Traditional treatment for knee osteoarthritis has been focused on knee strengthening, the use of non-steroidal anti-inflammatory medication (NSAIDs), and corticosteroid injections. Additional non-surgical options including viscosupplementation is also a treatment option for some with mild to moderate joint degeneration and have failed other first line treatment options.
Several studies have been published this year in regards to looking at the efficacy of PRP injections for patients who suffer from knee osteoarthritis.
A meta-analysis published by Campbell et al (May 2015), looked at the use of PRP versus corticosteroid injections, viscosupplementation injections, NSAIDs, and placebo. The findings from the literature searches did show that PRP injections led to significant improvements in pain and function at 6 months and maintained effect until 12 months post-injection. Those with milder findings of osteoarthritis radiographically appeared to have greater benefit from PRP injections.
A more recent double-blinded randomized clinical trial by Forogh et al (July 2015), evaluated one injection of PRP versus an intra-articular corticosteroid injection for symptomatic osteoarthritis of the knee. Patients with grade II/III osteoarthritis were randomly divided into two groups. Outcome measures included the Knee injury and osteoarthritis outcome score (KOOS), 20 meter walk test, knee range of motion, flexion contracture, and Visual Analog Scale (VAS) for pain assessment. Patients treated with one PRP injection had greater relief of pain compared to the corticosteroid group. A greater percentage of those treated with PRP were symptom free following injection, had improved activities of daily living and quality of life scores at follow-up.
In another randomized control trial conducted by Filardo et al (July 2015), researchers looked at the potential benefit of PRP injections compared to hyaluronic acid (viscosupplementation) injections for patients with at least a 4 month history of chronic knee pain and accompanying degenerative changes.
For this study, patients had 3 weekly intra-articular injections of either PRP or hyaluronic acid. Outcome measures included the International Knee Documentation Committee (IKDC) subjective score, KOOS score, EuroQol visual analog scale and Tegner score. The findings of the study revealed that both treatments were effective at improving knee functional status and decreasing pain. No significant differences were identified between PRP and hyaluronic acid.
While these studies do show the potential for PRP to be beneficial for those with knee osteoarthritis, it remains unclear as to how many injections are ideal. Furthermore, the preparation methods of the PRP, and the activating agent must also be considered.