[1] So Calif Permanente Med Grp, Dept Orthoped, Irvine, CA 92618 USA
[2] Univ Arizona, Dept Orthoped Surg, Tucson, AZ USA
[3] Kaiser Permanente, Dept Orthoped Surg, Irvine, CA USA
[4] Kaiser Permanente, Dept Orthoped Surg, San Diego, CA USA
[5] Kaiser Permanente, Dept Surg Outcomes & Anal, San Diego, CA USA