I had an acl reconstruction around 1990. However, my acl was injured about 10 years before that when acl's weren't being reconstructed, and the surguries required much cartilage removal. In fact, I've had 5 surgeries in all on the knee which included 2 more scopes for torn cartilage after the acl recon. About 5 years ago I found out that my acl had somehow worn away. My surgeon at that time told me not to bother with another reconstruction and told me to continue my normal exercise protocol and fitted me with a brace since I'm very athletic and like to ski, etc. Since then I've been having more problems with my knee and consulted a different specialist. This dr. recommends that I do have a 2nd reconstruction, but this time with an allograft. He stated that even though I'm 48 years old, I'm in great shape and seem physically much younger than my age. He thinks I'm an excellent candidate. He also explained that the procedure would slow down more onsetting arthritis being that I have so much play in my knee. When I asked him about the rehab he explained that things have changed in the past 20 years and that I could be wailking without crutches within a weak or 2. He also stated that in the future, if I need a partial knee replacement that I would need an acl. My questions are: Why the differeing opinions in dr.'s, and will it be worth the down time, pain, rehab. since I get around pretty good now and may need a knee replacement in the near future anyway? I must add that I have a 7 and 4 year old sons who are very active and I would like to keep up with their activity levels such as teaching them skiing, coaching, soccer/baseball, waterskiing, hunting, etc. Any advice would be truly helpful.