The significance of radiolucent zones surrounding pedicle screws. Definition of screw loosening in spinal instrumentation.

  title={The significance of radiolucent zones surrounding pedicle screws. Definition of screw loosening in spinal instrumentation.},
  author={Bengt Sand{\'e}n and Claes Olerud and marianne Petr{\'e}n-mallmin and Carina B. Johansson and Sune Larsson},
  journal={The Journal of bone and joint surgery. British volume},
  volume={86 3},
We examined the radiographs from a prospective clinical study of fixation by pedicle screws and those from an experimental study in a sheep model. In the clinical study, instruments were removed from 21 patients after implantation for 11 to 16 months and the extraction torques of the screws were recorded. A structured protocol was used for the radiological examinations. In the experimental study, loaded pedicle screw instrumentations were implanted in the sheep for six or 12 weeks. After… 

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