One of my patients, female high school athlete, tore her left ACL this past April and had surgery this June. I worked with her every day this summer and have continued through her school year only three times a week. Obviously her knee cap is numb to the touch. Her numbness continues down the front left of her leg about halfway down her leg. I realize this is completely normal. However, during her sessions, I have noticed where she is numb in the front part of her leg, a bruise will appear. It is not there before the workout. It only appears while working out. My colleagues and I have no explanation. Any plausible reasons for this?