I have performed alot of research on this type of exercise and also called one of the physician's I used to work with since he specializes in Sport's Medicine and he directed me to a couple of websites I am going to list below, some of which you may have seen while researching this also. He stated that for some this not performed properly can cause damage to the knees if you do not perform this exercise with care and slowly. If the knee is not in proper position that is where alot of injuries occur when you rebound you compromise the knee. If performed correctly this can be used as a part of your daily or bi-weekly exercise routine and have no issues whatsoever. But he did advise caution as with some the exercise itself does not cause injury but long term you may have resulted damage as you get older. He highly recommended what they call a Dead Lift as an alternative in your routine workout or bodybuilding as so many have long term issues later in life. Even if you are careful about having correct knee placement at any time you can become displaced or off balance and that it when you compromise the knee. I value his opinion very much, he was the one who gave my husband a very careful exercise regiment after his surgery and he now does everything he was told he would never be able to do again a year later he was 100%. He said the reason there are so many pro's and con's is due to the amount of people who have had long term injury from the exercise versus the ones who have not had any problems. So you are going to always have some that are all for it, and some who advise against it. While not everyone who performs this on a regular basis has an issue or injury there are some who will always experience soreness and that is a sign that the exercise is being performed incorrectly.

So he did advise caution with using this as a regular part of your exercise or weightlifting routine as the problem is possible injury from improper knee placement but also the fact that only time could tell whether this will cause an issue later in life for you. The knees enable you to do so many more things in terms of range of motion later in life that you should not take a chance on injury to them that can have long tem effects. I hope this will be of help to you, I know for me it allowed me to learn alot about exercise routines and possible injury that I never even knew also and as I said I do value his opinion since this is an area of specialty for him. Read more about this in the links below but if you do choose to keep this exercise as part of your routine keep in mind correct stance and safety precautions.

Knee Squats and Deadlifts

Full Body Exercises

Mechanics of the Squat