That really sucks, +vibes to your knee......I would be more careful skiing, at least at first. Torn Ligaments and sprains never heal back to their full strength. I sprained my ankle skimboarding this summer and my doctor told me that it takes about 6 months on average to regain about 75% of the strength, and after about a year it is healed to about 90% which is as good as it gets.