Patients were randomly divided into two groups. The rst group (G1) received 4-minute US therapeutic acoustic radia- tion treatments, performed exercise, and received transcuta- neous electrical nerve stimulation. The second group (G2) received an identical treatment, but instead these patients were treated with 8-minute regimens of US therapeutic acoustic radiation. Continuous ultrasonic waves were deliv- ered at a 1 MHz frequency and at an intensity of 1.5 watt/ cm2 via a transducer with a diameter of 5 cm (Chattanooga, USA). The patient maintained a supine position with both knees fully extended throughout treatment while US thera- peutic acoustic radiation was directed around the knee joint.