Evidence and published data is gaining ground in proving the benefits of platelet-rich plasma (PRP) in the treatment of knee osteoarthritis. This evidence has emerged rapidly and has fueled the desire to increase the use of affordable, minimally invasive treatments to reduce osteoarthritis-associated pain prior to surgical intervention. Patients with mild-to-moderate knee osteoarthritis at Cleveland Clinic Florida have shown favorable clinical outcomes with ultrasound-guided intra-articular PRP injections. Here at the Scottsdale Sports Institute, we perform approximately 2-4 injections per month. PRP injections have an 80% success rate with an average duration of pain relief of between 9 to 12 months.
HOW PRP WORKS
Platelets are activated by substances both inside and outside the blood including calcium chloride, thrombin and/or intra-articular cartilage. Once activated, a-granules within the platelets degranulate and secrete growth factors and anti-inflammatory cytokines, including insulin-like growth factor, platelet-derived growth factor and interleukin receptor antagonists. These mediators have been shown to inhibit cartilage degradation by regulating and promoting gene expression of tissue inhibitors of metalloproteinases. This reduction in cartilage degradation makes PRP particularly beneficial in the treatment of osteoarthritis.
PREPARATION AND EFFICACY OF PRP
PRP is prepared by the centrifugation of whole blood. This process separates the patient’s blood into 3 layers: plasma, platelets and white blood cells and red blood cells. There are a few PRP systems which have a second centrifugation process by which there is separation of plasma-rich plasma from the plasma-poor plasma, thus further concentrating the platelets. Various factors affect the efficacy of the PRP injectate, including the container size, the spin time and the spin rate among different PRP systems
PRP VERSUS HYALURONIC ACID
At least 11 studies have directly compared intra-articular PRP with intra-articular Hyaluronic Acid and 9 of the 11 studies showed better symptom scores and clinical outcomes 6-12 months post-treatment in the PRP groups.
CLINICAL IMPROVEMENTS NOTED WITH PRP
Current literature suggests that patients with osteoarthritis of the knees have a positive response to intra-articular PRP treatments. Patients who are younger and more active with mild osteoarthritis tend to have better clinical improvements with PRP when compared to older patients with more severe osteoarthritis
PRP is both affordable and minimally invasive and has a low complication rate with a rapid recovery time. Patients are generally able to bear weight immediately after the procedure and can return to normal activities following completion of treatment.
IDEAS TO CONSIDER FOR THE FUTURE
Different preparations of PRP yield different results; it would thus be beneficial to focus on comparing leucocyte-rick PRP versus leucocyte-poor PRP in the treatment of osteoarthritis. Another idea would be to look at protocols for injection technique, post-injection rehabilitation and longer follow-up times which will give better information regarding treatment outcomes.
Campbell KA, Saltzman BM, Mascarenhas R, et al. Does intra-articular platelet-rich plasma injection provide clinically superior outcomes compared with other therapies in the treatment of knee osteoarthritis? A systemic review of overlapping meta-analysis. Arthroscopy. 2015;31:2213-2221.
Meheux CJ, McCulloch PC, Lintner DM, et al. Efficacy of intra-articular platelet rich plasma injections in knee osteoarthritis: A systemic review. Arthroscopy. 2016; 32:495-505.
Sundman EA, Cole BJ, Karas V, et al. The anti-inflammatory and matrix restorative mechanisms of platelet-rich plasma in osteoarthritis. Am J Sports Med. 2013;42(1):35-40.