No Benefit to Platelet-rich Plasma Over Placebo Injections in Terms of Pain or Function in Patients with Hemophilic Knee Arthritis: A Randomized Trial

Hemophilic knee arthritis is one of the most common presenting symptoms of hemophilia, and its management continues to be challenging to practitioners. Preliminary research has suggested that platelet-rich plasma (PRP) may have short-term efficacy in the treatment of hemophilic knee arthritis, but evidence for this treatment is limited. Questions/purposes: What is the effectiveness of PRP compared with placebo in (1) reducing pain and improving knee joint function (as measured by WOMAC, VAS, and Hemophilia Joint Health Score [HJHS]) and (2) improving quality of life (as measured by SF-36 scores) in patients with hemophilic knee arthritis through 24 months of follow-up?

Among patients with hemophilic knee arthritis, three intraarticular PRP injections, compared with placebo injections, did not improve hemophilic knee symptoms, function, and quality of life over 24 months. The results of this study do not support the use of PRP injections in patients who have hemophilic knee arthritis. Level of evidence: Level I, therapeutic study.

This was a prospective, parallel-group, double-blinded, single-center, placebo-controlled randomized clinical trial that included participants from a tertiary care center starting January 1, 2019, with follow-up completed on November 30, 2021. Participants were older than 18 years and had hemophilic knee arthritis confirmed by MRI, and they were randomly allocated to interventions in a 1:1 ratio. The investigators were not informed of the randomization sequence generated by the computer. Patient groups were comparable with respect to age, gender, BMI, hemophilia type, and disease severity at baseline. Physicians delivered three sessions (one per week) of a standard intraarticular injection of PRP (n = 95) or placebo (n = 95). The rate of successful blinding was balanced across the groups, which was assessed by asking participants which injection they thought they had received. The primary outcome was the WOMAC score (range 0 to 96; higher scores indicate more pain and worse function; minimum clinically important difference, 6.4 points) over 24 months. Among the 190 patients assigned to PRP or saline injections (mean age 31 ± 7 years), 100% (190) of patients were men). There was no between-group difference in the proportion of patients who completed the trial; 97% (92 of 95) of patients in the PRP group and 94% (89 of 95) of patients in the placebo group completed the trial. The most common adverse events were injection site discomfort 8% (8 of 95) in the PRP group and 4% (4 of 95) in the placebo group. An intention-to-treat analysis was planned, but there was no crossover between groups. All patients were included in the analyses. With 95 patients in each group, the study was powered a priori at 90% to detect a difference in WOMAC score of 6.4 points, which was considered a clinically important difference.

There were no clinically important differences in the mean WOMAC, VAS pain, HJHS, SF-36, and MRI scores between groups at any timepoint. Intraarticular PRP did not ameliorate function, symptoms, and quality of life in patients with hemophilic knee arthritis. At 24 months of follow-up, the mean difference between the PRP and placebo groups in the WOMAC score was -1 (95% CI -5 to 2; p = 0.42). The mean difference in the VAS pain score was -0.3 (95% CI -0.8 to 0.2; p = 0.19), in the HJHS was -0.6 (95% CI -1.4 to 0.1; p = 0.10), in the SF-36 physical component summary was 0 (95% CI -2 to 3; p = 0.87), and in the SF-36 mental component summary was -1 (95% CI -3 to 2; p = 0.64). The mean differences in the MRI scores of soft tissue and osteochondral subscore were 0.1 (95% CI -0.3 to 0.5; p = 0.59) and -0.3 (95% CI -0.7 to 0.1; p = 0.19), respectively.