Photobiomodulation Therapy Modulates Inflammatory and Cartilage Biomarkers in Patients with Knee Osteoarthritis: A Pilot Case Series.

Introduction: Knee osteoarthritis (KOA) is a common degenerative joint disease characterized by pain, inflammation, and progressive cartilage degradation. Current treatments often provide limited relief, encouraging the exploration of adjuvant, non-invasive modalities such as photobiomodulation therapy (PBMT). Although PBMT has demonstrated analgesic and anti-inflammatory potential, its biochemical effects in KOA remain underexplored. Case Report: This pilot clinical investigation included 30 patients with clinically and radiographically confirmed KOA, allocated into two groups (PBMT, n = 15; placebo, n = 15). All participants received identical treatment protocols, with the placebo group undergoing sham irradiation. Synovial fluid and blood samples were collected before and after the intervention to assess inflammatory and cartilage metabolism biomarkers, including interleukins (IL-1, IL-6, and IL-10), tumor necrosis factor-alpha (TNF-α), matrix metalloproteinases (MMP-3 and MMP-13), collagen type II C-telopeptide (CTX-II), and prostaglandin E2 (PGE2). Results: PBMT produced significant biochemical and clinical modulation compared with placebo. In serum, PBMT reduced IL-1, IL-6, TNF-α, and PGE2 levels while increasing IL-10 concentrations. In synovial fluid, significant reductions were observed in MMP-3, MMP-13, CTX-II, IL-1, IL-6, and TNF-α, accompanied by increased IL-10 levels. Clinically, PBMT participants reported substantial pain reduction and improved joint mobility.The observed reductions in inflammatory cytokines and cartilage degradation biomarkers indicate that PBMT exerts both systemic and intra-articular modulatory effects. The increase in IL-10 suggests activation of anti-inflammatory regulatory pathways, which may contribute to the clinical improvements observed. These findings reinforce the hypothesis that PBMT acts not only through symptomatic relief but also through modulation of disease-related biochemical mechanisms. Conclusion: PBMT demonstrates beneficial local and systemic effects on inflammatory and cartilage degradation pathways in KOA, supporting its potential as an adjunctive therapeutic strategy. Larger controlled clinical trials are warranted to confirm these findings and establish standardized treatment parameters.