04/12/2025
What PRP actually is :
PRP is made by drawing a small amount of a person’s blood, spinning it in a centrifuge, and separating out the layer that contains a high number of platelets in a small volume of plasma. Platelets are not just clotting cells; they are tiny packets full of growth factors and signalling proteins that tell tissues when to start healing after injury.
In a standard tube of blood, platelet levels are modest, but PRP processing increases their concentration several fold, so the injected joint sees a short, controlled “burst” of healing signals that would not occur with normal circulation alone. Because the PRP comes from the patient’s own blood (autologous), the risk of allergy or rejection is very low compared with donor products.
One way to think of an osteoarthritic or chronically painful joint is as a neighbourhood stuck in a low grade “smouldering fire”: inflammatory chemicals keep being released, pain nerves are over sensitive, and repair cells are present but demoralised. PRP is like sending in a clean up and repair crew that also convinces the trouble makers to quiet down: anti-inflammatory signals go up, aggressive inflammatory ones go down, and local cells receive a strong “repair, don’t destroy” message.
At the microscopic level, PRP releases growth factors such as platelet derived growth factor (PDGF), transforming growth factor beta (TGF β), vascular endothelial growth factor (VEGF), and insulin like growth factor 1 (IGF 1). In simple language, these messages tell nearby cells to move into the area, divide, lay down new matrix, and improve local blood supply, which together support tissue recovery in cartilage, ligaments, and synovium.
In painful joints, inflammatory chemicals like tumour necrosis factor alpha (TNF α) and interleukin 1 beta (IL 1β) keep the joint capsule, synovium and cartilage in an “angry” state and also sensitise pain nerves. PRP has been shown to tilt this balance by increasing anti-inflammatory mediators and reducing some of the pro inflammatory signals, which is similar to turning down the volume on the joint’s internal irritation.
Nerve growth factor (NGF) and prostaglandins in an osteoarthritic joint behave like amplifiers for pain messages. When PRP lowers some of these pain promoting substances and improves the overall fluid and tissue environment, pain fibres become less irritable, so the same mechanical load produces less discomfort.
Chondrocytes exposed to PRP in laboratory and animal studies show more production of building block molecules such as type II collagen and proteoglycans, and less production of enzymes that break cartilage down. In plain terms, PRP encourages cartilage cells to behave more like “builders” than “demolition workers”, which may slow wear and tear even if it does not regrow large amounts of cartilage in established osteoarthritis.
In the synovium and joint lining, PRP can support better production of hyaluronic acid and improve the lubricating quality of the joint fluid. For patients, this often translates into less stiffness and “grinding” sensation because the joint surfaces slide more smoothly, reducing mechanical irritation each time the joint moves.
Clinically, many randomised trials and meta analyses in mild–moderate knee osteoarthritis show that PRP often improves pain and function more than saline or, in several analyses, more than hyaluronic acid, with benefits lasting around 6–12 months for a proportion of patients. In everyday language, patients are more likely to report “less pain and better walking or activity” for several months after a short series of PRP injections compared with some standard injections, though it is not a cure and results vary.
However, at least one large, well designed trial found no meaningful difference between PRP and saline at one year, which tells us that not all PRP protocols or patient groups respond the same way and that PRP is not universally effective. Current reviews emphasise that preparation (leukocyte poor vs leukocyte rich, platelet dose), number of injections, and disease stage probably matter, and international guidelines still regard PRP as promising but not yet fully standardised.
