1. The Robert Jone & Agnes Hunt Orthopaedic Hospital. Oswetsry. U.K. Prof. G. Slee. Abril 1975.
  2. The Nuffield Orthopaedic Hospital. University of Oxford. U.K. Prof. Dathie and Prof. Goodfellow. Mayo 1975.
  3. The Royal National Orthopaedic Hospital of London . U.K. Prof. A. Catteral, Prof. M A. Edgard, Praf. M. Mheta. 1979
  4. Institut Saint Pierre. Palavas. Montpellier. Profesor A. Dimeglio and Profesor J.G. Pous. 1983.
  5. The Chidren’s Hospital. Boston Harvard Medical School, Boston . U.S.A. Profesor J. Hall. 1983.
  6. Hammersmith Hospital. Royal Postgraduate Medical School. University of London. Profesor V. Dubowitz. 1984.
  7. Hartshill Orthopaedic Hospital. Stroke – on Trent. Manchester. Profesor J. Dove 1987.
  8. L’Institut Calot. Berk Sur Mer. Normandia. Francia. Profesor Chopin, Profesor J. Chopin, Profesor I. Cotrel, Dr. C. Morin. 1988.
  9. Twin Cities Scoliosis Spine Center. University of Minnesota. Minneapolis. Minnesota . U.S.A. Profesores : D.S. Bradford, J. Ogilvie., O. Boachie – Adjei. 1989.
  10. Texas Scottish Rite Hospital For Children. Dallas. Texas. U.S.A. Profesor. J.A..Herring. 1991
  11. Hôpital d’Enfants de la Timone. Marseille. Francia. Profesor G. Bollini. 1992,
  12. Twin Cities Scoliosis Spine Center. University of Minneasota. Abbot Northwestern Hospital. Minneapolis, Minnesota. U.S.A. Profesores : E. Transfeld, J. Oguilvi. 1993.
  13. Children’s Hospital Medical Center. Cincinnati. Ohio. U.S.A. Prof. Alvin Crawdford. 1995.
  14. The Hospital for Special Surgery. Scoliosis / Spine Seminar.New York. Prof. Boachie-Adjei, M.D. Chief, Scoliosis Service. 2003
  15. Christus Santa Rosa Children’s Hospital. The University of Texas (San Antonio). Prof. R. Campbell. 2003