I am sorry to hear about your medical problems. If the ACL has not healed then the pain will continue despite PT and pain medications. Ask your doctor for another MRI of the knee. Also, any infection, fluid build up and hemorrhage can delay healing. So, ask your doctor regarding other options for you. Take a second opinion from another ortho specialist in your area. Ask if knee replacement will help?
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.