Platelet-rich plasma (PRP) therapy involves using a concentration of platelets derived from a patient’s own blood to support healing processes. This autologous product leverages the natural healing properties of platelets for tissue repair. For knee issues, PRP delivers these concentrated healing factors directly to the affected area. The effectiveness of PRP therapy depends on the precision and quality of its preparation, a multi-step process beginning with blood collection.
The Initial Blood Draw
Preparing platelet-rich plasma starts with collecting a blood sample from the patient, similar to a routine blood test. This involves drawing venous blood, typically from an arm vein. The volume of blood collected can vary depending on the specific protocol and the desired concentration of the final PRP product. To prevent clotting, the collected sample is placed into tubes containing an anticoagulant, such as acid citrate dextrose (ACD-A). Maintaining a sterile technique is important to avoid contamination.
Centrifugation: Separating the Components
After collection, the blood sample undergoes a process called centrifugation, where it is spun at high speeds in a specialized machine known as a centrifuge. This spinning action separates the blood components based on their different densities. As the blood spins, it naturally stratifies into distinct layers. The heaviest components, red blood cells, settle at the bottom of the tube, forming the lowest layer.
Above the red blood cell layer lies a thin, yellowish or brownish middle layer known as the “buffy coat,” which contains concentrated platelets and white blood cells. The uppermost layer consists of platelet-poor plasma (PPP), which is plasma with a low concentration of platelets. The goal of this separation is to isolate the platelet-rich layer while minimizing contamination from other blood components. Different centrifugation protocols exist, including single-spin and double-spin methods, with double centrifugation often yielding higher platelet concentrations and less contamination by red and white blood cells.
Extracting the Platelet-Rich Plasma
Following the centrifugation process, the distinct layers within the blood sample become visible, allowing for the careful extraction of the platelet-rich plasma. Using a syringe or a specialized collection device, the medical professional precisely draws out the buffy coat layer, along with a portion of the plasma. This step requires considerable precision to ensure that the highest concentration of platelets is collected while minimizing the inclusion of red blood cells, which are less desirable in the final product. The extracted PRP appears as a clear to yellowish liquid. The accuracy of this extraction directly influences the quality and therapeutic potential of the prepared PRP.
The Final Product and Its Application
The preparation process culminates in the final platelet-rich plasma product. This solution is a concentrated form of the patient’s own platelets, suspended in a small volume of plasma. The concentration of platelets in PRP can be significantly higher than in normal blood, often ranging from 2.5 to 9 times the baseline concentration, though specific values depend on the individual’s blood and the preparation method used. This prepared PRP is ready for direct application. For knee issues, this typically means the PRP is now prepared and available for injection into the knee joint.