Platelet-Rich Plasma, Hyaluronic Acid, and Cortisone Injections for Knee Osteoarthritis

Most patients with osteoarthritis in the United States are prescribed NSAIDS, non-steroidal anti-inflammatory drugs like ibuprofen. The “non-steroidal” in NSAID is to differentiate them from anti-inflammatory steroids like cortisone that can be injected directly into the joint. A Medicare sample of a half million knee osteoarthritis patients found that about a quarter were treated with at least one corticosteroid injection. This can help with pain in the short term, but actually makes the disease worse in the long run.

Those getting steroid injections can end up with a worsening of pain, stiffness, and disability with accelerated joint deterioration and progression to total knee replacement surgery. This is in addition to complications that include osteonecrosis (bone rot) and rapid joint destruction. In a randomized controlled trial that has been deemed be perhaps the “final nail in the coffin” for the practice, two years of steroid injections for knee osteoarthritis led to a significantly greater loss of cartilage volume (and ironically no better pain relief) than a placebo injection of saline (basically water).

Doctors have been injecting steroids like cortisone into arthritic knees for more than 70 years. In light of the available evidence, a commentator on the cartilage loss study concluded that any case made today for the procedure “seems mostly to be based on rock solid prejudice.”

What about other injections? The inner linings of our joints naturally synthesize hyaluronic acid, which acts as a lubricant and shock absorber. So, what about injecting extra? Clinical guidelines are all over the place with 30 percent of professional societies recommending against it, 30 percent recommending for it under certain circumstances, and 40 percent expressing uncertainty or releasing no recommendation at all. This is presumably because the dozen meta-analyses that have been performed are all over the place as well, so it’s easy to cite robust data that supports a desired outcome. My predilection is to rely on the meta-analysis that includes the largest number of randomized controlled trials. It found no effect on function for hyaluronic acid injections and such a small effect on pain as to be deemed “clinically irrelevant.” This led the Academy of Orthopedic Surgeons to conclude that hyaluronic acid injections cannot be recommended. Double-blinded trials found the overall treatment effect may be less than half the minimal threshold for clinical importance.

There is more uniformity on the question of injecting PRP, which stands for Platelet-Rich Plasma (though also derided as “Profit-Rich Placebo”). It involves injecting concentrates of your own blood into the effected joints. All of the surveyed guidelines-setting bodies—the American Academy of Orthopedic Surgeons, the American College of Rheumatology, the European League Against Rheumatism, Osteoarthritis Research Society International, and the Royal Australian College of General Practitioners—recommended against the use of platelet-rich plasma for osteoarthritis due to the lack of supporting evidence.