I have never received ART and can't really tell what techniques they use to break up scar tissue.
But, if you hyperextended your knee, I don't see why you're getting ART for all these months. Hyperextending your knee doesn't directly damage muscle tissue. It most likely damages ligaments or other supporting structures. ART or any other soft tissue modality cannot get inside the knee joint to realign scar tissue, although myofascial work may be beneficial. Soft tissue work can be beneficial for addressing issues that arise from compensation patterns due to the injury (which may be beneficial for preventing aggravation of the injury or a re-injury down the road), but it won't directly aid in the healing of the damage in the knee joint.