Long term improvement of knee osteoarthritis after injection of single high/very high volume of very pure PRP: A retrospective analysis of patients optimally managed in dedicated centers

•A single injection of a high/very high volume of very pure and biologically controlled PRP allows for a significant improvement in function and pain over 18 months.•The proportion of responders according to OMERACT-OARSI criteria at 6 months reached 56.2 % and 60.4 % for the total cohort and severe patients, respectively.•Previous PRP injections, lower baseline WOMAC score or Pain VAS, and patellofemoral localization were criteria associated with poor improvement at 12 months.•PRP preparation in dedicated centers allows for systematic monitoring of biological qualityand collection of efficacy data in real life at a reasonable cost while strictly adhering to recent international recommendations in the field.