1. Department of Neurosurgery, Harvard University, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
2. Department of Orthopedic Surgery, Thomas Jefferson University, The Rothman Institute, Philadelphia, Pennsylvania, USA.
3. Department of Orthopaedic Surgery, Childrens Hospital of New Orleans, LSU Health Science Center, New Orleans, Louisiana, USA.
4. Department of Orthopedic Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA.