Abstract
Platelet-rich plasma (PRP) consists of a volume of plasma with a platelet concentration
above whole blood baseline values. Based on the group of bioactive molecules that
platelets release when activated and the regenerative and healing potential they have,
the use of PRP has followed a rapid development and application in orthopedics, with
applications that frequently outpaces the basic science and clinical evidence supporting
its use. Currently, significant heterogeneity and discrepancies exist between the
different types of available PRP formulations. Because of this, although there is
a vast literature on PRP, the published results are often contradictory, making it
challenging to obtain definitive conclusions. Therefore, the purpose of this review
article is to provide an overview of PRP with a focus on (1) preparation protocols;
(2) nomenclature and classifications; (3) biological effects; and (4) clinical evidence
of its role in the treatment of knee osteoarthritis. On the basis of the current evidence,
although PRP injections reduced pain and improved function more efficiently when compared
with controls, these findings need to be interpreted with caution due to the limited
level of evidence and high risk of bias. There is a need for a standardized scientific
approach for analyzing PRP formulations composition, beginning with standardization
of PRP preparation protocols, and detailed characterization of the final product (e.g.,
platelets and leukocytes content, volume, growth factors profile). Good quality and
sizeable double-blinded randomized trials will be required to establish whether or
not PRP injections are effective and should be included as a standard of care for
the management of patients with knee osteoarthritis.
Keywords
osteoarthritis - knee - platelet-rich plasma - intra-articular injections - PRP
