After patients are positioned to supine, a pillow is placed to support below their knee to be treated. Anteroposterior (AP) fluoroscopic image of the knee joint is obtained with C-arm fluoroscopy. 1% of lidocaine is injected 2 ml under the skin at locations corresponding to joint space both of sides of the patellar ligament and A 10 cm 22-gauge two radiofrequency electrode needles with a 5 mm active tip (NeuroTherm® RF Cannula) are bilaterally inserted at the same points and advanced under fluoroscopic guidance entering the cavity of the knee joint at the both medial and lateral sites until needle tips are in the middle of the joint space. Pulsed Radiofrequency (PRF) is bilaterally performed in 42oC of temperature during ten minutes. After positioned to supine, a pillow is placed to support below their knee at the planned procedure site. Anteroposterior (AP) fluoroscopic image of the knee joint is obtained with C-arm fluoroscopy. Under fluoroscopy at locations corresponding to joint space both of sides of the patellar ligament, 1% of lidocaine is injected 2 ml under the skin and at the same points with 22 gauge of thickness, 10 cm in length, 5 mm of length active tipped two radiofrequency electrode needles (NeuroTherm® RF Cannula) are bilaterally inserted and advanced under fluoroscopy entering the cavity of the knee joint at the both medial and lateral sites until needle tips are in the middle of the joint space. PRF is bilaterally performed with a unipolar mode, 45V voltage, 2 Hz frequency, at a temperature of 42oC, 10 msec pulse width for 10 minutes in group U. The same procedure is bilaterally performed with a bipolar mode for 10 minutes in group B. All procedures are performed by one practitioner who is not informed about the type of procedure (unipolar or bipolar mode) and also patients are not aware of which type of treatment received.