I am coming of surgery from a torn acl and meciscus......I have been thinking about swithching to skiis that are a just little shorter and more forgiving.
Does this make sense ? Will there be much difference or less stress on my knee ?
I wouldn't go shorter. Shorter typically means quicker turns and less stability at any kind of speed. I'd think you would want a longer radius ski that wouldn't stress your knees as much.
A softer more forgiving ski wouldn't be a bad idea though.
A couple of years ago I bought my wife the 'Knee' binding (she is post meniscus and ACL repair). It is supposed to release under conditions that stress the knee joint. I don't know if it really is better than a standard binding, but thus far she has had no knee issues skiing. Unfortunately, she did prang her shoulder pretty badly this past week. Possibly she needs to give up skiing and take up knitting.
I basically agree with MikeC, shorter skis are less stable than longer skis, generally. However, if the shorter skis is significantly wider than the longer skis the shorter ones could be more stable. I have two pair of 161cm skis and the fatter ones, Icelantic Shamans, are definitely more stable than the skinnier ones, Volkl Supersport Allstars.
More important than the gear however is your rehab. Having had 4 surgeries for a ruptured Achilles tendon, I can tell you that rehab is really critical. If you haven't started physical therapy yet, try to find a PT who is a skier. If the therapist is knowledgeable about the sport you want to return to doing it makes a huge difference in outcome.