1. Department of Orthopaedics, Kaiser Permanente Southern California, Baldwin Park, California, USA.
2. Department of Orthopaedics, USC Keck School of Medicine, Los Angeles, California, USA.
3. Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA.
4. Department of Orthopaedics, Kaiser Permanente Southern California, Panorama City, California, USA.
5. Department of Orthopaedics, Kaiser Permanente Southern California, San Diego, California, USA.