Leukocyte-rich PRP vs Leukocyte-poor PRP for the Treatment of Knee Cartilage Degeneration: a Randomized Controlled Trial

Platelet-rich Plasma (PRP) is the most exploited biologic agents currently used for the treatment of osteoarthritis (OA) of different joints, in particular knee OA. In previous studies, it has been showed its potential to reduce pain and improve functional status in patients treated by simple intra-articular injections. However, there are several PRP formulation currently available in clinical use, and therefore it is very difficult to compare data coming from trials using different products. The most debated aspect concerning PRP formulation is the role of leukocytes, which might stimulate an early inflammatory response in the joint due to the release of metalloproteases and other pro-inflammatory cytokines. The investigators hypothesized that the presence of leukocytes in PRP could be clinically relevant in terms of outcome, so the present double blind randomized controlled trial was designed to compare leukocyte-rich and leukocyte-poor PRP injections for the treatment of knee OA. A power analysis has been performed for the primary endpoint of IKDC (International Knee Documentation Committee) subjective score improvement at the 12-month follow-up for PRP. From a pilot study, a standard deviation of 15.2 points was found. With an alpha error of 0.05, a beta error of 0.2 and a minimal clinically significant difference of 6.7 points corresponding at 1/3 of the documented mean improvement, the minimum sample size was 83 for each group. Considering a possible drop out of 15%, 96 patients per group are required for total 192 patients, selected according to well-defined inclusion criteria (see 'Eligibility criteria' section). Patients are then assigned to two different treatment groups, according to a randomization list. The first group of treatment consists of three weekly intra-articular injections of autologous leukocyte-rich PRP, whereas the second group of patients will be treated by three intra-articular injections of leukocyte-poor PRP. PRP will be obtained wi