Relationship Between the Underlying Factors and the Treatment Results of Platelet-Rich Plasma (PRP) Injection in Degenerative Knee Disease; A Blinded Randomized Study

Background: To investigate the therapeutic effects of PRP injection + conservative treatment as the intervention group versus normal saline injection + conservative treatment as the control group. Objectives: This study we determined the effects of underlying factors, including age, gender, and body mass index (BMI), on the therapeutic effects of PRP. Methods: In this single-blinded randomized clinical trial, 60 patients with grade 2 knee OA with an age of 40 - 65 years were enrolled. In the intervention group, leukocyte-poor PRP with double spinning, and in the control group, normal saline was injected with a similar protocol. All patients in both groups were also provided with a conservative protocol, including oral celecoxib 100 mg BID for four weeks, modifying physical activity, and 15 sessions of physiotherapy. Results: Demographic characteristics (age, gender, and BMI) and pre-treatment scores were similar between the two groups (all P > 0.05). The WOMAC score was improved from pre-treatment to first week post-treatment in both groups (from 54.89 ± 3.4 to 64.9 ± 3.7 in the intervention group and from 53.7 ± 3.1 to 63.8 ± 3.9 in the control group). It means that PRP + conservative treatment was effective, similar to normal saline + conservative treatment. After adjusting BMI as an underlying variable, it was indicated that in the patients with lower BMI, PRP + conservative provided a better outcome in comparison to saline + conservative treatment (P = 0.014 and P = 0.019, respectively). Also, the comparison of functional scores changes with age as an underlying variable, demonstrating that younger cases obtained a better response from PRP + conservative rather than normal saline + conservative (P = 0.012 and P = 0.007, respectively). Conclusions: PRP seems to be an appropriate choice for treatment of moderate osteoarthritis, especially in younger patients and those with lower BMI.