Shoulder problems after TOS surgery are usually just shoulder problems. I personally had problems with rotator cuff bursitis and tendinitis due to poor scapular positioning. The scapular stabilizing muscles need to be strengthened and sometimes shoulder mechanics need retraining, a common problem with TOS sufferers (I used Stott Pilates for retraining and my shoulders are doing great now). A tight pec minor can cause the shoulder problems as well as the symptoms in the elbow. Unless she is having parasthesias/radiculopathy from the armpit down into the fingers, I wouldn't immediately suspect scar tissue.