I haven't had to deal with the pain and rehab of an ACL tear (yet, at least) but I do have to have double knee replacement at the ripe old age of 45.   I saw on Bridge Street this morning the report with Carrie and Kim and her unfortunate accident on the ski slope.  There has been alot of ACL injuries in female's lately and I have yet to hear a reason why.  I have a feeling it's due to the same reason my surgeon told me regarding my knee replacement.  I was told that the structure of the knee differs in men and women.  It seems that the knee cap is aligned in the middle of the knee in men, therefore, the knee cap tracks up and down.  In women, due to our body structure and the way our bodies are designed for childbearing, etc, our knee caps are not aligned in the middle, but somewhat off to the outside of the knee.  Because of this, the knee cap does not track up and down in a straight line, and this causes many knee problems in woman.  I feel that because of this mis-alignment, so to speak, it's the reason why so many woman are having problems with their ACL.  In my case it caused the carliage to wear away, producing a bone on bone situtation causing severe arthritis.  The only way to keep it from going out of place is to strengthen the leg, but that's easier said then done.