Joost Peerbooms

22 Chapter 2 95% CI. Differences in concentrations within and between the different PRP separation systems were explored informally by the eyeball test. Additional statistical analyses of differences within and between the different separation systems were not conducted. As a substantial part of the data in the included studies was presented in graphs, which led to missing quantitative data, descriptive results of the studies that compared 2 PRP preparation systems were summarized in a table. Analyses were conducted in SPSS (version 15.0; SPSS) and Excel (Microsoft). RESULTS Search Results The search was performed on September 17, 2016, with a final search update to check for recently published relevant articles on April 11, 2017. The search of MEDLINE/ PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE databases provided 1079 citations, of which 179 were duplicates. After reviewing the titles and abstracts of the 900 remaining studies, 791 studies were excluded for not meeting the inclusion criteria. The articles of the remaining 109 studies were reviewed, after which 90 studies were excluded: 19 studies were selected for inclusion in this review (Figure 1). No additional studies were found by checking the references of the selected articles. Characteristics of Included Studies The characteristics of the included studies are summarized in Table 1. Fourteen studies compared the concentrations of blood components in PRP between different PRP separation systems. In 8 studies, commercially available separation systems were compared. Five studies reported the concentrations of blood components of single separation systems. The number of samples analysed varied between 3 and 102. Ten different commercially available separation systems were studied. The GPS III system (Zimmer Biomet) was studied the most, with 10 articles in total, followed by the ACP system (Arthrex), which was studied in 5 articles. The Endoret (BTI Biotechnology Institute), Magellan (Arteriocyte), and SmartPrep (Harvest Technologies) systems were all studied in 3 articles; the Cascade (Musculoskeletal Transplant Foundation) and RegenPRP (RegenLab) systems were studied in 2 articles; and the Prosys (Prodizen), KYOCERA (Kyocera Medical), and GLO (Glofinn Oy) systems were only studied in 1 article. Outcome Measures The platelet concentration was the most studied outcome measure, studied in 13 of 17 articles. Other outcome measures were the leukocyte concentration (12/17), red blood cell concentration (5/17), and platelet enrichment factor (7/17). With regard to growth factors, TGF-ß1 was studied the most (9/17), followed by PDGF-AB and VEGF (both 8/ 17). Other reported growth factors were IGF (4/17), PDGF-BB (3/17), EGF (3/17), HGF (2/17),