Movements of the sacroiliac joints. A roentgen stereophotogrammetric analysis.

Twenty-five patients (21 females and 4 males) with sacroiliac joint disorders were studied with roentgen stereophotogrammetry in physiologic positions as well as in the extreme of physiologic positions. There was a constant pattern of motion with different load, especially around the transverse axis. The rotations were small and in mean between position 2.5 degrees (0.8 degree-3.9 degrees). The translation was, mean, 0.7 mm (0.1-1.6 mm). There was no difference between symptomatic and asymptomatic joints.