I had the opposite the ACL injury due to a skiing accident. Since there was no cartilage tear revealed in the MRI I did not go the operative route. I used cycling to strengthen the muscles around the knee. It has been 14 years since and I have not had any problems with the knee. My cycling is at the same level and is not affected by the ACL tear although impact sports on the knee such as basketball, soccer, volleyball where there are situations of jumping and landing on one leg will likely hurt my ACL again.
What did your doctor say? Get several opinions from several doctors before you decide.
I never took drugs to improve my performance at any time. I will be willing to stick my finger into a polygraph test if anyone with big media pull wants to take issue. If you buy a signed poster now it will not be tarnished later. --Graeme Obree