Can feel a grinding feeling in knees when bending them when hands are on them seems like i can hear it then too. sometimes give out why is that?

Crepitance: The sound/ sensation of grating is common and does not correlate with chondrosis -- it is often present in normal knees, but can also be present with arthritis . Goving way can be secondary to fleeting pain, inadequate muscle strength/ balance or forms of patellar instability that your knee expert can sort out. www.patellofemoral.com.