A Retrospective Analysis of Characteristic Features of Responders and Impaired Patients to a Single Injection of Pure Platelet-Rich Plasma in Knee Osteoarthritis.

(1) Background: The emergence of injectable "biologic" medication creates a new approach to treat osteoarthritis (OA). Among them, the use of intra-articular injection of PRP became widespread despite the absence of consensus regarding its optimal composition. The aim of this study was to retrospectively correlate an extensive biological characterization of injected PRP to the clinical responses of patients presenting knee OA. (2) Methods: This retrospective study included 75 patients with knee OA. Cartilage lesions were assessed using magnetic resonance imaging and the International Cartilage Regeneration Society (ICRS) classification. PRP extensive biological characterization was performed and patients' subjective symptoms were recorded before injection and 3 and 6 months after injection using the Knee injury and Osteoarthritis Outcome Score (KOOS). Responders were defined by an improvement of 10 points on KOOS. (3) Results: At 6 months, 63.0% of the patients were responders. Impairment was characterized by a significantly higher proportion of patients with three compartments altered at baseline MRI and receiving a significantly higher dose of platelets compared to responders. (4) Conclusions: Single injection of pure PRP resulted in significant clinical improvement in the management of knee OA. Both baseline MRI and PRP biological features may be predictive factors of the clinical response, highlighting that a better understanding of action mechanism of PRP is still required.

Technical and biological review of authorized medical devices for platelets-rich plasma preparation in the field of regenerative medicine.

Platelet-rich plasma (PRP) has seen increased interest and utilization over the past decade, particularly in the field of musculoskeletal disease. This growth has been accompanied by the development of medical devices to realize PRP preparation which includes blood collection, centrifugation, and PRP isolation. The final PRP composition is directly influenced by this preparation step and absence of biological quality control led to a lack of comparability between PRP products that could explain the large variability in the clinical benefit of PRP reported in literature. To circumvent this issue, the scientific community developed different PRP classifications but none of them have been adopted. The goal of this review is to furnish both technical and biological characteristics from PRP commercial systems. On review of 1379 studies, 105 studies were selected according to inclusion criteria for technical analysis and led to the identification of 50 commercial systems that have been classified in three technical categories based on the blood harvesting technique (tubes, syringes or bags). Twelve studies were selected and sufficiently describe biological characteristics from only 14 commercial systems from the 50 identified in the technical analysis. Inclusion of duplicates characterization from a same PRP system lead to the final analysis of 36 PRP preparations that met the inclusion criteria of the biological analysis. All these PRP preparations have been classified among the seven existing classifications. Comparison from all biological parameters and classifications revealed a large heterogeneity among the available current PRP commercial systems. Index of biological sensitivity of classifications to distinguish PRP preparations were also variable. Although these findings should help clinicians in selecting a system that meets their specific needs, this also raises the question to standardize the parameters to biologically define PRP preparation among users and to systematically performed PRP qualification when used.