Fig. 1.

The patient is secured in the lateral position with two chest supports and two pelvic supports with the high point of the shoulder, iliac crest, and greater trochanter aligned in a straight line. The coronal plane (the longitudinal axis plane of the body) is registered by touching two points on the posterior pelvic support and one on the posterior chest support in the shape of a triangle. (Reprinted with permission from the University of Iowa from Dorr LD, Hishiki Y, Wan Z, Newton D, Yun A. Development of imageless computer navigation for acetabular component position in total hip replacement. Iowa Orthop J. 2005;25:1–9.)