1. Reeve-Irvine Research Center, Department of Anatomy and Neurobiology, College of Medicine, University of California at Irvine, Irvine, California.
2. Reeve-Irvine Research Center, Department of Anatomy and Neurobiology, College of Medicine, University of California atIrvine, Irvine, California.
3. Orthopaedic Surgery, University of California at Irvine, Irvine, California.