The healing time for a torn ACL ranges from several months to a year after surgery or injury. The exact length of recovery depends on whether you have had surgery, how badly your ACL is torn, any additional knee injuries alongside the torn ACL, your general health, and the quality of your rehabilitation program. The healing time for a torn ACL ranges from several months to a year after surgery or injury. The exact length of recovery depends on whether you have had surgery, how badly your ACL is torn, any additional knee injuries alongside the torn ACL, your general health, and the quality of your rehabilitation program.