Gregg R Klein MD Vice-Chairman, Department of Orthopaedic Surgery, Hackensack University Medical Centre; Associate Professor, Department of Orthopaedic Surgery, Hackensack Meridian School of Medicine, Rothman Orthopaedic Institute, Montvale, New Jersey, USA P Maxwell Courtney MD Assistant Professor, Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University, Woodbury, New Jersey, USA