Effect of Low-Level Laser Therapy on Collagen Remodeling and Molecular Healing in Knee Osteoarthritis: A Quasi-Experimental Study

Background: Knee osteoarthritis is a degenerative joint disorder characterized by impaired collagen metabolism and progressive structural deterioration. Low-Level Laser Therapy (LLLT) has emerged as a non-invasive modality capable of modulating tissue healing and influencing molecular pathways involved in cartilage maintenance. Objective: To investigate the effects of LLLT on pain, functional performance, and key biochemical markers related to collagen remodeling in individuals with knee osteoarthritis. Methods: Thirty participants aged 40-65 years with Kellgren-Lawrence grade II-III knee osteoarthritis completed a four-week quasi-experimental pre-post study. LLLT was administered using an 808 nm diode laser (8 J/cm2, three sessions per week). Outcome measures included VAS, WOMAC, knee range of motion, quadriceps strength, and serum levels of Type II Collagen, MMP-13, and TIMP-1. Data were analyzed using paired t-tests with effect sizes calculated using Cohen's d. Results: Significant improvements were observed across all clinical measures, including reduced pain and enhanced functional performance. Biochemically, Type II Collagen levels increased, while MMP-13 decreased and TIMP-1 increased, indicating a shift toward a more favorable collagen remodeling profile. All outcomes demonstrated statistically significant differences with large effect sizes. Conclusion: LLLT elicited meaningful clinical and molecular improvements in individuals with knee osteoarthritis, suggesting its potential as a safe and effective adjunct to physiotherapy-based management. These findings highlight the therapeutic relevance of LLLT in supporting pain reduction, functional recovery, and cartilage-protective molecular activity.