Intervention
The LLLT of each group was performed at the knee joint in a sitting position three times per week for 8 weeks with no additional exercises or other interventions. Each machine has 3 panels with 4 treatment spots/panel as inversed U shape to cover each knee joint and give the energy of 5.76 J. This dosage met the minimum dosage recommended by the World Association for Laser Therapy for knee OA (a minimum dosage of ≥ 4 J per treatment point for the 808 nm wavelength but no recommendation for the 660 nm wavelength in guideline)Laser machine (