PRP stands for platelet-rich plasma. A small sample of your own blood is drawn, spun in a centrifuge to concentrate the platelets, and injected back into the knee. Platelets carry growth factors that signal tissue repair, so the idea is simple: deliver a concentrated dose of your own healing signals directly where the irritation lives.
For knee pain, the strongest evidence for PRP is in early to moderate osteoarthritis and in chronic tendon problems around the knee, such as patellar tendinitis. Several well-designed studies show PRP can reduce pain and improve function for months at a time, and in head-to-head comparisons it often outperforms cortisone and gel injections for arthritis beyond the first few weeks. It is not a miracle cure, and it does not regrow a knee that is bone-on-bone, but for the right knee it can meaningfully calm things down.
Who tends to do well? People with mild to moderate arthritis who still have reasonable joint space, people with tendon pain that has not settled with therapy and activity changes, and people who want to delay or avoid surgery. Who is less likely to benefit? Knees with severe, end-stage arthritis, major instability, or a mechanical problem like a large displaced meniscus tear — those usually need a different conversation.
One thing I emphasize with every patient: PRP is not the first step. The first step is the boring, proven stuff — strengthening the muscles that support the knee, adjusting activity, weight and load management, and sometimes a simple injection. When those have been given a fair trial and the knee still hurts, that is when biologics like PRP earn their place.
A word on what PRP is not. The PRP I use is made from your own blood, drawn and prepared in the office the same day. It is not a marketed “stem cell” product, and it contains no placental tissue, Wharton's jelly, or exosomes — products that are not FDA-approved for orthopedic use and that I do not offer. When we discuss cell-based options, we are talking about your own cells, only.
If your knee has been nagging you for months and the usual measures have not gotten you back to what you love, PRP may be worth a conversation. The right next step is an honest evaluation: an exam, a look at your imaging, and a frank discussion of whether your knee is the kind of knee PRP helps.
This article is general education, not a diagnosis or a treatment plan for your specific knee. If you have sudden swelling, locking, inability to bear weight, fever, or a hot red joint, seek urgent care rather than waiting on any injection.