I was backing out of laundry room and tripped over ironing board. Fell flat down on both knees (skinned them) on hardwood floors. Face fell on carpet..Hit nose and glasses. Knees hurt for a few minutes...That was 10 hours ago.....NO bruises on knees.. I walked all afternoon with family..on a downtown Octoberfest. I cannot believe I have NO bruises on my knees..and I take coumadin. Bonnie