Treatment CMT group The CMT group patients received, according to the CMT protocol described previously, CMT at the selected points with the CMT Electrotherapy Stimulator ("GEMORE" Multi-Function Electrotherapy Stimulator; GM390TE, GEMORE Co Ltd, Taiwan) to treat the affected OA knee. In brief, knee OA mostly induced knee pain at the medial side, the corresponding disease meridian of OA is AxI/3, the first yin meridian (AxI) over knee region ("3") on the medial aspect of the lower extremity (the spleen meridian in TCA). A reduction technique, to remove the obstructed overflowed Qi, was performed by treating the point "3" on the ipsilateral third yang meridian (TyIII) over the dorsal aspect of the upper extremity (TyIII/3:3), which corresponded to Tze Cheng (SI7) on the small intestine meridian in TCA; the aspect shares the same control C-point (the first "3" ) and F-point (the second "3") to divert the obstructed Qi from obstructed diseased meridian to the healthy one; the C-point is used to link the diseased meridian to the treatment healthy meridian; manipulating the F-point is for the treatment/removal of the disease/pain symptom. An enhancement technique was performed by treating contralateral meridian "Ax II/2:(3)," which represents treating "2" as the C-point and "3" as the F-point, and a number in parentheses signifies usage of enhancement technique on the contralateral second yin meridian of the medial aspect of the lower extremity (corresponding to San Yin Jiao (SP6) and Lou Ku (SP7), respectively, on the liver meridian in TCA). The 6-minute treatment (electrotherapy was set at 40 Hz biphasic and 30 mA) comprises reduction and enhancement procedures on the specific points (figures 1 and 2). Each patient received CMT twice per week for three weeks during the study.