Loads on internal spinal fixators measured in different body positions

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.