1 Department of Surgery, University of Nebraska Medical Center, Omaha, Neb.
2 Department of Biomechanics, University of Nebraska at Omaha, Omaha, Neb.
3 Department of Surgery, University of Nebraska Medical Center, Omaha, Neb; Department of Biomechanics, University of Nebraska at Omaha, Omaha, Neb; Department of Surgery, Veterans Affairs Medical Center, Omaha, Neb.