The aim of the study reported here was to provide some basic and general in
formation on the suitability of an experimental sheep model for conducting
in vivo orthopedic studies. The authors have classified the fundamental asp
ects that should be carefully evaluated when using sheep as an experimental
model in orthopedic research: factors strictly related to bone anatomy and
formation; and factors strictly affecting bone physiology, such as gastroi
ntestinal mineral and vitamin absorption, and reproductive cycle. Future in
vestigations should address all of the aspects highlighted, since there is
no animal with the same anatomic, biochemical, physiologic, and biological
characteristics as those of human beings. Moreover, useful data for treatin
g orthopedic patients are based not only on good planning and study design,
but also on perfect knowledge of the animal used and the differences betwe
en the model and the human being. The authors hope that this report will co
ntribute to extrapolation of reliable data for use of sheep in the orthoped
ics field.