Platelet Rich Plasma and Osteoarthritis
According to the World Health Organization (WHO), musculoskeletal injuries are the most common cause of severe long-term pain and physical disability and affect hundreds of millions of people around the world.(1)
Osteoarthritis (OA) is a chronic musculoskeletal condition that commonly affects the joints, especially large joints such as the knee, ankle, hip and shoulder. It is a major public health problem worldwide and is projected to rapidly increase as the population ages and rates of obesity escalate.(2) Osteoarthritis is the most common degenerative joint disease, affecting more than 25% of the population over 18 years-old. Pathological changes seen in Osteoarthritis joints include progressive loss and destruction of articular cartilage, thickening of the subchondral bone, formation of osteophytes, variable degrees of inflammation of the synovium, degeneration of ligaments and menisci of the knee and hypertrophy of the joint capsule.(3)
Osteoarthritis causes substantial pain and disability and impacts on quality-of-life. Hip and knee Osteoarthritis has been ranked as the eleventh highest contributor to global disability and two of the highest in years lived with disability. The disability associated with Osteoarthritis results in a considerable economic burden, both in direct costs related to treatment, particularly joint replacement surgery, and job-related indirect costs, including loss of productivity. (2) Thus, as Osteoarthritis is typically progressive with symptoms and structural deterioration driving the need for joint replacement, identifying efficacious, safe treatments that address both symptoms and joint reparation is an important objective.
The traditional management of orthopaedic and sports related injuries includes everything from conservative “RICE” treatment(1) which corresponds to the acronyms of rest, ice, compression and elevation of the site of the injury(4), and physical therapy, corticosteroid injections or surgical intervention. Recently, advances in biomedicine and biotechnology have enthused the use of cell therapy, tissue engineering, and autologous blood concentrates to enhance healing and stimulate growth in bone and soft tissue injuries.(1)
One of the most popular methods used to biologically enhance healing in the fields of orthopaedic surgery and sports medicine includes the use of autologous blood products, particularly, platelet rich plasma (PRP). PRP is an autologous concentration of human platelets to supra-physiologic levels. It is produced from a patient’s peripheral vein and centrifuged to achieve a high concentration of platelets within a small volume of plasma. It is then re-injected at a site of injury or inserted as a gel or other biomaterials during surgery. (1)
What is platelet-rich plasma?
PRP is an autologous blood product that contains an elevated concentration of platelets above that of whole blood. (2) Platelets are irregularly shaped, non-nucleated cytoplasmic bodies derived from fragmentation of megakaryocyte precursors. They circulate in the blood of mammals expressing glycoproteins on their cell membranes and play a pivotal role in hemostatis and wound healing via the formation of fibrin clots.(1)
Platelet-rich plasma is produced from blood obtained by phlebotomy, which is centrifuged to achieve a high concentration of platelets within a small volume of plasma. The platelet-rich product is then re-injected at a site of injury or prepared as a gel or other biomaterial and inserted during surgery. There are numerous protocols and commercial systems for producing PRP. Traditionally, two centrifugation steps are used to isolate the erythrocyte fraction from the buffy coat (plasma containing platelets, leukocytes, and clotting factors). The second step separates the platelet-poor plasma (PPP) from the platelet-rich fraction. (1)
PRP in the context of osteoarthritis
Osteoarthritis is a disease affecting all tissues of the joint including cartilage, bone, ligament, and muscle. It has long been considered the result of mechanical overloading causing damage to the joint. However, more recent progress in molecular biology has provided new understandings regarding Osteoarthritis pathophysiology in which inflammatory mediators, growth factors, chondrocyte apoptosis and imbalance between anabolic and catabolic mechanisms play an important role. It is now thought that inflammation might be a major driver of the OA process, rather than inflammation being a secondary consequence of the disease. Several cytokines, such as interleukin-1β and transforming growth factor β, proteases and nitric oxide synthetase all appear to be essential for cartilage degradation in the pathogenesis of Osteoarthritis. Although the biology of PRP is not completely understood, PRP may be beneficial in Osteoarthritis by interfering with catabolic and inflammatory events and by subsequently promoting anabolic responses. Activation of PRP releases an initial burst then a sustained release of biologically active growth factors and other molecules, including platelet-derived growth factor and vascular endothelial growth factor, These proteins are responsible for a range of critical tissue healing roles such as chondrocyte apoptosis inhibition, bone and vessel remodelling, inflammatory modulation, and importantly, collagen synthesis. Additionally, other bioactive molecules released by platelets, such as fibrin, act as a scaffold and chemo-attractant for further migration of stem and other cells to the damaged tissuethat trigger a healing response. In general, pre-clinical literature provides support for the ¡use of PRP injections to regenerate damaged joint tissue in Osteoarthritis due to its influence on the whole joint environment. In vitro studies mostlyshow a positive effect of PRP on cartilage with increases in chondrocyte proliferation without affecting chondrogenesisand enhancedproduction of type II collagen and proteoglycans. Effects on meniscal cells and synoviocytes have alsobeen reported. In studies using animal models of Osteoarthritis, PRP has been reported as leading to better cartilage regeneration.
- Middleton KK, Barro V, Muller B, Terada S, Fu FH. Evaluation of the effects of platelet-rich plasma (PRP) therapy involved in the healing of sports-related soft tissue injuries. Iowa Orthop J. 2012;32:150-63.
- Bennell KL, Hunter DJ, Paterson KL. Platelet-Rich Plasma for the Management of Hip and Knee Osteoarthritis. Curr Rheumatol Rep. mayo de 2017;19(5):24.
- Chen D, Shen J, Zhao W, Wang T, Han L, Hamilton JL, et al. Osteoarthritis: toward a comprehensive understanding of pathological mechanism. Bone Res. 2017;5:16044.
- van den Bekerom MPJ, Struijs PAA, Blankevoort L, Welling L, van Dijk CN, Kerkhoffs GMMJ. What is the evidence for rest, ice, compression, and elevation therapy in the treatment of ankle sprains in adults? J Athl Train. agosto de 2012;47(4):435-43.