answer:I don’t know how it would effect scar tissue. I used it for 6 months for a shoulder injury that flared up. I had a pin put in my left shoulder some years ago after a bad horse accident that severely dislocated my shoulder. I LOVED it! I utilized the electrical impulses as well and along with the basic accupuncture and some accupressure I walked out of the sessions on cloud nine. The therapist said I had a high tolerance for the electrical impulses into the muscles, I kept telling her to ramp up the voltage. It was bliss to the 10th power. lol I wonder, were you negligent in doing your physical therapy exercises after the surgery? I was, and while I have okay range I know it could have been better had I been more diligent. I’d call around and ask some therapists about scar tissue. If nothing else it WILL stimulate your muscles, reduce pain and leave you feeling amazing!