FRESNO, Calif. --Better watch your step. Every day in the U.S., there are 25,000 ankle sprains. Sprains happen when the ligaments in the ankle stretch or twist outside of their normal position. Usually, the pain only lasts a few days, but an ankle sprain can also lead to more chronic problems so painful that even surgery may not help. Now, a new kind of graft is helping these patients when nothing else works.