ACL is known as the major stabilizer of the knee joint. There is an increased chance for this ligament to get torn during rigorous sports activities. The standard form of treatment for the torn ligament is to have a surgery. The surgeon removes the middle section of the patellar tendon below the knee cap.
I think you are interested in skiing, which causes stress to the ligaments. Patellar tendonitis is a serious musculoskeletal problem that must be taken care of. I too had the problem of tendonitis and I had to undergo a mesotherapy treatment ( http://www.pinewoodhealth.ca/servicedetails.aspx?ServId=34e5d5af-6253-4276-b1bb-0303803c0c89
) from Toronto in order to find a solution to this problem. The results were immediate and I was totally happy with the results. Why don't you give a try?