[1] Thomas Jefferson Univ, Rothman Orthopaed Inst, Philadelphia, PA 19107 USA
[2] Southern Calif Permanente Med Grp, Dept Orthoped Surg, Pasadena, CA USA
[3] Drexel Univ, Coll Med, Philadelphia, PA 19104 USA
[4] Thomas Jefferson Univ Hosp, Sidney Kimmel Med Coll, Philadelphia, PA 19107 USA