[1] Scripps Clin, La Jolla, CA 92037 USA
[2] San Diego Spine Fdn, San Diego, CA USA
[3] Univ Calif San Francisco, San Francisco, CA 94143 USA
[4] Univ Pittsburgh, Med Ctr, Pittsburgh, PA USA
[5] Cedars Sinai, Los Angeles, CA USA
[6] Univ Michigan, Ann Arbor, MI 48109 USA
[7] Louisiana Spine Inst, Shreveport, LA USA
[8] Univ S Florida, Tampa, FL USA
[9] Int Spine Study Grp, Res, Brighton, CO USA