[1] Swedish Med Ctr, Swedish Neurosci Inst, Seattle, WA USA
[2] Seattle Sci Fdn, 550 17th Ave,Suite 600, Seattle, WA 98122 USA
[3] St Josef Hosp Essen Werden, Dept Orthoped & Trauma Surg, Propsteistr 2, D-45239 Essen, Germany
[4] Ruhr Univ Bochum, BG Univ Hosp Bergmannsheil, Dept Gen & Trauma Surg, Burkle Camp Pl 1, D-44789 Bochum, Germany