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Knee osteoarthritis (KOA) is a chronic degenerative disease characterized primarily by knee pain and dysfunction. Non-surgical treatments, such as oral non-steroidal anti-inflammatory drugs (NSAIDs) and intra-articular injections of corticosteroids or hyaluronic acid, are commonly employed to alleviate symptoms. For patients with advanced KOA, total knee arthroplasty is often the treatment of choice. However, no current treatment can halt or reverse the progression of KOA.

Platelet-rich plasma (PRP) has emerged as a promising treatment due to its rich concentration of active growth factors. These factors stimulate chondrocyte proliferation and differentiation, promote collagen synthesis, inhibit the inflammatory response in cartilage, regulate the environment of damaged tissues, and delay KOA progression. PRP intra-articular injections have been widely used in clinical practice with notable success.

What is PRP?

PRP is derived from autologous peripheral blood through centrifugation, resulting in a platelet concentration over three times that of normal blood. PRP injections are characterized by their lack of immune rejection and high safety profile. The growth factors in PRP, such as platelet-derived growth factor and vascular endothelial growth factor, enhance the production of type II collagen and proteoglycans, fostering chondrocyte proliferation and preventing chondrocyte apoptosis. Additionally, fibronectin in PRP promotes the adhesion and migration of cartilage precursor cells, aiding in cartilage repair and reconstruction.

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Types and Mechanisms of PRP

As research advances, various types of PRP are being developed, including platelet-rich fibronectin and leukocyte-rich or leukocyte-poor PRP. PRP's multiple growth factors enable it to accumulate at cartilage injury sites. In subchondral bone PRP treatment for KOA, PRP infiltrates the osteochondral complex and mesenchymal stem cells (MSC), thereby inhibiting inflammation, promoting tissue repair, reducing oxidative stress, and regulating MSC proliferation and differentiation.

Efficacy of PRP in KOA Treatment

Intra-articular injections are a primary treatment method for KOA, with corticosteroids, hyaluronic acid, and PRP being the most commonly used. PRP intra-articular injections not only reduce symptoms but also promote articular cartilage repair and can halt KOA progression. However, this method primarily affects the articular cartilage and synovium, not the subchondral bone.

Subchondral bone lesions are a key feature in KOA development and progression. Lychagin et al. treated 17 osteoarthritis patients with bone marrow edema using PRP subchondral bone injections. After one year, patients' WOMAC and KOOS scores significantly improved, and serum levels of cartilage oligomeric matrix protein were elevated for up to three months post-treatment. This suggests that PRP subchondral bone injections offer long-lasting effects and can significantly enhance patients' quality of life.

Combination Therapies and Future Directions

Su et al. compared the clinical efficacy of combined intra-articular and intra-bone PRP injections, intra-articular PRP injections alone, and intra-articular hyaluronic acid injections in KOA treatment. An 18-month follow-up revealed that combined PRP injections improved knee function, alleviated pain, and enhanced patients' quality of life more effectively than the other methods. PRP subchondral bone injections demonstrate significant clinical efficacy, and combining intra-articular and subchondral PRP injections yields superior results in KOA treatment.

These findings underscore the potential of PRP in treating KOA and highlight the need for further research to optimize treatment protocols and improve patient outcomes.

Reference

1. Zhang Y, Chen X, Tong Y, Luo J, Bi Q. Development and Prospect of Intra-Articular Injection in the Treatment of Osteoarthritis: A Review. J Pain Res. 2020 Aug 4;13:1941-1955.

2. Prizov A, Tchetina E, Volkov A, Eremin I, Zagorodniy N, Lazko F, Pulin A, Belyak E, Kotenko K, Eshmotova G, Glukhova S, Lila A. Long-Term Structural Changes in the Osteochondral Unit in Patients with Osteoarthritis Undergoing Corrective Osteotomy with Platelet-Rich Plasma or Stromal Vascular Fraction Post-Treatment. Biomedicines. 2024 May 9;12(5):1044.

3. Baird HBG, Ashy CC, Kodali P, Myer GD, Murray IR, Pullen WM, Slone HS. Most Publications Regarding Platelet-Rich Plasma Use in the Knee Are From Asia, Investigate Injection for Osteoarthritis, and Show Outcome Improvement: A Scoping Review. Arthroscopy. 2024 Mar 25:S0749-8063(24)00252-4.

4. Balusani P Jr, Shrivastava S, Pundkar A, Kale P. Navigating the Therapeutic Landscape: A Comprehensive Review of Platelet-Rich Plasma and Bone Marrow Aspirate Concentrate in Knee Osteoarthritis. Cureus. 2024 Feb 23;16(2):e54747.

5. Ye Z, Chen H, Qiao Y, Wu C, Cho E, Wu X, Li Z, Wu J, Lu S, Xie G, Dong S, Xu J, Zhao J. Intra-Articular Platelet-Rich Plasma Injection After Anterior Cruciate Ligament Reconstruction: A Randomized Clinical Trial. JAMA Netw Open. 2024 May 1;7(5):e2410134.

6. Lychagin A, Lipina M, Garkavi A, Islaieh O, Timashev P, Ashmore K, Kon E. Intraosseous injections of platelet rich plasma for knee bone marrow lesions treatment: one year follow-up. Int Orthop. 2021 Feb;45(2):355-363.

7. Su K, Bai Y, Wang J, Zhang H, Liu H, Ma S. Comparison of hyaluronic acid and PRP intra-articular injection with combined intra-articular and intraosseous PRP injections to treat patients with knee osteoarthritis. Clin Rheumatol. 2018 May;37(5):1341-1350.