1. Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269, United States
2. Department of Orthopedic Surgery, University of Connecticut Health, Farmington, Connecticut 06032-1941, United States
3. Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut 06269, United States
4. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-0001, United States
5. Department of Orthopedic Surgery, School of Medicine, Emory University, Atlanta, Georgia 30322-1007, United States