Vancouver, British Columbia, Canada.An Instructional Course Lecture, The American Academy of Orthopaedic Surgeons.*Printed with permission of The American Academy of Orthopaedic Surgeons. This article will appear in Instructional Course Lectures, Volume 47, The American Academy of Orthopaedic Surgeons, Rosemont, Illinois, March 1998.(dagger)Although none of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, foundation, educational institution, or other non-profit organization with which one or more of the authors is associated. No funds were received in support of this study.(Masterson, Masri, Duncan) Department of Orthopaedics, Vancouver Hospital and Health Sciences Centre, Room 3114, 910 West 10th Avenue, Vancouver, British Columbia V5Z 4E3, Canada. The e-mail address for Dr. Masterson is firstname.lastname@example.org, the e-mail address for Dr. Masri is email@example.com, and the e-mail address for Dr. Duncan is firstname.lastname@example.org.