Research Progress of Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: Mechanisms, Efficacy, and Clinical Practice

Knee osteoarthritis (KOA) affects approximately 28% of adults older than 45 years in China. About 20% to 30% of patients experience neuropathy-like pain features (burning, shooting pain, allodynia) that respond poorly to conventional nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, or hyaluronic acid. Platelet-rich plasma (PRP) has emerged as a promising autologous biologic for KOA. This narrative review summarizes the mechanisms, clinical efficacy, and practical considerations of PRP for KOA, with emphasis on its unique ability to relieve neuropathy-like pain through central immunomodulation. PRP exerts effects via tissue repair (growth factors: TGF-β, PDGF, VEGF), pain relief, and immunomodulation. Unlike conventional treatments targeting only inflammatory pain, preclinical evidence suggests that PRP modulates spinal microglial M1→M2 polarization, potentially reducing central sensitization. Clinically, leukocyte-poor PRP is superior to leukocyte-rich PRP. PRP combined with hyaluronic acid provides 6 to 12 months of efficacy. Optimal platelet concentration ranges from 600 to 900 × 109/L, with a minimum of 3.5 × 109 platelets per injection. PRP offers a unique advantage over existing non-operative KOA treatments by relieving neuropathy-like pain through central immunomodulation—a mechanism not shared by NSAIDs, corticosteroids, or hyaluronic acid. For patients with KOA and neuropathy-like pain features that respond poorly to conventional analgesics, PRP represents a promising therapeutic candidate that warrants further dedicated clinical trials.