Ulrich J Spiegl1, Scott C Faucett2, Peter J Millett3. 1. Department of Trauma and Reconstructive Surgery, Spine Center, University of Leipzig, Liebigstrasse 21, 04103, Leipzig, Germany. 2. George Washington University Medical Faculty Associates, 2150 Pennsylvania Avenue, NW, 7-408, Washington, DC 20037. 3. Steadman Philippon Research Institute, Suite 1000, and The Steadman Clinic, Suite 400, 181 West Meadow Drive, Vail, CO 81657. E-mail address for P.J. Millett: drmillett@thesteadmanclinic.net.