1. Hospital General de Chilpancingo Dr. Raymundo Abarca Alarcón; Chilpancingo, Guerrero Mexico
2. National Institute of Rehabilitation; Mexico City Mexico
3. La Raza Medical Center IMSS and Universidad Nacional Autónoma de México; Mexico City Mexico
4. Universidad Anáhuac-Mayab; Mérida, Yucatán Mexico
5. Tufts Medical Center and Tufts Medical School; Boston Massachusetts
6. ABC Medical Center, Mexico City, Mexico, and Tufts Medical School; Boston Massachusetts
7. Hospital Angeles, Tijuana; Baja California Mexico