My left knee has no cartilage in it and walking is painful. Since I have bought these shoes, it has strengthened my knees tremendously and I have had virtually no pain.  The limp I used to have because of a painful walk, has gone away completely. For the first time in years, I can walk normally.  My husband also bought a pair and he swears his back is stronger and he is sold on them as well. A little pricey, but worth every penny.