Can you play football with a torn acl if you use a brace and are careful?

No: Football is a contact sport. No matter how careful you try to be, you place yourself and your team mates at risk by playing with an ACL deficient knee; with or without a brace. No brace is 100% effective. If you tear your acl, it can be reconstructed, but other innjuries, like a torn meniscus, are not all reparable. A torn meniscus increases the change of developing arthritis later in life.

Not recommended: Your acl provides stability during pivoting type activities. Assuming that you are young with minimal arthritic changes to your knee, pivoting sports are not recommended with a ruptured acl. The abnormal motion experienced by an acl-deficient knee may increase your risk for early arthritis.

Not Recommended: Football is a contact sport. The risk of sustaining a subluxation (partial dislocation) event is high with cutting and pivoting. When this happens further damage can occur to the knee in terms of meniscal tears, cartilage damage, and tears of other ligaments. A brace won't protect you.

Yes: At age 47 i'm assuming you are playing recreational football.If you have a well-fitted functional acl brace(don-joy defiance for example)and no other intrarticular injuries(meniscus tear) then u can try to play.Test it first by doing some hard 'cutting' on it at home or your local park.If it feels like its going to "give way' then u shouldn't play and possibly consider having it reconstucted.!