Objective: To assess the effect of neuromuscular electrical stimulation (NMES) of quadriceps muscle on pain and functional level in knee osteoarthritis. 
 

Materials and Methods: Forty patients diagnosed as knee osteoarthritis participated in the study. Patients were randomized to two groups. First group received hotpack, ultrasound, transcutaneous electrical nerve stimulation (TENS) and isometric quadriceps exercises (control group), and second group received NMES of quadriceps muscle in addition to this therapy program. All patients were given treatment for 3 weeks, 5 sessions per week. Pain severity (VAS 0-10), Western Ontario McMaster Osteoarthritis Index (WOMAC), and duration of 50 m walking and stair climbing up and down were assessed before and after the treatment. 
 

Results: There were significant differences in NMES group regarding pain severity, walking duration, stair climbing up and down duration, WOMAC-pain, stiffness and physical function scores between pre and post-treatment measurements (p=0.000, 0.008, 0.021, 0.002, 0.002, 0.001, respectively) and in control group regarding pain severity, WOMAC-pain and physical function scores (p=0.005, 0.021, 0.013, respectively). There was a significant difference between groups regarding percent change in 50 m walking duration (p=0.018).
 

Conclusion: Isometric quadriceps exercises together with physical therapy interventions are effective in decreasing pain and improving functional level in knee osteoarthritis. Additive benefit, especially on walking was observed after adding NMES of quadriceps muscle to this therapy program.