[Stress measurements with an instrumented internal spinal fixator].

Little is known about the loads acting on internal spinal fixation devices. The effective forces and moments associated with different external loads have now been measured using instrumented implants. Measurements were obtained in intact cadaver spines and following vertebrectomy. The influence of the implant itself on the distribution of the loads was also investigated. It was found that the implants are not loaded symmetrically. Following vertebrectomy, the forces acting on the fixation device are significantly higher than in the case of an intact spine.