Damaged mouse knee joint bone spur (IMAGE) Keck School of Medicine of USC Caption Following ligament injury, a bone spur forms at the edge of the damaged mouse knee joint (middle right). This pathological bone spur (pink) is made by the same type of stem cells (green) that normally participate in the repair of broken bones. Credit Stephanie Kuwahara/USC Stem Cell Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.