[1] Thomas Jefferson Univ, Rothman Orthopaed Inst, Philadelphia, PA USA
[2] Univ Utrecht, Univ Med Ctr, Dept Orthoped Surg, Utrecht, Netherlands
[3] Unfallklin Frankfurt Main, Frankfurt, Germany
[4] Univ Washington, Harborview Med Ctr, Dept Orthopaed Surg, Seattle, WA USA
[5] Catholic Univ Parana, Cajuru Univ Hosp, Dept Orthopaed, Spine Surg Grp, Curitiba, Brazil
[6] Assiut Univ, Dept Orthopaed & Trauma Surg, Assiut, Egypt
[7] Schon Klin Nurnberg Furth, Ctr Spinal Surg, Furth, Germany
[8] Thomas Jefferson Univ, Rothman Orthopaed Inst, 925 Chestnut St,5th Floor, Philadelphia, PA 19107 USA