Knee osteoarthritis is a degenerative wear and tear of the cartilage (cushion between the joints) that often occurs with repeated motions. This exercise will not fix the damage to the cartilage. However, the symptoms it may be causing can be modulated. This distraction can also be used for improving knee range of motion if limited by the joint.
This exercise can be done by placing a towel in between the distal part of your femur & proximal aspect of your Tibia, right under the knee crease. Pull in your Tibia towards you, although you are going into flexion of the knee the towel will allow you to get a distraction force OPENING and STRETCHING the joint capsule.
The second part is more aggressive and can more easily be done with both knees at the same time. In a tall kneeling position slowly lean back onto your heels. Initially use arms for support to prevent a sudden stretch.
In this video I am slowly working to my end-rage. However, at end range you can oscillate back and forth up to 50 times if you want to stretch the capsule. It is important to note this is NOT meant to be a quadriceps stretch, and you should feel a pull/opening in the knee joint capsule. The joint capsule is a thick fibrous sleeve surrounded by many ligaments, the capsule will not afford much motion and the oscillations should be minimal.