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Arthroscopic Knee Surgery or Platelet Rich Plasma (PRP) injection for Knee Arthritis?





So which one is better? Arthroscopic knee surgery or PRP injection for the treatment of symptomatic knee osteoarthritis? Head to head trials comparing PRP to placebo, PRP to hyaluronic acid, and PRP to cortisone injections all show that PRP has much better and much more sunstained symptom relief when used to treat arthritis. But what about surgery? Let’s look at this randomized controlled trial to find out more.


Knee osteoarthritis results in significant pain and disability. It’s caused by the progressive wear and tear and eventual loss of articular cartilage. And cartilage is what helps protect and pad our long bones. It’s what gives our bones a nice smooth surface to glide against. But when you start losing articular cartilage, you start losing that smooth surface. Damaged cartilage is thought to cause rubbing and catching in the knee, similar to rubbing sandpaper together. In addition, fragments of cartilage can break off and cause locking and clicking inside the knee. All of this results in degeneration of the knee as well as inflammation and pain.


And this is why some surgeons recommend arthroscopic surgery to go inside the knee to clean everything up. Using minimally invasive techniques, surgeons can remove loose tissue as well as polish up the articular surfaces to try to restore the smooth motion of the knee. This would in theory decrease symptoms related to knee osteoarthritis.


So how does PRP compare to arthroscopic surgery? Let’s look at this randomized controlled trial that looked to directly answer this question. The authors randomized 70 patients to get either one PRP injection or arthroscopic knee surgery. Participants had KL grade 2 and 3 osteoarthritis which means that they all had either mild to moderate osteoarthritis and were between 40 to 60 years of age. All of the participants had failed an initial trial of conservative treatment.


For their PRP group, patients had 20 cc’s of blood drawn which was concentrated down to a final product of around 4 to 5 cc’s. This resulted in about 4 billion platelets in their final PRP product. No activating agent was used. Interestingly, injections were done landmark based and not ultrasound guided.


For the arthroscopic surgery group, an instrument was used to make micro fractures in the subchondral bone to induce subchondral bleeding. They then had the cleanup portion of the surgery with debridement of damaged portions of articular cartilage, meniscus, and synovial membranes. The joint was then irrigated and washed out with sterile solution.


So what were the results? The authors first report that both arthroscopic surgery and PRP injections helped improve function and reduce pain scores in those who suffered from knee osteoarthritis. But now let’s look at the comparative results.


With regards to functional scores as measured by the WOMAC osteoarthritis index, the authors report that at all follow up time periods of 3 months, 6 months, and 9 months, the arthroscopic surgery group had worse scores when compared to the PRP group. With regards to pain scores as measured by the visual analog scale, the arthroscopic surgery group again had worse scores when compared to the PRP group at all follow up time periods.


The authors go on to report that “by 9 months, the percent reduction in functional scores was only 9% in the PRP group and 0% in the arthroscopic debridement group. Similarly at final follow up, percent reduction in pain scores was 8% in the PRP group as compared to 3% in the surgery group.”


Ok so this article adds to the growing body of medical literature that PRP is effective for the treatment of symptomatic knee osteoarthritis. We have head to head trials comparing PRP to pretty much every other treatment for arthritis and it really seems like PRP comes out ahead in every instance.


This is actually one of the very few studies that have directly compared PRP to arthroscopic debridement. Not only does PRP result in better functional improvements and better pain scores, it’s so much easier to do and much lower risk. All it involves is a simple blood draw and a quick injection that can be done in the office. You walk in, walk out and everything is done in about 40 minutes.


On the other hand, arthroscopic surgery comes with all the risks associated with surgery including infections, blood clots, and complications. Not to mention the post operative rehabilitation and down time. But it’s actually worse than that. Because whatever is cut out during surgery is gone forever, specifically the meniscus. Multiple studies have shown that if you cut out the meniscus, you are increasing the risk for more wear and tear and more osteoarthritis in the future.


Now here’s the thing with this study. Some would argue that their results could have been even better. They used a 20 cc blood draw which gave about 4 billion platelets. Better kits can process 50-60 cc of blood which nets 8-10 billion platelets. Other studies like this one suggest that if you administer around 10 billion platelets, that you would get even better functional improvements and reduction in pain and that the effects are sustained out to 1 year. The study we just reviewed found that one injection of a lower dose PRP, 4 billion platelets, provided pain relief for less than 9 months.


In addition, the authors decided to administer the PRP injections using a landmark based technique rather than with ultrasound guidance. Landmark based knee injections have an accuracy as low as 55% whereas ultrasound guided injections have an accuracy between 96 to 100%. This really makes you wonder what kind of results we would have seen if the authors had used closer to 10 billion platelets and administered the PRP treatments with ultrasound guidance.


But even with these limitations, the authors report that PRP still had better results than arthroscopic surgery. Hopefully as more and more studies like these are done, insurances will start to cover platelet rich plasma.

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