5 +/- 183.2 x 106/ml, with a mean platelet fold increase of 2.14 +/- 0.71 compared to the baseline. Multi-linear regression modeling showed that older age and higher mean platelet concentration were predictors of higher post-injection Lysholm scores, with beta coefficients of 0.34 and 0.28, respectively, and p values of 0.013 and 0.036, respectively.Conclusion Autologous conditioned plasma provided clinical benefits in this cohort study of knee OA patients for at least 6 months post-injection. Older age and a higher mean platelet concentration in the ACP were identified as predictors of a higher Lysholm score.