Telemeterized internal spinal fixation devices were implanted in ten patien
ts. The loads acting on the fixators were compared for different body posit
ions, including standing, sitting, and lying in a supine, prone, and latera
l position. Implant loads differed considerably from patient to patient dep
ending, for example, on the indication for surgery and the surgical procedu
re. They were altered by anterior interbody fusion. Mostly, only small diff
erences in implant loads were found for the various lying positions. Flexio
n bending moments were significantly higher in upright than in lying body p
ositions. Loads on the fixators were not higher for sitting than for standi
ng, patients who have undergone mono- or bisegmental spine stabilization sh
ould therefore be allowed to sit as soon as they can leave the bed.