Transcutaneous electrical nerve stimulation (TENS) — 2 times per week for 6 weeks
tingling sensation
In our study, we used the following TENS device settings, such as the frequency of 32–50 Hz, the pulse width of 80 ms, and symmetrical biphasic waveform. The surface electrodes were placed on the medial and lateral superior borders of the patella, as well as the medial and lateral inferior borders of the patella. The electrodes were not placed on the quadriceps or the anterior leg muscles. The pairs of electrodes kept crossing to cover the large surface area. The device intensity was regulated by the attending physical therapist until subjects reported a bearable tingling sensation.