The anatomy of the acetabulum: what is normal?

Published studies of the human hip make frequent reference to the normal pelvis and acetabulum. However, other than qualitative descriptions we found no clinically applicable published references describing a normal pelvis and acetabulum; such information is important for designing certain kinds of implants (eg, reconstruction cages). We describe a method to quantify, average, and apply data gathered from normal human specimens to create a standard representation of the ilium and ischium. One hundred healthy hemipelves from 50 human skeletons were evaluated. We measured angles and distances between major anatomic landmarks in the pelvis. The data collected were analyzed for variance and averaged to create a normal topographic map. Finally, we examined several commercially available acetabular reconstruction cages to determine the fit to the anatomically determined normal pelvis. These results provide a representation of true acetabular geometry and may serve as the basis for future acetabular reconstruction cage design.