In vivo measurement of implant loads in a patient with a fractured vertebral body.

It is not known what loads act on an internal spinal fixation device in patients with a fractured vertebral body. To measure the implant loads in vivo, telemeterized internal spinal fixators were implanted in a patient, and the implant loads measured for numerous body positions and activities before and after anterior fusion. The highest implant loads were found while the patient lifted both extended legs in a supine position. High implant loads were also measured for lateral bending during standing as well as for walking and carrying a load in one hand. The implant loads were small in recumbent positions. In contrast to findings in another patient, who was treated for degenerative instability, implant loads were smaller in the first months after anterior fusion than before. The indication for stabilization and surgical procedure strongly influence implant loads.