PRP knee injection · Persistent knee pain · St. Louis
Knee pain that keeps
coming back
A PRP knee injection takes platelets from your own blood, concentrates them, and places them into the knee using ultrasound. When your MRI shows bone marrow lesions, it also goes into the bone under the cartilage. It reduces pain and the need for pain pills in knees from early arthritis to bone-on-bone. At Regen.MD in St. Louis it is one part of a plan that also treats the inflammation driving your knee.
Why the pain keeps returning
Cortisone calms inflammation for weeks, and repeated shots are linked to faster cartilage loss. The trial data is here. Physical therapy builds the muscles around the joint but cannot reach the chemistry inside it. That is why knee pain often comes back after therapy. Daily ibuprofen trades the knee for the stomach, kidneys and heart over the long run.
Bone-on-bone is not the end of the options
At the most advanced grade, a blinded, placebo-controlled trial tested a series of PRP shots. PRP reached a meaningful gain in pain and function at three and six months, and saline did not. Bone marrow concentrate in grade III and IV knees has four-year follow-up. Most knees improved, and there were no replacements in that series.
At that stage, structure is not restored. What you gain is time and fewer pain pills. Those are real goals when the alternative is another year of rising pain pills. Replacement stays the final fix for the structure, and for the people who want it. Bone on bone knee? Why nothing can be done is wrong.
Inside the bone, not only the joint
Arthritis pain often comes from the bone under the cartilage, where MRI shows bone marrow lesions. An injection into the joint space does not reach it. Intraosseous subchondral PRP places platelets into that bone, which is why it is reserved for knees that show it.
PRP, bone marrow concentrate or microfragmented fat
PRP fits most knees. Bone marrow concentrate and microfragmented fat carry more for knees that have lost more ground. The full evaluation decides, using your exam, your imaging and how the choice is made.
What the knee needs from the rest of you
Every pound of body weight adds several pounds of force across the knee with each step. And insulin resistance feeds the same inflammation that breaks cartilage down. A job on your feet all day, or a commute that ended your walking, matters too. You cannot out-inject a broken metabolism, so we measure the metabolic markers before we plan the injections.
Not sure this is your problem? Take the 60-second candidacy check: am I a candidate?.
Questions patients ask
How long do PRP knee results last?
Trials measure benefit at three, six and twelve months. Many patients repeat a series when pain returns. How long it lasts depends on the grade of the knee, your metabolic health and how the knee is loaded afterward. We recheck you instead of guessing.
How long do I need to rest my knee after a PRP injection?
Expect soreness for a few days and protected activity for about a week, then a graded return to loading. Skip anti-inflammatory pills during that window, because the early inflammation is the repair signal. Why rest, ice and ibuprofen can sabotage recovery.
What causes PRP to fail?
Most failures come from the terrain, the dose or the placement, not the biology. Think of an injection into an inflamed, insulin-resistant joint, too few platelets, or the wrong structure. Why PRP injections fail.
Does insurance cover a PRP knee injection?
Most plans do not. That is a payer decision, not evidence about whether it works. Why insurance rarely covers orthobiologic procedures explains the difference.