Optimal stimulation frequency of transcutaneous electrical nerve stimulation on people with knee osteoarthritis

Objective: This is a double blind study that examined the optimal stimulation frequency of transcutaneous electrical nerve stimulation in reducing pain due to knee osteoarthritis. Subjects: Thirty-four subjects were randomly allocated into 4 groups receiving transcutaneous electrical nerve stimulation at either: (i) 2 Hz; (ii) 100 Hz; (iii) an alternating frequency of 2 Hz and 100 Hz (2/100 Hz); or (iv) a placebo transcutaneous electrical nerve stimulation. Methods: Treatment was administered 5 days a week for 2 weeks. The outcome measures included: (i) a visual analogue scale; (ii) a timed up-and-go test; and (iii) a range of knee motion. Results: The 3 active transcutaneous electrical nerve stimulation groups (2 Hz, 100 Hz, 2/100 Hz), but not the placebo group, significantly reduced osteoarthritic knee pain across treatment sessions. However, no significant between-group difference was found. Similarly, the 3 active transcutaneous electrical nerve stimulation groups, but not the placebo group, produced significant reductions in the amount of time required to perform the timed up-and-go test, and an increase in the maximum passive knee range of motion. Conclusion: Our findings suggested that 2 weeks of repeated applications of transcutaneous electrical nerve stimulation at 2 Hz, 100 Hz or 2/100 Hz produced similar treatment effects for people suffering from osteoarthritic knee.